Resolution Question

[aybesea]

OK gang, a question for all of you.

I started evaluating Dr. Divx to see how good/bad of a job it did in doing automatic conversions from DVD to Divx. The original DVD is a 4:3, NTSC disc at 720x480.

Dr. Divx recommended that I encode this to 4:3, 640x480.

This got me to thinking, 720x480 is NOT a 4:3 aspect ratio, whereas 640x480 is! What gives here? Any insight? Would the best Divx resolution be 640x480 or 720x480? Why is 720x480 a 4:3 ratio?

As P.T. Gumby once said, "Ooooh... my brain hurts!"

 

[celtic_druid]

That's because 640x480 is the 1:1 4:3 aspect ratio where as the 720x480 source really is 4:3 and is scaled as such on playback.

Same as how both 4:3 and 16:9 DVD's are both 720x480/576, it is just that one has a 4:3 flag and the other has a 16:9 flag.

You could encode also using a 4:3 aspect ratio, however you would need to use a format that supports such flags.

As for 640x480 being the best res, I guess that would depend on the movie. It may be too high if the movie is long/hard to compress.

 

[ChickenMan]

The picture dot size of a DVD and a DivX are not the same also. A DivX dot is square (intended for PC screen playback), while a dvd dot is rectangular and differes in size for both PAL and NTSC (intended for TV playback). Just to confuse the issue further