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The Brava broadcast archive programme impairments dictionary

 

The BRAVA project aims at developing further the results of the AURORA project, to ensure the widest possible access to valuable TV broadcast archive material by significantly enhancing the efficiency of the video and film programme restoration process and preparing the restored material for dissemination via multi-resolution digital video broadcasting standards.

 

A pre-requisite to designing tools for correcting impairments affecting video-originated and film-originated material, was to prepare a complete survey of these impairments. When one tries to reference a problem on a video programme, there is often a vocabulary problem, as no standard dictionary exists for these problems. Different people use the same word for different problems (jitter, twitter...), or vice-versa. Additionally terms are borrowed from English and used improperly (scratch is commonly used instead of dirt and sparkle). Therefore this work intends to reduce the ambiguities by providing for each impairment, a code, one or several common names, both in English and in French, and a textual definition in a few lines.This document is the result of the refinement, within the scope of the Brava Project, of the impairments list prepared at the beginning of the Aurora project. It is very much oriented towards completeness. Every know impairment is described in a few lines. Therefore technical details may sometime be missing, and the readers are invited to look into the relevant technical reference documents if they want to get into more details.

 
Some impairments lists already exist, published by the broadcasters, in order to be able to reference the impairments met during tape checking before broadcast. These lists provide a good basis for starting, but are in no way as complete as the dictionary presented hereafter. This dictionary contains overall 190 different referenced impairments, although in some cases some of them are only sub-categories (for example several types of drop-outs are referenced).
 

This dictionary was originally intended for internal project use, but it is considered that it could be profitable to the whole broadcasting industry, therefore it is made available here. There are probably still errors, and even more likely divergences on the names or the signification or the employed terms, therefore this work should be considered and an ongoing process : please address comments, suggestions, and requests for changes to : brava_mgt@ina.fr.

The interested reader may also want to look at the following links :
http://ourworld.compuserve.com/homepages/PeterFinklestone/2inchQuad.htm is a complete guide of impairments due to 2 Inch VTR origination, with picture samples.
http://users.ox.ac.uk/~photo/facts/defects.pdf is a list of film faults and their solutions.
 

Copyright : copying and exploiting part or totality of this page for internal use is authorised, provided an explicit reference is made to the origin of the information. Do not publish on the web the totality of the page : make a reference to the current page instead. For other uses, please get in touch with brava_mgt@ina.fr.
 

Table of contents

The list is broken down according to the origin of impairments. The different origins are summarised here :

 

1. Problems related to film

Problems due to film technology, handling, scratching, ageing, storage conditions, are numerous, and some of them well know (dirt and sparkle, scratches, unsteadiness...). Some others are less documented such as flicker, dirty splices, fading...

 

2. Film recording (kinescope) impairments

It is worth noting that the use of VTRs for producing TV programmes took off much later than the actual broadcast start. To keep memory of the programmes directly broadcast from studios or from events, The only solution was to use a film recording device : kinescope was more ore less a film camera aimed at a video monitor. In addition to the usual film impairments, some problems are specific of film recording of TV pictures : kinescope moiré, suppressed field problems...

 

3. Video problems related to the VTR technology

The Video Tape Recording Technology has evolved considerably from the introduction of the 2 Inch quad in 1956, to Digital Betacam, in 1993, and is still evolving at fast pace. The heritage is a constellation of different standards, and playing back the tapes is often difficult, when not impossible. In addition to the impairments due to the standard itself (bandwidth reduction, drop-outs...), other problems may be caused by poor settings during the original recording, equipment obsolescence, know-how losses, tape ageing and storage conditions. The most recurrent problem is the drop-outs problem (transient signal loss due to loss of contact between head and tape), but may other problems can arise, such as head-clogging or synchronisation problems.

 

4. Video problems related to the composite colour systems

The technical history of Television is paved of compromises between different constraints. Among others, the requirement to transmit colour in addition to luminance, still keeping the same bandwidth, has led the engineer to pack the colour information too near from the luminance, causing in some cases undesired leakage between the two, called cross-chroma and cross-luminance. Other problems can also arise, detailed in the list.

 

5. Video problems related to video transmission

Analogue video transmission is supposed to be transparent. But, cables, RF links, amplifiers, filters, multiple paths, interferences, result in several different problems referenced in the list : bandwidth problems, echoes, overshoot, streaking, sound in picture...

 

6. Problems related to video shooting

It can be questioned whether impairments resulting from the original camera should be considered for restoration. Nevertheless these impairments do exist and are worthwhile mentioning, such as colour convergence problems, comet tails...

 

7. Problems related to video edition and post-production

As for the previous item, it is sometimes difficult to decide whether an impairment should be corrected or kept because accepted and desired by the director. However the analogue technology for post-production very often led to impairments one would like to correct now : early chroma-keying, PAL shifts...

 

8. Other video problems related to VTRs, transmission, and shooting

Some problems whose origin are multiple, or cannot be determined strictly are classified here : they include continuous and impulsive noise, line jitter, bearding, off-locks...

 

9. Problems related to standard conversion

Early Television standards used a different number of lines per picture : 405, 819, instead of the current 525 and 625 lines. Even now, two different frame rates co-exist : 30 and 25 Hz. Conversion devices were used (and are still in use) to convert from one standard to another. These conversion systems could be very primitive, and generate their own problems.

 

10. Other video-related problems

This category contains other problems related to video, that cannot be classified in the previous categories.

 

11. All kinds of media

This category contains other problems related any kind of media (video or film), that cannot be classified in the previous categories.

 

12. Soundtrack problems

Although there may be more comprehensive lists of audio impairments, here have been referenced the most common television programmes soundtrack problems. Some are common with audio-only technology, some are more specific of television programmes, such as synchronisation problems or vinegar syndrome.

 
 

Impairments Reference List

1. Problems Related to Film
 
English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
F1 Film Grain Grain Film
Film / 
Overlaying of film grains (processed silver halide crystals) at different depths in emulsion. random patterning, loss of focus, density errors. 

 

F2 Dirt Salissures
Film / 
Surface dirt, ingrained dirt. Can be printed/duped in copying stock from original. 
F3 Neg.  sparkle Salissures sur Negatif
Film / 
Fine specs of dirt, dust printed through from original onto print stock. 
F4 Gelatin Loss  Eclats de gélatine
Film / 
Gelatin was used as vehicle for carrying silver halide in film emulsion. 

Image content removed when scratched. 

