24bits are only 14% more information than 16bits, not as much as it looks. I presume the downsampling introduces some noise which compresses poorly (bigger residuals) and pretty much outweighs the advantage. This does not happen with a lossy codec, if the same error tolerance is imposed on each stage: a 5% noise introduction (say) at one stage does not create a problem if a 5% error is allowed to be introduced later to discard the noisiest 5% of the data. So, heuristically I would expect most all the gains of reduced detail to be realised in lossy codecs, and rather little or no space saving with lossless codecs.
Nicholas ----- Nicholas Wilson: [email protected] (ncw33) Site and blog: www.nicholaswilson.me.uk Peterhouse, CB2 1RD • 86 Heath Road, GU31 4EL On 2 December 2010 13:15, scott brown <[email protected]> wrote: > Someone sent me a question late last night and I briefly looked at his file > this morning and couldn't figure out the answer, so I'm posting here. > > A friend has a a ~275MB 24 bit, 48khz stereo wav file of rock music that > when compressed using flac level 8 gives a flac file under 110 MB in size. > When I dithered his file to 16/48 and converted that file to flac, the > resulting flac file was actually 2 MB *bigger* than the corresponding 24/48 > flac file. Does this make sense to anyone? > > He says that his 24/48 files always compress to around the same size as the > same files converted to 16/48 or 16/44.1. I couldn't give him an answer as > to why. > > Does anyone have an answer? > > Thanks, > > Scott > > _______________________________________________ > Flac mailing list > [email protected] > http://lists.xiph.org/mailman/listinfo/flac > > _______________________________________________ Flac mailing list [email protected] http://lists.xiph.org/mailman/listinfo/flac
