Is there an industry standard for picture quality? When we compressed a DVD movie, is the picture quality also reduced by the same percentage?
No, there is no cut and dried standard for video encoding used in commercial dvds. Determining the best combination of encoding parameters varies according to the type of movie, the amount of action, the “look” of the film, etc.
[QUOTE=nochewanoy;2497635]When we compress(ed) a DVD movie, is the picture quality also reduced by the same percentage?[/QUOTE]
That’s an interesting question. The answer depends on the video source that you’re compressing. If the source is a dual layer DVD (or similar large good quality source) which uses a high-bitrate for the entire movie, then the chances are that you can compress it a fair bit without noticeable loss of quality using a variable bitrate mode where the bitrate remains high for fast action sequences and scene changes, but is lowered when the video is (almost) still. If, however, the source is already highly compressed in this manner, then reducing the bitrate further will reduce the picture quality noticeably.
The other thing that you can do to reduce the size of a given movie is to re-encode it with a more efficient codec such as H264 which can produce better results at lower bitrates, but this is only useful if you use a PC for playback or have standalone equipment that supports H264 containers such as mkv and mp4.
Thanks for the info.