wretchasketch
Member
I'm recording 7 tracks per song onto an SD card at 24 bit / 44.1 khz. How many minutes of 7 track songs can I get onto one 8mb card? Is there a formula I can plug into or a resource online somewhere I can reference?
recording at 24 bit / 44.1 khz - calculating the space needed
- Thread starter wretchasketch
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jonny deep
Disappointing Member
You do it like this - bits per second equals bit depth multiplied by sample rate (24 * 44,100 = 1,058,400 bits/second) [if working with stereo, multiply this by two]. Divide this by eight to give bytes per second (1,058,400 / 8 = 132,300 bytes/second). Then divide by 1,024 to give kilobytes per second (132,300 / 1,024 = 129.199 KB/second). Then divide by 1,024 again to give megabytes per second (129.199 / 1,024 = 0.126 MB/second). Multiply by sixty to give megabytes per minute (0.126 * 60 = 7.57 MB/min)
You have seven tracks, so multiply by seven to give your total MB per minute (7.57 * 7 = 52.99 MB/minute). To convert from GB to MB you multiply by 1,024, so your 8GB card is 8,192 MB. Therefore it will hold 154.59 minutes (8,192 / 52.99 = 154.59 minutes).
I realise you got the answer above, but this shows how it's done so you can do similar in future.
You have seven tracks, so multiply by seven to give your total MB per minute (7.57 * 7 = 52.99 MB/minute). To convert from GB to MB you multiply by 1,024, so your 8GB card is 8,192 MB. Therefore it will hold 154.59 minutes (8,192 / 52.99 = 154.59 minutes).
I realise you got the answer above, but this shows how it's done so you can do similar in future.
Bobbsy
Boring Old Git
Jonny Deep has given you the maths.
Boring old pedant time....
This is one of those times when the difference between a "b" and a "B" is important (and "m" and "M" for that matter.
In computer related topics, "B" stands for "Byte" which is 8 bits ("b") of data. Similarly, "M" stands for "Mega" which means million; "m" is "milli" which means 1/1000th. So, technically, your card is 8MB (Mega Bytes). 8mb would (if it existed) be 8 millibits (which, as 8 thousandths of a bit doesn't exist anyway).
In this case, we all knew what you meant but there ARE times when specs can be in bits or bytes.
Boring old pedant time....
This is one of those times when the difference between a "b" and a "B" is important (and "m" and "M" for that matter.
In computer related topics, "B" stands for "Byte" which is 8 bits ("b") of data. Similarly, "M" stands for "Mega" which means million; "m" is "milli" which means 1/1000th. So, technically, your card is 8MB (Mega Bytes). 8mb would (if it existed) be 8 millibits (which, as 8 thousandths of a bit doesn't exist anyway).
In this case, we all knew what you meant but there ARE times when specs can be in bits or bytes.
jonny deep
Disappointing Member
I think we've also all assumed it is an 8GB card, rather than an 8MB card, which wouldn't hold very much at all!
wretchasketch
Member
Thank you all for your help. My bad on the size of the card (8 gigabytes).