TMPGEnc: AVI->DVD inconsistent size files with 2 pass VBR

[var1ety]

TMPGEnc 2.513.53.162

I'm trying to convert some anime from AVI (divx and xvid) to DVD compatible mpeg-2, but am having some problems with inconsistent results. As a side note, I'm only encoding video in TMPGEnc, using ffmpeg to transform the mp3 audio into ac3.

I would like to fit between 4:30-5:00 on a disk, which, for the first disk, means 12 episodes, at a total time of 4:48:25. Using the DVDR Help bitrate calculator (the java applet) it tells me I should use 1885 averate bitrate, with a max of 9570.

The problem is that two similar files encoded with these settings will return radically different results - one file will be 350 megs, as expected, while the next will be well over 1 gigabyte in size. At the least extreme point files still differ by well over 100 megs, one will be 430 megs, while the next will be 230.

In turn, encoding times will vary from around 5 hours to well over 13 hours.

I'm using the CG/Animation Quantize matrix, 720x480 output size, 4:3 aspect ratio, 29.97 FPS. I'm using 2-pass VBR with an average of 1885 and a max of 9570. I'm using High quality (slow) motion search precision, Full screen (keep aspect ratio), and 1:1 (VGA) source.

The source files are 23 minutes in length, around 200mb in size, and are 640x480 resolution.

These settings are mostly the same I would use when encoding SVCDs, with the exception of the max bitrate - could it be that the difference between the average and maximum bitrate is what is causing the results to vary so much?

I'd appreciate any help people can give on what has worked for them in similar situations.

[bugster]

Starnge. Have been using Tmpgenc for several years and never come across this much discrepancy in file size with 2-pass VBR!

All I can suggest is this: I see you are using 720 * 480 res and only 1800Kbs bitrate. This will not look good. Reduce the res to 352 * 480 if you want a decent looking result.

A possibility (and this is just a wild guess) is that TmpGenc simply cannot encode some of your videos to such a low bitrate and high resolution. Open your mpegs in bitrate viewer to see what TmpGenc actually produced.

[DaveS]

did you try encoding at a CBR just to see if the file size comes back down when you do? Use the same bitrate & don't worry about what it looks like, as a first step. Just try it to see if the file sizes get more in line with each other - it shouldn't really matter (e.g. file sizes w/ CBR and VBR should be similar just bit allocation would vary over time), but this may help track down what's happening. Just a thought..

[var1ety]

I'll giving encoding in 352x480 a shot - I didn't know that DVDs could be in any resolution other than 720x480. Are there any other valid resolutions besides those two?

[bugster]

I'll giving encoding in 352x480 a shot - I didn't know that DVDs could be in any resolution other than 720x480. Are there any other valid resolutions besides those two?

yes, 352* 240.

[Gazorgan]

with a max of 9570

is a very very bad idea. ESPECIALLY with an average rate under 2000. Try a peak of no more than 5000 for anything under 1/2D1.

1/2D1 = 352x480 (4:3 DAR only) and you can get....oh 4-6 hours per DVD depending on bitrate. I usually encode at Peak of 5000 and an average of at least 2500. This is comparable to SVCD bitrates (really good bitrates), but with a lower resolution. The end results are excellant!

352x240 is pretty low res. You should also encode as PROGRESSIVE, not interlaced. Try that (it's really the MPEG2 version of MPEG1). For 352x240 I do VBR with a peak of 2500 and an average around 1400-1800. Quality is like a 'perfect VCD'. It's fine for smaller TV's but it looks course on 25"+ TV's. It's pretty much the same as VHS, and I have great luck with VHS captures at this resolution.