VIDEO_TS -> Divx w/5.1 ac-3 audio

[brysongilbert]

i'm having a problem encoding from a VIDEO_TS folder to Divx (mencoder) using ffmpegx 0.0.9p. the source has 6-channel (5.1) ac-3 audio, and i'd like to pass that through to my final .avi. the problem is that even with the passthrough codec selected, encode audio checked, bitrate at 448 kbps, channels set to 5.1, and the 5.1 audio track selected, i _always_ end up with a 2-channel ac-3 track in the final file. here's the relevant output:

Opening audio decoder: [liba52] AC3 decoding with liba52
dec_audio: Allocating 3840 bytes for input buffer.
dec_audio: Allocating 6144 + 65536 = 71680 bytes for output buffer.
Using AltiVec optimized IMDCT transform
AC3: 5.1 (3f+2r+lfe) 48000 Hz 448.0 kbit/s
A52 flags before a52_frame: 0x2A
A52 flags after a52_frame: 0xA
Checking for AltiVec resampler : 0x0000000a, 2
Using AltiVec optimized resampler
AUDIO: 48000 Hz, 2 ch, 16 bit (0x20), ratio: 56000->192000 (448.0 kbit)
Selected audio codec: [a52] afm:liba52 (AC3-liba52)

this line also comes later:
audiocodec: framecopy (format=2000 chans=2 rate=48000 bits=16 bps=56000 sample-1)

note in the 5th line, it's definitely a 5.1 audio track, but it chooses to output to 2-channel for whatever reason.

am i doing something wrong here? any help would be greatly appreciated.

[major]

This seem an issue in mencoder core which appear to always decode 2:0. I'll check this in more detail. ffmpeg engine supports 5:1 but it needs VOB input.

[brysongilbert]

interesting. i'll try not using the mencoder engine then. thanks for a very fast reply and a great app in ffmpegx, major. keep it up.

[jmusd]

I am also trying to use mencoder for Video_TS --> mpeg4[.avi]( mencoder) and get a 5.1 audio track. I have found if AC3 is selected and bitrates and sampling match source the end result is a stereo audio track. However, if passthrough is selected even though in the terminal I am getting the same read out as brysongilbert (2 channel). When I play it on XBMC it is telling me it is 6 channels. Can anyone verify this is accurate? I tried using ffmpeg engine but the audio/video was so out of sync. Can someone give me some advice on this for better syncing using the ffmpeg engine? Should "use quicktime" be selected? I prefer the mencoder engine because the syncing is always perfect.

[brysongilbert]

after slapping my dumb self over WHXY vs. TBLR cropping issues and successfully getting my video to encode with the ffmpeg engine AND 5.1 audio (hooray!), i am sad to report that i, like jmusd, am having major a/v sync issues in the final file.

[major]

To avoid sync issues, don't change framerate and don't change sampling rate compared to source file. Or, let me download your source file so as I can reproduce the issue and try to fix it.

[jmusd]

Major,

Can you verify my results ...
"I am also trying to use mencoder for Video_TS --> mpeg4[.avi]( mencoder) and get a 5.1 audio track. I have found if AC3 is selected and bitrates and sampling match source the end result is a stereo audio track. However, if passthrough is selected even though in the terminal I am getting the same read out as brysongilbert (2 channel). When I play it on XBMC it is telling me it is 6 channels."

Thanks

[major]

Apparently it is always 2 channels, and it needs to be fixed.