This is a good topic emerging from a problem That Mister Mike is having. I think it deserves a seperate string for the benefit of the forum members. Could the forum experts begin explaining the difference between these two terms (assuming there is one), why they are important and when/how to change them in a UVS project?
Thanks
Video Data Rate vs. Video Bit Rate
Moderator: Ken Berry
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rwindeyer
Well I'm not an expert, but here goes 
Video Data Rate and Bit Rate are the same thing. (IMHO)
So what does it all mean? If you have ever worked with still photos, and saved them to Bitmap format, you know these are huge files. Jpgs, on the other hand, are compressed and much smaller. If you use a halfway decent photo program, and choose jpg as the format, you will be asked what quality you want - high, medium or low (or a scale of 1 to 10 in Photoshop). The file size varies accordingly; high quality jpg's are much bigger, and sometimes you can't really tell the difference.
Now imagine a video as a series of jpgs that the computer has to read at 25 (or 29.97) pictures per second. (The mpeg compression process is clever and complicated, and it's not as simple as this, but the analogy serves..) If the computer is trying to read high quality images, then the data transfer required (bitrate) will be huge. The file size is also bigger, and you can fit less video on a disc.
As a rough guide, top quality video - the best you can get - will be obtained at a bitrate of 8000 (kbps). With LPCM sound this gives you about 60 minutes video on a DVD; with AC-3 you would get about 70 minutes. Medium quality - bitrate 6000 - is still very acceptable, and gives about 90 minutes. A bitrate of 4000 is lower quality, but if your original source is VHS you may not notice any difference, and you will easily get 2 hours video on a disc.
In the end it's up to you to work out a tradeoff between quality and length.
As for changing them: when you are in the burning module, look for the little cogwheel icon at the lower left of this screen. This gives you Project Settings. If you select Change Mpeg Properties, then Customise, you have a whole raft of choices - variable or constant bitrate, the magic bitrate number you want, and the type of audio - LPCM or AC-3 (if you have the plugin). After you have done this the space indicator bar will tell you if there is enough room for the project on a disc.
Personal note: if the indicator strays into the orange portion, the burning process may well fail. The estimate is a guess; it sometimes happens that during the final burn there's just enough variation to push the project size over the edge.
Video Data Rate and Bit Rate are the same thing. (IMHO)
So what does it all mean? If you have ever worked with still photos, and saved them to Bitmap format, you know these are huge files. Jpgs, on the other hand, are compressed and much smaller. If you use a halfway decent photo program, and choose jpg as the format, you will be asked what quality you want - high, medium or low (or a scale of 1 to 10 in Photoshop). The file size varies accordingly; high quality jpg's are much bigger, and sometimes you can't really tell the difference.
Now imagine a video as a series of jpgs that the computer has to read at 25 (or 29.97) pictures per second. (The mpeg compression process is clever and complicated, and it's not as simple as this, but the analogy serves..) If the computer is trying to read high quality images, then the data transfer required (bitrate) will be huge. The file size is also bigger, and you can fit less video on a disc.
As a rough guide, top quality video - the best you can get - will be obtained at a bitrate of 8000 (kbps). With LPCM sound this gives you about 60 minutes video on a DVD; with AC-3 you would get about 70 minutes. Medium quality - bitrate 6000 - is still very acceptable, and gives about 90 minutes. A bitrate of 4000 is lower quality, but if your original source is VHS you may not notice any difference, and you will easily get 2 hours video on a disc.
In the end it's up to you to work out a tradeoff between quality and length.
As for changing them: when you are in the burning module, look for the little cogwheel icon at the lower left of this screen. This gives you Project Settings. If you select Change Mpeg Properties, then Customise, you have a whole raft of choices - variable or constant bitrate, the magic bitrate number you want, and the type of audio - LPCM or AC-3 (if you have the plugin). After you have done this the space indicator bar will tell you if there is enough room for the project on a disc.
Personal note: if the indicator strays into the orange portion, the burning process may well fail. The estimate is a guess; it sometimes happens that during the final burn there's just enough variation to push the project size over the edge.
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Mister Mike
If you select Change Mpeg Properties, then Customise, you have a whole raft of choices - variable or constant bitrate, the magic bitrate number you want, and the type of audio - LPCM or AC-3
Can you explain the difference between Variable & Constant bitrate. Which one is better?
Which audio (Assuming I don't have any plugins) should I be selecting?
Can you explain the difference between Variable & Constant bitrate. Which one is better?
Which audio (Assuming I don't have any plugins) should I be selecting?
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rwindeyer
Constant Bitrate: the encoding engine renders, or codes, the whole movie at a constant rate.
Variable Bitrate: the engine scans the movie first (so the coding process takes longer). Parts of the movie that have lots of motion and action will be encoded with a higher bitrate, and parts with very little happening will get a lower bitrate. It happens automatically and if you view the information screen in a DVD player you will see the bitrate fluctuating around an average.
Theoretically, variable bitrate is better; you get better quality video, with the bitrate matched to the complexity, and you fit slightly more video on the disc. In practice there probably isn't a lot of difference. I personally use VBR always.
It may not be a coincidence that all commercial DVDs are encoded using Variable Bitrate.
For audio: If you don't have the AC-3 plugin, then I would use LPCM audio. It's universally compatible.
Variable Bitrate: the engine scans the movie first (so the coding process takes longer). Parts of the movie that have lots of motion and action will be encoded with a higher bitrate, and parts with very little happening will get a lower bitrate. It happens automatically and if you view the information screen in a DVD player you will see the bitrate fluctuating around an average.
Theoretically, variable bitrate is better; you get better quality video, with the bitrate matched to the complexity, and you fit slightly more video on the disc. In practice there probably isn't a lot of difference. I personally use VBR always.
It may not be a coincidence that all commercial DVDs are encoded using Variable Bitrate.
For audio: If you don't have the AC-3 plugin, then I would use LPCM audio. It's universally compatible.
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Mister Mike
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rwindeyer