I have a WD TV, and somehow, MKVs with 6 channels ac3 do not play sound on my TV, but 2 channels ones ac3 do.

UPDATE: I had my WD TV to DIGITAL AUDIO, instead than STEREO.

It looks like if the audio is 2 channels, the WD TV would do STEREO anyway, but for the 6 channels, it would try to do DIGITAL.

So i set it back to STEREO and all is playing perfectly.

But i'm still interested on knowing:

1) how can i specify FPS while doing the MKVmerge on the command line:
mkvmerge -o test.mkv video.h264 audio.ac3 sub.srt

EDIT2: --default-duration 0:24000/1001fps would do it.

2) if i already have an mkv, how do i add another file to it?

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So i'm trying to find out the quickets way of extracting the the ac3, downsampling it to 2 channels, and then remerging to the mkv.

I-m experimenting a little, since i-m really not much into video, unless i need to do something like now, so:

1) eac3to a.mkv
MKV, 1 video track, 1 audio track, 0:41:46, 24p /1.001
1: h264/AVC, English, 720p24 /1.001
2: AC3, 5.1 channels, 384kbps, 48khz, dialnorm: -27dB

2) eac3to a.mkv 1: video.h264 2: audio.ac3

3) eac3to audio.ac3 audio2.ac3 -down2

4) eac3to audio.ac3 audio2.wav

5) neroaacenc.exe -q 1 -if audio2.wav -of audio2.aac

So now i have:

video.h264 (original video)
audio.ac3 (this is the original 6 channels ac3)
audio2.ac3 (ac3 downsampled to 2 channels)
audio2.aac (aac downsampled to 2 channels)

I then tried:

mp4box -add "video.h264:fps=23.976" -add "audio2.aac:lang=en" "a-audio2-aac.mp4"

mp4box -add "video.h264:fps=23.976" -add "audio2.ac3:lang=en" "a-audio2-ac3.mp4"

mkvmerge -o a-audio2-aac.mkv video.h264 audio2.aac

mkvmerge -o a-audio2-ac3.mkv video.h264 audio2.ac3

I ended up with:

a-audio2-aac.mp4 plays perfectly.

a-audio2-ac3.mp4 no sound (is an mp4 restriction?)

a-audio2-ac3.mkv 1 sec delay

a-audio2-aac.mkv 1 sec delay

So, i was wondering, why the 1 sec delay (audio plays latter than the vide)? Is it because i-m not specifying the FPS? How do i do it?

And last, since i already have an MKV with audio and ac3, how can i add the 2 channel ac3?

Thanks.

oh well, you just have to test and find whatever will work, i would go for a final file that looks like:

1. video
2. new stereo audio, can you use AAC here?
3. original ac3
.mkv

(so basically i would go for insertion of the new stereo track into original file, that way you can still play ac3 with some PC)

edit: if you can post a small sample somewhere i may find time to play around.

UPDATE: I had my WD TV to DIGITAL AUDIO, instead than STEREO.

It looks like if the audio is 2 channels, the WD TV would do STEREO anyway, but for the 6 channels, it would try to do DIGITAL.

So i set it back to STEREO and all is playing perfectly.

But i'm still interested on knowing:

1) how can i specify FPS while doing the MKVmerge on the command line:
mkvmerge -o test.mkv video.h264 audio.ac3 sub.srt

2) if i already have an mkv, how do i add another file to it?

1. http://www.bunkus.org/videotools/mkvtoolni...c/mkvmerge.html
try −−default−duration 25fps
2. no idea, but −−append−to seems to be it.

open both files (your .mkv and other file) in mkvtoolnix, select which audio,video and subtitle tracks you want to remain in the container than mux it again