Question about permissible picture sizes to play in DVD player

[jimdagys]

I am planning to get about 7.5 hours of pal Mpeg2 and author into DVD on a 4.7GB disk so that any DVD player will play it. In the past, I used a bit rate of 1250kbps and a picture size of 352x288. Also, in the past, I experimented with a picture size of 720x576, but there were too many artifacts. I understand that it is necessary to make the picture blurry
(small picture size) to hide the artifacts. However, my question is, is it possible to make the picture size somewhat larger than 352x288 and still be playable in all DVD players? If so. what picture size should I try to use? I don't want to create any vertical/horizontal distortion stretching of the picture.

[redwudz]

For PAL video, you could try 1/2D1 format, 352 x 576 pixels MPEG2 as a compromise. But 7 1/2 hours is pushing it even in that format for quality. 1/2D1 is a valid DVD format and should play back with no problems. I would also consider reducing your audio quality/bitrate as much as possible to make room for more video bitrate.

A better alternative would be to use a higher compression format like Divx/Xvid and use a set top Divx player instead.

[jimdagys]

One thing I don't understand. If you look at the ratio of 352x288 (first number larger than second number) and then compare to 352x576 (second number larger than first number), wouldn't 352x576 cause the length/height ratio of the picture to be completely wrong? I thought that the number 352x288 would nearly preserve the 4x3 aspect ratio and so 352x576 would cause the picture to be distorted to make the height much bigger than the length.

[manono]

...wouldn't 352x576 cause the length/height ratio of the picture to be completely wrong?

No, not after being resized at playback time.

[yoda313]

@jimdagys - why don't you consider dual layer discs? They can hold 8gbs of video. Though dl discs may have more compatiblity issues than single layer (don't know for sure since I've only burnt a couple).

If you have only have a single layer burner dual layer burners can be had NEW at prices of $35.00 USD or even cheaper.

Granted blank dl discs are more expensive than single layer blanks the fact that you would be able to get more video without such extreme measures might be something to look into.

------

Also have you tried encoding the video as MPEG1 VCD format? That is in the dvd spec assuming you have the audio at 48khz instead of the traditional vcd 44.1khz format . That might be more acceptable than squeezing the life out of mpeg2.

[jimdagys]

Well, it is a 7.5 hour TV program that I record and distribute in a school. I've done this before and just am tweeking up ideas for doing it again. I must use the single layer disks for cost reasons. Last year when I did this, I used mpeg2, 352x288, 1250kbps, 48K audio and authored into DVD. Played fine on all DVD players, including older players. Also played fine on all computers except those that didn't have the mpeg2 codec installed. However, there was still about 200MB of unused space left on the disk. To use up the free space, I am wondering if I should increase the bit rate. Also wondering if I should change to mpeg1 instead of mpeg2 (although somebody on this website said that mpeg1 and mpeg2 should be identical in clarity for these low bit rates). Also I was wondering about increasing the picture size a small percentage (from 352x288) to, for example 528x432 (I just multiplied each number by 1.5, which should maintain the same aspect ratio). But apparently one cannot change picture size to just any desired number, (as you can do with bit rate) and have it play correctly in all DVD players and computers). This thing about picture size is confusing, so I will probably just keep it at 352x288.

[jagabo]

The only valid frame sizes for PAL DVD are 352x288, 352x576, and 704x576, and 720x576. If you use any other size you run the risk of the video not playing properly on some (many?) DVD players.

DVD supports two display aspect ratios: 16:9 and 4:3. None of the legal frame sizes matches either of those aspect ratios. It's the DVD player's job to adjust the aspect ratio while it plays the video.

[jimdagys]

Thank you for clarifying the bit about frame sizes. To be safe, I am going to leave the frame size at 352x288. I think I once experimented with 352x576 and if I recall correctly, one software player did not play that frame size without vertical distortion. Maybe there is some setting in the software player to fix that problem, but these DVD's that I author have to work correctly without any user adjustments.

[theewizard]

352x576 would have to be 'interlaced', the frame would be the same size on the screen, but have double the amount of video data.