[FFmpeg-trac] #6915(avformat:new): DASH audio segments duration doesn't match exactly with video segments duration.

FFmpeg trac at avcodec.org
Tue Dec 19 08:10:20 EET 2017

#6915: DASH audio segments duration doesn't match exactly with video segments
             Reporter:  beloko      |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avformat
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |

Comment (by stevenliu):

 Replying to [comment:2 beloko]:
 > I know the specification about the #EXT-X-TARGETDURATION since its first
 > In this audio stream playlist some .m4s segments have a duration of
 4.010667 seconds. So to be compliant with the specification
 #EXT-X-TARGETDURATION is rounded to the upper value 5. It's correct.
 > The issue is about playback and synchronisation for smooth streaming.
 With multiple video bitrate streams and audio tracks at adaptive bitrate,
 the video player switch automatically to different quality according to
 the bandwidth. When a video or an audio track isn't cut exactly at the
 same duration, sometimes spectator can detect a video freeze, a strange
 click noise in the audio rendering. Or the voice is a bit desynchronized
 with the mouth that's speaking.
 > The Apple mediastreamvalidator tool check the #EXT-X-TARGETDURATION is
 the same for all embed streams/tracks specified as a #EXT-X-STREAM-INF:.
 And returns this kind of error message if the longest segment duration is
 different between streams/tracks.
 > {{{
 > Error: Different target durations detected
 > --> Detail:  Target duration: 4 vs Target duration: 5
 > --> Source:  hdready/tears_of_steel_4k_2112_720p.m3u8
 > --> Compare: veryhigh/tears_of_steel_4k_1056_480p.m3u8
 > }}}
 > So to be square with the required specification all segment duration
 should be 4 seconds long exactly.

 No, That should be modify by one of the two space, specification, or
 mediastreamvalidator :D

 whatever, maybe it cannot cut at 4s is a bug.

Ticket URL: <https://trac.ffmpeg.org/ticket/6915#comment:3>
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