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Hello David

On 27/10/06, David Seubert wrote:
> Tom and Don el al.,
> This argument against compression has been around as long as there has
> been data compression and it doesn't really hold up. Data corruption
> can corrupt any data, compressed or uncompressed. Data corruption is
> an argument *for* backing things up or running checksums, not
> *against* compression.
> Lossless compression is so widely used now that it isn't an issue to
> argue over anymore. Every PNG and GIF file on the internet is
> compressed losslessly and we aren't worrying about corruption there.

Ever tried to rescue an image from a dodgy floppy disk?

The decompression routine can't get past the wrong bit.

Now, these are small files, so if there are (say) 40 faults on a CD,
almost all the GIFs will be OK. But if there are two 300 Meg audio files
on that disk, they will probably both be unusable.

OTOH if there are two WAVs or AIFFs, there will be 40 little clicks.

Even for images, IMO compression is risky for any archive. An
uncompressed TIF would be safer.

> TIFF has LZW compression built in and it is the archival image
> standard. 

LZW compression is optional for TIFFs.

> The issue is that it has to be implemented correctly and
> widely supported. I don't think FLAC is there yet. I'll be interested
> in investigating mpg4als which Bob Olhsson mentioned.
> Off the top of my head I'd say these would be the basic requirements
> for a lossless compressed format to take off in the audio world and
> supplant wav as the standard format for archiving:
> 1) Files should inflate when opened in *all* the commonly used audio
> editing tools (no need for helper aps). Can you imagine if you had to
> decompress a jpeg in a helper app before opening it in Photoshop? 

I can imagine it easily. It is the kind of thing that happened when
JPEGs first appeared on the scene.

> 2)
> Transparent support of wav/BWF metadata both on inflate and on
> deflate. In other words, your metadata doesn't get screwed up when you
> open a file in another app, make changes, and then save as compressed
> again. 3) Files play back on/in *all* standard consumer playback
> hardware/software (itunes, ipods, real, winamp, etc)
> Anything come close yet?

I would ask a different question. Are we likely to be using more than 24
bits, 192 KHz sampling, and six channels?

Are current storage media big enough and cheap enough to archive such
files uncompressed? Or will they be in the next five years?

Don Cox

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