I have made great progress in the last two weeks. Therefore i am now able to present some first compression results for multi channel audio.
It wasn't easy to obtain appropriate test files for the codec tuning. And since multichannel audio files are quite big, each test run took a lot of time. That's quite annoying if you know you have to repeat this procedure for many other codec variations you want to try. It remined me of my very first attempts in lossless audio compression when i owned a i486...
Here comes the comparison:
TAK FLAC WavPack
Mode -p2m -p4m -8 -hhx
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DXD (mostly): 24 bit, 96 khz, 6 channels (5.1)
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m6_96_a 41.69 41.40 43.96 44.11 Samples from 2L - the Nordic Sound
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DVD-A (PCM): 24 bit, 96 khz, 6 channels (5.1)
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m6_96_b 53.77 53.61 55.85 56.56 Eagles - Hotel California
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DTS: 16 bit, 44 khz, 6 channels (5.1)
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m6_44_a 30.22 29.38 33.17 32.42 Al Di Meola - Consequence Of Chaos
m6_44_b 41.69 41.41 45.04 44.35 Pink Floyd - The Dark Side Of The Moon
m6_44_c 41.28 41.06 42.69 42.18 Roxy Music - Avalon
m6_44_d 40.18 39.76 43.23 42.09 The Police - Every Breath You Take
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Vinyl-Rip: 24 bit, 96 khz, 4 channels (quadro), denoised and decklicked
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m4_a 65.46 65.36 67.19 66.84 Pink Floyd - Wish you were here
m4_b 62.30 62.22 63.94 63.42 Santana - Caravanserai
Compression ratio expressed as percentage of the original file size. Each data row represents a complete album or a collection of files.
I couldn't test Monkey's Audio or Optimfrog, because both seem to have no support for multichannel audio. I didn't try a stronger mode for WavPack, beacuse this would have taken too long (4-5 hours were enough...).
I have tested only TAK -p2m and -p4m, because all other presets still have to be constructed (from the many internal encoder options) for optimum performance, what will require a lot of further testing.
I have some more ideas to further improve the compression. Some of them already have been tried and seem to work well. But this is getting very complex and time consuming. I have deceided, to stop the evaluation for now and to start to work on a release. Ok, some minor tuning might take place...
I am quite happy with the current results.
Maybe this helps to get a bit of the picture.
This was very helpful! Thank you.