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Mabsey

720p

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720p does not mean "720 x 304"

 

720p is "1240 x 720"

Edited by Mabsey

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720p does not mean "720 x 304". 720p is "1240 x 720"

I'd like to elaborate on Mabsey's comment above.

 

When you hear people talk about a 720p (720 progressive) signal, 720 is describing the horizontal lines - not vertical. Assuming a 16:9 ratio, this means a total pixel ratio of 1280 x 720.

 

Remember, it's customary to list the vertical line count first and the horizontal line count second when describing screen sizes (ie. 640 x 480 = 640 vertical lines by 480 horizontal lines).

 

A 720p signal is much higher quality than that of a standard DVD, which typically delivers 720 x 480 pixels. Notice that in this case, 720 is describing vertical lines, which is much less than the 1280 vertical lines (at the minimum) that an HDTV can display.

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Thanks for the elaboration (and correcting my 1240, yes - it should be 1280!). I don't think Adam is the only person that has made the mistake when referencing screen resolutions. :rolleyes:

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Moreover, the "maximum resolution" is rather a pixel count (at least as far as non-.h264 mpeg4 video is concerned). This means that (since 640 x 480 = 307,300) there is no problem to have a resolution of 720 x 304 (218,880 pixels).

 

Earlier the limit was 480 x 480 (240,400 pixels) for the 5G ipod, which allowed me to encode video in e.g. 512 x 288 (16:9 format with 234,720 pixels). With the 640 x 480 pixel count one can use 720 x 405 (291,600 pixels) for video with a 16:9 aspect ratio.

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