F5 Severe Emulsion Loss Pertes importantes de gélatine 
Film / 
Extreme cases of gelatin losses : the information is wiped off the film support on a large area of the image, for long periods. 
F6 Base scratches Rayures coté support
Film / 
Black in appearance in print stock, commonly seen as tramlines. White in appearance if printed through from negative stock. 
F7 Emulsion scratches Rayures coté 
émulsion
Film / 
As above except it can cause discoloration, dependent on depth of scratch. 
F8 Film Hair Poussières
Film / 
Duped/printed in copying stock. original camera fault, hair in gate camera or printer. Fraying of film due to physical damage.  
F9 Film scuffing Egratignures multiples
Film / 
Small type scratches due to poor loose wind on film. Usually found at head and tail of material. 
F10 Visible Scotch-tape cut edition or repair Collant Scotch visible
Film / 
Scotch-tape edition is often visible : the scotch tape is dirty, or coloured. Trapped in dirt, racking problems, frame bar errors, clicking on optical tracks. 
F11 Ageing Scotch tape joins, dirty splice Collant Scotch Détérioré
Film / 
As above except old joins tend to seep glue causing film material to stick damaging emulsion.  
F12 Black Images Images Noires
Film / 
Some images may be black, due to a problem in the camera shutter, or lab printer problems. 
F13 Colour Grading problems  Défaut d’Etalonnage
Video+Film / 
Each scene has to be corrected differently. Poor grading causes unbalanced colour changes in scenes and density / contrast problems. 

It may happen that colour grading is not applied exactly at the cut : a few frames will show different grading. 

F14 Black and White Grading Défaut d’Etalonnage noir et blanc
Video+Film / 
Printer light setting errors at printing stage causing density contrast problems . 
F15 Colour fading  Virage Colorimétrique 
Film / 
One or several colour layers have changed or disappeared  
F16 Varying colour Instabilité couleur
Film / 
Same problem, but the change is not uniform in time . Individual colour layers fading at different rates. Positive cut material from different origins. Duped in material from different sources. 
F17 Non-Uniform colour Couleur non uniforme
Film / 
Same problem, but the change is not uniform in space (Film Edges) 
F18 Scene cut Image Instability Saute de changement de plan
Film / 
Scotch-tape edition may not be perfectly realised, or may have moved : the perforations are not correctly aligned or damaged, hence a jerk around the scene cut on some telecines. 
F19 Film unsteadiness Instabilité film
Film / 
Film transport-generated Image unsteadiness : the picking mechanism on perforations was not reliable enough, or the perforations were damaged. 

Also know as 'Position Flicker' : 'Unsteadiness' is preferable.

F20 Planarity problems  Défaut de planéité
Film / 
The film is not kept planar : the images are non-uniformly distorted and unfocused. 
F21 Veil ? Voile
Film / 
Accidental exposition of the film to light before or during development, resulting in clearer or darker images (usually at reel ends) 
F22 Mixed Geometry Changement de Géométrie
Film / 
Mixed geometry in positive cut and duped material. 
F23 Vinegar Syndrome Syndrome du Vinaigre
Film / 
Breakdown of gelatine due to poor ambient storage conditions. In extreme cases loss of signal. 
F24 Flicker (Luminance Flicker) Pompage, Battements, Flicker
Film
Variations of intensity, possibly due to uneven chemical degradation of the film pack, or uneven shutter operation.
F25 Twin-Lens Telecine Flicker Battements de Telecine à double trajet optique
Film-Video  / Telecine
In Twin-Lens Telecines, poor setup or dust on the two optical paths results in a different intensity for even and odd fields. The visual effect is of a fast permanent flicker (at frame rate). Subtle occurrences are met, but very few extreme cases : the problem is easily solved by proper setup of the telecine. Furthermore, Twin-lens telecines are less and less exploited. 
F26 Twin-Lens Telecine Unsteadiness Instabilité Telecine à double trajet optique
Film-Video  / Telecine
In Twin-Lens Telecines, poor setup of the electronic or physical registration between the two optical paths results in a different position, scaling, and angle for even and odd fields. The visual effect is of a fast permanent judder (at frame rate). Subtle occurrences are met, but very few extreme cases : the problem is easily solved by proper setup of the telecine. Furthermore, Twin-lens telecines are less and less exploited. 

 

2. Film Recording (Kinescope) Impairments
 

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
K1 Setup Error of glycerine ND filter Défaut de réglage du filtre à glycérine
Video +Film / Kinescope
Due to incorrect setup of glycerine ND (?)  filter used to correct luminance decay between stored and active picture, there will be a luminance error approximately 1/3 of the way down the frame. 
 
K2 Severe Phasing Défaut de Phase Kinescope
video +film / Kinescope
Loss of synchronisation between camera and display may result in several peculiar effects including two non matching fields being recorded on the same frame of film making a rather strange half mix. 

Very common in early recordings. 

K3 Suppressed field pixelation Défaut de Kinescope à Trame Unique
video +film / Kinescope
In order to allow non fast pull down cameras one field of the image is omitted. This leads to loss of vertical resolution - visible line structure and pixelation. 
K4 Spot wobble resolution impairment
video +film / Kinescope
To eliminate suppressed filed pixelation the scanning spot was wobbled vertically. this produced an alternative impairment in which the image has astigmatism with very soft focus in the vertical axis 

used on both telecines and film recorders. 

K5 Vertical instability due to fast pull down camera Instabilité verticale due a une Caméra a avance rapide
video +film / Kinescope
Use of non suppressed field display requires extremely rapid film movement which leads to excessive vertical tearing and blurring 
 
K6 Defocused recording Défaut de mise au point sur Kinescope
video +film / Kinescope
An alternative to spot wobble was to simply defocus the camera lens so that line structure was not resolved. The problem is that everything else is also made very soft. 
K7 Motion blur due to long persistence tube Défaut de persistance Kinescope
video +film / Kinescope
Extra long persistence tubes were used for 35mm non suppressed field Kinescopes. This yields maximum resolution on stills but degenerates on motion due to tube memory. 
K8 Dirty window effect (kinescope)  Effet de fenêtre sale (kinescope)
video +film / Kinescope
Dirt and fluff attracted to the CRT in the film recorder appears as though the scene were viewed through a dirty window. Most noticeable on pans and tracking shots. 
K9 Non linearity of scans  Défaut de linéarité Kinescope
video +film / Kinescope
Due to poor linearity of original CRT display aspect ratio and/or vertical or horizontal linearity of image may be distorted 
K10 Kinescope MoirŽ (Line scan Aliasing & moirŽ) Moiré Kinescope 
video +film / BW / Kinescope
Occurs when a previously film recorded item is the telecine transferred. Visible line structure causes a beat pattern with telecine scanning, with a nearly periodic phase variation. 

