Video_TS to Avi encoding

[macbuz]

Wondering if http://homepage.mac.com/major4/videots_divx.html is an up to date guide. I tried following it and found myself lost in a couple spots. I 'punted' and have an encode going ATM ...... guess I'll see how I did (in a while - forgot I selected 2 passes - LOL).

[macbuz]

All righty then. Well that didn't work worth a (fill in the blank).

The avi opens in QT and plays some intro (a little pixelation) and then QT quits after idk - less than half a minute. Not sure which encoding details are most relevant, but .......

Summary:
From: Video_TS; mpeg-2; 23.976 w/ 3:2; ac3; 192 kbps
To: AVI DivX; mencoder mpeg4; 937 kbps; 23.976; crop

Video Tab:
MPEG4 [.avi] (mencoder);
Bit rate calc: 937kbps; 91 min; 1 80m mode-1;
Video Para's: 640x272; 2.35:1; NTSC Film

Audio Tab:
Audio Bitrate 448; 48000; stereo; cbr
Audio track ac3

Options:
High Quality
Use B-Frames
Two-pass
Trellis quantization

Anything relevant here?

[macbuz]

Working through the guide again and where it asks you to set bitrate by video length (time) and source media, then click 'Auto' - I get an applescript error - specified object is a property not an element. (?)

Encoding efforts now fail immeditately.

Edit: Strange too - MediaInfo reports the aspect at 4/3 and VLC reports it at 16:9.

[tomlee59]

I didn't see anything obviously amiss there. Perhaps unchecking "Use B-frames" is worth trying. Using B-frames buys you very little in quality, but it sure as heck increases the computational burden.

That said, if you continue to have mysterious difficulty, I recommend using D-Vision3 for this particular task. I find that there's less fuss and bother (and peculiar behaviors) with this tool. It's free, well written, and plain "just works" without much user intervention. It's worth a look-see, at least.

[macbuz]

That seemed to do the trick. I didn't change any default settings though ... so am wondering about general quality once it hits the 'big' screen.

Any settings suggestions regarding D-Vision?

[tomlee59]

As I mentioned, using B-frames buys very little. B-frames are bidirectionally interpolated frames -- they're already estimates. Using those estimates to generate still more estimates (for motion detection) will be a bit dodgy, so whether or not you use them, the result ends up pretty similar, but you get that similar result after a much longer wait. Not a win in my book.

If you're going for higher quality, use a reasonably high bitrate and high quality, two-pass encoding. D-Vision defaults to a moderate bitrate and one-pass, medium quality. It's a very good tradeoff between quality and speed that satisfies most users. But if you're more focused on quality and not so much on conversion speed, then feel free to turn the knobs in the higher-quality direction. I find 2Mb/s, hi-quality, two-pass XviD to be perceptually lossless to a good approximation. Indeed, my own default settings are 2Mb/s, high-quality, single-pass encoding. For most of what I do, that's entirely sufficient. Two-pass helps out most in those cases where you are using an aggressively low bitrate and there is a lot of motion in scenes with a lot of high spatial-frequency content. But individual tastes vary, so experimentation is in order. But you can start with those values, and iterate from there until you find a combination that you personally find acceptable.

As for audio, D-Vision defaults to 128kb/s. Again, if you are fussy about quality, you might want to crank that up to at least 192kb/s. I am a musician, and I find 128kb/s MP3 to be a bit annoying at times (string instruments are particularly challenging for MP3 at those rates). At 192kb/s, I don't notice any annoying artifacts unless someone is pointing them out to me.

[macbuz]

Enough said and thank you. I'll move ahead with some more encoding now that I have a means.

[macbuz]

Actually just getting back to some conversions and do like D-Vision, very simple. One question regarding your quality selections .... the 2Mb/s setting? where is that in D-Vision, I can't seem to find that option?

Thank you

[tomlee59]

On the very front page is a collection of settings. You can specify the target file size, after which D-Vision will make some selections for you, regarding resolution and bitrate (look carefully at the page; you'll see it). Or you can override these manually, with the understanding that doing so will affect the other parameters. For example, if you specify a small target size and large bitrate, screen resolution will have to suffer, etc.

And just to be clear, there's no pulldown menu with a pre-defined 2Mb/s bitrate setting. You enter a numerical bitrate value into the bitrate window. In this case, the units are kb/s, so you would type the value 2000 if you wanted 2Mb/s.

[macbuz]

In this case, the units are kb/s, so you would type the value 2000 if you wanted 2Mb/s.

....... and there's my answer, just that the 2Mb/s was a bitrate setting. Thanks again tomlee59.