movie pixelation

[shd17]

When I convert divx movies to mpeg2, there is usually a lot of pixelation and blurriness whenever it gets to action parts or when it is fast moving. I wonder why this is because the other parts are really good quality. It's just these particular action parts that's really bad. Here's some stats with a movie I just did with that problem:

Source: 640x352, 23.976 fps, 1290 kb/s, 48000 Hz audio
Result: 704x480, 29.97 fps, 1500 kb/s, 48000 Hz audio

Note: I use tmpgenc.

[jimmalenko]

Your bitrate is waaaaaaay too low IMO. If keeping the frame size roughly the same or resizing up, IMO you should look at roughly 3X-4X the DivX bitrate to get a similar result in MPEG-2. I'd be looking at a 2-Pass VBR with Max 8000, ave 4500 and min 1000, based on the info you've supplied.

[shd17]

Then how come when I used the SVCD template in tmpgenc to make a mpeg2 it didn't have this problem at all? Cuz I'm basically trying to fit 3 movies into 1 DVD with about SVCD quality.

[jimmalenko]

Then how come when I used the SVCD template in tmpgenc to make a mpeg2 it didn't have this problem at all? Cuz I'm basically trying to fit 3 movies into 1 DVD with about SVCD quality.

Because SVCD is 480 * 480. You said above that you're trying to make 704 X 480, so you're encoding an extra 224 pixels in the horizontal per frame. This means you have to allow more bitrate to keep the same quality.



EDIT:

Also, you're encoding a 23.976fps video to a 29.976fps video. I would look at keeping this as 23.976, but adding a 3:2 pulldown so it will be accepted by your authoring software.

[shd17]

Will changing resolution to 352x480 help reduce the pixelation while keeping the video about the same quality as 480x480? Thanks for your help so far.

[jimmalenko]

Will changing resolution to 352x480 help reduce the pixelation while keeping the video about the same quality as 480x480? Thanks for your help so far.

Quality is largely dependent on the bitrate, however changing the frame size can assist, because if you change the frame size, then there's less screen area to encode with the same bitrate, which generally will eliminate a lot of the pixelation caused by insufficient bitrate for the original frame size in the first place.

[shd17]

So if you were trying to put 3 movies with about SVCD quality into one DVD. what settings (bitrate, resolution, etc) would you apply when encoding? Cuz I tried changing the settings around to get the way I want but it usually ends up with low quality or a lot of pixelation. I also tried to encode with SVCD template(just the way I want it but won't go onto DVD) and use DVDPatcher to change the header so DVD author to make the DVD, but my DVD player didn't play it right. Ran out of ideas so any recommendation is appreciated.

[jimmalenko]

Add up the entire running time of the three movies. Plug this time into a bitrate calculator, choose what audio bitrate you're going to use, and then take note of the calculated bitrate (called ave for the rest of this post).

Sometimes the bitrate determines what frame size we should use, other times the source. It is best to choose the nearest resolution to your source, always rounding down where possible. Choose between 352 * 240/288, 352 * 480/576, or 720 * 480/576 (there may be times when you have a resolution smaller than 352 * 240 - that is OK, you'll just have to use 352 * 240). Your source's frame size is the first half of the Aspect value in the picture above from GSpot.

Given a high-res, high-quality source, I use the following:

(where ave is the value the bitrate calculator gives you)

If ave is < 1000kbps, I'd use 352 * 240/288 2-Pass VBR (min 100 ave ave max 2000)
If ave is > 1000kbps & < 2000, I'd use 352 * 240/288 ave CBR
If ave is > 2000kbps & < 5000, I'd use 352 * 480/576 2-Pass VBR (min 1000 ave ave max 6000)
If ave is > 5000kbps & < 7500, I'd use 720 * 480/576 2-Pass VBR (min 1000 ave ave max 9000)
If ave is > 7500kbps, I'd use 720 * 480/576 ave CBR

If a resolution is "forced" because of the source, keep this in mind when perusing the above chart (ie. if your nearest resolution is 352 * 240/288, there is no point using a bitrate > 2000kbps).