Bug#740773: /usr/bin/avconv: aconv does not handle ac3->ac3 5.1 sound conversion

[Reinhard Tartler]

Control: tag -1 moreinfo upstream

On Tue, Mar 4, 2014 at 4:33 PM, Juergen Pfennig <info at j-pfennig.de> wrote:
> Package: libav-tools
> Version: 6:0.8.10-1
> Severity: normal
> File: /usr/bin/avconv
>
> Dear Maintainer,
>
> today I tried to convert DVD data (with 5.1 ac3 sound) to some smaller
> mp4. I learned that there is almost no way to keep 5.1 sound. The best I
> could get was downmixing to stereo (using -ac 2). Here is input/output
> from my 1st try [I still believe that it should work out of the box
> without having to add spurious parameters like -c:a ac3_fixed -b:a 448]:
>
> -START-------------------------------------------------------------------------------
> local at peter0:~$ avconv -loglevel info -ss 6 -i
> "concat:/mnt/xxx/VIDEO_TS/VTS_01_1.VOB|/mnt/xxx/VIDEO_TS/VTS_01_2.VOB|/mnt/xxx/VIDEO_TS/VTS_01_3.VOB|/mnt/xxx/VIDEO_TS/VTS_01_4.VOB|/mnt/xxx/VIDEO_TS/VTS_01_5.VOB"
> -vf yadif -c:v mpeg4 -c:a ac3 -aspect 16:9 -async 1000 -threads 2
> -strict 1  -b:v 2M -bt 18M -f mp4 -y x.mp4
> avconv version 0.8.10-6:0.8.10-1, Copyright (c) 2000-2013 the Libav
> developers
>   built on Feb  5 2014 03:52:19 with gcc 4.7.2
> [mpeg @ 0x189a300] max_analyze_duration reached
> Input #0, mpeg, from
> 'concat:/mnt/xxx/VIDEO_TS/VTS_01_1.VOB|/mnt/xxx/VIDEO_TS/VTS_01_2.VOB|/mnt/xxx/VIDEO_TS/VTS_01_3.VOB|/mnt/xxx/VIDEO_TS/VTS_01_4.VOB|/mnt/xxx/VIDEO_TS/VTS_01_5.VOB':
>   Duration: 02:52:59.55, start: 0.287267, bitrate: 3593 kb/s
>     Stream #0.0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x576 [PAR
> 64:45 DAR 16:9], 8490 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
>     Stream #0.1[0x82]: Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s
> [buffer @ 0x18a1f00] w:720 h:576 pixfmt:yuv420p
> [yadif @ 0x18a26c0] mode:0 parity:-1 auto_enable:0
> Incompatible sample format 's16' for codec 'ac3', auto-selecting format
> 'flt'
> [ac3 @ 0x189bec0] invalid bit rate
> Output #0, mp4, to 'x.mp4':
>     Stream #0.0: Video: mpeg4, yuv420p, 720x576 [PAR 64:45 DAR 16:9],
> q=2-31, 2000 kb/s, 90k tbn, 25 tbc
>     Stream #0.1: Audio: ac3, 48000 Hz, 5.1, flt, 200 kb/s
> Stream mapping:
>   Stream #0:0 -> #0:0 (mpeg2video -> mpeg4)
>   Stream #0:1 -> #0:1 (ac3 -> ac3)
> Error while opening encoder for output stream #0:1 - maybe incorrect
> parameters such as bit_rate, rate, width or height
> -END----------------------------------------------------------------------------------

I'm sorry for taking so much time to get back to you.

This really seems like a usability issue to me.  I agree that the
error messages and the user-interface could always be better. Would
you please mind discussing this with upstream? Please follow the
instructions at https://libav.org/bugreports.html and report back with
the bugzilla number.

> I do not want to flood you with too many bug reports, but avconv (or
> avlib?) is not fit for practical use. [...] I will switch away completely from
> ffmpeg/avlib.

Can I take that you are not interested in testing new versions of libav/avconv?

Best,
Reinhard