How much space does an hour of HD take up?

Discussion in 'Professional Video Production' started by Happ Sapp7, Jan 15, 2006.

  1. Happ Sapp7

    Happ Sapp7 Guest

    I know that an hour of SD DV takes up approx. 13 GB on my hard drive, or one
    miniDV tape at SP speed.

    Thinking of HD vameras, and wanted to know how much space an hour of video
    in HD format takes up....from what i gathered, it still uses miniDV tapes.
     
    Happ Sapp7, Jan 15, 2006
    #1
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  2. Happ Sapp7

    David McCall Guest

    There are many HD formats and compression schemes, so the size
    could vary widely. I think you are asking specifically about HDV, which
    is a High Definition variant of DV. I believe that the tape, and data-rate
    are the same as DV. That being true, then the disk space requirement
    would be the same as for DV.

    If you are going to edit it, then the question becomes more complicated.
    HDV adds complexity to editing, from a programming standpoint.
    Many people prefer to convert the HDV file to a less compressed format
    for editing, and this makes for much bigger files.

    David
     
    David McCall, Jan 15, 2006
    #2
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  3. Happ Sapp7

    PTravel Guest

    HDV uses mpeg2 and, I'm almost certain, uses a variable bit rate. As such,
    I don't think it's possible to tie specific file sizes to specific times.
    Is that true? I'm not working in HDV yet so I haven't tried it, but Adobe
    Premiere Pro, for example, has the ability to import HDV directly.
     
    PTravel, Jan 15, 2006
    #3
  4. Happ Sapp7

    Frank Guest

    Yes, the same tapes or better yet, special higher-grade,
    lower-dropout-rate tapes such as JVC's M-DV63HD tape and Sony's
    DVM-63HD or PHDVM-63DM tapes.
    HDV video is always MPEG-2 CBR (constant bit rate). HDV comes,
    however, in two flavors, 720p and 1080i. The 720p flavor of HDV is
    written at an approximate 19.7 Mbps data rate. The 1080i flavor of HDV
    is written at an approximate 25 Mbps data rate, the same as DV
    (including Sony's DVCAM and Panasonic's DVCPRO variants of DV).
    Therefore, when stored on a hard disk drive in its native .m2t (MPEG-2
    Transport Stream) format, the 1080i flavor of HDV has approximately
    the same storage requirements as DV content with the same running
    time.

    In contrast, Panasonic's DVCPRO HD flavor of HD, which is usually
    stored in the form of an .mxf file, has a data rate of approximately
    100 Mbps, so its storage requirements would be approximately four
    times that of DV, DVCAM, DVCPRO, or 1080i HDV content with the same
    running time. The storage requirements for Sony's HDCAM and HDCAM SR
    formats, owing to their much higher data rates, would be even greater.
    The data transfer rate of an HD-SDI link, by the way, is in excess of
    1 Gbps, just to put this in perspective.
     
    Frank, Jan 15, 2006
    #4
  5. Happ Sapp7

    PTravel Guest

    I didn't know that, thanks.
    Interesting that 720p HDV actually has a lower bit rate than DV-25.
    Do you think HDCAM will be supported in any prosumer machines? I was under
    the impression that Sony was drawing a clear dividing line between HDV,
    which will be an amateur/prosumer format, and HDCAM which, much like DVCAM,
    will be for higher end pro units.
     
    PTravel, Jan 15, 2006
    #5
  6. Happ Sapp7

    Frank Guest

    That's because you didn't read my Web page. :)
    Less data (after lossy compression, that is) = lower data rate.
    I do indeed believe that a dividing line has been drawn (Sony needs to
    protect the HDCAM and HDCAM SR product lines while simultaneously
    offering XDCAM gear and promoting HDV), but I also wouldn't be too
    surprised if Sony didn't come out with both HDV camcorders and HDV
    VCRs with more professionally-oriented features. Look what they did
    with DV in terms of DVCAM. The DSR-2000, for example, sells for about
    U.S. $12,000, which doesn't exactly make it an amateur/prosumer
    product.

    What I wonder about is whether Ikegami plans to get into the high-end
    HDV market.
     
    Frank, Jan 16, 2006
    #6
  7. Happ Sapp7

    Larry J. Guest

    Waiving the right to remain silent, "PTravel"
    IIRC, it requires a plug-in costing $2-$300.
     
    Larry J., Jan 16, 2006
    #7
  8. Happ Sapp7

    PTravel Guest

    Adobe released an upgrade to Pro 1.5 (now it's 1.5.1) which, I thought, was
    to enable HDV handling without the plug-in. Since I haven't moved up to HDV
    yet, I haven't been following it too closely.
     
