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

FFmpeg trac at avcodec.org
Thu Dec 21 11:54:52 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 j_karthic):

 Replying to [comment:8 stevenliu]:
 > Replying to [comment:7 j_karthic]:
 > > Well, if we round the target duration to '''nearest integer''' as per
 the spec, part of the problem is resolved. Right now we are '''ceiling to
 the upper integer''' which is not according to HLS specifications.
 > >
 > > {{{
 > >
 > >    The EXT-X-TARGETDURATION tag specifies the maximum Media Segment
 > >    duration.  The EXTINF duration of each Media Segment in the
 > >    file, when rounded to the nearest integer, MUST be less than or
 > >    to the target duration; longer segments can trigger playback stalls
 > >    or other errors.  It applies to the entire Playlist file.  Its
 > >    is:
 > >
 > >
 > >    where s is a decimal-integer indicating the target duration in
 > >    seconds.  The EXT-X-TARGETDURATION tag is REQUIRED.
 > >
 > > }}}
 > >
 > > So as per the spec, the EXT-X-TARGETDURATION should rounded to 4
 instead of 5.
 > >
 > > But when I submitted a patch for fixing such an issue in hlsenc, it
 was rejected by Steven. See thread http://ffmpeg.org/pipermail/ffmpeg-
 devel/2017-September/215630.html more details. During that time, I was not
 able to provide a concrete example with mediastreamvalidator like @beloko
 has done now. But I thought the spec was very clear about it without any
 room for confusion.
 > >
 > > @stevenliu
 > > If you have a change of mind after seeing these results, please let me
 know. Maybe I will send a new patch which fixes the target duration in
 dashenc, and we can take forward our discussions there.
 > The spec said "EXT-X-TARGETDURATION must > EXTINF", we have talk and you
 have sent twice patch about it. you can see the spec said "MUST be less
 than or equal to the target duration.", attention the MUST, MUST, MUST, we
 should don't care the tool, we should care the spec. If the tool different
 with the spec, that maybe apple's mistake, you should push apple.
 I think you missing the important line "'''when rounded to the nearest
 integer'''" in the spec. I am also only talking about the spec. This is
 just a pure argument, about interpreting that English line. This is where
 I feel some other people in the ffmpeg community should also pitch in
 moderate a discussion, rather than leaving it as "'''Maintainer is always
 > >
 > >
 > >
 > >
 > >

Ticket URL: <https://trac.ffmpeg.org/ticket/6915#comment:9>
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