<div dir="ltr">A related technical question. Can we split a large Iframe nal frame into slices after the fact? Sometimes the encoder is a closed piece of hardware/firmware. Is it possible to split it into slices at a macroblock boundary?<br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Jun 18, 2014 at 10:19 AM, Vikram Singh <span dir="ltr"><<a href="mailto:vikram@vizexperts.com" target="_blank">vikram@vizexperts.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div link="blue" vlink="purple" lang="EN-US"><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hi ross,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I am having -- </span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">unsigned OutPacketBuffer::maxSize = 900000; <span style="color:#376092">in mediaSink.cpp<u></u><u></u></span></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#376092">If I decrease the maxSize then the frames I get are truncated.<u></u><u></u></span></p><p class="MsoNormal">
<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#376092"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#376092">Can you please specify how to decrease the nal unit size without decreasing the value of maxSize.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#376092"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#376092">Thanks <u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#376092">Vikram Singh</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><div><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> live-devel [mailto:<a href="mailto:live-devel-bounces@ns.live555.com" target="_blank">live-devel-bounces@ns.live555.com</a>] <b>On Behalf Of </b>Ross Finlayson<br>
<b>Sent:</b> Wednesday, June 18, 2014 7:03 PM<br><b>To:</b> LIVE555 Streaming Media - development & use<br><b>Subject:</b> Re: [Live-devel] Starting Frames are corrupted<u></u><u></u></span></p></div></div><p class="MsoNormal">
<u></u> <u></u></p><div><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><p class="MsoNormal">I am testing the testH264VideoStreamer.cpp provided in the testprogs of<br>live555 library folder.<br>This file will stream a h264 file.<br>
My h264 file is not corrupted.<br>I am viewing the stream using vlc player.<u></u><u></u></p></blockquote><div><p class="MsoNormal"><u></u> <u></u></p></div><p class="MsoNormal">(Sorry, I sent my previous email before I read your last email, in which you explained what you're doing.)<u></u><u></u></p>
</div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">Your problem is that your stream contains extremely large 'I- frames' (also known as 'key frames'), and your encoder is encoding each I-frame so that it takes up a single H.264 NAL unit.<u></u><u></u></p>
</div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><div><p class="MsoNormal">If you're using VLC as a client, then be aware that - if your I-frame NAL units are excessively large - the first few received frames *will* be truncated. VLC notices this and increases its buffer size, so after a few seconds should have increased its buffer size large enough. That's why you see video corruption only for the first few frames. (There may be an option in VLC to use a larger initial buffer size. However, VLC is not our software, so we can't help you with VLC-related problems.)<u></u><u></u></p>
</div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">It's important to understand that each outgoing NAL unit - if it is larger than the RTP/UDP packet size (about 1500 bytes on most networks) - will be broken up into multiple outgoing RTP packets, and the receiver must receive *all* of these packets in order to be able to reconstruct the frame. In other words, if even one of these packets is lost, then the receiver will lose the *entire* NAL unit. That's why the NAL units - generated by your encoder - should be as small as is reasonable.<u></u><u></u></p>
</div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">The best solution here - for streaming - is to to not send extremely large NAL units. I-frames should be encoded as multiple 'slice' NAL units. Reconfigure your encoder to break up 'key frames' into multiple (therefore much smaller) 'slice' NAL units.<u></u><u></u></p>
</div></div><p class="MsoNormal"><u></u> <u></u></p><div><p class="MsoNormal"><span><span style="font-family:"Helvetica","sans-serif";color:black">Ross Finlayson</span></span><span style="font-family:"Helvetica","sans-serif";color:black"><br>
<span>Live Networks, Inc.</span><br><span><a href="http://www.live555.com/" target="_blank">http://www.live555.com/</a></span></span> <u></u><u></u></p></div><p class="MsoNormal"><u></u> <u></u></p></div></div><br>_______________________________________________<br>
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