359:. Television industry standards organizations have established acceptable amounts of audio and video timing error and suggested practices related to maintaining acceptable timing. The EBU Recommendation R37 "The relative timing of the sound and vision components of a television signal" states that end-to-end audio/video sync should be within +40 ms and -60 ms (audio before/after video, respectively) and that each stage should be within +5 ms and -15 ms.
375:. The resulting audio-video sync error can be annoying to the viewer and may even cause the viewer to not enjoy the program, decrease the effectiveness of the program or lead to a negative perception of the speaker on the part of the viewer. The potential loss of effectiveness is of particular concern for product commercials and political candidates. Television industry standards organizations, such as the
269:) can delay the video signal by one or more frames. Audio and video signal processing circuitry exists with significant (and potentially non-constant) delays in television systems. Particular video signal processing circuitry that is widely used and contributes significant video delays include frame synchronizers, digital video effects processors, video noise reduction, format converters and
250:. If the sound source is 340 meters from the microphone, then the sound arrives approximately 1 second later than the light. The AV-sync delay increases with distance. During mixing of video clips normally either the audio or video needs to be delayed so they are synchronized. The AV-sync delay is static but can vary with the individual clip.
339:. Pixelated displays utilize complex video signal processing to convert the resolution of the incoming video signal to the native resolution of the pixelated display, for example converting standard definition video to be displayed on a high definition display. Synchronization problems are commonly caused when significant amounts of
203:
In industry terminology, the lip-sync error is expressed as the amount of time the audio departs from perfect synchronization with the video where a positive time number indicates the audio leads the video and a negative number indicates the audio lags the video. This terminology and standardization
382:
Because of these annoyances, AV-sync error is a concern to the television programming industry, including television stations, networks, advertisers and program production companies. Unfortunately, the advent of high-definition flat-panel display technologies (LCD, DLP and plasma), which can delay
453:
to precisely signal when each audio and video segment is to be presented and avoid AV-sync errors. However, these timestamps are often added after the video undergoes frame synchronization, format conversion and preprocessing, and thus the lip sync errors created by these operations will not be
433:
standard ST2064, published in 2015, provides technology to reduce or eliminate lip-sync errors in digital television. The standard utilizes audio and video fingerprints taken from a television program. The fingerprints can be recovered and used to correct the accumulated lip-sync error. When
280:
and deinterlace processing in video monitors can add one or more frames of video delay. A video monitor with built-in speakers or line-out may not delay sound and video paths equally. Some video monitors contain internal user-adjustable audio delays to aid in correction of errors.
343:
is performed on the video part of the television program. Typical sources of significant video delays in the television field include video synchronizers and video compression encoders and decoders. Particularly troublesome encoders and decoders are used in
383:
video more than audio, has moved the problem into the viewer's home and beyond the control of the television programming industry alone. Consumer product companies now offer audio-delay adjustments to compensate for video-delay changes in TVs,
609:
307:
When a digital or analog AV system stream does not have a synchronization method or mechanism, the stream may become out of sync. In film movies these timing errors are most commonly caused by worn films skipping over the
414:
with expert viewers and found that the threshold for detectability is 45 ms lead to 125 ms lag. For film, acceptable lip sync is considered to be no more than 22 milliseconds in either direction.
261:), reception and playback that can get introduce AV-sync errors. A video camera with built-in microphones or line-in may not delay sound and video paths by the same amount. Solid-state video cameras (e.g.
557:
288:
require an out-of-band method for synchronizing media streams. In some RTP systems, each media stream has its own timestamp using an independent clock rate and per-stream randomized starting value. A
204:
of the numeric lip-sync error is utilized in the professional broadcast industry as evidenced by the various professional papers, standards such as ITU-R BT.1359-1, and other references below.
355:
In broadcast television, it is not unusual for lip-sync error to vary by over 100 ms (several video frames) from time to time. AV-sync is commonly corrected and maintained with an
619:
242:. The AV-sync delay is normally fixed. External AV-sync errors can occur if a microphone is placed far away from the sound source, the audio will be out of sync because the
732:
654:
885:"SVCD2DVD: Author and burn DVDs: AVI to DVD, DivX to DVD, Xvid to DVD, MPEG to DVD, SVCD to DVD, VCD to DVD, PAL to NTSC conversion, HDTV2DVD, HDTV to DVD, BLURAY"
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usually contain some sort of synchronization mechanism, either in the form of interleaved video and audio data or by explicit relative
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associated with the media may be used to synchronize media. A server may then be used for synchronization between multiple receivers.
