Screen capture from a DVD?

fudgamfudgam Upstate New York
edited April 2006 in Internet & Media
Ive got a highlight video here that I would like to grab a couple of screenshots from. Does anyone know of software that ACTUALLY WORKS for taking screenshots of dvd video?

Comments

  • RichDRichD Essex, UK
    edited April 2006
    Im fairly sure power DVD does it. Only problem is that capturing stills from digital video rarely gets very good quality results. The theory is that digital video uses whats called key frames. The compression has a true full image, known a a key frame, and the following five or so frames only record the changes to the key frame. Then you get another key frame followed by another five or so intermediate frames. This results in still images being rather blured. The ratio of key frames to intermediate is dependant on how it is encoded.

    Slow moving video with little change to the key frames is fairly successfull but anything fast moving will just blur.
  • ThraxThrax Professional Shill, Watch Slut, Mumble Hivemind Drone Austin, TX
    edited April 2006
    Hypersnap DX.

    Keyframes come every (FPS * 10) on average.
  • DexterDexter Vancouver, BC Canada
    edited April 2006
    RichD wrote:
    Im fairly sure power DVD does it. Only problem is that capturing stills from digital video rarely gets very good quality results. The theory is that digital video uses whats called key frames. The compression has a true full image, known a a key frame, and the following five or so frames only record the changes to the key frame. Then you get another key frame followed by another five or so intermediate frames. This results in still images being rather blured. The ratio of key frames to intermediate is dependant on how it is encoded.

    Slow moving video with little change to the key frames is fairly successfull but anything fast moving will just blur.


    Power DVD does do captures, use the little camera icon in the main control screen.

    If you pause your video playback then step through frame by frame, you will get a very good capture. Fast movement is going to get blurred regardless, because some of that blurring will be on the master, especially if it was a film source, the 3:2 pulldown method to get from 24 fps film to 29.97 fps NTSC video will inherently add some blur to fast motion segments when paused. You won't be able to tell the difference if you are on a keyframe or not, the keyframes (called I frames in MPEG) are fully rendered, and the in between frames (either P frames or B frames) are rendered on the fly within the decoder when playing but when paused, most DVD players will give you a clean pause by reading the frame before and the frame after the one you paused on, and give you an interpolated mix of those 3.


    Thrax wrote:
    Keyframes come every (FPS * 10) on average.


    You mean (FPS / 10). Otherwise you would have an I frame every 300 frames for NTSC.

    Actually the most common GOP sizes are 15 frames or 12 frames. Smaller GOPs can be used but then the resulting file size is bigger. Since most studio-produced DVD's will be encoded using 2 pass variable bit rate, they will get very good quality out of a larger GOP.

    Dexter...
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