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

[Juergen Pfennig]

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 do not want to flood you with too many bug reports, but avconv (or
avlib?) is not fit for practical use. It handles only some 60% of my use
cases without trouble. Unfortunately I have no experience with ffmpeg.
But if avlib is not better than ffmpeg there is no reason to have it in
debian. It just doubles the trouble. I will switch away completely from
ffmpeg/avlib.

Thanks
Jürgen

-- System Information:
Debian Release: 7.4
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.2.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages libav-tools depends on:
ii  dpkg                 1.16.12
ii  libavcodec-extra-53  6:0.8.10-1
ii  libavdevice53        6:0.8.10-1
ii  libavfilter2         6:0.8.10-1
ii  libavformat53        6:0.8.10-1
ii  libavutil51          6:0.8.10-1
ii  libc6                2.13-38+deb7u1
ii  libpostproc52        6:0.8.10-1
ii  libsdl1.2debian      1.2.15-5
ii  libswscale2          6:9.10-1~bpo70+1

libav-tools recommends no packages.

libav-tools suggests no packages.

-- no debconf information