[x264-devel] 答复: Question about interpolate

[Kenter(GMAIL)]

Thanks to Siping, You do help me a lot

 

 

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发件人: x264-devel-bounces at videolan.org [mailto:x264-devel-bounces at videolan.
org] 代表 SiPing Tao
发送时间: 2010年3月22日 10:02
收件人: Mailing list for x264 developers
主题: Re: [x264-devel] Question about interpolate

 

Hi kenter,

When I reading the x264 code, I find the same thing as you mentioned. Here
is my thinking of this problem.

x264 interpolates (W+8*2)*(H+8*2) region, it's true, this is because only
W*H region is NOT enough. H.264/AVC standard defines the reference picture
interpolation process where padding samples also need to be interpolated.

However, if the six input samples are the same value T, sub-pixel
interpolation result will be T too, so we don't need to interpolate the
whole padding edge, and simple expanding is OK for some samples. I think
this is why x264 interplolates (W+8*2)*(H+8*2) region, and expands the rest
of the samples.

Hope this can help.

Best Regards,
Siping

-----Original E-mail-----
From: kenter <kenter83 at gmail.com>
Sent Time: 2010-3-19 14:57:24
To: "Mailing list for x264 developers" <x264-devel at videolan.org>
Cc: 
Subject: [x264-devel] Question about interpolate

Hi,

    I have a question about interpolation. It seems x264_frame_filter will
interpolate one MB line for each invoke. However, I find it also interp
"margin" data as well. Let's suppose the dim of image is W*H and margin is
32 for both x and y direction. The x264_frame_filter  will interpolate
(W+10*2)*(H+8*2) sized region and in x264_frame_expand_border_filtered, only
(W+4*2)*(H+8*2) sized region will be choosed as "right" and leave other
region to padding.

    My question is that why we interp so much data? Firstly, we can just
interpolate W*H sized image, this can save some computing power. Secondly,
it seems the excrescent interpolate of data out of image makes some
difference to it's edge.

 

Thanks

 

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