Which is best data rate to use? Constant or variable???

[funkydude74]

Hi all. I've got a question regarding when encoding video to mpeg DVD, which is the best data rate to use, constant or variable???

Reason I ask is because I tend to wonder if DVD's glitch when the data rate decides to vary in video that is set to constant bit rate? Also when looking at a DVD one of my mates made for me, when viewing the OSD the data rate varied between I think 4800Kbps and 7000Kbps. So it makes me wonder if DVDs cope better with varying bit rate than trying to keep at a constant bit rate?

Cheers

[mats.hogberg]

With no intent of starting a CBR/VBR war, IMHO VBR will always (using a good encoder) look better than CBR at a given file size.

when the data rate decides to vary in video that is set to constant bit rate?

If data rate varies in a CBR encoded mpeg, something's wrong with the encoding.

/Mats

[proxyx99]

Constant BR is the basic/standard/normal way of encoding. VBR was developped to allow for more efficient disc space use (why waste bits for picture that's for example dark and steady, this is where BR drops). DVD player should play both equally well. Virtually every commercial disk is encoded with VBR now. If you plan to put say 1 hr of your home movie on a DVD you may code it with 8k CBR. If you want to squeeze more onto one disk you would then use VBR. This principle is identical to MP3 encoding. See how it works there and you will get a good grip of CBR and VBR issues.

[funkydude74]

Thanks for the info guys. I learn something new everyday . I thought VBR makes the video more tolerant if the playback bitrate varies wheras CBR glitches. Anyhow now that I know facts I can know when to use VBR or CBR.

Cheers
Troy

[Gazorgan]

Just to confuse you more there's CQ as well. CQ is faster than VBR but not as fast as CBR when encoding. Quality is pretty much the same as VBR. Size predicition is the hardest of the three........

[marvel2020]

Now everyone after me......


VBR
VBR
VBR

[SeeingMole]

Let's just use some simple logic.

VBR is best when space/file size is an issue.

If space/file size is not an issue, such as when the movie is very short, a CBR at high bitrate such as 9000+ will of course beat any VBR.

[proxyx99]

Now everyone after me......


VBR
VBR
VBR

... and what was that supoposed to mean? Very insightful and educational posting... Don't scream so loud, you woke up my kids...