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Learning from the masters

 
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barakori



Joined: 17 May 2003
Posts: 1
Location: Israel

PostPosted: Sat 17 May 2003, 5:56    Post subject: Learning from the masters Reply with quote

Does anyone knows what parameters are used in commercial (professional) DVDs? I'm talking about avg. bit rates, GOP structure, etc.

Does anyone knows of a way to scan a DVD (I have plenty of those Smile ) and get that information? I have a Sony DVD player, and it can show the video and audio bit rate while playing. It looks like the video bit rate is usually around 5Mbit. How can they put 2 hours on a single side DVD when all the conversion routines I see on the net say that we should use around 6Mb/sec for the video, which yields about 90 minutes per DVD?

Thanks,

Barak
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RMN
Site Admin


Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Sat 17 May 2003, 6:11    Post subject: Reply with quote

The GOP structure of commercial DVDs is usually hand-tuned for each scene. They usually start with 1/5/2 or 1/7/1, then watch the result and change the settings for scenes that did not encode properly.

Nearly all commercial DVDs are VBR, with the maximum set to (approx.) 8 Mb/s, the minimum set to (approx.) 2 Mb/s and the average set to a value between 4 Mb/s and 6 Mb/s. Film transfers to MPEG better than video so, for film, an average of 5 Mb/s usually produces good quality. For video, you should generally use an average of 6.5 Mb/s or more.

Regarding the size, commercial DVDs are dual-layer (8.5 GB, instead of 4.3), so they have enough room for the full movie plus the extras.

RMN
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Josse



Joined: 29 Apr 2003
Posts: 9

PostPosted: Sat 17 May 2003, 22:27    Post subject: Reply with quote

You can have a look at what the bit rate does on a DVD with Bitrate Viewer.
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