The BBC flying spot Telecines were able to overcome this problem by modulating the beam careful line-up required to eliminate streaking. Can be eliminated depending on the type of TK used.

K11 Kinescope Film impairment  Défauts Film Kinescope 
Video / BW / Kinescope
Nearly every film impairment can be seen on kinescope documents. 

Plus electronic problems such as streaking . Flare was another problem 

 

3. Video Problems related to the VTR Technology
 

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
V1 2 Inch Scratches  Rayures 2 Pouces 
Video / 2 Inch
Scoring and damage causing a white quincunx-organised grid of dots to appear superimposed on the video. Often mistaken for drop-out and switcher phase error.  

It can be argued that this is the single most commonly encountered fault appearing on material originated from 2 Inch - as most of the others should have been eliminated at replay - whereas this - along with more general physical errors cannot be.

V2 2 Inch Tip Penetration Error (Geometrical Error : 2 Inch Venitian Blind or Jogs) Défaut de Pénétration 2 Pouces (Défaut de Géométrie) : Stores vénitiens, Dents de Scie
Video / 2 Inch
Vertical lines and image edges exhibit stable 15-16 lines saw-tooth distortion due to an incorrect setting of the vacuum guide projection. Usually corrected by the 2 Inch internal TBCs. See "Broadcast Video Tape Recording Technology", Todorovic, p 48 

This should be corrected at replay - TBC on most VTRs have a wide window of tolerance

V3 2 Inch Height Error (Geometrical Error) : Scallop Error  Défaut de Hauteur 2 Pouces (Défaut de Géométrie) : Défaut de Feston 
Video / 2 Inch
Vertical lines and image edges exhibit stable 15-16 lines scallop distortion due to an incorrect setting of the guide height. Note the velocity error associated to this problem. See "Broadcast Video Tape Recording Technology", Todorovic, p 48 

This should be corrected at replay - TBC on most VTRs have a wide window of tolerance

V4 2 Inch Quadrature Errors (Geometrical Error)  Défaut de Quadrature 2 Pouces (Défaut de Géométrie)
Video / 2 Inch
Every 4th group of 15-16 lines is shifted due to an incorrect setting of the 90¡ angle between heads. Usually corrected by the 2 Inch internal TBCs if not too important. See "Broadcast Video Tape Recording Technology", Todorovic, p 46 

Very rarely seen, as should be corrected at replay.

V5 2 Inch Velocity Errors Erreur de vitesse 2 Pouces
Video / 2 Inch
Synonym for scallop+tip Error.
V6 1 Inch B Tension Errors : venitian blind Défaut de tension 1Pouce B : Stores vénitiens
Video / 1 Inch B
Same saw-tooth pattern as for 2 Inch, but with 52/53 blocks. Usually corrected by internal TBCs. 
V7 Flagging, hooking, 1 Inch C Tension Errors  Drapeau, Défaut de tension 1 Pouce C: 
Video / 1 Inch C
In some formats such as 1"C the tape speed would not be held as tight as one might desire, or the Time base or Velocity error is larger than the TBC can compensate for, or there will be other problems (including guide problems as already mentioned) that will cause flagging. Visually this will be seen at the top of active video, the top lines will appear skewed in horizontal position and sometimes fold down on top of other lines. This can also be caused by head switching in the wrong area in vertical interval, but the important point here is that the top portion of the picture, as much as 10-20% can be skewed. It generally does not remain constant (that is why it is called flagging) but is extremely bothersome to watch.
V8 Flagging, Hooking, 3/4" Skew Problems  Drapeau, Hooking, défaut de skew 3/4 " 
Video / 3/4
As for 1"C, and some other formats, the image is hook-shaped due to an incorrect tension of the tape. 
V9 2 Inch Drop-Outs Drop-Outs 2 Pouces
Video / 2 Inch
The duration of drop-outs on two Inch is usually of 1 to 10 usec, the number of lines affected varies from 1 to 4 (SECAM). When DOCs are in use, the line or part of line affected are usually replaced by one of the preceding lines. 

Can be worse on a VR 2000.

V10 1"B Drop-Outs Drop-Outs 1 Pouce B
Video / all / 1 Inch B
The duration of drop-outs on 1"B is usually of 1 to 10 usec, the number of lines affected varies from 1 to 4 (SECAM). When DOCs are in use, the whole line (in SECAM), or part of line affected, are usually replaced by one of the preceding lines. 
V11 1"C Drop-Outs Drop-Outs 1 Pouce C
Video / all / 1 Inch C
The duration of drop-outs on 1"C is usually of 1 to 10 lines. When DOCs are in use (always ?), the line (in SECAM), or part of line affected, are usually replaced by one of the preceding lines. 

1"C dropout compensation is usually quite good.

V12 3/4 " Drop-outs Drop-outs 3/4
Video / all / 3/4 Inch
The duration of drop-outs on 3/4 Inch VTRs is usually of 1 to 10 lines. When DOCs are in use (always ?), the line (in SECAM), or part of line affected, are usually replaced by one of the preceding lines. 
V13 Beta Drop-outs Drop-outs Beta
Video / all / Beta, Beta SP
The duration of drop-outs on Beta and Beta SP is usually of 5 to 100 lines. The line, or part of line affected, are always replaced by the preceding line. This is a very common problem.
V14 2 Inch Head Switcher Phase Error Erreur de commutations de têtes 2 Pouces
Video / 2 Inch
The commutation between heads during playback occurs late, which results in the beginning of each 15-16 lines group being switched to black 

Also known as head switcher phase - a std adjustment. Fault should not be seen in practice, but happens to be out-of-range if incorrectly recorded. Worse on VR 2000.

V15 2 Inch Tracking Error Erreur de Tracking 2 Pouces 
Video / 2 Inch
The heads are not aligned with the tracks, reduces the SNR (moirŽs). It is usually due to an incorrect position of the control track during recording. If not out-of range, it may be corrected by a manual tuning of the tracking parameter. 

