iTunes Might Overburn? Maybe.

Posted:
in Genius Bar edited January 2014
Does iTunes or Mac for that matter support overburning? I just burnt a mix CD and I thought I had crammed too many songs into the playlist but iTunes happily burnt it. But when I hit Get Info on the CD it says it contains 748 MB of data! I didn't think this was possible. Someone please explain this for me.



Side note: I'm using iTunes 4.0.1, LaCie 48X FW burner, Memorex 700MB/80min 48X CD-Rs.



Has anyone else tried this or am I missing something obvious?

Comments

  • Reply 1 of 11
    Seeing as this generated so much interest the first time......



    I can't burn over 700mb when burning as a MP3 CD or as a Data CD. But this CD burned/plays fine. The run time of the CD is 73 minutes-could this make a difference. Sorry if the answer is obvious but I can't seem to rap my head around this.
  • Reply 2 of 11
    1337_5l4xx0r1337_5l4xx0r Posts: 1,558member
    That's very weird. 73 mins of music is slightly less than 650MB. 700MB CDs allow 80 minutes of music. So why it says 748 MB when you "Get Info" is beyond me...



    strange.
  • Reply 3 of 11
    baumanbauman Posts: 1,248member
    I've tried many, many times to get iTunes to do exactly that, and I have never had success.



    I dunno That's really strange, especially the 748MB part.
  • Reply 4 of 11
    I got all giddy when people responded so I decided to see if it was a one-off kinda of dealy. Burnt the same playlist...again 748mb. Created a new playlist, burnt it, now iTunes and Finder says the CD contains 801mb of data. Again, the length of the CD is under 80 minutes but I can't see how this would make a difference. I've took a screenshot of the whole mess if anyone wants to host it for me. I am utterly baffled by this. 801mb just seems way too big.



    Here is the screenshot, kinda big though.



    http://www.geocities.com/inactionman_2001/AI.html



    Fekking Geocities, can't make it link directly to image. Or at least I can't figure it out. Just load the page and right click>open image in new window.
  • Reply 5 of 11
    pesipesi Posts: 424member
    an audio CD contains no file system information as to the amount of data stored on it.



    what you are seeing is an improper estimate calculated by the finder.
  • Reply 6 of 11
    Quote:

    Originally posted by pesi

    an audio CD contains no file system information as to the amount of data stored on it.



    what you are seeing is an improper estimate calculated by the finder.




    Does it also estimate the size of the individual aiff files on the CD? Does iTunes also estimate the size of the CD? If it's an improper estimate why do I end up with 801mb of data if I drag each aiff file from the CD to my desktop?



    Thanks for the reply. But I'm still confused.
  • Reply 7 of 11
    pesipesi Posts: 424member
    Quote:

    Originally posted by InactionMan

    Does it also estimate the size of the individual aiff files on the CD? Does iTunes also estimate the size of the CD? If it's an improper estimate why do I end up with 801mb of data if I drag each aiff file from the CD to my desktop?



    Thanks for the reply. But I'm still confused.




    yes. it does that for individual AIFF files on the CD as well. because in reality there are NO individual AIFF files on the CD. an audio CD is actually one continuous data stream with the "header" info about when tracks start and stop encoded at the beginning. so there are no actual individual files.



    the reason why you get larger files when you drag to the desktop:



    the file system.



    an audio CD has no file sytem, per se.



    think of a CD as being 650MB unformatted. since there is no real file system, and it one long continuous stream of data, all that space can be used.



    when you make an AIFF file to your desktop, it needs certain other info to actually exist as a file. as well as the individual block size of sectors that make the file appear larger, etc. etc. etc.



    hope that helps explain a bit...
  • Reply 8 of 11
    costiquecostique Posts: 1,084member
    Yeah, something like this.

    a 80-min Audio CD is a different beast than a 700 MB data CD. Don't let the same media confuse you, because these are two essentially different formats for essentially different types of data. When you write AIFF files to an HFS volume, the audio consumes much more space than on an Audio CD because you also write a lot of other audio-unrelated stuff like a file system.

    In short, it's just normal.
  • Reply 9 of 11
    stevewmstevewm Posts: 1member
    I'll try to explain this simple as possible....



    AudioCDs and plain Data CDs are burnt very differently.



    A CD can hold 2352 bytes of data per sector.



    The Red Book AudioCD format uses the entire 2,352 bytes in each sector to store audio data. On a 80 minute disc this equates to 807.5MB of data.



    On a Data CD the first 304 bytes of each sector are used to store error correction data, this leaves only 2,048 bytes in each sector available to store YOUR data. This inclusion of error correction reduces the disc's storage capacity from 807.MB to 703.1MB. This type of disc is known as a Mode 1 disc.





    So to recap:



    A CD can hold 2,352 bytes in each sector.



    AudioCD: All 2,352 bytes store audio data. 807.5MB total.



    DataCD: 304 bytes for EC, 2,048 for your data. 703.1MB usable.



    Now you can burn a DATA CD in whats called Mode 2. This is the mode VideoCDs and Super VideoCDs are burnt in. In this mode the first 28 bytes of each sector are used to store sync information. This leaves 2324 bytes available for data storage. A disc burnt in Mode 2 will have more usable space than a disc burnt in Mode 1, but still not as much as a Audio CD. But since Mode 2 uses virtually no error correction a scratch could easily make data on the disc unreable and unrecoverable, not good for a DATA CD..... (VideoCDs only use Mode 2 as the MPEG video format used on them is quite tollerant when it comes to missing bits, so all the error correction Mode 1 provides is not needed.)







    Hope this puts the topic to rest
  • Reply 10 of 11
    russsrusss Posts: 115member
    stevewm did such a good job of explaining this that there isn't much left to say.



    So here's a simple illustration to go along with his explanation:



  • Reply 11 of 11
    Thanks for replies. My head doesn't hurt anymore. I knew there was a logical explanation, I just couldn't rap my head around it.
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