Dear Luke, <div><br></div><div>Thanks for your advance, unfortunately, my raw data is stored at memory, I get it directly. So, I can not use av_read_frame(), and I am working embedding system, we have memory usage limit for app and lib, we resize the ffmpeg lib to take off encodec and decodec function. So, I can not use avcodec_decode_video2(), so sad~</div>
<div>So, do you know how to calculate the pts value for mpegts container.</div><div>this is big issue for me, please help, thanks a lot.</div><div><br></div><div>Regards, Eric Hsieh, 09/08<br><br><div class="gmail_quote">
2011/9/8 Luke Clemens <span dir="ltr"><<a href="mailto:lclemens@gmail.com">lclemens@gmail.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">The magic is in avcodec_encode_video() and avcodec_decode_video2(). The documentation for it is in the header file where it's defined. There are some examples online. You setup a codec context, then pass an uncompressed image to avcodec_encode_video(), and it will spit out a compressed buffer.<div>
<br></div><div>There are different options for sending over the network. </div><div><br></div><div>1) You can use the current network method you use now, and just send those compressed packets instead of uncompressed frames. The only catch is that you may have to send some setup information to your client as well so it knows how to setup the decoder. If you always use the same format, then you won't have to worry about that. It's slightly more complicated if you use P frames. for 16ms or less, you won't want to use B frames. The simplest is mjpeg, but it will use 3x more bandwidth than mpeg4 or H.264.</div>
<div><br></div><div>2) The other option is to use libavformat to send over the network. You setup an ouput context and then write those frames to it with av_write_frame(), and it will send the packets via RTP or another format that you specify.</div>
<div><br></div><div>At the client end you also have two choices, which depend on the option you chose for the server. </div><div><br></div><div>If you chose option 1, then you'll need to setup a decode context, receive the packets you sent, and feed them to avcodec_decode_video2(). You might need extra information about the codec so you might have to receive that also and use it to determine how to setup the decode context.</div>
<div><br></div><div>If you chose option 2, then you'll setup an input format context and repeatedly call av_read_frame() and feed the resulting frames into avcodec_decode_video2().</div><div><br></div><div>There are a few examples and tutorials on the web if you google around. Especially for the compression/decompression parts. Unfortunately, those few tutorials are all that's out there. One of the popular ones for decoding is here: <a href="http://dranger.com/ffmpeg/" target="_blank">http://dranger.com/ffmpeg/</a>. There is one for encoding in libavcodec/api-example.c . And of course the source code for ffplay, mplayer, vlc, and other opensource players is available, but if you're a C++ guy like me, you'll probably find it pretty ugly.</div>
<div><br></div><div>Also, make sure you have enough space in your buffers for padding at the end - I didn't realize it and it took a long time to figure out why I was getting errors. The details are in the documentation for the encode/decode functions.</div>
<div><br></div><div>--luke</div><div><br><div class="gmail_quote">On Thu, Aug 25, 2011 at 1:49 PM, <span dir="ltr"><<a href="mailto:david.weber@l-3com.com" target="_blank">david.weber@l-3com.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div lang="EN-US" link="blue" vlink="purple">
<div>
<p class="MsoNormal">Hey all, I have searched quite a bit, but haven't found a
good answer. So I thought I'd post it here.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I have a custom video device which gives me a simple framebuffer,
(24-bit BGR).<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I am trying to stream it elsewhere, but would like to
encode/compress it in realtime.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">On the client side, I would decode it, and display it in an
OpenGL window.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I have it working today, with uncompressed images, but it is
killing the network (as one would expect).<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Are there any examples for making something like this work?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">In short:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">[Custom Video Framebuffer] -> [encode] -> [network]
-> [decode] -> [display]<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Considerations that I have to deal with:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p style="margin-left:27.0pt"><u></u><span>1.)<span style="font:7.0pt "Times New Roman""> </span></span><u></u>Relatively
realtime. I have <16ms to encode a 640x480x3 frame buffer, and ship it
off.<u></u><u></u></p>
<p style="margin-left:27.0pt"><u></u><span>2.)<span style="font:7.0pt "Times New Roman""> </span></span><u></u>I
need a streaming-type on the wire format. The clients may be turned on/off
at any point, so i need to support this.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">The naive implementation, is simply running the video frames
though zlib, which is shrinking the data nicely, but it's rather expensive, and
makes me feel dirty. All of the examples I can find, are reading off an
existing encoded file, but not quite what I need.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks for your input<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">--dw<u></u><u></u></p>
</div>
</div>
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<br></blockquote></div><font color="#888888"><br><br clear="all"><div><br></div>-- <br>-<br>-<br>-<br>-<br>Luke Clemens<br><a href="http://clemens.bytehammer.com" target="_blank">http://clemens.bytehammer.com</a><br>
</font></div>
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