Thank you for the response.<div>As i had mentioned I am try to compress RGB 24 bit VGA video.</div><div>My input has mainly grayscale data and very little color information.</div><div>I have succeeded in separating the two. now i have an 8 bit grayscale video (and *r*e*s*i*d*u*e*).</div>
<div>The previous reply had the steps to make x264 work with yuv 420. Thank you very much for that.</div><div>Before i start with that i feel if x264 works with YUV 4:0:0, it can be used to compress 8-bit video.</div><div>
I also think if this feature is 'added' to x264, it will be become possible to use it in many other useful ways easily.</div><div>Can you kindly tell me the steps to make x264 accept YUV 4:0:0. </div><div>Thank you</div>
<div><br></div><div><br><div class="gmail_quote">On Tue, Dec 23, 2008 at 4:30 PM, <span dir="ltr"><<a href="mailto:x264-devel-request@videolan.org">x264-devel-request@videolan.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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Today's Topics:<br>
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1. Lossless H.264 encoding (Ram prasad)<br>
2. Re: Lossless H.264 encoding (Jason Garrett-Glaser)<br>
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Message: 1<br>
Date: Tue, 23 Dec 2008 15:26:14 +0530<br>
From: "Ram prasad" <<a href="mailto:ramprasad85@gmail.com">ramprasad85@gmail.com</a>><br>
Subject: [x264-devel] Lossless H.264 encoding<br>
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Hi allMy source data is raw 24 bit RGB VGA video. I want to encode it into a<br>
h.264 video. my requirement is that this should be a lossless compression.<br>
Looking at the code i think x264 does not support any other format other<br>
than YUV 420. I am planning to modify the code to make it work on high<br>
quality YUV 444 or if possible on the RGB data itself.<br>
Before i embark on this task i would like to know whether it is feasible or<br>
not. if it is yes, how much effort would it require.<br>
Please share your thoughts.<br>
Thank you<br>
<br>
Regards<br>
Ramprasad N<br>
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Message: 2<br>
Date: Tue, 23 Dec 2008 05:05:24 -0500<br>
From: "Jason Garrett-Glaser" <<a href="mailto:darkshikari@gmail.com">darkshikari@gmail.com</a>><br>
Subject: Re: [x264-devel] Lossless H.264 encoding<br>
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2008/12/23 Ram prasad <<a href="mailto:ramprasad85@gmail.com">ramprasad85@gmail.com</a>>:<br>
> Hi all<br>
> My source data is raw 24 bit RGB VGA video. I want to encode it into a h.264<br>
> video. my requirement is that this should be a lossless compression. Looking<br>
> at the code i think x264 does not support any other format other than YUV<br>
> 420. I am planning to modify the code to make it work on high quality YUV<br>
> 444 or if possible on the RGB data itself.<br>
> Before i embark on this task i would like to know whether it is feasible or<br>
> not. if it is yes, how much effort would it require.<br>
<br>
RGB support is probably not feasible; I don't even know if the spec<br>
supports it, and even if it does, I know of no decoders that do--you'd<br>
have to modify a decoder to support it to, and you'd probably end up<br>
having to use the Separate Chroma Plane coding feature, where each<br>
chroma plane is its own image.<br>
<br>
YUV444 is definitely feasible. It would require the following changes:<br>
<br>
1. In all cases where chroma planes are handled, instead of >>1 to<br>
get the size of chroma, or chroma stride, or whatever, a variable<br>
would have to be used. This is probably the most time consuming step<br>
by far--going through all the code, finding all places where 420 is<br>
assumed, and fix it.<br>
2. AFAIK, a different Hadamard transform is used for chroma coding<br>
for 422/444. This isn't important in lossless mode, but it would have<br>
to be implemented for the feature to be accepted (since lossy is also<br>
useful...). It probably wouldn't be much work though. In fact, if<br>
I'm right, you might be able to just use the luma transform for chroma<br>
in 444, as I think they might be the same.<br>
3. Deblock would have to be called on more chroma edges accordingly.<br>
Not important in lossless, but would be needed for lossy.<br>
4. Increase the size of the necessary dct blocks in x264_t to add<br>
enough room for all the chroma DCTs and adjust CABAC/CAVLC coding as<br>
necessary.<br>
<br>
Dark Shikari<br>
<br>
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End of x264-devel Digest, Vol 19, Issue 23<br>
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</blockquote></div><br><br clear="all"><br>-- <br>"Love all serve all" - ..::Sri Sathya Sai::..<br>
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