Hi Josh, I made some choices for the encoder based upon how quickly the pocket pc could convert files. I think that I chose flac -0 because of this and also I think that I may have increased the buffer already to 4608.
However, I will do some additional testing. The cpu's used are in the ARM family. Xscale (PXA255) as found on the hp 5100/5500 series and 2200 series. The best performer right now is the Dell X50v 624mHz(PXA270), again same processor family. Because this is programmed I/O, media writes contribute largely to cpu utilization. FLAC helps, but it is a trade-off between lowering the amount of data written and the increased cpu requirements for conversion. Gordon > > From: Josh Coalson <[EMAIL PROTECTED]> > Date: 2005/09/27 Tue AM 11:09:22 CDT > To: [email protected] > Subject: Re: [Flac-dev] question regarding compression % > > --- Gordon Gidluck <[EMAIL PROTECTED]> wrote: > > Hi, > > For those of you who don't know, I now have an application on pocket > > pc using flac. Live2496 does realtime encoding while recording. > > Live2496 typically is used to record a digital source using the Core > > Sound PDAudio device. Links are now on the main flac page if you are > > interested in learning more. > > > > I have a question. We have run across a 24-bit file that when we > > record it, flac level zero compression only results in about a 2% > > reduction in the file size. I use flac level zero because we don't > > have the computing power required for (higher level flac) realtime > > encoding on pocket pc's and windows CE. > > > > What is it about a file that would cause such a poor encoding rate? > > hard to tell without a sample. or you could decode and reencode > the sample on another machine with -1 .. -8 switches and post > the compresses sizes, that could also give a clue. > > if there's no way to do -1 on the pocketpc (which is equivalent > to -0 -M and will help with stereo), there are a couple of > tweaks you can try that shouldn't affect the encoding time but > might help for hi-res recording. you could try increasing the > blocksize with -b. -0 defaults to -b 1152, try 2304 and 4608. > > also -0 defaults to -r 2,2; you could try other values like > 1,1 3,3 4,4 ... increasing -r tends to work better with larger > blocksizes. > > what kind of CPU is in it? > > Josh > > > > > __________________________________ > Yahoo! Mail - PC Magazine Editors' Choice 2005 > http://mail.yahoo.com > _______________________________________________ > Flac-dev mailing list > [email protected] > http://lists.xiph.org/mailman/listinfo/flac-dev > _______________________________________________ Flac-dev mailing list [email protected] http://lists.xiph.org/mailman/listinfo/flac-dev
