CBR vs VBR

[prl]

Hello,

I'm authoring a personal DVD and I have this question. I have a ~35 mins video that I edited in Sony Vegas 8.0. Now, I want to encode it to MPEG-2 to author in Adobe Encore DVD 2.0..

My question is this: since disk space is not a problem how should I encode it? CBR or VBR? I'm guessing CBR would be enough for the video, but I'm wondering if VBR would be the best solution.

And by the way... since the audio track is PCM WAV (that has a bitrate of 1536 kbps) the max video bitrate would be around 8000 kbps right?

Thanks in advance,
Paulo

[mh2360]

CBR would be fine at those bitrates, I doubt you would see any difference using VBR.

[guns1inger]

If you are using PCM audio then VBR is probably the best method. Set the average at 8000, the max at 8200 and the min at 4000. This sill push the bitrates close the spec max, which some players may have issues with when reading from burned media. If you want to play it safe, drop the average to 7800 and the max to 8000

[prl]

guns1inger, why is VBR probably the best method with PCM audio?

Thanks for your answers!

[guns1inger]

Only because the audio is taking up so much space, leaving less for video. If you converted the audio to AC3, even at 384 kbps for 2 channels (which is probably overkill), you push the video bitrate up to 9000 kbps and go CBR.

Of course this is also dependent on the content of the video. If it is noisy, moves a lot (hand held), poorly let etc. then is will need all the bitrate you can give it. If it is mostly motion graphics, tripad stable and well lit then you might be able to CBR at 8000 and still have it look good.

[prl]

Only because the audio is taking up so much space, leaving less for video. If you converted the audio to AC3, even at 384 kbps for 2 channels (which is probably overkill), you push the video bitrate up to 9000 kbps and go CBR.

Of course this is also dependent on the content of the video. If it is noisy, moves a lot (hand held), poorly let etc. then is will need all the bitrate you can give it. If it is mostly motion graphics, tripad stable and well lit then you might be able to CBR at 8000 and still have it look good.

It's actually hand held, lots of motion and with not much light.

I guess I'll try VBR at 7800 kpbs with PCM WAV and CBR 9000 kbps with AC-3 sound.

Thanks!