    PTravel, Jan 16, 2006
    #8
  9. I think David is referring to the problem of cutting on the I-frames. In
    DV25, each frame is compressed seperatly, and in HDV the frames are grouped
    together in a serie, the first frame becomes a master-frame, and the second
    frame is compressed based on the difference between the first frame and
    itself. Then the third frame is based in the difference between the second
    and itself.
    All this leads to a higher compression-rate because you only have to save
    the difference between two frames (hence it is always said that MPEG2 is
    more efficient than DV25). However if you want to cut the, say fourth frame
    in that sequence, you would have to have a look at all the previous frames
    in order to recreate the foruth frame. On old computers, which are slower,
    this led to a lag while editing. The newer ones are fast enough so you
    don't notice this.
    Another technique used is to convert the materials to an intermediate. Here
    you use a form of very low compression, which is I-frame only again (each
    frame compressed seperatly), and then you don't have that lag either.
    Now, may people here tell you to go for the first solution, cut on a fast
    computer. Purists (like me), would recommend the latter. The advantage of
    the latter is that if you do multiple layer with multiple renders, you have
    a lesser chance of render-artifacts. Also if you would do chroma-keying,
    converting to an intermediate is better.
    But in the end it is a matter of looking at your production-methods, which
    type of MPEG2-editing suits you best.

    cheers

    -martin-
     
    Martin Heffels, Jan 16, 2006
    #9
  10. Happ Sapp7

    PTravel Guest

    I understand the problem of editing mpeg (and I've written about it
    extensively, here). I don't know, however, how Premiere Pro handles HDV
    (or, for that matter, mpeg with the MainConcept plugin). I've edited to
    mpeg using the MainConcept plugin and can make frame-accurate cuts.
    However, the clips need to be rendered, which suggests to me that Premiere
    Pro doesn't convert to its internal format, as I understand it does with
    DV-Codec AVI.
     
    PTravel, Jan 16, 2006
    #10
  11. Happ Sapp7

    HID Guest


    If you are going for more professional format like HDV you should go
    for more professionals NLE software like Avid or FCP. Premiere is good
    for wedding's editing. I understand that it is very easy software but
    come on...
     
    HID, Jan 16, 2006
    #11
  12. From what I know, the Cineform Aspect HD plug-in transcodes, but that means
    once you are finished, you will have to render back to MPEG2 anyway (as
    with any solution which uses intermediate codecs).

    cheers

    -martin-
     
    Martin Heffels, Jan 16, 2006
    #12
  13. Happ Sapp7

    Pat Horridge Guest

    It's a shame to be going back to HDV at the end of an edit. I've heard that
    the re-encoding of decoded MPEG2 can be see quite clearly on some material.
    Which makes sense as the new I frames are not likely to fit with the old
    ones.
    I think capturing on HDV for acquisition is one thing but a really bad move
    to layback post edit.
     
    Pat Horridge, Jan 16, 2006
    #13
  14. Happ Sapp7

    PTravel Guest

    I am strictly amateur. I shoot travel videos (I have a VX2000 for this
    purpose). The point of the travel videos is so that my wife and I have a
    good record of journeys that recall the experience for us. When I move to
    HDV (which is not a professional format), it will be because high-definition
    better captures the experience. I don't do weddings. I shot one as a favor
    to a friend, and will never do it again.

    Premiere Pro provides every feature I could possibly need, in addition to
    which, there are a ton of third-party plug-ins available. I can't imagine
    why I'd want to consider Avid, which costs considerably more than Premiere
    but offers _me_ absolutely no advantage. As for FCP, I have no intention of
    dumping my PCs for a Mac.

    Premiere Pro is just fine for me, thank you.
     
    PTravel, Jan 16, 2006
    #14
  15. Happ Sapp7

    Larry J. Guest

    Waiving the right to remain silent, "PTravel"
    Paul,

    I'm just recalling what a friend told me after he acquired a Sony HDV
    camera and wanted to edit the stuff.

    He originally bought a copy of Vegas to edit HDV, but switched back
    to Premiere, saying that it handled the files better.
     
    Larry J., Jan 16, 2006
    #15
  16. BTW, there is a cool free "widget" download at Apple's site under
    "calculators": it will tell you just how many minutes worth of free
    space you have on your video drives for any and every codec and data
    rate and recording method you want to use. Excellent for FCP and imovie
    users.
     
    nobody special, Jan 18, 2006
    #16
  17. Happ Sapp7

    doc Guest

    IMO, that's the sum of the Sony problem. specialized formats and
    configuration. the result "a box" like apple/mac solutions.

    drd
     
    doc, Feb 15, 2006
    #17
  18. Happ Sapp7

    doc Guest

    good thinkin dude. down with apple/mac "in a box" solutions :eek:)

    drd
     
    doc, Feb 15, 2006
    #18
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