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Compression Problem

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Hi

I'm running the personal edition on XP sp3 and using it to back up files and folders to a second (smaller) hard drive, leaving ATI compression rate on default. On my latest backup I realised that the 200GB hdd was filling up so fast that it would soon be insufficient.

The files & folders I back up currently stand at 152GB but the combined incremental TI images are 150GB - making a compression rate of just over 1%.

I found an earlier thread regarding this re. ATI 2010 in which it was suggested that the problem might be that already compressed files are unlikely to be compressed any further during backup. However, I have around 100GB of uncompressed Wave files (and this figure is likely to increase significantly over coming weeks). If I have understood compression rates correctly, the TI images should total something in the order of 120 - 130GB (assuming the remaining files are mostly jpegs, mp3s etc)?

Does anyone have any idea why I'm not getting any real reduction?

Thanks

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mvp

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WAV is a container that can contain either uncompressed audio or compressed audio. Do you know that yours are uncompressed? You might try zipping a few to see if they compress further.

Yes, ATI uses compression. For an average set of user data and system files, IIRC I think it compresses around 60%.

My C: partition is about 25 GB, and its .tib archives at highest compression end up about 8 GB.
When I image my entire drive, excluding music, it's around 36 GB and the .tib archive ends up about 14 GB.
When I image my entire drive, including music, it does't compress much as my music is mostly already-compressed FLAC.

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Thanks for that.

I've zipped up a folder of this material and it compressed by about 50%. As a further test I then backed up the same folder on it's own (2.2GB) and it compressed to about 78%, so why there's practically no compression when this folder and others like it account for the majority of my full backup is a bit of a mystery.

When I get the time I may have to delete the existing .tib archive and try again from scratch; although I've double checked and I didn't mess up the settings and end up with no compression set, so I can't imagine it will make much difference.

If nothing else it has concentrated my mind a bit. Given the rate that I am adding to this data it may be neccesary to get a new hard-drive so I can do a full disc backup.

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mvp

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I can't explain why you're not seeing compression in the .tib archives. I've never heard of this issue.

ADDED: Wait a sec, I see that you wrote "combined incremental TI images". I'm not sure what that means, exactly, but you can't just add up all the incrementals in a chain and expect the size to compare to a compressed full backup image.
Try creating a full backup image, either of the whole drive or just files/folders, and compare the size of that .tib to the original.

BTW, why do you store your music as WAV? You could use FLAC, which is open-source, to save a lot of space and allow for metadata tagging. (WAV can be tagged, somewhat, but the format isn't standard and so is not well supported in software and players.) There's no advantage to WAV over FLAC, you just spend disk space and lose proper tagging.

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[quote=tuttle]

I can't explain why you're not seeing compression in the .tib archives. I've never heard of this issue.

ADDED: Wait a sec, I see that you wrote "combined incremental TI images". I'm not sure what that means, exactly, but you can't just add up all the incrementals in a chain and expect the size to compare to a compressed full backup image.
Try creating a full backup image, either of the whole drive or just files/folders, and compare the size of that .tib to the original.[/quote]

Did that and got about an 82% compression rate overall, which is certainly an improvement - but if what you say is true and that this will not neccesarily be reflected in a folder with incremental backups then I'm going to have to do a full backup every week in order to ensure that I have enough disc space for the job.

Which brings me to a second question - what are the implications of choosing a higher compression rate in Options? Is there a greater risk of data corruption or recovery failure or does it just take longer? If it is the latter, then it will still be quicker than full backup everytime.

[quote=tuttle]

BTW, why do you store your music as WAV? You could use FLAC, which is open-source, to save a lot of space and allow for metadata tagging. (WAV can be tagged, somewhat, but the format isn't standard and so is not well supported in software and players.) There's no advantage to WAV over FLAC, you just spend disk space and lose proper tagging.

[/quote]

My aim is to get as close to pure analogue recording as possible while gaining the portability of digital files and I admit my logic may be faulty as I'm no progammer. Presumably any sound recording software is going to have some influence, however minimal, as it 'interprets' the sound as a waveform. I presumed that compressing that file would effectively be taking another step further away from the analogue sound. Furthermore, FLAC isn't a native format to the software I use (although there is a 3rd party plug-in available nowadays).

TBH, as long as I have the disc space to continue that way it doesn't really matter if I'm wrong - it's only finding enough space for backups that has raised the question in the first place & following that logic a disc of at least equal size allowing for uncompressed backups would seem the best option.

Thanks for your replies anyway - they've been helpful.

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mvp

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1. Re. compression. No, AFAIK, there's no risk to higher compression. It just takes more time, but uses less disk space. I routinely use highest compression.

2. Re. audio formats. You misunderstand how lossless formats work. All true lossless audio formats (WAV, FLAC, APE, ALAC, etc.) are all lossless, so are all identical to source. No, there is no "interpretation" of the waveform. No, lossless compression removes nothing, it's like losslessly zipping up files: when you unzip them, they are identical to the originals.

WAV has zero benefits for such use. It eats disk space and doesn't allow standard metadata tagging. It doesn't sound any better than FLAC, APE, ALAC or other lossless formats, which is why those of us who archive lossless audio don't use WAV. Pick a lossless codec that is supported by your use: you'll save diskspace and gain the benefit of proper tagging.

I rip to FLAC and use that for certain things, but in iTunes I use ALAC. Both are lossless, both are identical to the corresponding WAV and to the original audio, but well supported and with proper tagging.

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Thanks tuttle - guess I should have asked that question in the first place.

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I know it may be late for your question but I  just solved the problem, so I'd like to share my experience with more friends. I compress my audio files from http://www.videoconverterfactory.com/tips/compress-wav-file.html WAV is one of the most commonly used formats for music enthusiasts, which stores two-channel LPCM audio sampled 44,100 times per second with 16 bits per sample. So the quality of the WAV file is almost the same as CD 44.1 kHz, 16-bit stereo, hence, WAV is known as the closest lossless music format. Uncompressed WAV files always have a large size, so file sharing of WAV files over the Internet is uncommon.