can anyone explain the diference between "Variable" and "Constant" when it come to Video Data Rate??

thanks

CBR stands for "Constant Bit Rate". VBR stands for "Variable Bit Rate". The bit rate is a measurement of how much your video is compressed. For DVD's the video portion can be anywhere from about 1.5Mbps (Megabits per second) to 9.2Mbps. When encoding in CBR, all the video is encoded to at the same (constant) bit rate. When encoding in VBR, the encoder performs some analysis of the video and varies the bit rate as appropriate for that portion of the video. VBR many times uses what is called 2 pass encoding, it passes through the video to analysis it, then it encodes it. But all encoders are not created equal and do not perform equally. Also as you lower the bit rate the quality of the video decreases. I use VBR with my encoders.


Rich

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OK thanks. That helps out. Im woking on this project and the final dvd quality is not as good as I had been hoping. Im seeing pixles and "square type" particles and just trying to narrow down the issue. I've been woprking on this one disc for weeks!! AAAARRRGGGGHH!!

There could be a variety of reasons for 'pixles and "square type" particles'. It could be how you are processing your video, how you are encoding your video. I don't have any experience with DVD Workshop.



I use this work flow for the basic process when I have had problems:

1. Shoot video with MiniDV camcorder
2. Transfer to computer via firewire as a DV AVI file
3. Edit the .AVI file in editor as desired.
4. Save render the .AVI file to hard disk.
5. Play the .AVI on the computer to insure it is working, effects are ok etc.
6. Encode the .AVI file to DVD compliant MPEG-2
7. Play the MPG file on the computer to insure it is working, effects are ok etc.
8. Run DVD Authoring program to import MPG files, create menus, create DVD file structures and write DVD.

We went through some of this before with some unanswered questions:
http://www.camcorderinfo.com/bbs/sh...90&postcount=15



Rich

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that is my work flow as well...what I have noticed is veiwing the burning on the actual disc, it's only half of the disc..Im burning it as "good-90min" so my 80 min project should fill up most of the dvd, right??
So does this mean it's getting compressed too much or does this mean nothing at all??

Hi there,

The "pixels" and "square type particles" you're seeing are most likely chroma artifacts (blockiness) - they are present when your bitrate is too low, or if the codec isn't up to scratch. Most codecs also have options relating to "speed" and "quality". Using the "fastest" option usually results in poor output. Go with the highest quality setting for your final encode.

The best way to avoid these artifacts is to render and compress to your destination format from your original timeline (which works off the original DV files). In your case, it would be the DVD format: MPEG-2.

In otherwords, don't re-render your previous "check to see if everything's OK" .avi file.

Using poncho's example, try using this as your workflow (changes in bold):

1. Shoot video with MiniDV camcorder
2. Transfer to computer via firewire as a DV AVI file
3. Edit the .AVI file in editor as desired.
4. Render your footage in preview or draft quality.
5. Play the draft/preview file on the computer to insure it is working, effects are ok etc.
6. Encode into MPEG-2 from your original timeline.
7. Play the MPG file on the computer to insure it is working, effects are ok etc.
8. Run DVD Authoring program to import MPG files, create menus, create DVD file structures and write DVD

If only half the disc is being filled, you should be able to safely increase your bitrate by at least 50% (in theory you could double it, but leave some room for safety). I'm not certain if your DVD authoring software or NLE lets you specify the bitrate.

If you have a DVD-RW, use a short 5 minute clip, and experiment with various bitrates and settings till you find something you're happy with.

Good luck!

vidman, I don't know if this will help but you might read over it:
Basic authoring steps for new users of DVD Workshop 2.0.
Ulead DVD Workshop 2 Tutorial
http://www.jonesgroup.net/media/dvd...ptwostepone.htm



Rich

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vidman, please also try what I suggested to you earlier, which was to save your edited video as an AVI file and do your menuing and chapters in Workshop in AVI format, then in the final stage select save to disc and burn to dvd also, and let workshop render and encode in the final stage.

The reason I suggested it, if you read back is because workshop uses some less than user friendly tool options/methods (choices of wording) of selecting checkboxes on how not to have the program re-encoding already compliant mpegs. If you are not sure of the settings and you encode in your NLE, you may end up encoding again in workshop. To avoid this situation all together, just save your project as a DV/AVI in Premiere and import it that way to DW.

Vidman ... I have a lot to learn, but, on this issue ... I've been to the mountain

happy holidays,
joe

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So much information... the more I learn, the more questions develop. If I keep learning at this pace, soon I'll be too dumb to continue!