Re: questions about lossless codecs
Reply #9 – 2021-07-20 15:48:46
With lossywav & Dualstream a vbr 'model' decides how much and where the noise goes - usually into the silent bits otherwise its masked by louder bits. At higher setting its buried in the noisefloor. Dualstream should give the highest quality per bitrate - objectively anyway. Wavpack doesn't yet apply a vbr estimation, instead working like cbr . However, The noise moves in infinite steps up and down according to signal and this usually gives good results esp at higher bitrate like 400k. The noise is applied to least important bit etc, noisefloor etc without the precisions of lossywav. At higher bitrates of 400+ this becomes less of an issue imo and at some point they converge and wavpack may even exceed lossywav objectively as lossywav is limited to 6db steps while wavpack has infinite. Wavpack also use noise shaping by default that works pretty well. It is 'dynamic' staying in the 'shadow' of the signal. This can be overriden to OFF -s0 , Or using a fixed value like s0.5 - that will shape noise higher in the frequency and helps with sharp transients with lots of HF content. These type of signals can pose problems. In most cases these custom overrides aren't required at all though. Joint stereo is used as fixed or as needed if using -x switch. Can be turned off with -j0 but usually not needed to bother with this. So using a sufficient bitrate say 400k and hight quality switches should give you what you are after. Something like -b400hx4 is a good starting point and likely all that is needed. Dualstream offers the highest quality per bitrate compared to wavpack and losswav in addtion to a quality mode. Its also slower but you can use --mode fast --quality 5 and get exactly the same lossy file as vbr will simply tweak bitrate only and retain exact quality. The encoding and decoding will be faster. Downside is playback is currently limited to pc / notebook. But its something to consider if your OK with that. Replies such as this one are more like a quick tutorial, and it is in times like these I wish there were some sort of bookmarking in here. As that isn't the case, this goes straight into my My Pocket feed - properly tagged - so I can refer to it later on. Thanks (again) SK. I'm starting to sound repetitive, I know, but you've notoriously been putting a lot of effort (and time) into your testing, so thanks where it's due, IMO.