387:
and A/V receivers, and several companies manufacture dedicated digital audio delays made exclusively for lip-sync error correction.
185:
750:
419:
950:
909:
323:
industry because of the use of large amounts of video signal processing in television production, television broadcasting and
705:
Sara Kudrle; et al. (July 2011). "Fingerprinting for
Solving A/V Synchronization Issues within Broadcast Environments".
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The result typically leaves a filmed or televised character's mouth movements mismatching spoken dialog, hence the term
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807:
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131:
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332:
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fingerprints have been generated for a TV program, and the required technology is incorporated, the viewer's
470:
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993:
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Appropriate A/V sync limits have been established and the range that is considered acceptable for film is
719:. The range for video, according to the ATSC, is up to 15 ms lead time and about 45 ms lag time
466:
450:
262:
422:
has published a set of recommendations for how digital television receivers should implement A/V sync.
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655:"Effects of Audio-Video Asynchrony on Viewer's Memory, Evaluation of Content and Detection Ability"
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and storing television programs on consumer and professional recording and playback devices.
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During creation AV-sync errors happen because of internal AV-sync error due to different
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sprockets because the film has torn sprocket holes. Errors can also be caused by the
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65:
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Sieranoja, S.; Sahidullah, Md; Kinnunen, T.; Komulainen, J.; Hadid, A. (July 2018).
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Inter-Destination Media
Synchronization (IDMS) Using the RTP Control Protocol (RTCP)
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There are different ways in which the AV-sync can get incorrectly synchronized.
34:
17:
637:"The relative timing of the sound and vision components of a television signal"
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462:
239:
189:
1037:
2018 IEEE 3rd
International Conference on Signal and Image Processing (ICSIP)
188:, reception and play-back processing. AV synchronization can be an issue in
501:
324:
53:
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1010:"Factors affecting perception of audio-video synchronisation in television"
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506:
465:
on an arbitrary timeline. A real-time clock such as one delivered by the
384:
379:, have become involved in setting standards for audio-video sync errors.
160:
733:"CEA-CEB20 R-2013: A/V Synchronization Processing Recommended Practice"
532:"ITU-R BT.1359-1, Relative Timing of Sound and Vision for Broadcasting"
496:
96:
58:
48:
992:. TV Technology, originally from Broadcast Engineering. Archived from
959:
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has the ability to continuously measure and correct lip-sync errors.
611:
IS-191: Relative Timing of Sound and Vision for
Broadcast Operations
406:
and audio should lag video by no more than 45 ms. However, the
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173:
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Synchronization errors have become a significant problem in the
197:
1029:"Audiovisual Synchrony Detection with Optimized Audio Features"
831:"MPEG-2 Systems FAQ: 19. Where are the PTSs and DTSs inserted?"
407:
328:
112:
399:
recommends that audio should lead video by no more than
857:"MPlayer-G2-dev: mpeg container's timing (PTS values)"
558:"Audio/Video Standards and Solutions A Status Report"
363:
Viewer experience of incorrectly synchronized AV-sync
254:
effects can delay video causing it to lag the audio.
454:corrected by the addition and use of timestamps.
902:A. Williams; K. Gross; et al. (June 2014).
796:SMPTE Standards Update: The Lip-Sync Challenge
772:SMPTE Standards Update: The Lip-Sync Challenge
556:Patrick Waddell; Graham Jones; Adam Goldberg.
348:compression systems utilized for broadcasting
943:R. van Brandenburg; et al. (June 2014).
132:
8:
653:Byron Reeves; David Voelker (October 1993).
1008:R.A. Salmon; Andrew Mason (January 2009).
139:
125:
29:
958:
917:
316:misthreading the film in the projector.
871:"birds-eye.net: DTS - Decode Time Stamp"
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32:
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604:
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397:Advanced Television Systems Committee
377:Advanced Television Systems Committee
7:
303:Effect of no explicit AV-sync timing
686:"Lip-sync error: Causes, solutions"
172:) refers to the relative timing of
806:, 10 December 2013, archived from
731:Consumer Electronics Association.
234:delays between image and sound in
27:Relative timing of audio and video
25:
395:For television applications, the
299:in order to synchronize streams.
