Meanwhile I did some hearing tests and would use --tvbr 63 with qaac when the source is lossless Stereo. I cant hear any difference when encoding with higher quality than 63. I tested some Stereo Audio CD Rips.
Still, the question remains what quality setting in qaac makes sense when coming from lossy AC3 384kpbs 5.1. As I understand so far, you have 5 full channels and 1 channel at 1/3 the bit rate of the full channels. That would mean for 384kbps 5.1 there are 5 channels /w 72 kbps and 1 channel with 24 kbps. Is that correct? If so, how does it relate to the choosen quality setting in qaac? --tvbr 63 means about 128 kbps. Does it mean 128 are devided by 5.1 channels, meaning 5x 24kbps and 1x 8kbps? Well, I just did a test with an AC3 384kpbs 5.1 (135 MB) and
eac3to.exe my.ac3 my.wav -normalize
qaac64 my.wav --ignorelength --no-optimize --no-delay --tvbr 63 --quality 2
which resulted in a M4A 5.1 (100 MB) for which MediaInfo claims to find an overall bitrate of 296 kbps. Makes me wonder, I'm still trying to get the big picture here.
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