[x264-devel] Re: Motion Estimation in X264

[Måns Rullgård]

Panagiotis Issaris <takis.issaris at uhasselt.be> writes:

> Hi,
>
> On Mon, Nov 13, 2006 at 10:04:02AM -0500, Guy Bonneau wrote:
>> I was wondering about the reference buffers used in the motion
>> estimation algorithm for the Test Model of h264 as well as
>> X264. Does X264 and the Test Model JM10.1 used the reconstructed
>> reference Y buffer or the original reference Y buffer to search for
>> Motion Estimation. I know H263 uses the reconstructed reference Y
>> buffer but I think Mpeg2 used the original reference Y buffer. I
>> know all specifications don't provide guidelines regarding this
>> matter. So I was wondering what was decided when implementing the
>> JM10.1 and X264.
>
> Weird, I thought you'd always need to use the reconstructed frame,
> as that's what the decoder will base it's prediction on. I thought
> errors would accumulate otherwise.

If you are encoding with high quality and frequent I-frames, I guess
you could get away with using the original picture for reference.  It
would save a few cycles in the encoder avoiding the reconstruction
step.

-- 
Måns Rullgård
mru at inprovide.com

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