If I'm watching a DVD, how many [inverse?] descrete cosine transforms per second is my computer performing?

If I'm understanding this correctly, DVD video uses MPEG 2, which is basically MPEG 1 but with only one possible resolution and frame rate. [Also interlaced, because legacy.]

I'm by no means an expert in this area, but I got the impression MPEG 1 works similarly to JPEG, in that you transform to a luminance-chrominance colour-space [rather than RGB], split the image into 8x8 pixel blocks, perform a DCT on each block, and then truncate the resulting frequency coefficients based on what you think the audience won't notice.

Since all DVDs use the exact same resolution and framerate, I guess that means that theoretically you can put a hard number on exactly how many DCTs per second you need to do to play one. Does anybody have that number?


1 Answer 1


DVD is typically either: 720x480i @ 60 fields/second or 720x576i @ 50 fields/second

4:2:0 means that there are two color (difference) pixels per 4 luma pixels.

MPEG-2 use 8x8 DCTs AFAIK.

720x240x60x(3/2)/(8x8)= 243000 DCT/second

720x288x50x(3/2)/(8x8)= 243000 DCT/second


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.