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Uses for Wavpack hybrid mode?
floyd
post Jul 8 2002, 10:56
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I'm in no way dissing Wavpack or its dev(s) with this question, but here it is: what practical use is wavpack's hybrid mode? The only use I can imagine is keeping the lossy files on HD (for playback) and burning the correction files to disk (for backup). But you will likely only be able to burn 2 cds worth of correction files to 1 cd. Am I missing something? Also the lossy file + the correction file appeared to be larger than an extra high lossless file alone.
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bryant
post Jul 8 2002, 18:39
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The one area that I think that the hybrid mode provides something that isn’t available anywhere else is in high-resolution audio (i.e. > 16/44) which is a big interest of mine. For example, I have been using it to compress 24/96 audio (which is 4608 kbps uncompressed!) to around 1000-1200 kbps while still retaining the advantages of the higher resolution.

For someone just interested in CD audio I think it can still be useful in some situations, but everyone has to make their own decision about which format to use for what purpose. Obviously the somewhat primitive seeking and tagging capabilities of WavPack (and the lack of cross-platform or hardware support) must be taken into account.

As an example, I sometimes backup CDs with both the lossy and correction files burned to CD-R. If I want to burn an audio CD, I can use both files for lossless, but if I just want to play it on the computer I just copy the [320 kbps] lossy files to the HD. This takes somewhat less space and is much faster to create than a pure lossless plus some other lossy format, and should only be a couple percent bigger than pure lossless alone. In a sense, the lossy file is free.

For downloading music, someone could download the lossy version first and play that until they decided whether or not they wanted the lossless version. If they wanted the lossless later, they wouldn’t waste the time they had already spent downloading the lossy version.

I would not worry too much about offending anyone with comments like yours. I created the hybrid mode because several people thought it might be neat and I figured it wouldn’t be too hard. I am really happy with the results, but ultimately the users will decide whether or not it makes any sense. I appreciate anyone trying it out and offering comments or suggestions, whether they’re negative or positive. Now, if you say something bad about my cat... smile.gif
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floyd
post Jul 8 2002, 20:45
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haha, no way, your cat is cool, bryant smile.gif

I think hybrid mode is an interesting concept, for sure. I just couldn't get my head around what the main use was.

I'm thinking maybe if lossy mode was mp3 rather than a proprietary codec, then you could use the lossy on your portable, and save the correction files on your hd. I dunno, just a thought wink.gif
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bryant
post Jul 9 2002, 16:52
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QUOTE
Originally posted by floyd
I'm thinking maybe if lossy mode was mp3 rather than a proprietary codec, then you could use the lossy on your portable, and save the correction files on your hd.
You’re right, that would be ideal. Unfortunately I don’t think something like that is possible because of the fundamental difference between how WavPack’s type of lossy mode works compared to a perceptual codec like MP3.

WavPack’s lossy mode attempts to recreate the original waveform as closely as possible given the specified bitrate, and I believe that it is very pretty close to 100% efficient at doing this. In fact, at the same bitrate, WavPack will more faithfully recreate an audio file (i.e. less RMS difference sample by sample) than any of the perceptual codecs. So, the amount of information required for the “correction” file is kept to a minimum.

On the other hand, perceptual codecs attempt to recreate the original audible sound as closely as possible, which may or may not have anything to do with the original waveform. This is obviously a more important criteria when creating a transparent lossy codec, but makes them much less suitable for a lossless hybrid.

At least that's what my cat thinks. rolleyes.gif
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rjamorim
post Jul 9 2002, 17:32
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Ogg + Flac as lossy + recovery has already been suggested.

http://www.hydrogenaudio.org/forums/showth...=1088&highlight

Unfortunately, it seems it's not as efficient as WavPack's lossy + recovery scheme (at least, the way it was tested)

Regards;

Roberto.


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Get up-to-date binaries of Lame, AAC, Vorbis and much more at RareWares:
http://www.rarewares.org
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bryant
post Jul 9 2002, 23:09
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Hey, thanks Roberto, I forgot all about that thread!

Yeah, you're right, this has been discussed before (and at great length!)
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