Renato,<div><br></div><div>How would one go about rendering the stream for only the luminance plane? Do you mean going into my MF H.264 encoder? You must. Otherwise I don't know how to analyze the compressed output to omit the color. And for the MF H.264 encoder, I don't think there's any way to tell it to do only Y. Is this what you were suggesting? If so, then how would one get around the problem I just indicated? If not, what did you really mean.</div>
<div><br></div><div><br><div class="gmail_quote">On Fri, Jan 4, 2013 at 8:47 AM, Renato MAURO (Libero) <span dir="ltr"><<a href="mailto:renatomauro@libero.it" target="_blank">renatomauro@libero.it</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
NV12 is similar to I420 (or YUV420, if you prefer), so it is 12 bit
per pixel, 8 for luminance and 4 for CrCb (or U and V if you
prefer). See <a href="http://www.fourcc.org/yuv.php#NV12" target="_blank">http://www.fourcc.org/yuv.php#NV12</a>.<br>
Obviously, "4 bits for CrCb" means that each byte is used for 4
pixels (a 2x2 quad), and so NV12 is a planar only format.<br>
<br>
So: 640 x 480 x 1,5 = 450 kBi = 3.51 Mbi uncompressed => 3.51 Mbi
/ 160 kbi = 22,5 times.<br>
<br>
I suggest to render the stream for the luminance plane only (like
old TV sets!!): if you get a good output, the problem is the way the
renderer works on the U and V plane.<br>
<br>
<br>
Regards,<br>
<br>
Renato<br>
<br>
<br>
<div>Il 04/01/2013 13.49,
<a href="mailto:temp2010@forren.org" target="_blank">temp2010@forren.org</a> ha scritto:<br>
</div>
<blockquote type="cite"><div><div class="h5">Thanks very much for your help, Ross.
<div><br>
</div>
<div>BACKGROUND: (CLARIFICATION ONLY) Indeed I only have one
thread calling doEventLoop(). That's all I meant by my
penultimate background sentence. The last background sentence
points out a separate thread for MF, that's independent of
Live555, and is in fact the thread taking advantage of the one
exception within Live555: calling triggerEvent().</div>
<div><br>
</div>
<div>FOLLOWUP QUESTION: Having incorporated your question one
answer, my output is better and now only "very poor" rather than
"horrible". My uncompressed stream is 640 x 480 x 30fps. It
passes through NV12 format, which when considered as YUV I think
has about 16 bits of info per pixel (8 bits for Y, 8 bits for
UV, like YUV422). So an uncompressed 640 x 480 frame should
have nearly 5Mbits of info. However, the compressed frames I'm
sending to Live555 are generally 160kbits each (after an initial
384kbit frame). I realize you're not responsible for MF, but
perhaps you can give your opinion, please. This suggests to me
that my MF H.264 encoder is compressing roughly 5Mbits/160kbits
= 31 times. Perhaps my remaining "very poor" quality is because
this is too much compression. I reconfigured the encoder for 10
times the average bit rate, but this typical 160kbits/frame
output size didn't really change. DO YOU AGREE that I ought to
be able to increase encoder output quality by increasing average
bit rate, and that the 160kbits per compressed frame should rise
toward 5Mbits?</div>
<div><br>
</div>
<div>Thanks again.</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<br>
<fieldset></fieldset>
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