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How much can you _really_ get on a cd?
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| mr_smidge |
Your average CD holds 80 minutes of audio data.
CD music has 44100 samples per second.
Every sample is two bytes (16-bit).
There are two channels.
This makes 44100 * 2 * 2 = 176400 bytes per second.
So, for the whole 80 minutes, this is:
176400 * 60 * 80 = 846720000 bytes possible storage space.
Divide by 1024 twice, it makes 807.5MB of storage space.
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So considering that 80 minute CDs are labelled as "700MB".. imagine I fill a CDR with 700MB of stuff, using the Joliet file system, where has the other 107.5MB of space gone? Surely the lead in/out and file table can't possibly use the WHOLE 107.5MB??
Knowing this, is it possible to 'overburn' as such, i.e. fit a larger amount of stuff onto a CDR?
Thanks people, it was just on my mind... |
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| Nook |
oke, thank you so much for sharing that with us.
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| Az |
| quote: | Originally posted by mr_smidge
Your average CD holds 80 minutes of audio data.
CD music has 44100 samples per second.
Every sample is two bytes (16-bit).
There are two channels.
This makes 44100 * 2 * 2 = 176400 bytes per second.
So, for the whole 80 minutes, this is:
176400 * 60 * 80 = 846720000 bytes possible storage space.
Divide by 1024 twice, it makes 807.5MB of storage space.
---
So considering that 80 minute CDs are labelled as "700MB".. imagine I fill a CDR with 700MB of stuff, using the Joliet file system, where has the other 107.5MB of space gone? Surely the lead in/out and file table can't possibly use the WHOLE 107.5MB??
Knowing this, is it possible to 'overburn' as such, i.e. fit a larger amount of stuff onto a CDR?
Thanks people, it was just on my mind... |
so many problems |
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| mr_smidge |
| quote: | Originally posted by Nook
oke, thank you so much for sharing that with us.
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Well if you've got an itch you've gotta scratch it. |
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| trancaholic |
| Audio CDs contains up to 30% extra data for error correction purposes. |
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| mr_smidge |
| quote: | Originally posted by trancaholic
Audio CDs contains up to 30% extra data for error correction purposes. |
Thanks, but this still means that extra storage space is available... |
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| DJ Pudl |
Audio CDs do use error correction, but the error correction used results in about 1 error per hour. This is obviously not good enough for data. So when the data CD format (Mode 1) was developed, an additional layer of error correction was added.
From http://www.mscience.com/faq62.html, "Every 2352 byte Mode 1 sector contains 12 bytes of sync, a four byte header, 2048 bytes of data, and 288 error correction bytes. Read failures for high quality discs are now reduced to about one every 100 years. This is clearly the preferred format for data."
There is another format (XA Mode 2) that reduces the error correction used and should only be used for audio/video files. However, the disks are more fragile to scratches, etc. To complicate things further, there are multiple forms of Mode 2, some of which add synching features but which reduce the usable space on the CD.
Go to http://www.mscience.com/faq62.html for more info on the specifics.
Hope this helps,
Jonathan |
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| Endre |
hey! lets make this a babe thread!
im first:
Jessica Alba
common guys, work your magic! :D
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| mr_smidge |
Thanks Jonathan...
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Looking at the last few posts though, it all seems to have gone a bit Pete Tong. |
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| BluNine |
| quote: | Originally posted by mr_smidge
Thanks Jonathan...
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Looking at the last few posts though, it all seems to have gone a bit Pete Tong. |
:haha: :haha: :haha: :haha: :haha: :haha: :stongue: :stongue: |
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| mr. poopyhead |
while we're on the topic of cds...
i've downloaded a bunch of movies that are split into 2 parts, cd1 and cd2... but each part is 780MB... how could they have possibly fit on a cd? i have a bunch of 80 min cds, but i'm thinking none of them are big enough... are there cds that can actually fit 780MB? |
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