Should not occur only when tracking error is out-of-range of the manual setup. Can happen on an edit made with tach(ymeter ?). phase out and tracking error during line-up

V16 2 Inch Head Axial Error (Head-Banding) Erreur de positionnement axial 
Video / 2 Inch
One of the heads is not aligned with the tracks, which reduces the SNR of every 4th 15-16 lines group. See "Broadcast Video Tape recording Technology", Todorovic, p 47. 

very rare

V17 2 Inch Head azimut Error (Head-Banding) Erreur d'azimut sur une tête 2 Pouces 
Video / 2 Inch
One of the heads is not oriented correctly, which reduces the SNR of every 4th 15-16 lines group. See "Broadcast Video Tape recording Technology", Todorovic, p 46. 

very rare

V18 2 Inch Head-Banding (Equalisation) Défaut d’égalisation 2 Pouces
Video / 2 Inch
On 2 Inch, there are four head that alternatively read 15 or 16 lines blocks ; in case of incorrect equalisation, the signal will be more noisy, or band-limited, or show moirŽ pattern, on 16-line blocks. 

should be optimised at replay - residual errors are usually small 

V19 2 Inch Head-clogging (Dirt) Encrassement têtes 2 Pouces
Video / 2 Inch
Different kind of head-banding, due to dirt on one head, either during playback, or during recording. 

Should try to correct at replay because resultant increase in noise and loss of resolution will be quite severe. But if clogging occurred during recording, cannot be corrected during replay.

V20 2 Inch edge of track-Banding  Bruit de bord de bande 2 Pouces
Video / 2 Inch
Due to the impact of the heads on the tape, the first line of each block could exhibit a lower SNR - can also result in hue and saturation errors. 
V21 1"B Head-Banding (Equalisation) Défaut d’égalisation têtes 1 Pouce
Video / 1 Inch B
On 1 Inch B, there are two head that alternatively read 56 lines blocks ; in case of incorrect equalisation, the signal will be more noisy, or band-limited, or show moirŽ pattern, on 16-line blocks.
V22 1"B Head-Banding (clogging) Encrassement têtes 1 Pouce B
Video / 1 Inch B
Head-banding on 1 Inch B can be caused by head-clogging. 
V23 2 Inch FM MoirŽ Moiré FM 2 Pouces
Video / 2 Inch
Specific case of spectrum folding of the FM signal (Briefly described in "Broadcast Video Tape recording Technology", Todorovic, p 22). 

Much more noticeable on highly saturated areas

V24 1 Inch MoirŽ FM  Moiré FM 1 Pouce
Video / 1 Inch
Spectrum folding, different from 2 Inch because of the different FM frequencies 
V25 2 Inch Mechanical Editing Shift Collant Mécanique 2 Pouces
Video / BW, Early SECAM, Early PAL ? / 
Early mechanical editing on 2 Inch give horizontal and/or vertical instabilities, or various kinds of drop-outs. 
V26 2 Inch Tracking breaks Perte de tracking 2 Pouces
Video / 2 Inch 
Temporary deterioration of the control track give horizontal and/or vertical instabilities. 

Worse when control track returns with a phase change. Can occur on assemble edits

V27 2 Inch Tape Problems Problèmes de Bande 2 Pouces
Video / 2 Inch
Extensive scoring oxide shedding, white powder, sticky oxide, curling, and other physical tape problems . Very large set of picture impairments. Also the most common underlying cause of other problems listed above. 

Very serious and usually virtually impossible to cure - examples are difficult to produce as one has to look inside the box- at the actual tape material to see the problem. The effect can render the tape unplayable.

V28 1 Inch B Tracking Error Défaut de Tracking 1 Pouce B
Video / 1 Inch B
FM Noise due to tracking errors -> MoirŽs 
V29 1 Inch C Tracking Error Défaut de Tracking 1 Pouce C
Video / 1 Inch C
FM Noise due to tracking errors (different from above) -> moirŽs 

Error would probably remain constant

V30 1"C Equalisation Errors Défaut d'égalisation têtes 1 Pouce
Video / 1 Inch C
Difference of reaction between the equalisation of the two playback heads. Could result in a difference between odd and even fields.  

Usually not visible to the eye

V31 1"C Head-clogging Encrassement têtes 1 Pouce
Video / 1 Inch C
Due to dirt on one head, A different SNR between odd and even field appears, possibly combined with field beating 
 
V32 3/4" Equalisation Problems Problème d'égalisation 3/4
Video / 3/4
Different SNR between odd and even fields, or field beating. There are several formats for 3/4, they all have different characteristics  
V33 Beta Equalisation Problems Problèmes d'égalisation Beta
Video / Beta, Beta SP
Different SNR between odd and even fields, or field beating, for luminance or chrominance (2 heads for luminance, 2 heads for chrominance) 
V34 Field switching inside Image Commutation Trame dans Image
Video / 3/4
The switching between odd and even head occurs during the active period of the image : the head or the bottom of the image is lost. 
V35 Betacam chroma head clogging Encrassement tête couleur Betacam
Video / Beta, Beta SP
Dirt on chroma head : only one field has chroma 
V36 Betacam Luminance head clogging Encrassement tête luminance Betacam
Video / Beta, Beta SP
Dirt on one luminance head : only one field has luminance 
V37 Betacam saturation (bearding) Saturation Betacam (flammèches)
Video / Beta, beta SP
When picture is complex, with high frequencies areas, these areas may be followed by white flames. 
V38 other obsolete VTR Problems Problèmes liés aux autres formats périmés de magnétoscopes
Video / 1/2 Inch, ...
Too many to enumerate them 
V39 Consumer VTR Problems  Problèmes liés aux magnétoscopes grand public
Video / Betamax, VHS, V8, Hi8...
For memory only ... 

 

4. Video Problems related to the Composite colour systems
 

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
C1 PAL Cross-Colour Cross-Color PAL
Video / PAL / 625 / 
Luminance information around the subcarrier centre frequency (4.43 MHz) is incorrectly interpreted as colour (Coloured MoirŽ). Inconvenience depends on the content of the picture. 
C2 PAL Delay-Line decoded Décodage PAL avec Delay-Line
Video / PAL / 625 / 
Slight vertical colour blurring, colour error on diagonal and Horizontal edges, colour slightly shifted downwards. 

