Comments

MJhig wrote on 9/19/2003, 2:01 PM
>>>>It isn't something that I as an engineer only making albums would want to mess with is it? <<<<

Well that's hard to say. Do you want to reduce the size of a *.wav/project to approx. 1/2 the size with no loss?

*.pca is SF's lossless compression format. You can use *.pca in Vegas or Sound Forge, edit, apply FX etc. just like *.wav.

Simply, it's just like working with and saving *.wav only at 1/2 the file size on the positive. The negative is it's proprietary to Sonic Foundry/Sony.

MJ
PipelineAudio wrote on 9/19/2003, 4:30 PM
well then, two follow ups.

1 Are we SURE that its lossless?

2. As a compressed format wouldnt it take more cpu to use x amount of tracks of pca as the same amount of tracks of wav?
MJhig wrote on 9/19/2003, 4:39 PM
>>>>>1 Are we SURE that its lossless?<<<<<

Sonic Foundry says it is and to my ears it is. If it's not and they lied in the documentation, hopefully they will come clean here.

>>>>2. As a compressed format wouldn't it take more CPU to use x amount of tracks of pca as the same amount of tracks of wav? <<<<<

I'm not seeing this at all but this may be system typical, I'd love to hear from SF on these details. Even more critical to me is I can archive to CD/HDD at half the cost. Who would ignore that?

MJ
Geoff_Wood wrote on 9/19/2003, 6:23 PM
PCA is verifiably lossless. Try it - copy an event. save one as WAV, one as PCA. Reload the PCA one and compare (invert/add) to the original...

Just like ZIP (or WaveZip) is lossless. Same principle.


geoff
bgc wrote on 9/19/2003, 9:47 PM
1. lossless like a zip file input = output.

2. if vegas is streaming from a compressed .pca file then it would need to decompress the audio data before processing it in Vegas' audio engine. this would add some overhead, but depending upon the process it could be negligible. peter would be the best to provide insight on that.

Might be worth making a 24 track test file using wav files and pca versions of the waves and see if the cpu needs differ at all.

B.
MarkWWW wrote on 9/20/2003, 7:46 AM
1. PCA is definitely lossless - you can easily verify this for yourself if you have any doubts. Just take any WAV file, save it as a PCA, then open the PCA file again and save it as a second WAV. Compare the two WAVs in SF (subtract one from the other) and you will find that the difference is zero, i.e. the files are identical.

2. It does take a bit more CPU horsepower to deal with PCA than with WAV, but it's not too much of a hit - less than it would be with MP3 for example.

You can find some information from SoFo on this subject in the thread that starts at http://www.sonicfoundry.com/forums/ShowMessage.asp?MessageID=92096&Page=0 This thread was initially about W64 but went on to deal with PCA too.

Mark
Rednroll wrote on 9/22/2003, 5:51 PM
This post interested me and had something to do with things I was investigation at work. I generated a 1 minute long 44.1Khz/16bit Stereo Pink Noise and saved that pink noise in a numerous amount of compression formats with various Kbs compressions. I did frequency analysis of each file and compared it to the original wave file. This was a quick study, so I didn't go into before/after stereo seperation, but the frequency response information is definately useful. I found PCA was lossless, but the amount of space you saved was really neglible compared to other compressed formats. I'm going to post the data in a new post, so others can view it.

Red
chrisgrand wrote on 9/22/2003, 6:09 PM
I believe that the assumption of the negligable difference is due to the nature of the pink noise. It is very 'busy', therefore not very 'compressable'. Much like zipping a wav file. Not enough patterns for the engine to smash.

In regular use I have seen anywhere from about 25% to about a 75% reduction in file size.