* Posts by Richard Shepherd

1 post • joined 29 May 2007

Elgato Turbo.264 H.264 encoder

Richard Shepherd

h264

768x576 can easily be "widescreen" if it is encoded anamorphically. Your "widescreen" DVDs are encoded at 4:3 NTSC or PAL resolution but are flagged as anamorphic and the DVD player/screen just stretches then accordingly.

Also 768x576 should be okay for turbo.264 From the data sheet as long as the size is below 800x600 (and 768x576 certainly is) the image is not scaled. Only video above 800x600 will be downsampled.

I've just ordered one of these and I'm sure I'll see an improvement in encoding times even on my 2Ghz core duo iMac. As far as I can see what is happening is that Quicktime has to do the decoding to YUV from the source file in software with the GPU. There will be no way the elgato can do the decoding from the miriad formats QT supports so will have to be passed a common format (this is usually 4:2:2 YUV I think) This will then be passed to the elgato which then sends it back as h264.

Either way you look at it some of the encoding will be taken off the GPU which then allows it to have more cycles for the decoding/bus transfers etc. It really is an h264 co-processor.

RS

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