ffmpeg conversion => broken duration

[vanilla38]

Hello, i downloaded some files with this command:

youtube-dl --extract-audio --max-quality=18 http://www.youtube.com/watch?v=ZnXZR6MB5qI

Then

youtube-dl --extract-audio --max-quality=6 http://www.youtube.com/watch?v=ZnXZR6MB5qI

The 2 mp3 files have different durations for the same video :o it's only a graphic bug since the video stops at the correct time but show a different duration.

this is due to ffmpeg calculating wrong duration for files when converting.

[Shuro]

Same error here, noticed it also yesterday.

[yasoob]

I guess its ffmpeg's bug not of youtube-dl's because youtube-dl is just calling ffmpeg for file conversion and all the rest of the work is handled by ffmpeg.

[vanilla38]

maybe we can modify some options in the call, any idead on where i can set it ? Thanks.

[JMSwag]

@vanilla38 In module Postprocessors.

[vanilla38]

thanks I'll check for smthg to change.

[Shuro]

Is there some sort of workaround for this problem?

[jaimeMF]

First the downloaded videos doesn't even have the same duration (according to ffprobe):

• for youtube-dl --extract-audio --max-quality=18 http://www.youtube.com/watch?v=ZnXZR6MB5qI: Duration: 00:07:11.94, start: 0.000000, bitrate: 671 kb/s
• for youtube-dl --extract-audio --max-quality=6 http://www.youtube.com/watch?v=ZnXZR6MB5qI: Duration: 00:07:11.88, start: 0.000000, bitrate: 393 kb/s

The duration of the audio files is 00:07:11.94 and 00:07:12.07, it may happens with all videos, but you have noticed here because players seem to truncate the duration.

[vanilla38]

Yea but we're talking about 2 or 3 minutes of difference between two quality selections.
I'm actually working on it but it seems to be an ffmpeg bug.

[phihag]

@vanilla38 Can you post a command line (like @jaimeMF did) of two videos that differ significantly?

[jaimeMF]

After doing some tests with different versions of avconv (see #1866), I have more information:

• version 8.9 reports the wrong duration.
• version 9.10 and ffmpeg 1.2.4 works fine.

I guess that any player using the version of avconv with the bug will also report the wrong duration, you'll have to report the problem to its author. For example Quicktime player and VLC report the right durations.

Could someone confirm if this is the problem, please?, so that we can close the issue.