Chrobrego wrote: > I don't buy the bit-perfect statement as a scientific fact. What about > the timing in this reasoning? Should we also state that a cd should > always sound the same in whatever hardware it is read only because it > contains the same bits in both situations? > > The reality is instead that there IS a process difference between "AIFF > to sound" and "ALAC to sound" chains. If the ALAC file was fully > transformed to AIFF before it follows the same decoding then that would > be a different story. But that is not the case with those systems which > manage the transcoding in real-time. > > So the real question is if that results in audible difference or not. > And I can believe that sometimes yes, sometimes not. And that may > depends on persons ears as well. We need to respect each other views and > differences, no need to have an ideological conflict there. > > BTW: I am using flac so don't categorize me as audiophile :-)
Let's not confuse what might or might not plausibly happen -after- a losslessly compressed file is decompressed with the fact that the compression/decompression itself is bit-perfect. I think you make this point yourself when you say "If the ALAC file was fully transformed to AIFF before it follows the same decoding then that would be a different story.", but I just wanted to make it clear :) However, I do still differ on the "real-time" question. There is always buffering, so as long as your compressed file is being decoded fast enough to fill the buffer with the PCM stream faster than the audio output subsystem is counting out the bits to the DAC, there is no logical difference between full decoding prior to playback, and what might be called "just in time" decoding. If the just in time approach fails, the playback system is seriously broken, and playback will simply stop. One way of thinking about this is as follows: we could play a track as it is being decoded from FLAC, for example. Or we could decode one track completely to an uncompressed file on disk, then play that -at the same time as- decoding a second track to disk. What is the difference? The audio output system cannot "know", still less "care", whether the bits it hasn't yet received (and doesn't yet need) are part of the same, or a different, track. Of course, there might still be a possibility that the different processing requirements of decoding various formats versus simply reading an uncompressed PCM file into the audio buffer might upset the audio stream to the DAC in some way. This might include jitter, or it might involve electrical noise, not part of the digital stream, being injected. Both have been postulated in many threads on this forum. But this is where Archimago's previous reply comes in - even if it is happening, can we measure it?, and can we hear it? I would agree with Archimago that any such effects which approach anything near audibility indicate a broken system, and that if their audibility can be demonstrated through double blind testing, it is time to examine the system, rather than agonise over which (if any) lossless compression stream to use. ------------------------------------------------------------------------ darrell's Profile: http://forums.slimdevices.com/member.php?userid=13460 View this thread: http://forums.slimdevices.com/showthread.php?t=98630 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
