[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 08:32:12 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):

 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 Playlist
    file, when rounded to the nearest integer, MUST be less than or equal
    to the target duration; longer segments can trigger playback stalls
    or other errors.  It applies to the entire Playlist file.  Its format


    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.

 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.

Ticket URL: <https://trac.ffmpeg.org/ticket/6915#comment:7>
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