lossyWAV Development
Reply #904 – 2008-03-04 08:30:30
I take back my previous concerns. With It's much harder to make the quality fall off a cliff... You do realise that you've engineered a kind of crude psychoacoustic model? I wonder how it will sound at 200kbps. Has there been any experimentation on that low of a bitrate? I'm fairly certain it would be inferior to the average mp3, but I starting to get curious as to just how much the bitrate can be lowered... So here's my suggestion. Why not go all the way to the bottom of the bitrate barrel, and tune your way up? That's what Aoyumi did/does with Vorbis, which gave it (literally) the best lossy quality in the world. Apparently, you can scale up the changes you make in the lower bitrates to the higher ones, and all bitrates would end up with the benefit. The point is, it's much easier to catch and tune for artifacts at low bitrates. Once tuned, though, the tuning would apply to practically all bitrates, making all quality levels better...see what I'm saying? There's no way I can abx 350kbps, but if you sent me down to 200, I could, and we can "tune things up." [edit]On a different note, on many files, the difference between -7c and -6c is under 7kbps. This doesn't seem like what was intended... I do not really want to try to go that low.... Some of the albums I've processed using v0.8.0 -7 are coming in at about 280kbps - with no glaring artifacts. I think that the main objectives of the development process have been met (or exceeded) and I am content with the current -7. Overall, as the encoded processed file will carry the file extension of the encoder, I want to make sure that the quality of any processed output will not negatively skew public opinion against the lossless encoder. I too am interested in "how low can we go?" - so I'll post beta v0.8.1 with a revised -nts maximum value. On the -7c / -6c bitrate delta, I think that that means that we are approaching a limit imposed by the combination of the parameters used to maintain quality and therefore it is working perfectly. Always remember, lossyWAV is pure VBR. lossyWAV beta v0.8.1 attached to post #1 in this thread. From a test using my 53 problem sample set:|-----|-----------|-----------|-----------| | SNR | NTS=18 | NTS=21 | NTS=24 | |-----|-----------|-----------|-----------| | 6 | 305.8kbps | 295.2kbps | 287.8kbps | | 7 | 307.3kbps | 297.1kbps | 289.9kbps | | 8 | 309.2kbps | 299.2kbps | 292.3kbps | | 9 | 311.2kbps | 301.6kbps | 294.9kbps | | 10 | 313.6kbps | 304.2kbps | 297.8kbps | | 11 | 316.3kbps | 307.3kbps | 301.1kbps | | 12 | 319.7kbps | 311.1kbps | 305.2kbps | | 13 | 323.8kbps | 315.6kbps | 310.1kbps | | 14 | 328.3kbps | 320.6kbps | 315.4kbps | | 15 | 333.2kbps | 326.0kbps | 321.1kbps | |-----|-----------|-----------|-----------| From which, -snr 15 -nts 18 and -snr 14 -nts 21 might be reasonable. I listened to -snr 6 -nts 24 and it was awful and -snr 9 -nts 24 wasn't much better.... I would consider the lower limit for -snr to be 12 and the upper limit for -nts to be 21.