[FFmpeg-trac] #2481(avformat:new): libavformat doesn't update file duration when file size changes during playback

[FFmpeg]

#2481: libavformat doesn't update file duration when file size changes during
playback
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             Reporter:  gjdfgh    |                     Type:  enhancement
               Status:  new       |                 Priority:  normal
            Component:  avformat  |                  Version:  unspecified
             Keywords:            |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
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 I would expect that libavformat updates AVFormatContext.duration when the
 size of the opened file changes, e.g. when playing partial files that are
 downloading.

 This should work for all file formats or cases where the file duration is
 estimated from the size.

 I tested with getting the first 10 MB of an avi file, starting a player
 using libavformat (mplayer based), then appending the next 30 MB to that
 file while the player was running. The AVFormatContext.duration field
 didn't change, and always contained the initial estimate.

 Unfortunately this can't be reproduced with ffplay, it doesn't show the
 duration in its status line. Likewise, the ffmpeg program doesn't seem to
 show it anywhere.

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2481>
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