bitrate question

[beerbaron]

I am going rip a 94 minute movie and on 2 cd's, dvd2svcd tells me thats a 2118 bitrate for video. if thats so, then why cant i encode with 256 bitrate sound? cus thats only 2374 (audio+video) yet it tells me its 2809. i only have english ac3 6 chan with 1 audio stream selected for rippage and ive selected "stereo" for toolame mode. 192 works but not 256 or even 224 (2777).

[Nick]

To rip a 94 min movie onto 2 CD's gives an AVERAGE bitrate of 2118 for the video. However if you are encoding VBR, then the actual bitrate will vary throughout the disc between your minimum and maximum bitrate settings.

In order to fall within SVCD specs the total bitrate (video + audio) may not venture above 2756 at any point. So if you increase your audio bitrate settings you have to decrease your MAXIMUM video bitrate setting accordingly so total (max video + audio) < 2756.

That should do it. Good luck

Nick

ps - To be within SVCD specs the bitrate for the audio should always be 224 anyway but I've never come across a DVD standalone player which objects to this particular specification being breached. Therefore increasing/decreasing should not cause you problems.

[beerbaron]

yea i guess i was jsut taking the last column figures too literally, and if 224 is standard then ill use that, thx.

also, so its safe you think to push it right on the edge of 2756? or should i leave a few bits of padding just in case?

[Nick]

You shouldn't need to leave any padding. As long as the maximum doesn't exceed 2756 you'll be fine. Even then most DVD players will let you break the rules a little bit. Check the list on http://www.dvdrhelp.com/dvdplayers for info on your particular player.

Non-standard SVCD's are called XSVCD's. If your player will play them it will give you a suggested maximum bitrate. However if you stick to 2756 max total, with 224 audio you can be sure any future player you buy that supports SVCD will play them.

[beerbaron]

hmm am i reading this right?? i have an apex ad 5131 and it said xvcd 5000k kbit/s...does that mean i can go up to 5000 in the bitrate tab??

[r6d2]

@beerbaron,

D2Sroba plugin will make most of this decisions for you based on the quality you expect for your encode.

http://forum.doom9.org/showthread.php?s=&threadid=59054

Download latest RC from the indicated site.

Also, I suggest you to read this guide:

http://forum.doom9.org/showthread.php?s=&threadid=62858

Hope it is of use to you.

[beerbaron]

that is a nice read but i kinda like having control over the bitrate specifics. i am not completely new to this but its been over a year since i last dabbled...i made some very nice quality rips tho using the 4 pass vbr method. is the guide saying that using the d2robo is BETTER/equal to vbr 4 pass or just easier and less time consuming and nearly as good? cus i let it go overnight and it is usually done sometime the next morning after i wake up.

also, maybe my understanding of opv is poor but if you take a 1% sample of a movie, an action flik for example, how can it tell what compression will be needed for any given part of that movie from 1%? some sequences will be more dense than others and if the sample is too mellow, youll get a small output file or if its got heavy movement, a much larger file will result, right? cus its thinking that the 1% represents what will be needed for the whole movie?

[r6d2]

Originally posted by beerbaron
that is a nice read but i kinda like having control over the bitrate specifics.
Of course you're free to do so, but I'd rather do it based on quality and not on bitrate. Bitrate is the result of the quality I expect and not otherwise.
is the guide saying that using the d2robo is BETTER/equal to vbr 4 pass or just easier and less time consuming and nearly as good?
You know, "better" is a relative concept. But if you analyze the BR distribution after RoBa and after 4 passes, you'll find no significantly different ditribution. Try yourself and see.
some sequences will be more dense than others and if the sample is too mellow, youll get a small output file or if its got heavy movement, a much larger file will result, right?
Actually, compressability and motion are not related in exactly the way you describe, but the second pass fixes any estimation error that may be produced.
cus its thinking that the 1% represents what will be needed for the whole movie?
You'd be surprised to see that even 0.5% is enough. ;)