AVI to MPEG2 conversion

[Alexstarfire]

OK, while I'm not a newb to converting video this question certainly belongs here. Is it just me or do you always lose a lot of quality when converting from AVI to MPEG2. I'm using TMPGEnc Plus and it just seems that no matter what the setting are that I keep getting blocky MPEG2 files. Even at the highest settings I can think of it's still not anywhere near the quality of the smaller AVI file. Am I doing something wrong?

[thecoalman]

Lots of variables, most important is your source. What are you trying to convert? AVI could be anything.

Having said that conversion from a decent source should produce nearly identical results. You would really have to look closely to see a difference.

[Alexstarfire]

It's either Xvid or DivX, but I'm not sure. Is there any way to tell?

Also, for some reason when I'm doing this conversion the output length is 3x longer than the input length. In other words, the input source is 3 seconds long, but after converting it's 9 seconds. What's up with that? And before you ask, I'm not sure if it's PAL or NTSC input. It's some Japanese Anime if that's any help.

BTW, I think I figured out why it was so bad. Though I'm still not sure why it affected the still frames.

[thecoalman]

As the saying goes garbage in is garbage out. Compressed formats like Divx were not made to be converted, they are menat to be viewed. Add to that it most likely is using a odd resolution. If your scaling it up that is most likely the source of most of your macroblocking. Try using a lower resolution. You'll lose some detail but you won't get the macroblocks.

Also, for some reason when I'm doing this conversion the output length is 3x longer than the input length. In other words, the input source is 3 seconds long, but after converting it's 9 seconds.

Does the video run slow after conversion? Whats the original framerate?

[Alexstarfire]

OK, I got GSpot so I can give you some more information. It's using DivX3 Low-Motion codec at 23.976 FPS. The resolution is 640x480, which isn't bad considering. I'm upscaling, but not THAT much.

Hard to tell if the video is running slow of not since I only took a tiny section of it, there is no movement. I'll get another section and test it.

EDIT: OK, after testing a section that has motion it looks like the first 3 seconds are what it's supposed to be and the rest is just still image. I don't understand why it's doing that. Could it be the codec?

[thecoalman]

The resolution is 640x480, which isn't bad considering. I'm upscaling, but not THAT much.

It doesn't matter, scaling video up generally produces poor results even with a good source. Your situation is compounded by the fact its already compressed which is going to have macroblocking. You just amking them bigger. Try 352x480 @4000kbps. I'm sure you'll find it looks much better.

[Alexstarfire]

That still doesn't address the issue of the output being longer than the input.

[mats.hogberg]

the issue of the output being longer than the input.

AVI with VBR (MP3?) audio throws TMPGEnc (and many other encoders) off. The solution is to extract audio from the AVI to WAV first, then use the wav as audio source when encoding.

/Mats

[Alexstarfire]

Ok, I broke down and just bought a DivX DVD player. I decided that converting 100+ hours of Anime would just take too long. So I get the player and burn a DivX CD and guess what? The picture runs off the top and bottom of the screen. Do I need to convert to a different resolution or what?

EDIT: OK, so changing the resolution to 640x450 on the file makes the subtitles show up properly. Man, I guess I just can't escape having to convert something. Least it's only gonna take about 35 minutes for each 20 minute file instead of 2 hours or more.