[X4U] Most advanced Video Codec WMV?

[Neil_ Pollack]

I've been meaning to reply to this list but I've been having problems with my e-mail as you might know if you saw my other thread.  

I know you aren't planning to post hi-def video to the web, but I was saying that if hi def H.264 is pushing the limits of a dual G5, then even low def content might be too much for a G3 or P3 class computer when using such a CPU intensive codec.

Anyway, as far as MPEG2, I think that one of the reasons it works so well on old systems is that the video cards have hardware acceleration of MPEG2.  That takes the load off of the main CPU.  I don't know of any Mac video cards that have acceleration for H.264 nor WMV although I've seen a card for Windows that will do it. Of course, MPEG2 also saves CPU cycles by not compressing as much (ie. larger files for a given quality).

If you use the H.264 codec for web distribution, then be sure to use the two-pass encoding.  That will use extra CPU cycles on the content creators computer, but that is a one time deal.  Every time somebody downloads a file, they will get the increased compression benefit (higher quality at any given bit rate) without burning any extra CPU cycles.  

I've heard that you can also make the H.264 codec less CPU intensive, at the expense of a little bit of compression efficiency by turning off cabac and deblocking.

I played that Turtle trailer on my dual G5 in hi def, 1080p.  Even when the video panned across a scene I was still able to get around 10-15 frames per second out of the 24.  That isn't too terrible.  I could still easily follow the action.  That was much better than other 1080p content I've seen in H.264.  I'm not sure why it worked so well.  Maybe animation is easier to compress than regular video or the studios can do more on their end to make the experience better for the end user.  I've recorded 1080 MPEG2-TS broadcast TV onto my Mac.  I could play it although it would drop a lot of frames.  I then used QT to compress it into H.264 and it was unplayable even on my dual G5.
 
Neil