[opendtv] Re: (no subject)
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Fri, 11 Dec 2009 08:26:28 -0500
At 9:40 AM -0800 12/10/09, dan.grimes@xxxxxxxx wrote:
"MPEG-2 specifies using an 8x8 Discrete Cosine Transform. I don't
think anything else would be legal but am not sure." --Tom
"H.262 uses only 8X8 block sizes, discrete cosine transforms (rather
than FFT), and floating point arithmetic." --Bert
I think I was misunderstood. I only spoke of the FFT because that
is the last time-domain to frequency-domain transfer function that I
have written code for, implementing it on a DSP. At the time, I
researched many different ways that could an FFT could be
implemented and all the mathematicians called their unique technique
an algorithm. Therefore, I considered them different algorithms to
perform the FFT.
By defining the operation of the decoder you necessarily determine
what the encoder must produce and the tools available in the decoder
to reconstruct the image.
The DCT transform is central to the functionality of the entire
standard as it is used for the initial transform, the reverse
transform in the decoder, and to encode the differences from the
predicted frames that are reconstructed in the decoder.
As others have described, the DCT was replaced with an integer
transform n h.264.
Regards
Craig
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