Itlan;272649 Wrote: > > Some techweenies did some high end comparison of ripped files versus > the original and they were damn near identical. You can searhc on their > forums and find it under reviews or something.
I'd believe it is actually quite close, but I expect it is technically feasible to recompress the PCM back into an AAC stream that is _identical_ to the original. Probably this could be done by first doing a regular PCM->AAC compression, and then repeatedly decode that AAC file, each time identifying differences and tuning the compressed data until the decompressed output exactly matches the "master" PCM version. In other words, you're doing a kind of search, and you'll know you've found the right input stream when it generates the same output. This may sound like it would be too CPU intensive for practical purposes, but actually I think it's quite feasible and could be done in only a few passes. However, to be efficient it require that the algorithm know a bit about AAC, and have some ability to figure out which way to tweak the stream by comparing the input to the output. So it's a significant engineering challenge, requiring intimate knowledge of AAC. Also this would be done one frame at a time - that's a fairly short signal, and therefore a small search space, so it seems to me that this should be tractable. -- seanadams ------------------------------------------------------------------------ seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=43829 _______________________________________________ discuss mailing list discuss@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/discuss
