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Digi Audio/Data Conversion Question
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| zenperson |
So, who can tell me how much recording time I would get from an 18 Gig. hard drive with a 24 track project sampled at 88.2 kHz and 24 bit resolution....
If you can get the answer, tell me how you solved it... :D |
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| Atlantis-AR |
A 24 bit sample is 3 bytes (24 / 8).
As you're probably working in stereo, you'll want to multiply this by 2 (2 channels) to get 6 bytes (3 * 2) per sample.
Because there are 88,200 samples per second, that's 529,200 bytes (6 * 88,200), or 517 kilobytes (529,200 / 1,024) for every second of audio.
As there are 24 tracks, that gives 12,403 kilobytes (517 * 24), or 12 megabytes (12,403 / 1,024) per second for the entire project.
You have 18 gigabytes, or approximately 18,432 megabytes (18 * 1,024) of space, meaning you can store 1,536 seconds (18,432 / 12), or approximately 25 minutes (1,536 / 60) of audio if you store a 24 track, 24 bit project at 88,200 kHz, stereo. |
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| zenperson |
So, when you take the 3 bytes and multiply times two for stereo, would you only be doing this to determine the recording time?
Like, if you had 24 tracks @ 50 minutes, 88.2 kHz sample rate and 24 bit resolution, you'd just take:
32 tracks * 3 bytes-sample * 88,200 samples-sec = 6,350,400 bytes-sec
Then, you'd take 6,350,400 bytes-sec / 1024 / 1024 = 6.056 MB-sec
Then 6.056 MB-sec * 3000 seconds = 18168.6 MB or 17.7 GB
Just wanna be clear on the stereo portion of the sample rate.... |
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| Atlantis-AR |
| Well it depends on if you're recording in stereo or mono. A mono sound (whether recorded or stored on your computer) takes up half the space of a stereo one, which is where the 6 megabytes per second you've calculated comes from (I assume the 32 tracks should be 24, by the way). |
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| Atlantis-AR |
I think I may have confused this more. Just remember that a stereo sound is made up of 2 channels, hence the reason for multiplying by 2. Even if you're going to record in mono, you'll probably still want to convert to stereo (or it's likely the sequencer will do this internally) before applying effects such as reverb.
Stereo doesn't have anything to do with the sample rate, other than that you would multiply by 2 because there are 2 channels. So each channel has 88,200 samples per second when using a sample rate of 88,200 Hz (I see I made a typo in my first post too).
So it really depends whether your project will be in stereo or mono, but at most you will be able to hold 25 minutes of audio, or 50 minutes if the tracks are all mono. |
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| zenperson |
Thanks for the help... We're learning these conversions in my digital recording class and that one totally threw me, although i did find out that it's Mono, not stereo, for the sake of our exercises...
Thanks again mate! :) |
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