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  1. Member
    Join Date: Sep 2009
    Location: Canada
    Search Comp PM
    Hi guys! Great site, lots of info.

    I have some tech. question to which im unable to locate the answer. I read several guide/how-to on here but the info can easily get very overwhelming and i get lost.

    I was not able to locate my answers in the guides. So here we go!

    1- Does an mp4/avi file that has a size of approx. 600-700mb fit on a cd (vcd/svcd)? I asked this because when i try to create the said cd, the size it takes goes from 700mb to about 1.4G. I do remember however, making a cd that was about 600mb that did fit on a cd with 600mb. I dont understand while these other would not work the same. I then tried to make a DVD of the said mp4/avi file, and to my surprise, actually wants to take the whole space avail on the disc (4.7G).

    So my question on this - is this normal? Why does this happen?

    2- Follow up to above question - can you put several videos on cd/dvd and play them on a regular dvd player? I dont see how this would be possible since i am no longer able to put a 600mb file on a regular cd. If i understand correctly, you can make a data cd and put your avi/mp4 files on the disc and would only use the actual file size on the disc, and play them on a dvd player that supports divx/xvid correct?

    I hope im clear on what i tried to explain!

    Thanks for the help!
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  2. Member
    Join Date: Oct 2004
    Location: Freedonia
    Search Comp PM
    1) Whatever you are using to "create" the CD is actually converting it, probably to DVD format. Yes, you can burn MP4 and AVI files to CD discs if they are small enough to fit. You just have to burn a data disc. I'd suggest that you junk whatever you are using and learn how to burn with ImgBurn. It's free. You just need to burn your files to disc and it can do that without conversion.
    2) Yes, BUT... and it's a big "but"... it depends on what format you use and whether or not your DVD player supports it. If your DVD player supports AVI or MP4 (MP4 support is rare), then you just burn as many as will fit on a disc. We have a sticky here that describes some Divx (that's AVI) encoding options that can cause playback problems on some DVD players:
    http://forum.videohelp.com/topic352457.html
    Any videos you have that use these options might have playback problems on a DVD player. Or you can convert videos to DVD format and that will work but the more videos you try to convert, the lower the quality will be. A tool like ConvertXtoDVD might be useful to someone starting out.
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  3. Member DB83's Avatar
    Join Date: Jul 2007
    Location: United Kingdom
    Search Comp PM
    The size of your mp4/avi is dependant on two things - the play length of the video and the compression ratio of the video and audio codecs. The higher the data rate of the compression = the larger the file.

    A program like autogk has some presets ie 1 CD (700 mb) 2 CD (1400 mb).

    If your file is only 700 mb then it will fit on to a CD.

    However, a DVD is using a different compression system with much higher data rates. One hour at 8000 kbps is going to fill that 4 gig disk. Two hours at 4000 kbps will also fill the same disk.

    But, if you are making xVID/Divx CDs then you can fill a CD up to it's capacity and play the files in a compatable player.
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  4. Member
    Join Date: Sep 2009
    Location: Canada
    Search Comp PM
    Ah got it now guys! Thanks!

    BTW Jman, im using Nero for my burning purposes. Its the only one ive ever used for any burning needs. I just did not fully understand what was happening exactly. Especially since i *was* able to burn 1 avi file to vcd on regular cd that did play on my dvd player. I understand now that alot factors come into play as to how the file is handled in nero. The thing is i was trying to make a VCD out of the file while choosing "cd" option in nero.

    So is it normal then that the same 600-700mb file becore 4.7G once choosing the DVD authoring option? I used Nero Vision to create the dvd out of the mp4/avi files - which i like because i could do menus and and audio and such.
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  5. Member
    Join Date: Aug 2005
    Location: Palo Alto, California USA
    Search Comp PM
    Simple math will give you your answer:

    Filesize = bitrate x runtime.

    Lower bitrate --> smaller file (but lower quality, too)

    Shorter movie --> smaller file
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  6. Member Cornucopia's Avatar
    Join Date: Oct 2001
    Location: Deep in the Heart of Texas
    Search Comp PM
    Hopefully, this will shed a little more light...

    Audio & Video files all follow the same formula:
    Length (of time) * Bitrate = Filesize
    Files need to fit on the medium they intend to occupy. Since, the user-accessable data sectors on the various discs are:

    1. CD (Audio Mode) - 2352 bytes/sector
    2. CD (Data XA Mode2F2) - 2324 bytes/sector (this is what's used on the media tracks of (S)VCDs)
    3. CD (Data Mode 1) - 2048 bytes/sector
    4. DVD, BD (All discs are = Data Mode1) - 2048 bytes/sector

    And the (usual/average) # of sectors available on a disc works out to:

    1. CD - 360000
    2. DVD, SL - 2295104
    3. DVD, DL - 4171712
    4. BD, SL - 12219392
    5. BD, DL - 24438784

    **Note that this is an average, which depends upon variations in the manufacturing process of both pressable and burnable (dye or phase-change) discs**

    You can do the math and figure out that:

    1. Audio CDs hold ~807MB max
    2. (S)VCDs hold a little less than ~797MB max (there's a Filesystem track with some overhead)
    3. Data CDs hold ~703MB max
    4. SL DVDs hold ~4.37GB max
    5. DL DVDs hold ~7.95GB max
    6. SL BDs hold ~23.3GB max
    7. DL BDs hold ~46.61GB max

    For Audio CDs and VCDs which have a CONSTANT bitrate, it makes much more sense to just think of these discs in terms of time length (# Minutes), which in both of these above cases = ~80Min.

    Since all the others are DATA, and whether AUTHORED (which requires certain formats, codecs and bitrate constraints) or not, they will follow that first formula mentioned above. This is just a basic "do all these files add up to less than the max available?" type of question. And, of course, all these would be burned in DATA mode, whether authored or not.

    The problem with some burning software is that they sometimes make some assumptions:
    1. You want a "consumer-friendly" type of format, like AudioCD, VCD, or authored DVD-Video
    2. You want their software to do all the conversion to get your stuff into that format (and possibly make all the decisions).

    That's why people are recommending ImgBurn, etc vs. Nero. It doesn't make those assumptions or try to do anything you don't tell it to do.

    HTH,
    Scott
    "When will the rhetorical questions end?!" - George Carlin
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