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  1. Thread AuthorThread Author   #1  
    Punchinello's Avatar
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    Default How many GB needed per minute of video on 3GS?

    Anyone have an authoritative spec or reference on how many GB it takes to shoot and store 1 minute video on the new iPhone?
  2. #2  
    cobra302's Avatar
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    thats a good question, i was wondering the same thing myself. perhaps that's why the base was moved to 16gb instead of 8?
  3. #3  
    JustinHorn's Avatar
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    Calculating image size in Adobe Premiere

    To calculate the size in kilobytes (K) of one frame of uncompressed video, use the following formula:

    Frame size K = ([Pixel Width x Pixel Height x Bit Depth] / 8) / 1024

    Where 8 represents an 8-bit byte, and 1024 equals the number of bytes per kilobytes. For example, the size in kilobytes of an uncompressed frame of full-size (640 x 480), 24-bit video is:

    Frame size K = ([640 x 480 x 24] / 8) / 1024 = 900K

    To determine the file size of one second of uncompressed video, multiply the image size by the number of frames per second (fps). For example, one second of uncompressed, full-size, full-speed (30 fps), 24-bit video is:

    900K x 30 = 27 MB

    To determine how compression affects file size, divide the file size by the compression ratio. For example, a 10:1 compression ratio will make a 27 MB file 2.7 MB.

    Video playback
    Video formats supported:
    H.264 video, up to 1.5 Mbps, 640 by 480 pixels, 30 frames per second, Low-Complexity version of the H.264 Baseline Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats;

    H.264 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Baseline Profile up to Level 3.0 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats;

    MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
    I would assume 10:1 is a good estimate for the H.264 compression so the example above is probably pretty close.

    Or just using the 2.5Mbps as a reference a 30 second video will be 2.5 (Mb / s) * 30 s = 75 Mb / 8 (b/B) =~ 9.375 MB

    EDIT: Just realized that says video PLAYBACK and not record, so my "Or just using..." might not be accurate.
    Last edited by Justin; 06-10-2009 at 03:31 PM.
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  4. #4  
    JustinHorn's Avatar
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    Does anyone know what the compression ratio actually is for H.264? I think MPEG-4 is about 30:1 and H.264 (or MPEG-4 AVC) is about 50:1. Anyone can confirm this?
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  5. #5  
    JustinHorn's Avatar
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    Thanks to Punchinello I just lost the last 4 hours of my life, but I think I've got it "kinda" figured out and wrote up a big long post on my blog about it here:

    I basically boiled it down to 0.45 MB/s. This number could vary though depending on the compression ratio that is actually implemented on the phone.
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  6. #6  
    brengla's Avatar
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    Default On an equivalent Nokia

    Quote Originally Posted by Punchinello View Post
    Anyone have an authoritative spec or reference on how many GB it takes to shoot and store 1 minute video on the new iPhone?
    With essentially the same specs, the Nokia's were 22Mb a minute!
  7. #7  
    JustinHorn's Avatar
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    Quote Originally Posted by brengla View Post
    With essentially the same specs, the Nokia's were 22Mb a minute!
    Which Nokia? Do you know what compression they used? Also, did you mean 22MByte and not 22Mbit per min?

    My figure of 0.45MB/s would come out to 0.45 MB/s * 8 b/B = 3.6Mb/s * 60 s/min = 216 Mb/min a ton more than 22Mb a minute.

    If you meant 22 MB, then my figure of 216 Mb/min / 8 b/B = 27 MB / min would be a lot closer.
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  8. #8  
    JustinHorn's Avatar
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    Ok, I found a link that goes with what you were saying. Basically the same specs as the iPhone and it comes out to 22MB / min which is almost on target with my 27MB/min for the iPhone.



    But back to the N93. Poring over the tech specs, highlights are:

    Tri-band, 3G
    50MB internal flash storage, miniSD expansion (up to 2GB)
    Transformer form factor (N90-alike fold-out camcorder mode, landscape clamshell mode for viewing, portrait clamshell for talking/phone use) - weight is 190g, heavy for a smartphone
    320 by 240 pixel screen
    S60 3rd edition (of course)
    Comms technologies: Wi-Fi, UPnP, Bluetooth, USB 2.0, Mass Storage Class
    Direct connection to compatible TV (PAL/NTSC) via Nokia Video Connectivity Cable (CA-64U, included in box) or wireless LAN/UPnP
    3.2 Megapixel still images (2048 by 1536), Carl Zeiss optics, 3x optical zoom, mechanical shutter
    MPEG-4 640 by 480 video capture, 30fps, stereo audio at 48kHz, digital video stabilization,
    Adobe Premiere Elements 2.0 bundled for clip editing/enhancement and DVD burning
    Usual S60 refinements, including Visual Radio, stereo music, Media Player integration

    That's some list, especially on something retailing for £400 or so. One implication of the rise in video specs is increased file sizes for your captures, of course.

    The N70 captured at around 4MB per minute of footage, the N93 will need 22MB per minute, by Nokia's own estimates, fitting 45 mins of video on a 1GB card, or 90 mins on a 2GB card, comparable to the capacity of a standalone tape-based camcorder.

    With the optics involved, with the 'digital video stabilization', with the resolution and frame rate, the N93 is going to be absolute first choice for any self respecting journalist or mobile professional with a need to shoot video quickly and easily.
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  9. #9  
    Jellotime91's Avatar
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    That's a lot of storage space for one minute of video. I wonder if next year there will be a 64GB iPhone...
  10. #10  
    JustinHorn's Avatar
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    Did a test and I was really close with my 0.45MB/s guess. The actual from one 7 second video I took was 0.48MB/s.
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