284:Some transmission protocols like
420:Consumer Electronics Association
951:Internet Engineering Task Force
910:Internet Engineering Task Force
783:from the original on 2021-12-15
461:clocks media using origination
180:(image) parts during creation,
1081:Audio to video synchronization
1046:10.1109/SIPROCESS.2018.8600424
1014:BBC Research & Development
152:Audio-to-video synchronization
1:
988:Cugnini, Aldo (Sep 1, 2007).
618:, 2003-06-26, archived from
475:Session Description Protocol
459:Real-time Transport Protocol
327:television displays such as
905:RTP Clock Source Signalling
1097:
447:Presentation time stamps
164:, or by the lack of it:
471:Precision Time Protocol
246:is much lower than the
707:Motion Imaging Journal
563:. ATSC. Archived from
451:MPEG transport streams
449:(PTS) are embedded in
473:and described in the
467:Network Time Protocol
263:charge-coupled device
1040:. pp. 377–381.
779:, 10 December 2013,
276:Processing circuits
990:"Managing lip sync"
855:Arpi (7 May 2003).
570:on 17 February 2016
410:performed strictly
271:compression systems
209:audio video streams
92:Audio-to-video sync
33:Development of the
996:on October 8, 2015
973:Proposed Standard.
932:Proposed Standard.
487:Audio synchronizer
357:audio synchronizer
350:digital television
321:digital television
293:Sender Report (SR)
267:CMOS image sensors
207:Digital or analog
156:AV synchronization
108:Video Concert Hall
1055:978-1-5386-6396-7
667:on 2 October 2008
278:format conversion
232:signal processing
194:videoconferencing
149:
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16:(Redirected from
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960:10.17487/RFC7272
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889:www.svcd2dvd.com
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412:controlled tests
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341:video processing
223:Sources of error
158:, also known as
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44:Illustrated song
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18:Audio video sync
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391:Recommendations
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337:plasma displays
310:movie projector
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297:for each stream
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182:post-production
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373:lip-sync error
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295:may be needed
257:Transmission (
248:speed of light
244:speed of sound
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166:lip-sync error
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1017:. Retrieved
998:. Retrieved
994:the original
972:
945:
938:
931:
904:
897:
888:
879:
865:
850:
839:. Retrieved
835:the original
825:
815:, retrieved
808:the original
795:
789:
771:
765:
751:
745:
737:the original
726:
714:
706:
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689:. Retrieved
680:
669:. Retrieved
662:the original
648:
620:the original
610:
584:
572:. Retrieved
565:the original
551:
539:. Retrieved
492:Clapperboard
456:
445:
429:
426:SMPTE ST2064
417:
394:
381:
372:
368:
366:
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318:
306:
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283:
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259:broadcasting
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236:video camera
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217:timestamping
206:
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186:transmission
176:(sound) and
169:
165:
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155:
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91:
71:Musical film
537:. ITU. 1998
213:video files
35:music video
1019:2013-06-02
1000:2008-10-19
841:2007-12-27
817:2016-06-09
691:2024-06-13
671:2008-10-19
513:References
463:timestamps
442:Timestamps
265:(CCD) and
240:microphone
190:television
184:(mixing),
717:+/- 22 ms
502:Input lag
385:soundbars
325:pixelated
219:of data.
54:Scopitone
1075:Category
1064:51682024
781:archived
507:Lip sync
481:See also
401:15
369:lip flap
170:lip flap
161:lip sync
574:4 April
497:Dubbing
97:Lip dub
87:Literal
59:Cinebox
49:Soundie
1062:
1052:
759:, 2015
591:
541:30 May
76:Insert
1060:S2CID
1032:(PDF)
811:(PDF)
804:SMPTE
800:(PDF)
777:SMPTE
757:SMPTE
711:SMPTE
665:(PDF)
658:(PDF)
640:(PDF)
568:(PDF)
561:(PDF)
535:(PDF)
431:SMPTE
196:, or
178:video
174:audio
1050:ISBN
968:7272
927:7273
616:ATSC
593:3550
576:2012
543:2015
457:The
418:The
346:MPEG
335:and
290:RTCP
238:and
198:film
1042:doi
965:RFC
955:doi
924:RFC
914:doi
589:RFC
469:or
408:ITU
371:or
333:DLP
329:LCD
286:RTP
211:or
113:MTV
1077::
1058:.
1048:.
1034:.
1012:.
963:.
953:.
949:.
922:.
912:.
908:.
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628:^
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403:ms
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154:(
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.