Aloha Forum!
I know about how the amount of space the video data will take up on a DVD will depend upon the resolution quality etc... But some of what we are discovering just doesn't seem possible. For instance, how in the world can 182 minutes be put onto a SINGLE LAYER DVD?! We purchased El Cid (http://tinyurl.com/22yvd8). We expected a Dual Layer disk, but it was single layer! Yet we see so many movies with far less running time - even some that are a bit over 100 minutes sometimes using all of a dual layer disc. ?????
How in the world do they do that?! Of course the resolution wasn't that good but it surely wasn't that bad either. It was not a true widescreen as it was really a 4:3 with the black lines (forgot what that is called), but still that is an awful long movie for only a SL disc.
Just curious
Thanks for any info on this.
DVD Mysteries?!
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There are two "keys" to the great commercial DVD mystery.
First, they are pressed, not burned with a laser like you do in your computer. A master is burned with VERY expensive equipment then copies are pressed from the masters. This allows very accurate and precise recording onto the DVDs allowing the data to be physically jammed together very closely and still provide no reading problems for the players.
Second, the MPEG encoders. The average home MPEG2 encoder will allow a "two pass" encode. The first pass calculates the the motion/scene changes etc and works out where the bitrate can go low and where it has to go high to maintain quality. The second pass does the actual encode. Compare that to the commercial encoders which will "read" the motion in the video up to 20 times before the actual encode. This is the point that makes them so efficient and allows so much to be included on a commercial DVD.
Most commercial DVDs have an average bitrate of around 4000kbps. If you or I did that on our home set up it would look like VCD quality. To get the same quality, depending on source material, we would have to go up to at least 6000kbps.
First, they are pressed, not burned with a laser like you do in your computer. A master is burned with VERY expensive equipment then copies are pressed from the masters. This allows very accurate and precise recording onto the DVDs allowing the data to be physically jammed together very closely and still provide no reading problems for the players.
Second, the MPEG encoders. The average home MPEG2 encoder will allow a "two pass" encode. The first pass calculates the the motion/scene changes etc and works out where the bitrate can go low and where it has to go high to maintain quality. The second pass does the actual encode. Compare that to the commercial encoders which will "read" the motion in the video up to 20 times before the actual encode. This is the point that makes them so efficient and allows so much to be included on a commercial DVD.
Most commercial DVDs have an average bitrate of around 4000kbps. If you or I did that on our home set up it would look like VCD quality. To get the same quality, depending on source material, we would have to go up to at least 6000kbps.