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Topic: Compression calculators - do they exist? (Read 4331 times) previous topic - next topic
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Compression calculators - do they exist?

Anyone know if such a thing as compression calculation tables exists?

For example:

I have 100Gb of WAV files and would like to convert to MP3.

If I encode at 320, what file size will I end up with?

Like wise, if I encode at 256 what will the size be?

And how about FLAC - what size would that reduce to (sorry, I know this is the MP3 forum but not worth posting again!).?

If nothing definitive exists, can anyone give me some rough estimates...?

Thanks
Nick

Compression calculators - do they exist?

Reply #1 –
For CBR, the file size estimation is fairly easy.

If you have 100 GB of stereo WAV files at 16-bit, 44.1 kHz (1411 kbps), you can just divide 100GB by 4.409375 (1411 kbps divided by 320 kbps). Ergo, you'll need roughly 23 GB. If you add large album artwork, you may need 23.5 to 24 GB.

For 256 kbps, you'll need 100/(1411/256)=roughly 18GB.

Because FLAC does not utilize a constant bit rate, any type of estimation would be somewhat futile, but others may be able to point you in the right direction to obtain a "ballpark" for the type of content you'll be compressing.

Compression calculators - do they exist?

Reply #2 –
Your 4.409375 looked quite a bit odd, especially since you've only specified the uncompressed bitrate with 4 significant figures.  For 320kbps, 4.41 is actually the correct figure (44100*32/320000).  This doesn't change your GB figures, though.

For a ballpark estimate with flac, I think 65% of original size should be pretty good.  It will smaller with mono tracks or classical music, larger with modern metal music.

Compression calculators - do they exist?

Reply #3 –
My library of 10960 tracks averages 880kbps in FLAC and 191kbps in LAME -V2.

Compression calculators - do they exist?

Reply #4 –
I posted these values in an older thread, but am happy to repost here to save lookup time.

(1.0 MB = 1,000,000 bytes)

Encoding at 128kbps bitrate yields about 1.0 MB data per minute of audio.

Encoding at 192kbps bitrate yields about 1.5 MB data per minute of audio.

Encoding at 256kbps bitrate yields about 2.0 MB data per minute of audio.

Encoding at 320kbps bitrate yields about 2.5 MB data per minute of audio.


Thus, a typical 4 minute song will be:

about 4 MB if encoded at 128kbps bitrate.

about 6 MB if encoded at 192kbps bitrate.

about 8 MB if encoded at 256kbps bitrate.

about 10 MB if encoded at 320kbps bitrate.


Furthermore, every 1 GB (= 1 billion bytes) or 1000 MB of WAV data will encode to:

about 90 MB of MP3 data @ 128kbps bitrate.

about 136 MB of MP3 data @ 192kbps bitrate.

about 181MB of MP3 data @ 256kbps bitrate.

about 227MB of MP3 data @ 320kbps bitrate.

NOTE: This is assuming a standard 44/16/2 WAV file such as those generated by ripping redbook audio CDs.

Compression calculators - do they exist?

Reply #5 –
Just what I was after! Thanks.

Supplementary question:

If I convert my 100GB of WAV to MP3 320CBR (I know, it's overkill) but then decide I need more space at a future date, can I convert from 320CBR to say, 256VBR without any trouble (retaining all meta data etc)?

Or would I be better off going back to my WAV archive and starting again?

Or is there no difference?

Compression calculators - do they exist?

Reply #6 –
Quote from: Nick777VVV on
can I convert from 320CBR to say, 256VBR without any trouble

Converting from a lossy source (such as MP3) to another lossy source, even if it's the same format, causes further losses in quality, so it's not recommended. Of course, you could do it without much trouble, but you'd be better off converting from a lossless original.

Speaking of a lossless source, converting your WAVs to a lossless format such as FLAC or Wavpack will compress them to about 75%-80% of their size, saving you some space. Not to mention they support metadata. Not sure how you are able to "tag" your WAVs, if at all.
UED77
wavpack 4.50 -hx3; lame 3.97 -V4 --vbr-new

Compression calculators - do they exist?

Reply #7 –
Quote from: Nick777VVV on
Just what I was after! Thanks.

Supplementary question:

If I convert my 100GB of WAV to MP3 320CBR (I know, it's overkill) but then decide I need more space at a future date, can I convert from 320CBR to say, 256VBR without any trouble (retaining all meta data etc)?

Or would I be better off going back to my WAV archive and starting again?

Or is there no difference?


So what is your time worth? You can get a 500GB drive for $70, 1TB for $100 and 1.5TB for $130 and not have to deal with any of this. Even if it's 100% automated, it's going to take some time to process 100 GB. I vote for (and use) FLAC at around 65% and have all options available later if needed.

I consider FLAC / WAVE files to be like film negatives - not to be handled. While I down-res photos to email, I never toss the original files.

G²

Compression calculators - do they exist?

Reply #8 –
A long time ago I found a tool called "Bitrate Calculator version 1.2" on http://www.telos-systems.com/
The developer off the tool was so kind to implement some of my wishes and send me a new version.
I never have found a newer version than 1.2 on their site.
So here is an updated version of that tool: http://forum.netjukebox.nl/share/brcalc_v1.4.zip