Very oversized SVCD file when converting from DIVX

[Mocha]

Searched the forum for 2 days, but can't find anyone else who has the following problem.

I have 2 divxs, ac3 audio, each about 50 minutes and 700MB ,each with a ssa subtitle file, which I want to encode to 2 SVCDs, mp2 audio and subtitles

2 pass vbr in Tmpgenc produced a subtitle encoded SVCD file that is 42 MB larger than the target size. I input 1875 avg bitrate to get an estimated filesize of less than 800 MB for a 50 minutes of video, and left room for subtitles. Instead the file was 842 MB. I frameserved .SSA subtitles using virtualdub. To check how much the subtitles contributed to the final filesize, I encoded 2 5 minute samples, with and without subtitles. Only less than 1 MB differenc in size between the 2 clips.

File Information in Virtualdubmod states that the avg video bitrate of the encoded svcd is almost 2100...nowhere close to the 1875 I set for avg bitrate in TMPGENC 2 pass VBR, hence the significantly larger file size.
Opening the source divx in virtualdub didn't pop up any messages about audio skew. THe audio is in ac3, which I converted using GOldwave to wav, and used besweet ot convert to mp2. 44.1khz frequency and 224 btrate. The encoded SVCD was perfectly in sync

Here is some of the relevant File Information that virtualdubmod produced for the source divx:

720x480, 23.976 fps.
# frames 72236 (50min 12 secs)
Four CC code: Four CC (DIV3) Divx 3.11 low Motion
Decompressor Divx 5.03 codec
# key frames 5929


I also encoded 5 minute samples at progressively lower avg bitrate settings for 2 pass vbr to check file sizes and avg bitrates of the encoded svcd. 1550 avg bitrate 2 pass vbr produced a svcd with an average bitrate of 2061, and a file size of 83.3 MB for a 5 minute clip....but estimated target size was 64.86 MB..

When I input 1500 for avg bitrate, I finally got the estimated target and output files to match.

Why is this happening? I thought 2 pass VBR was supposed to set the average bitrate at whatever I set the average bitrate in the settings, thus the file size can be predicted. If I input anything down to 1550 for 2 pass vbr avg bitrate, the avg video bitrate of the resulting svcd is between 2050 and 2080.

I can only think of 2 options. One, take the encoded svcd, input that into tmpgenc, and reencode to the filesize I want using 2 pass vbr. Using a 5 minute sample, this was possible, and ironically, the output size was larger than the target size. But the video wasn't as good. Two, is to somehow combine the 2 divx'x into one large divx(frameserve perhaps), combine the ssa subtitle files, encode in tmpgenc at a high bitrate, and then split the encoded svcd into 3 parts. To encode 1 divx takes 15 hours.

Anyone know of a way I can simply encode the divx to the video bitrate I want using 2 pass vbr? I woould like a bitrate of about 1900, not 1500. I've encoded over a dozen divx videos this way, and this is the first time this has happened. I am wondering if the problem is there are way too many key frames.

Thanks

[tito13kfm]

I've recently had this same problem with TMPGenc producing way undersized files, asked for a 2400 avg bitrate got about an 1800.

I still can't figure this out.

[MOVIEGEEK]

EDIT:nevermind

[wulf109]

don't use the Wizard in TMPEG,set your bitrate manually. A 50 minute file with 192bit audio would use an average bitrate of 1950. Then set the minimum to 500 and maximum to 2520.

[Mocha]

As I said before, any bitrate I enter, with or without wizard, down to 1550 produces an output with at least 2050 video bitrate. That's the problem. I have always used max bitrate of 2520. Also, I want 224 bit audio.
Audio bitrate wouldn't affect video bitrate. And according to fitcd, changing from 224 to 192 would only shave off 11929 kb from the final file size.

I tried your settings your suggested settings and the video bitrate ended up over 2050. You see what I mean.

[Mocha]

No one has ever experienced this before?

[Mocha]

Ok to hell with 2 pass vbr. Can't get the avg bitrate to come out correctly. Might work if I had CCE and could do 5-6 passes, but I don't want to spend $1750.

Since I now have an extra hour, I will give the kvcdx3 template a shot. I see the template doesn't include audio. Is it ok to add audio within tmpgenc at the same time the video is encoding, or should I just encode the video first and mux back in later with bbmpeg?

[Mocha]

Dammit I figured it out. My version of Tmpgenc is over a year old. I just go the newest version and the avg bitrate works out. According to the revision history, the newer versions improved bitrate allocation in the first pass. Now for example, setting avg bitrate to 1950 produces a sample file with 1923 kpbs instead of 2096 kbps with my older crappy version. Hopefully I can finally encode this on 2 svcds. phew.