04-11-2010, 04:03 AM
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kpmedia kpmedia is offline
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Some water scenes especially the towards the end had very noticable artifacts. There shouldn't be any considering the short runtime and 4gb of space used. Can you tell me what the cause could be and what you can do to prevent it? Is it possible that your using constant bitrate? Or something else? I really want my vhs conversions artifact free.
I pulled up the transfer, and I only see artifacts if I look for them, and play it on a very large TV set. I wouldn't call them "very noticeable" by any means. However, you've asked a great question, and I've therefore put it in the forum, as it may help others.

DVDs and most cameras use compression, be it DV, HDV, MPEG-2 or AVC H.264. Compression is based completely off predicted or analyzed motion within the image. Sometimes it's only in-frame motion, and sometimes it's motion between frames (i.e., temporal compression); for example, the DVD-Video MPEG-2 standard.

There are several kinds of complex motion that don't compress well under any codec, at any bitrate. These include:
  • wide-angle crowd views (sporting events, usually)
  • explosions, including shrapnel
  • choppy or rippling water
  • fire and flames
  • smoke
  • clouds
  • fast panning motions
  • sand
  • hair
  • screen doors and window screens
  • ... basically anything with
    • fine detail
    • small size on screen (less than 1% of overall image)
    • randomness to the pattern
Sometimes the compression displays itself as color palette compression (a.k.a. posterization or banding). In other cases, it shows as blocks or mosquito noise, which leads some to falsely believe a simple upping of bitrate would fix it. The bitrate required to insure a complex image is noise-free would exceed the DVD specifications for bit rate. Even DV's 25Mb/s compression is insufficient.

If you look for errors in video, you'll always find it, even in commercially-released content, and all the way into the supposedly-superior Blu-ray specs.

This is the one benefit of analog video: it handled complex scenes and detail without adding noise, although it generally did it with reduced detail. And of course, put it on a medium that loses quality with each generation copy.

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