Not Applicable in a broadcast environment

C3 PAL Subcarrier Phase Error (with DL) Erreur de Phase PAL (avec DL)
Video / PAL / 625 / 
A subcarrier Phase Error decoded with a delay-line decoder results in Colour Desaturation of uniform areas, colour errors on diagonal and horizontal edges 

Important to correct this before decoding

C4 PAL Subcarrier Phase Error (without DL) : Venitian Blind Persiennes (Erreur de Phase PAL (sans DL)
Video / PAL / 625 / 
A subcarrier Phase Error decoded with a simple PAL decoder results in Hue Errors alternating each line and each field.  
C5 PAL Cross-Luminance Cross-Luminance PAL
Video / PAL / 625 / 
Residual Colour Subcarrier in Luminance Signal. Uniform areas and vertical edges. 
C6 SECAM Cross-Colour Cross-Color SECAM
Video / SECAM / 625 / 
Luminance information between 3.9 MHz and 4.75 MHz is incorrectly interpreted as colour (Coloured MoirŽ). More disturbing than in PAL and NTSC because "illegal colours" are generated.  
C7 SECAM Cross-Luminance Cross-Luminance SECAM
Video / SECAM / 625 / 
Residual Colour Subcarrier in Luminance Signal. Visible both in uniform areas and vertical edges. 
C8 SECAM Erroneous Horizontal. & Diagonal Edges Erreur de couleur sur les Transitions Horizontales
Video / SECAM / 625 / 
Errors on diagonals and horizontal edges, due to the use of last line's previous DR or DB information. 
C9 SECAM Colour Antiphase Antiphase Couleur
Video / SECAM / 625 / 
Permutation of DR and DB components (from a few lines to a whole field). May be due to loss or attenuation of field identification signals, loss, attenuation, or incorrect timing of colour burst. 
C10 SECAM Antiphase Edition Montage en Antiphase Couleur
Video / SECAM / 625 / 
The four-field sequence (DR,DB,DB,DR) may not be respected when editing early SECAM programs, decoding these programs results in a permutation of DR and DB components (from a few lines to a whole field) on the first field after the cut. 
C11 NTSC Cross-Colour Cross-Color NTSC
Video / NTSC / 525 / 
Luminance information around 3.58 MHz is incorrectly interpreted as colour (Coloured MoirŽ) 
C12 NTSC Subcarrier Phase Error Erreur de Phase NTSC
Video / NTSC / 525 / 
An phase error in transmission of subcarrier or burst will result in a rotation of colour space in NTSC 
C13 NTSC Cross-Luminance Cross-Luminance NTSC
Video / NTSC / 525 / 
Residual Colour Subcarrier in Luminance Signal, visible in uniform areas and vertical edges. 
C14 Loss of Luminance detail Perte de détail en Luminance
Video / SECAM, PAL, NTSC / 
Due to the principles of composite coding, the luminance signal, in addition to cross-luminance, suffers a band-cut or low-pass filtering around the chrominance subcarrier frequency.  
C15 Loss of Chrominance Detail Perte de détail en Chrominance
Video / SECAM, PAL, NTSC / 
Due to the principles of composite coding, in addition to cross-colour, the chrominance signal suffers a low-pass filtering below half the subcarrier frequency.  
C16 Short Colour Loss Perte de Couleur Courte
Video / SECAM, PAL, NTSC / 
the "Colour-Killer" system triggers when the Colour Burst is not recognised on time. It can happen on several lines, or fields. 
C17 Temporary Colour Loss Perte de couleur Temporaire
Video / SECAM, PAL, NTSC / 
the "Colour-Killer" system triggers when the Colour Burst is not recognised on time. It can last for a few seconds. 
C18 Complete Colour Loss Perte de couleur permanente
Video / SECAM, PAL, NTSC / 
For some reason, the Colour Information is lost for a duration of more than a few seconds. 
C19 Undecoded composite stored as Component Signal Composite Non décodé
Video / SECAM, PAL, NTSC / 
Due to an error in cabling, a failure in the colour system identification, or made on purpose. The Luminance signal is then identical to the original composite signal, but the colour burst may be lost.  
C20 SECAM incorrectly recorded as PAL, or vice-versa SECAM enregistré en PAL, et réciproquement
Video / SECAM, PAL / 1 Inch, 3/4
Due to an error in cabling, or an incorrect composite standard selection on VTRs, the colour bursts and identification sequences will be damaged or lost, resulting in distorted signals. 
 

 

5. Video Problems related to Video Transmission
 

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
T1 High Frequency Loss, Bandwidth limitation. Perte de Bande Passante
Video / 
This is a general problem : when high frequencies are not filtered out by VTRs or other equipments, they are filtered out by colour coding and decoding processes. This problem is limited to horizontal frequencies. 
T2 Non-uniform frequency response Réponse en fréquence non uniforme
Video
Incorrect cable compensation or pre-post accentuation filters may boost high frequencies, and different frequency bands may not be uniformly amplified. High frequency boosts are especially noticeable on faces. 
T3 Echoes  Echos
Video / 
Often due to incorrect daisy-chaining or poor radio reception, a distorted and delayed signal copy was added to the signal. Echoes may be positive or negative, Multiple echoes are very common. 
T4 Overshoot, Over-oscillations, Suroscillations
Video / 
Overshoot with oscillations visible on abrupt transitions (vertical edges). Can be caused by rapid cut-off bandwidth limitation, echoes, excessive aperture correction. 
T5 Undershoot Sous-oscillations
Video / 
>1 MHz band amplification error, abrupt transitions undergo an exponential distortion, (decay time up to 1µsec) making objects followed by a short trail. 
T6 Delay-frequency errors. (Non-uniform group delay ?) Inégalité de temps de groupe
Video / 
Could cause overshoots 
T7 Streaking (Trail ?) Traînage
Video / 
<1 MHz band amplification error, abrupt transitions undergo an exponential distortion, (decay time from 1µsec to several lines) making objects followed (on the right hand side) by a trail, and look flat and transparent. See L.E. Weaver, p 103. 
T8 Colour Streaking (Trail ?) Traînage Couleur
Video / 
Same as above, but chrominance being more affected. 
T9 Luminance Chrominance Delay Délai luminance Chrominance
Video / 
Due to different signal paths, the chrominance and luminance may not be delayed equally. This is especially visible on vertical edges. 
T10 Luminance Non-linearity Non-Linearité en Luminance
Video / 
Non-linear relationship between the input luminance signal and the output. The eye is usually very tolerant to this problem, but simple corrective measures can be taken, once the desired correction is estimated. See L.E. Weaver,  p 104 
T11 Non-linearity transmission of composite signal Non-Linearité dans la transmission d'un signal composite
Video / SECAM, PAL, NTSC / 
Same as above, but the different paths between the luminance and the chrominance signals usually generate saturation errors. See L.E. Weaver,  p 104 
T12 Differential Phase  Phase Différentielle
Video / SECAM, PAL, NTSC / 
Phase of the modulated chrominance changes according to the amplitude of the luminance signal. In NTSC, it appears as a variation of hues in the picture according to brightness and saturation. In PAL, it is in part corrected with DL. See L.E. Weaver,  p 105 

SECAM is usually not affected, but complex phenomena may appear along the transitions.

