Capturing video: mega bits per second configuration.

Discussion in 'Amateur Video Production' started by mr_ravi_patil, Mar 19, 2006.

  1. If I am capturing video from a VHS tape for playing back on PC at 720
    X 480 resolution, what is the maximum mega bits per second that I can
    capture?

    The manual for capture device explains that DVD players don't support >
    9 mega bit per second, and therefore not to configure higher than that,
    but I am not sure how it applies to playing back on PC.

    Manual:
    "
    MPEG-2 is an excellent choice for any type of movie. Your new video
    capture hardware allows you to capture directly from your camcorder to
    the MPEG-2 format, then allows you to perform frame-accurate editing,
    and create a final movie in the same format. You can then use a DVD
    authoring tool to create a DVD that can be played directly on a home
    DVD player or the DVD-ROM on your PC.



    The MPEG-2 standard allows for bit rates from 2 mb/sec. up to 15
    mb/sec. Since Instant DVD can connect to a USB 1.1 port (12 mb/sec.
    Max) or USB 2.0 port (480 MB/sec.) we can achieve video bit rates of up
    to 15 mb/sec. very reliably. If your goal is to capture video for
    burning to DVD disk, don't capture at a rate higher than 9 Mb/sec.
    because DVD Players cannot bit rates higher than this. Also, if your
    goal is to get the most video on a DVD disk, you will want to select 4
    or 5 MB/sec. using a variable bit rate.



    Keep in mind that most Hollywood DVD's are produced at 4.5 mb/sec.
    this allows up to 133 minutes of audio and video on a DVD disk. With
    the ability to capture MPEG-2 and create DVD movies at 4 or 5 mb/sec.
    with variable bit rate you can produce video with the same high quality
    achieved on Hollywood DVD movies.
    "
     
    mr_ravi_patil, Mar 19, 2006
    #1
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  2. mr_ravi_patil wrote ...
    Your question is too generic to have a definite answer.

    The simple answer is: whatever your computer can handle.
    No way to predict that at this distance.
    Actually, I thought the number was lower than that, but you
    are correct, the DVD player limits don't apply to computers.

    We don't know what you are trying to achieve? If you are
    going for maximum quality on your computer screen, you
    may be happier with DV than with MPEG. DV is compressed
    only 5:1 where MPEG is compressed 20-30x and frequently
    much more. Also DV preserves every frame while MPEG
    preserves only every 7~12 frames and discards (permanently)
    a lot of data by storing only changes beween frames.

    You didn't mention what this manual is for, but it seems
    rather simplistic and contains factual errors which may
    or may not be important to the casual user.
     
    Richard Crowley, Mar 19, 2006
    #2
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  3. The quote is from the manual for the capture device from ADS. It has
    several grammatical errors and I wouldn't be surprised if, as you
    mentioned, it contained factual errors (what are the errors?).

    My question is:
    If capturing in mpeg2 format (720 x 480) and playing back from PC hard
    drive, at what point will there be no noticeable increase in picture
    quality?
    I've noticed that 5 mbps is clearer than 3 mbps. Will 10 mbps be
    clearer? 15 mbps, 20 mbps?

    As for the DV format, I will check if the device supports that format
    (I don't think it does).
    And would DV formats be easier to edit?

    There doesn't seem to be an easy way to edit mpeg2 file. I wish to cut
    off the first 2 minutes of a 5 minute mpeg2 video clip.
     
    mr_ravi_patil, Mar 19, 2006
    #3
  4. mr_ravi_patil

    PTravel Guest

    mpeg2 supports variable bit rates -- some material, having lots of motion,
    will require a higher bit rate than other. Everything depends on your
    material and your display.

    Absolutely. Unless all you are doing is simple cuts editing, DV-coded AVI
    is a far better choice in which to edit, and universally supported by all
    but weird niche editors.
    That's easy. VideoReDo, tmpgenc and a number of other programs can do
    simple trims like that.
     
    PTravel, Mar 19, 2006
    #4
  5. mr_ravi_patil wrote ...
    It appeared to imply that commercial DVDs are encoded at some
    constant bitrate. In reality, a skilled human operator goes through
    the movie scene by scene and "budgets" the bitrate vs. data volume
    to ge the best compromise for each scene while remaining within
    the overall capacity of the disc.
    That point is likely beyond the definition of MPEG. In other
    words, ANY lossy compression will produce SOME artifacts,
    it just depends on what your particular tradeoff factors are.
    Yes, Yes, and Yes.
    You appear to have bought a hardware MPEG converter.
    No, it does not appear to do DV, only MPEG.

    It would be great if you are making DVD video discs.
    Maybe not the best choice if you are looking for high-
    quality playback on a computer screen (assuming that
    is your goal?)
    Without question.
    Didn't your capture gadget come with software?
     
    Richard Crowley, Mar 20, 2006
    #5
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