CBR vs VBR

[greenstrat]

I've creating content on DVD-R via DVIitLE. In a discussion someone mentioned that he's had much more success in DVD-R with CBR authoring vs. VBR--I was taught to always author in VBR. I've tested my DVD-R and it has played on 3 out of 4 set-tip players so far. Any input?

[Specialist]

I like to use high bitrate CBR for a couple of reasons:

1. It looks nice.

2. It can be more easily edited without a lot of re-rendering.

But generally speaking, I try to edit in DV .avi format first and then ENCODE to MPEG as my final step before burning.

For me, VBR's main advantage is space savings.

The variable encoding determines which segments require a lot of work from the encoder and which segments don't.

As long as your encoding parameters are set up correctly, VBR should work great.

There's no compatibility difference in connection with set top players as far as I know.

Jerry Jones
http://www.jonesgroup.net

[jaeshin]

If you keep your movie under an hour, there is no reason to go with VBR. You can set CBR as high as possible and still the movie fits in one DVD.

VBR saves you space and it allows you to go higher bitrate if you are working with longer movies but I found out it is better to keep the movie under an hour to obtain the best possible result.

[troyvcd1]

Is this true about cbr vs vbr. I have been reading conflicting posts on how to get the best quality dvd regardless of file size.

[next]

I've always prefered cbr but i think it was a patience thing. When I was producing svcd's i never had a complaint and it happened almost in real time.

[duhmez]

VBR will always result in a better quality based on filesize. But here is the real issue:

DVD spec allows for approximately 9.8 Mbps or so. So if the video spikes above this bitrate it is out of spec and not guarenteed to work on all players.

if the movie is short enough that 9.8(or so I forget the exact max bitrate allowed) - including audio - will fill the disk nice, then you will not see any benefit from VBR. If the file was to be played only off the hard drive then you could have an average of, say, 9.8 Mbps, but with VBR allow it to spike to 15 Mbps, and go as low, like 3000 Mbps. This wil result in a file of technically better quality than the 9.8 CBR disk, but that is the constraint of being maxed out with respect to the DVD spec.

[jsnkc1]

You should always use VBR if your video contains any fast moving objets, lots of fades and transitions, and any dark video. This will give you the best final quality, and the best disk management. If your video is just a talking head, then just do a CBR. If you do a CBR at 9mbps just because you can and you have the space, it might do more harm than good, some DVD players have a lot of problems reading discs with that high of a bitrate, usually the cheaper models as well as desktop and laptop CD ROM drives. You should only use the highest bitrate you need to get acceptable results. Never use a high bitrate just because you can, if a lower bitrate will give you just as good of a picture quality.

[troyvcd1]

Thanks jsnkc1. I am talking about best quality regardless of disk size. If I can use 9000 and it will play on my dvd player then why not use it and the quality will be better then vbr.

[vitualis]

If you do a CBR at 9mbps just because you can and you have the space, it might do more harm than good, some DVD players have a lot of problems reading discs with that high of a bitrate, usually the cheaper models as well as desktop and laptop CD ROM drives.

Please don't guess answers.

CBR at the DVD maximum bitrate is perfectly acceptable and ALL DVD players can read this with no troubles on a DVD. Why? Because all DVD drives intrinisically read the DVD at a constant 1x speed and throws away the data it doesn't need if the bitrate is lower. This ensure that the drive doesn't have to spin up or spin down during video playback.

Laptop CD-ROM drives or any type of CD-ROM drives aren't going to read DVD-R discs (which is what this thread is about) so that is completely irrelevant.

If your video is relatively short and you can fit the entirety of the clip onto one DVD-R disc at the maximum bitrate, there is little to no benefit in using VBR encoding at all. Just use CBR at the maximum bitrate.

If your video clip is of sufficient length such that you cannot use the maximum allowable bitrate, then VBR encoding can yield better results than a comparable CBR encoding at the same average bitrate.

Regards.

[greenstrat]

thanks!! so if I understand
VBR is better
1) for faster moving video
2) saves space

95% of my work is sports editing (lots of motion), and it's rare I'll ever go over 60 minutes--as I tell my client's that's all they can get if the want HQ results.--so I guess my using VBR was the right way to go. If a DVD player can't handle my video, then that client is stuck w/VHS/SVHS.

Thanks

[duhmez]

You need ot use the max bitrate (9.8 Mbps or 10.08 Mbps,, somehitg like that - ask here for specifics, remmeber this bitrate must also include the audio track)

And use CBR. Only use VBR if the size of the video you want on the disk will not fit.

If they are 1 hour videos, definately CBR.