T13 Differential Gain  Gain Différentiel
Video / SECAM, PAL, NTSC / 
Amplitude of the modulated Chrominance signal varies according to the amplitude of the Luminance signal. In PAL and NTSC, saturations are affected, especially yellows and reds. SECAM is not affected. See L.E. Weaver,  p 105 
T14 Luminance Chrominance Intermodulation Intermodulation luminance Chrominance
Video / SECAM, PAL, NTSC / 
The luminance signal is affected by the amplitude of the modulated chrominance signal. 
T15 Signal Bounce (Low-Freq.) Pompage Longue durée 
Video / 
Oscillatory very low frequency (~1 sec) behaviour of signal level following abrupt changes of luminance level. Usually eliminated by black level clamp, but, at higher levels, can generate periodic signal losses. See L.E. Weaver,  p 105 
T16 DC Wander Variation de la composante continue.
Video / 
Very low frequency additive noise whose consequence is a slow variation of the intensity of the signal. Especially noticeable when overloading results. 
T17 Crosstalk (Phantom Images ? ) Diaphotie, Images Fantômes
Video / 
Superimposition of distorted images from other channels. Impairment is worse if the two signals are not synchronous. See L.E. Weaver,  p 107. 
T18 50-60 Hz Noise, Mains Hum  Ronflette Secteur (ronflement d'alimentation)
Video / 
Superimposed 50/60 Hz parasite signal from electromagnetic devices. Subjective impairment is worse when the parasite signal is not locked to the field frequency. See L.E. Weaver,  p 60.  
T19 Periodic Noise (Interferences) Bruit Périodique (Interférences)
Video / 
Superimposed quasi-periodic parasite signal from electromagnetic devices. Visibility and disturbance depends on the frequency and of the stability of its pattern. See L.E. Weaver,  p 106 
T20 Inverter Noise Bruit d'inverseur
Video / 
Cited By L.E. Weaver, Breakthrough of inverter switching pulses, narrow bandwidth random noise. 
T21 Sound in picture Son dans l’image
Video / 
Superimposed parasite signal from sound 
T22 Quantification Noise Bruit de Quantification
Video / 
May be seen when images are converted to low word size digital media. Further degradation if these images are converted back to analogue, and digitised again, or if successive operations during post-production results in several rounding stages. 

Early digital TBCs (3/4 Inch external TBCs) used internal 6 or 7 bits formats. D1's and many digital equipment truncate to 8 bits.

T23 Blocking due to digital compression Blocking du a la compression
Video / 
Block effect due to digital compression 
T24 Fading Evanouissements
Video / 
Generally appears on terrestrial Hertzian transmissions : SNR decreases during small periods (seconds) 

 

6. Problems related to Video Shooting

 
English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
S1 Colour convergence defects Misconvergence  Défauts de convergence couleur
Video / 3-pickup tubes cameras
RGB images are not coincident. (rotation, focus, concentration, h&v linearity, h&v amplitude, h&v position) 
S2 Excessive Aperture Correction Correction de contour excessive
Video / All cameras
Early aperture correctors were monodirectionnal. Recent ones are bi-directional. Too much aperture correction leads to a hi-frequency boosting (cf. Overshoot). 
S3 Poor concentration (Blur) Défaut de concentration (Flou)
Video / Pickup tubes cameras
An incorrect focusing of the beam in the pickup tubes will make images blurred. 
S4 Poor Focus Blur Flou de Mise au point
Video / All cameras
May be due to an incorrect lens setting. But in common video broadcast documents, focus blur is made on purpose. 
S5 Motion Blur Flou de Bougé
Video / All cameras
Due to a long exposition time, motion blur is usually beneficial to the quality, but in some cases (fast panoramic movements), it may be inconvenient. 
S6 Blooming Eblouissement
Video / All cameras
Saturation of pickup devices together with a dispersion of charges around the saturated point, usually caused by a spotlight in direct view of the camera. (limited by "Automatic Beam Optimizer" for pickup tubes).
S7 Comet Comète, Queue de Comète
Video / Pickup tubes
Memory effect associated with blooming and motion. 
S8 Lag  Rémanence
Video / Pickup tubes
Memory effect associated with dark areas and motion 
S9 Flare Halo (Flare?)
Video / Pickup tubes
Variation of black level dependent on global illumination, due to multiple diffusions and reflections inside the lens and pickup cavity. This variation is different for each colour channel.  
S10 CCD Halo Halo CCD
Video / CCDs
Halo around light sources, due to diffusion of light inside the CCD surface. Different on each colour channel (Red channel is usually affected first). 
S11 Smearing Smearing
Video / CCDs
Saturation of CCDs resulting in charges flowing between adjacent pixels or registers. The consequence is a saturation of one colour channel extending along rows (Red channel is usually affected first). 
S12 CCD Aliasing Aliasing CCD
Video / CCDs
Aliasing between high-frequencies of images and the CCD pixel pattern. Especially visible when the focusing is very precise, and when the useful area of the CCD pixels is lower than 80%.
S13 Cushion, barrel ? Coussin, Barillet
Video / All Cameras
Deformation of images due to radial optical distortion in lenses. Sometimes corrected in pickup tubes cameras, not corrected in CCD cameras (but the lenses have been improved accordingly) .
S14 Dynamic Shearing Cisaillement Dynamique
Video / pickup tubes
In pickup tubes cameras, the pickup of the images is continuous, i.e. the upper part of a field is sampled before the lower part. Usually not perceptible , but in some cases, such as very fast motion of objects or camera, the shape distortion generated may become visible. 
S15 Over-Exposition Sur-Exposition
Video / All Cameras
Sometimes made on purpose, may become problematic if the SNR is low 
S16 Under-Exposition Sous-Exposition
Video / All Cameras
Sometimes made on purpose, may become problematic if the SNR is low 
S17 Tube noise Bruit de Tube
video / Tubed cameras
Tube cameras exhibit a characteristic noise pattern which is particularly noticeable in low light. 
S18 Scan Ringing ?
video / Early vidicon cameras
Aliasing of left hand edge of frame. Appears as vertical stripes down picture. 
S19 Lens Cut-off  

 

Vignettage
video+Film / Cameras
Darker picture corners, due to lenses. 

