Ok, here it goes....
Say you have a file called movie5.mkv.... From the command line, run the following:
Typing that on my computer results in the following:
Code:
+ EBML head
|+ EBML version: 1
|+ EBML read version: 1
|+ EBML maximum ID length: 4
|+ EBML maximum size length: 8
|+ Doc type: matroska
|+ Doc type version: 2
|+ Doc type read version: 2
+ Segment, size 106828593
|+ Seek head (subentries will be skipped)
|+ EbmlVoid (size: 187)
|+ EbmlVoid (size: 4096)
|+ Segment information
| + Segment UID: 0xbb 0x91 0xd8 0x17 0x1b 0x2c 0x4c 0x51 0xca 0x2c 0xd7 0x52 0x06 0x1d 0x33 0x6d
| + Writing application: HandBrake 0.9.4
| + Timecode scale: 1000000
| + Duration: 267.267s (00:04:27.267)
|+ Segment tracks
| + A track
| + Track number: 1
| + Track UID: 254519045
| + Track type: video
| + Lacing flag: 0
| + Codec ID: V_MPEG4/ISO/AVC
| + CodecPrivate, length 44
| + Default duration: 33.367ms (29.970 fps for a video track)
| + Default flag: 1
| + MinCache: 1
| + Video track
| + Pixel width: 526
| + Pixel height: 296
| + Display width: 526
| + Display height: 296
| + A track
| + Track number: 2
| + Track UID: 1116757863
| + Track type: audio
| + Lacing flag: 0
| + Codec ID: A_AC3
| + Language: und
| + Default flag: 1
| + Audio track
| + Sampling frequency: 48000
| + Channels: 2
|+ Cluster
Now, knowing that information, we can see that the audio we want to extract is located on track 2, and it is encoded as AC3. From here, we can now do the following:
Code:
mkvextract tracks movie5.mkv 2:audio_track.ac3
From here, you can convert it using whatever you would like. Hope this helps.
Cheers,
Josh