New submission from Paul Rouget <[email protected]>:

I concatenate 2 webm files.

I use mkvmerge:
$ mkvmerge -o res.webm 1.webm + 2.webm

1.webm and 2.webm have both an audio and a video track.

If I play the result with Firefox or VLC, everything is ok, no problem.

But, if the audio track of 1.webm is just silence,
this silence is skipped (jump to the 2.webm content, both audio & video) when
ffplay or mplayer play res.webm, or when ffmpeg encode res.webm to another 
format.

Examples,

Files can be found here: http://people.mozilla.com/~prouget/2share/ffmpeg_bug/

I have 3 input files:
× 1_silence.webm → 5 seconds, video and audio. audio is silence.
× 1_sound.webm → 5 seconds, video and audio. audio is noise.
× 2_sound.webm → 30 seconds, video and audio. audio is noise.

1_silence.webm + 2_sound.webm = res_silence_then_sound.webm
1_sound.webm + 2_sound.webm = res_sound_then_sound.webm

res_sound_then_sound.webm is ok.

res_silence_then_sound.webm is not played correctly by ffplay or mplayer (the 5
first seconds of the audio AND the video are skipped).

If this file is encoded to another format with ffmpeg, same problem, the 5 first
seconds are skipped.

----------
messages: 13035
priority: normal
status: new
substatus: new
title: WebM: Silent track not taken into account if followed by a noisy track
topic: ffmpeg, ffplay
type: bug

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FFmpeg issue tracker <[email protected]>
<https://roundup.ffmpeg.org/issue2445>
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