[Matroska-users] Question regarding MKV

Ivan Kowalenko ivan.kowalenko at gmail.com
Sat Nov 3 15:36:17 CET 2007

On Nov 2, 2007, at 03.52, Sarreti Balazs wrote:

> If I  have a video in MKV with the following details:
> Video #0
> Codec : MPEG-4 AVC
> Codec/Info : MPEG4 ISO advanced profile
> Audio #0
> Codec : AC3
> Is there a fast way to convert/extract the video to the Playstation  
> 3 friendly format MPEG-4 AVC?? I used Ultra MP4 Video Converter,  
> but this took 8 hours of work. Is there a faster way? Thank you for  
> your help and great work!
This actually highlights the main reason Matroska has become so  
popular recently. MKV is the only container that supports a large  
amount of data (more than 4 GB), H.264 (A.K.A.: MPEG-4 AVC), and AC3  
(A.K.A.: Dolby Digital).

The task you're asking is actually simpler than you'd imagine. Your  
video (which consumes the most power to transcode) is already in an  
appropriate format. The PS3's too picky about AVI, so we can't use  
that, and our safest target container is an MP4 file. The MPEG-4  
specification doesn't support AC3, so we'll have to transcode that to  
something else. Fortunately, transcoding audio shouldn't take nearly  
as long as video (I'm actually surprised it took only 8 hours).

I'm going to assume you're running Windows, so I'm going to have to  
inform you that I'm dreadfully out of date on Windows tools, so I'm  
going to let you know of the tools I understand and am aware of, but  
if you know a tool that'll do these things too, you'll be fine.

MEncoder, a mature Linux tool, has a Windows port, but it runs in the  
command line, so it might seem intimidating. What we have to do is  
passthrough the video, and re-encode the audio. The command line for  
MEndcoder would look like this:
mendcoder (input) -ovc copy -oac faac -faacopts  
br=192:mpeg=4:object=2 -channels 6 -of lavf -o (output).mp4

Theoretically, that should crank out a video file that ONLY  
transcodes the audio, keeps your 6-channel configuration, and dumps  
it all to an MP4 file that the PS3 should have no problem with. The  
biggest trick in finding a similar app is that most will disgregard  
the fact that you're working with a 6-channel (probably 5.1) audio  
mix, and just downmix it to stereo (2-channel). Also, many apps don't  
seem to allow for passthrough.

VLC can do the job too, but you'll end up with stereo audio, and not  
a lot of control options. Still, it might be just what you need.  
QuickTime can also do the job, and very well I might add, but I'm not  
sure if there's an Matroska Plug-in, or even an AC3 plug-in, for  
Windows. I know one exists for Mac OS X (for both plug-ins), but  
Windows is a whole other story. QT would be ideal, since it supports  
multi-channel AAC, and Apple literally wrote the book on the MPEG-4  
specification (the container is based off of Apple's development of  
the QuickTime MOV container).

Good luck, man.
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