Encoding to greater than source resolution

[DRP]

I have a really good DVD player. It can play just about any size or format X(S)VCD I can throw at it. Given that's the case I'd like to ask a really quick and simple question.

Is there any point in transcoding a downloaded AVI to a resolution higher than the source AVI?

I have a PAL source AVI at 480x368. Is there any point in encoding that to 720x576 with TMPGEnc or would that be the video equivalent of re-encoding an MP3 to OGG - ie. pointless? (no gain in quality)

Is there a rule of thumb here? - Like say... always encode to the biggest size possible that is less then the source.

Retaining as much picture quality as possible is my main goal here - not reducing the number of discs required.

[mats.hogberg]

Whenever you reencode, there's loss in quality, at least if the target format is not lossless.
Increasing the frame size wont increase the quality, but will not necessarily make it any worse either, if you use some good resizing method.
However, higher resolution takes a higher bit rate.

/Mats

[roach76]

mats.hogberg is correct in saying higher resolutions require higher bitrates to keep the quality up. But if either the final encoded horizontal or the vertical resolution drops below the source's resolution there will be a drop in quality.

I say, 'my rule of thumb' is to encode the video at the lowest resolution your DVD Player will play that is equal or greater than both your source's horizontal and vertical resolutions. That way you are not just chucking away quality before you have even started encoding, and are minimising the loss of quality.

But this will not encrease the quality like mats.hogberg said, eg. if you double the horizontal and vertical you will just tell the encoder to encode the movie but use 4 pixels to just represent 1 pixel, UNLESS you shrink the size of the footage so this doesn't happen, but then when you watch it on your TV the picture will be small.

BUT!!! If the the video/movie is too long and the bitrate has to be low so it can fit on your chosen medium then you may be forced to either spread it over another disc or reduce the resolution so you don't get macroblocks.

[funkguy4]

I say, 'my rule of thumb' is to encode the video at the lowest resolution your DVD Player will play that is equal or greater than both your source's horizontal and vertical resolutions. That way you are not just chucking away quality before you have even started encoding, and are minimising the loss of quality.

This is my rule also. Infact, you can use my guide to make your SVCD. You should prolly make and SVCD. The guide is in my signature and will make an SVCD compatible MPEG.

[DRP]

mats.hogberg is correct in saying higher resolutions require higher bitrates to keep the quality up. But if either the final encoded horizontal or the vertical resolution drops below the source's resolution there will be a drop in quality.

I say, 'my rule of thumb' is to encode the video at the lowest resolution your DVD Player will play that is equal or greater than both your source's horizontal and vertical resolutions. That way you are not just chucking away quality before you have even started encoding, and are minimising the loss of quality.

But this will not encrease the quality like mats.hogberg said, eg. if you double the horizontal and vertical you will just tell the encoder to encode the movie but use 4 pixels to just represent 1 pixel, UNLESS you shrink the size of the footage so this doesn't happen, but then when you watch it on your TV the picture will be small.

BUT!!! If the the video/movie is too long and the bitrate has to be low so it can fit on your chosen medium then you may be forced to either spread it over another disc or reduce the resolution so you don't get macroblocks.

Excellent advice, thank you. I'm quite experienced with audio (MP3) encoding so I am fully aware of the fact that converting from one lossy format to another will never result in increased quality regardless of what you do. My main aim is exactly what you have suggested - to minimise the subsequent loss resulting from further downstream encoding as much as possible.

I have one more question of you if I may. What are macroblocks?
If I had to guess, would they be the big square blocks of black that I've seen appear in dark scenes on VCDs (MPEG1)? Kinda like the square blocks that appear mosaic style in JPEG images that have undergone multiple JPEG compressions?

If I'm right, then are macroblocks are symptom of too low a bitrate being used with too high a resolution?

Is there a recommended formula or ratio for matching resolution to bitrate for highest quality without waste? I'm guessing that for example a resolution of 320x240 encoded with a bitrate of 3000kbps would be overkill and wasteful with many bits being unnecessary whilst a resolution of 720x576 encoded at 1150kbps would go the other way with macroblocks and not enough bits. There has to be an optimum ratio of bits : resolution. How do you establish what that should be?

[Cecilio]

actually you can make a crappy mp3 sound better, but not by changing to a different format, you have to get down and dirty. but i dont know how to make a video look better than the original, but i do know how to keep as little video quality drop as possible, i use DVD2SVCD to make mostly CVDS. i use 3 pass VBR and get excellent results. The last movie i encoded was about 2 hours and 15 minutes and i made it on 2 cds as a CVD. i put 65 minutes on the first cd and 70 minutes on the second cd, and i didnt get any macroblocks, or bad shit just clear picture.

Macroblocks are like when you have a badly encoded video, and there is a very fast moving action scene and theres alot of people running or fighting, and you see alot of little squares inbetween movements.

use my guide its also in my signiture. if your encoding from an avi and have CCE [17] as image quality priority, and enable the anti noise filter, and set it to [2]

[roach76]

DRP, your assumption of what macroblocks are is spot on.