How do I preserve 1 audio track and change another?

[Han Solo1]

I have 2 audio tracks in an mkv file. I wish to change only one audio track from 6 channel dts to 2 channel ac3 and preserve the other. I asked the handbrake forum but handbrake can't handle vorbis.


Audio #1
ID/String : 2
Format : DTS
Format/Info : Digital Theater Systems
CodecID : A_DTS
Duration/String : 1h 33mn
BitRate_Mode/String : Constant
BitRate/String : 1 510 Kbps
Channel(s)/String : 6 channels
ChannelPositions : Front: L C R, Side: L R, LFE
SamplingRate/String : 48.0 KHz
BitDepth/String : 24 bits
Compression_Mode/String : Lossy
StreamSize/String : 1 009 MiB (15%)
Title : DTS 5.1
Language/String : English

Audio #2
ID/String : 3
Format : Vorbis
Format_Settings_Floor : 1
CodecID : A_VORBIS
Duration/String : 1h 33mn
BitRate_Mode/String : Constant
BitRate/String : 64.0 Kbps
Channel(s)/String : 2 channels
SamplingRate/String : 48.0 KHz
Compression_Mode/String : Lossy
StreamSize/String : 42.8 MiB (1%)
Title : Commentary
Encoded_Library/String : libVorbis 20090709 (UTC 2009-07-09)
Language/String : English

Any suggestions.

[jagabo]

Import the DTS track into Audacity (you need the ffmpeg source filter). Downmix to stereo. Export as AC3. Use MMG to mux the tracks.

[Han Solo1]

Thanks. But I did something different. I took audioconverter and converted the 6 ch audio to 2 ch which was then remuxed by audioconverter. Then I took MKVextract and demuxed all streams. I then took the 2 ch vorbis stream and used audacity to convert it to ac3. Lastly I took the new 2 auido streams both of which are 2 ch by now and remuxed them with the video stream to create a playable mkv on my lcd tv.