I have several blu-rays that have audio in 7.1. Most of these are encoded DTS-HD MA, one is encoded straight LPCM. In the thread above it was concluded the strange channel layout made it difficult to convert from DTS-HD to FLAC. So to investigate my options with converting with another tool, I had MakeMKV just mux the DTS-HD MA track into the output. Strangely, even just copying the stream resulted in a 5.1 audio track! ffprobe showed:
For some reason, 2 channels were not making it to the output.Stream #0:2(spa): Audio: dts (DTS-HD MA), 48000 Hz, 5.1(side), fltp, 1536 kb/s
Metadata:
title : Surround 7.1
Wanting to eliminate the possibility that this was due to the strange layout, I looked for other discs that had 7.1 audio. I found that the TV show Weeds season 2 was released with 7.1 LPCM, and season 3 was released with 7.1 DTS-HD MA. I used MakeMKV's "Default" conversion profile to rip an episode from each, selecting every possible thing to mux into the output.
The season 2 episode seems to copy the 7.1 LPCM audio correctly. mkvinfo shows the track codec ID as "A_MS/ACM" and ffprobe shows:
Stream #0:1(eng): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 7.1, s16, 6144 kb/s (default)
Metadata:
title : Surround 7.1
The season 3 episode has the same issue the blu-ray with the odd layout had: it seems to throw away channel data. ffprobe shows:
Stream #0:1(eng): Audio: dts (DTS-HD MA), 48000 Hz, 5.1(side), fltp, 1536 kb/s (default)
Metadata:
title : Surround 7.1
I suppose this could be a limitation in ffmpeg's ability to utilize DTS-HD MA (either while muxing it from MakeMKV or while examining the file afterwards). I'm using MakeMKV 1.8.13 x64 on Linux. It's compiled against ffmpeg 2.3.3, ffprobe is from that same compilation. Unfortunately I don't have any 7.1 TrueHD discs, to see what that might do.
Is there an error, with 2 audio channels getting thrown away? Is ffprobe simply mis-reading the files? ffmpeg supports 7.1 audio according to here. I don't know what's wrong here...
Any help is appreciated, if I've left out important details I'll do my best to provide them.