 

7. Problems related to Video Edition and Post-Production

 
English Name French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
P1 Staircase Edges Crénelage
Video / 
Staircase edges : sometimes visible on computer-generated images and early chroma-keys
 
P2 Early Chroma-key artefacts Défauts de Chroma-key
Video / 
Early chroma-key systems generated blue, crawling, and hard-shaped silhouettes, which are now less acceptable. 
P3 Lost Texture Perte de texture
Video / 
Some noise reduction devices making use of median filters suppress texture information 
P4 Dirty Window (video) Effet de Fenêtre Sale (vidéo)
Video / 
Abusive frame-averaging Noise-Filtering makes often noise look like affixed on a window through which the document is seen. 
P5 Editing irrespectful of PAL colour sequence Non respect de la séquence couleur en PAL
Video / PAL-NTSC / beta Only ?
Edition of PAL documents irrespectful of the colour sequence will often be compensated by VTRs by a horizontal shift of images of half a subcarrier period. This is mainly noticeable when the edition is made from two excerpts from the same shot. 
P6 Crystallisation  "Cristallisation"
Video / 
This phenomenon appears when analogue video passes successively through varied digital equipment (like external TBCs) with multiple A-D and D-conversions, or when excessive noise reduction is applied. 
P7 Multigenerations Multigénérations
Video / 
Several generation of processing on analogue devices usually lower the SNR, and attenuate the high frequencies. 
P8 Colour Grading Timing Errors Décalage Temporel des Corrections Colorimétriques 
Film / 
Early video or film colour grading systems were not temporally accurate, for instance these systems start the correction of a shot two images before or after the beginning of the shot. This results in a few frames with different and incorrect colour grading before or after cuts. Restoring affected programmes consumes considerable time to adjust the grading of the affected images.

 

8. Other Video Problems related to VTRs, Transmission, and Shooting
 

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
O1 Continuous Random Noise Bruit 
Video / 
Very large number of possible causes, with different spectral distributions : approx. flat for amplifiers, pickup tubes, CCDs, triangular for FM demodulated signals. In practice, most continuous random noises lie between the two. 
O2 Impulsive Noise Bruit Impulsif
Video / 
Erratic spikes or pulses of different origins, generally they impair seriously the picture. Narrow and high amplitude pulses are very frequent. 
O3 Continuous Random Chrominance Noise Bruit Continu de Chrominance
Video / PAL, SECAM, NTSC / 
When decoding noisy composite signals, the possibly high level of high frequency noise is translated to low frequencies. The demodulated chrominance signal can hence be considerably more noisy than luminance. 
O4 Line Jitter Jitter Ligne
Video / 
Random varying shifts of the lines of the picture, various origins, among others hum and TBC failures. 
O5 Full-Field Drop-out Drop-out Trame
Video / 
Many problems may result in a full field being completely distorted. 
O6 Colour Bearding (Colour Flames ?) Flammèches couleur
Video / SECAM Only ? / 
High-intensity areas show coloured tails. 
O7 VTR saturation  Saturation VTR
Video / / VTRs
Visible on recording as black "strikes" when the Rec. level of the RF is too misaligned or when recording was made with used heads. Known at least on Betacam, betacam SP, 3/4 U-Matic and BVU. 
O8 Off Locks due to sync disturbance. Décrochements à l'enregistrement
video & audio / 
Various picture and sound disturbances which are introduced at the time of recording and hence become "embedded" in the signal 

 

9. Problems Related to Standard Conversion
 

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
O9 819 lines Moiré Moiré 819 Lignes
Video / Scan-conversion
Old scan-conversions from 819 lines to 625 lines using a video monitor and a camera, will exhibit moirŽ patterns similar to kinescopes ones 
O10 525-625 Transcoded  Transcodage 525-625
Video / Scan-conversion
NTSC Transcoded footage usually exhibit serious artefacts of very different types : jaggies, blur, tooth-comb moving edges, poor colour, 5-10 Hz judder 
O11 625-525 Transcoded  Transcodage 625-525
Video / Scan-conversion
O12 4.43 to SECAM Moiré  Moiré 4.43 vers SECAM
Video / 
Aliasing between the 4.43 Mhz colour subcarrier and SECAM subcarrier. Happens on documents edited in PAL and broadcast in SECAM.
O13 Other Colour Transcoding Problems Autres Problèmes de Transcodage Couleur
Video / 

 

10. Other Video-related Problems
 

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
O14 Saturations (Crushing ?) Saturations
Video / 
When the video signals exceeds the limits of one of the components of the chain it passes trough, it is crushed, with sometimes numerous non-linear distortions, such as strikes. saturated areas are generally not recoverable. 
O15 Under-Black ? Infra-Noirs
Video / 
Forbidden luminance levels under black level over the maximum allowed range. 
O16 Super-White ? Sur-Niveau
Video / 
Forbidden luminance levels under black level generated by abrupt transitions such as titles from a character generator or computer-generated images. Usually not noticeable, but can generate off-locks later in he transmission chain. 
O17 Stroboscopic Effect Effet Stroboscopique
Video / 
Wheels running backwards ... 
O18 Interlacement-related aliasing Aliasing dû a l'entrelacement
Video / 
Flicking horizontal edges,  moving staircase on diagonals, flicker and moirŽ on horizontal stripes 

 

11. All kinds of Media

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
O19 Several Frames damaged beyond repair Plusieurs Images irrécupérables
Video+Film / 
Several Frames damaged beyond repair, due to mechanical tape Problems, damaged film, film breaks, off-locks... 
020 Full-Frame impairment Image en erreur
Video+Film / 
One frame damaged beyond repair, due to mechanical tape Problems, damaged film, film breaks, off-locks... 
021 Framing Errors Erreur de position Image, Errreur de cadrage.
Video+Film / 
The sides of the picture may not be at the expected position : a black bar will be visible on top, bottom, right, or left, or even inside the picture. 
022 Framing unsteadiness Instabilité Image
Video+Film / 
In addition to Film Unsteadiness, unsteadiness may also be caused by unsteady video cameras, or mains hum.  
O23 Saturation Saturation
Video+Film / 
Any kind of saturation. 
O24 Temporal Aliasing Aliasing Temporel
Video+Film / 
A special case of temporal Aliasing is very often seen on film-generated footage transferred to video : as the video 625 lines frequency is twice the film frequency, fast movements may look jaggy. 

This is usually not noticed by most viewers..  

