They don't just have the end-goal of producing a bit-perfect PCM stream, they both do produce a bit-perfect PCM stream. There is no problem with the FLAC lossless codec or its implementation. I know, I've tested it, and I've verified the algorithm and the underlying code. The digital stream coming from a FLAC file isn't just supposed to be identical to the WAV, it is identical, and provably so.

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Quote WAV exceeds the audio quality of uncompressed FLAC by a margin of 10% or so.

This is scientifically impossible. Were there a failure in the FLAC decoder or in the FLAC codec, the bitstream going into the DAC would differ. It does not, ever, 0% of the time, once again, provably beyond a shadow of a doubt.



Experienced EE hereIs there such a thing as bug free software? I'm rather shocked anyone would consider flac or any codec bug free. I assume your findings with flac is limited to a small subset of tests, but please do post your results, would be interesting to see. I assume you are not aware about Flac's changelog and their bug tracker that can disprove your outcome. There's several bugs there and that's not even the complete stack, so who knows what other bugs exist upstream or downstream of the codec! Every codec is bound to have bugs even if the algorithms, mathematics and provability are sound... Even how the software is compiled can introduce bugs which is why you see a big push for integer only compiles for these codecs.I have experience issues with ALAC files on the BDP-1 that doesn't exist with other players. These issues include hangs partway through a track and sometimes would pops/glitches between tracks and all reproducible. Clearly some issue with ALAC and the BDP. You can google about the quality of various AAC codecs and the issues there, but that is lossy format and will never be bit-perfect so might be a little uninteresting.A broader set of regressions with various hardware and software combinations will indicate there are bugs....Sure in academia where everything is ideal, you can formally prove they are equivalent, but in the real-world, there's a few more twists and turns. I agree WAV, AIFF, ALAC and FLAC should be bit-perfect, but a difference might indicate issues, and yes it very well could be PEBKAC, but could otherwise indicate an actual issue for a given scenario. My first hand issues with the ALAC files on the BDP does make me question all formats and all devices now. I even greatly questioned FLAC for a spell since I had ALAC and FLAC intermixed. I don't think any less of ALAC, and don't even have an issue using it on other devices, I just won't use it with the BDP until firmware is updated that has an upgraded codec. Even Squeezebox users have reported issues around various codecs and how everything gets converted to FLAC before streaming.There are a few manufactures that will provide a test file or test cd that is used in conjuction with the DAC to test the quality of the transport. (I believe you can do this with an HDCD if your DAC indicates it) That's pretty nifty test, it's not a complete test by any means, but useful nonetheless. Out of the several thousand ALAC files I had, very few caused the hang or the glitches between tracks, we are probably talking less than .2% of a hard failure-rate that would easily fail any bit-perfect test for a transport. Instead of debugging this further with ALAC, I just opted to switch to an uncompressed and more mature format. Using the notion that all lossless formats are bit-perfect, assuming no bugs, I did switch to AIFF since it supports tagging.Now why would one feel that one lossless format is X% better than another, vs my experience where there was a huge failure in playback? I think the squeezebox users probably could shed some light on this too. And the OP is comparing flac:uncompressed to wav and aiff, so that's even yet a closer file format. Perhaps it has to do with features like volume normalization with the playback (BDP is suppose to have that off with MPD) that is only enabled for one codec? Perhaps there is a higher CPU load with one format over another burning more watts that could be raising the noise level.... tons of little possibilities... I would agree that it's highly unlike there is an actual difference between the uncompress lossless formats, but I also don't mind scratching my head pondering why it could be different.