[MEncoder-users] ac3 reencode-channels confusion

[Bernd Butscheidt]

The Wanderer <wanderer at fastmail.fm>:
At a brief guess, read up on the '-af channels' filter. '-channels' by itself doesn't seem to provide a way to specify the channel layout.

--       The Wanderer

================================

O.K:

I added

-af channels 6

into the options, still I get the message:

"[ac3 @ 0x17cc6c0]No channel layout specified. The encoder will guess the layout, but it might be incorrect."

Again, the center obviously seems to have moved to the right speaker when playback the result.

2nd try:

-af channels=6:6:1:1:2:2:3:3:4:3:5:5:6:6

I wanted to route every channel to its origin place to make a start guessing who is who. Now the recode doesn't start, the output shows:

MEncoder SVN-r29484 (C) 2000-2009 MPlayer Team
success: format: 0  data: 0x0 - 0x16f14408
AVI file format detected.
[aviheader] Video stream found, -vid 0
[aviheader] Audio stream found, -aid 1
AVI: Generated index table for 14732 chunks!
VIDEO:  []  720x576  24bpp  25.000 fps  5190.2 kbps (633.6 kbyte/s)
libavformat file format detected.
[lavf] Audio stream found, -aid 0
[V] filefmt:65536  fourcc:0x10000002  size:720x576  fps:25.000  ftime:=0.0400
==========================================================================
Opening audio decoder: [liba52] AC3 decoding with liba52
Using SSE optimized IMDCT transform
Using MMX optimized resampler
AUDIO: 48000 Hz, 6 ch, s16le, 448.0 kbit/9.72% (ratio: 56000->576000)
Selected audio codec: [a52] afm: liba52 (AC3-liba52)
==========================================================================
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [harddup]
Opening video filter: [pp=fd]
==========================================================================
Opening video decoder: [mpegpes] MPEG 1/2 Video passthrough
VDec: vo config request - 720 x 576 (preferred colorspace: Mpeg PES)
[PP] Using external postprocessing filter, max q = 6.
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
The selected video_out device is incompatible with this codec.
Try appending the scale filter to your filter list,
e.g. -vf spp,scale instead of -vf spp.
VDecoder init failed :(
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Unsupported PixelFormat -1
Selected video codec: [ffmpeg2] vfm: ffmpeg (FFmpeg MPEG-2)
==========================================================================
Forcing output FourCC to 44495658 [XVID].
[channels] Invalid routing in pair nr. 5.
[libaf] Reinitialization did not work, audio filter 'channels' returned error code -2
Error at audio filter chain pre-init!


I guess "Invalid routing in pair nr. 5" shows some hint, but I'm clueless at the moment.

Greetings
Bernd B.