 

12. Soundtrack problems
 

English Name
French Name
Origin (Film, Video) / Colour System if relevant / Line system / Device
Description/Explanation
Comments
A1 Noise Bruit, Souffle
Audio
An unwanted part of a processed signal that is not related to the original signal Audio noise usually sounds like a continuous hiss. 
A2 Sporadic noise Bruit transitoire
Audio
Same as above, but with fluctuations in the noise level. 
A3 Synchronisation problems Mis-Sync  Défaut de synchronisation
Video-Audio
Sound is not precisely in phase with the picture content. It occurs mainly on the original sound track (bad post synchronisation, bad transfers during the original mix process, film breaks repair, poor processing during telecine transfer…) 

Poor " lip sync " is noticeable at -1 or-+1/2 frames. Sync of audio can also fluctuate along the programme. 
 

A4 Interferences (Hum ?) Fréquences parasites
Audio
This default is generally due to unwanted frequencies in the sound spectrum.  

Some examples of interference are: Head wheel rotation frequency of VTRs and their harmonics, hum, buzz, rumble, noises generated by cameras players or recorders and electronic stages and captured by microphones.(for example mechanical noise generated by the mechanism of recorders of cameras and captures by microphones, rumble of LP turntables..) 

Generally can be removed or dimmed by narrow filters. 
 

A5 Echo Echo
Audio
A reverberation artefact so spread out that the reflected signal is perceived as a distinct sound
 
A6 Print-Through Enregistrement entre spires
Audio / audio tape recorders
Specific case of echo due to accidental partial copy from one layer of magnetic tape to another, often happening immediately after recording. Very often pre-echo rather than post-echo, as for other types of echo.
 
A7 Cross talk Diaphonie
Audio
The leakage of a signal from one channel of a system to another. A system with low cross talk  has a good separation between channels
 
A8 Phasiness ??
Audio
On some stereo recordings, the left and right channels will appear to be in phase while the centre will appear slightly out of phase, attenuated and ill defined 
A9 Bandwidth losses Pertes de bande passante
Audio
Most losses in bandwidth occur in the high frequencies of the spectrum Sound has lower levels for trebles than lows

This is generally due to bad magnetic recordings or copies with mis aligned analogue recorders. Sometimes losses may occur in medium or low frequencies.

A10 Level variations Fluctuations de niveau
Audio
Global level may be too high or too low. 

When the global level is too high, the sound may be saturate. 

When the overall level is too low, noise is more present and tiny sounds cannot be heard. 

Level may also fluctuate along the programme. 

This can occur when the tape is damaged (for example edges or magnetic coat or wounding tape)

A11 Sound Holes (Gaps ?) 

Dropouts 

Trous de son, Pertes de son
Audio
Lack of sound on the audio tracks. This lack may have a very short duration or last several frames. 

It may occur on a damaged original tape or may correspond to a mute on digital recordings (it occurs when the concealment rate is too high.) 

Short sound holes may be considered as drop outs. A drop pout is the result of a coating defect or a dirt deposit on the tape creating a momentary discontinuity in the playback signal  

A12 Long Sound Holes (Gaps ?) Trous de son, Pertes de son importantes
Audio
Long sound holes may last from several frames to seconds. 

Often the lack of sound is due to a technical problem during the shooting or an undesired erasure of the recording. 

A13 Wow Pleurage
Audio / audio tape recorders
Wow is a pseudo-periodic fluctuation of the sound caused by cyclic variations of speed of the audio tape, causing a "taffy like" sound quality It occurs mainly during recording or playback on analogue tape recorders. Wow is mainly caused by misaligned capstan servo or damaged capstan and pinch roller. 

Wow is a slow speed variation. 

A14 Flutter Scintillement
Audio / audio tape recorders
As Wow, but Flutter is a rapid speed variation.
A15 Saturation Saturation
Audio
A magnetic recording term used to describe a condition when an audio tape becomes fully magnetised and an increase in signal input does not produce a corresponding increase in recorded levels. 

It can also occur when a tape head cannot carry all the signals to handle. 

Replayed sound is affected by distortion and part of information in the sound is lost. 

Saturation may also be caused by the distortion of a microphone cap. 

There is currently no way today to recover a good sound from a saturated sound. The only thing that can be done is to apply filters to improve a little the perception of the sound. 

 

A16 Clipping Ecrètage
Audio
Specific case of Saturation. In audio the result of an analogue signal being over driven to the extend that its peak levels cannot be accommodated and are "clipped" off the audible signal. 

Typically it is the most audible electronic distortion occurring in small amplifiers  

 

A17  Clicks and Pops, crackle  Clics et pops, grattements
Audio
Impulsive noise (not continuous) may appear ounce (sporadic)or may appear all along the program like crackles of the optical sound on film
A18 Azimut Error Erreur d'azimut
Audio / audio tape recorders
Azimut is the angle between the magnetic gap of the tape head and the direction of the travel ideally 90°.Azimut varies from one deck to another and impacts the response on high frequencies 
A19 Audio Vinegar Syndrome Syndrome du Vinaigre (audio)
Audio / magnetic tapes
Autocatalytic hydrolysis of acetate separate magnetic audio16mm film, and magnetic tracts of films, which results in different kings of audio impairments, up to the point the source material is no longer playable.
Number of items : 190

 
 

Some of the terms used in the previous lists are documented hereafter.
CCD Charge Coupled Device : current semi-conductor imaging technology in cameras.
CRT Cathode Ray Tube. Still in use technology for television displays.
DOC Drop Out Compensator : the video tape technology is prone to short losses of signal due to dust or tape problems (drop-outs). To make these faults less visible to the eye, the drop-out concealment devices replaced the lost signal by the signal from the previous line, or the 2nd previous line (SECAM).
Kinescope or film recordings Early TV programs could not be recorded on VTRs, because these devices did not exist, or because of the price of videotapes. The only way of keeping an archive of the broadcast programmes was to record them on film, using a CRT and a film camera.
Reversal Positive film, used directly for news gathering, or TV productions
Segmented VTRs A VTR format is segmented when one full field is not recorded on the tape by one single head. Instead, the recording is made using several heads on different tracks, each track storing a group of lines. 

Two VTR formats that have been in wide use : 2 Inch (15 to 16 lines per track), and 1 Inch B (approx. 56 lines per track).

TBC Time-Base Corrector : devices used to correct time-shifts. In the case of the VTRs, as is very difficult to read the tracks synchronously, most of the VTRs use TBCs to compensate for time-shifts. 
TK, Telecine Telecinema : Device used for obtaining a real-time video output from a film programme.
VR2000 A 2 Inch VTR model.
VTR Video Tape Recorder

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