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<p class="MsoNormal"><span style="color:#1F497D">Thank you for your answers and suggestions.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Miladin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext;mso-fareast-language:EN-GB">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext;mso-fareast-language:EN-GB">
live-devel [mailto:live-devel-bounces@ns.live555.com] <b>On Behalf Of </b>Joshua Kordani<br>
<b>Sent:</b> 20 June 2014 15:05<br>
<b>To:</b> live-devel@ns.live555.com<br>
<b>Subject:</b> Re: [Live-devel] Decoding H264 non-IDR picture<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On 6/20/14 5:42 AM, Miladin Sajic wrote:<o:p></o:p></p>
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<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I am trying to implement decoding of H264 NAL units that are received from the camera (using live555 rtsp streaming). Everything works fine if received NAL unit is IDR (see part of the code in PS) but it does not work for SLICE NAL unit
(nal_unit_type == 1). To decode image this NAL unit is not enough on its own and reference needs to be made to all the units since last IDR unit (key frame with nal_unit_type == 5). I do not know how to implement this.
<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal">How to combine last IDR unit with the following SLICE NAL units to produce H264 frame before sending it to the decoder?<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D;mso-fareast-language:EN-GB"><img width="468" height="94" id="Picture_x0020_3" src="cid:image001.png@01CF8C9A.19734270"></span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Can you give me any advice or point me to the right direction?<span style="color:#1F497D">
</span>Any help is greatly appreciated.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif";mso-fareast-language:EN-GB"><br>
<br>
<o:p></o:p></span></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>live-devel mailing list<o:p></o:p></pre>
<pre><a href="mailto:live-devel@lists.live555.com">live-devel@lists.live555.com</a><o:p></o:p></pre>
<pre><a href="http://lists.live555.com/mailman/listinfo/live-devel">http://lists.live555.com/mailman/listinfo/live-devel</a><o:p></o:p></pre>
</blockquote>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif";mso-fareast-language:EN-GB">Sorry Ross for continuing the OT discussion, but just real quick. The answer to your decoding question lies in the question itself, you said
that non idr slices can reference any prior nal up to the last idr. So in order to decode, you need to pass all prior nals up to the last idr. How exactly you do this depends on the decoder library you're using, ie ffmpeg requires that you provide the full
bitstream each call to the decoder, hence (sc = startcode)<br>
sps sc pps sc idr frame 1<br>
sps sc pps sc idr sc slice frame 2<br>
sps sc pps sc idr sc slice sc slice frame 3<br>
and so on.<br>
<br>
I can imagine a decoding library frontend that keeps track of the unchanging parts of the bitstream for you, and I wonder why it doesn't already exist, ie<br>
you pass nals in receive order to the decoder library and then ask the library to give you a frame. Eventually, once it has enough info, you get a frame back each call, while only having to briefly store the latest nal on behalf of the library.<br>
<br>
I know this is OT, but if I'm mistaken someone please speak up.<br>
<br>
<o:p></o:p></span></p>
<pre>-- <o:p></o:p></pre>
<pre>Joshua Kordani<o:p></o:p></pre>
<pre>LSA Autonomy<o:p></o:p></pre>
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