best tmpgnc setting for car chase action???

[efiste2]

ok two questions for you tmpgnc experts, im converting captured VHS using tmpgnc, the source is a mainly car chase action, i am currently uisng a 2 pass VBR setting, i require to put 95 mins on a dvd-r so is my bitrate setting the best one to use or would i get better results out of constant quality, I was under the impression that VBR gives a better bitrate when the action is faster etc am i right . and also would it create extra space on the disc if i could convert the audio to AC3, im thinking the more space for the video the better quality i could attain! im new to this ac3 thing as at the moment i use the mpeg2 audio setting

[Cobra]

I worked your bitrate out to be about 6000kbps. This is fine for anything.

VBR vs CBR - VBR really allows you to crush video into a smaller space with minimal quality loss over CBR, and I always use it. I'm not sure if it has any great advantages over CBR, but in my experience two passes are better than one. I'd continue using VBR mode.

As for AC3 - ffmpegGUI will compress to AC3, but I don't think if offers much of an advantage. They are both compressed audio formats, but I think AC3 can hit lower bitrates for the same quality. If you have the audio in an uncomressed WAV (one that hasn't ever been compressed, so not a WAV from the MP2) then compress them into both formats and see which you like best. You shouldn't make an AC3 from the MP2 because it will introduce two sets of compression artifacts and sound awful.

Hope this helps,

Cobra

[bugster]

High action requires high bitrate.

CBR Vs VBR

(as Cobra suggests)
CBR 6000Kbps Max 6000, Min 6000 Avg 6000
VBR 6000Kbps, Max 9800, Min 2000 Avg 6000

VBR allows the encoder to use more bitrate when needed. 6000 should be enough for most things but if your source is noisy (video noise that is, not audio!), or there is also flashing lights, smoke etc then more may be needed for best qualty and to avoid macroblocks.

So, unless you really need to speed up your encodes, use VBR.

(TmpGencs CQ mode (one pass VBR) is pretty good quality output, but difficult to predict final filesize)

[efiste2]

thats great info, thanks for your help guys, im gonna stick with the 2 pass vbr, it really does give good results!!