Hi , Thanks for the kind reply, I could more info from class AVCDecoderConfigurationRecord of 14496-part 15, thanks to your pointers. --vineeth <div class="gmail_quote">On Sun, Sep 12, 2010 at 5:38 PM, Sandeep Prakash <<a href="mailto:123sandy@gmail.com">123sandy@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> Hi Vineeth, <div class="im"> vineeth wrote: > > For few mp4 files, the first 4 bytes correspond to NumBytesInNalUnit and > for few other the first 2 bytes tell the Nal Unit size. Is there a way to > determine if the first 4 or the first 2 bytes give the size on Nal unit? > </div>In case of h264 streams qtdemux will give the decoder config info in the caps as "codec_data", as a GstBuffer. Note that this is not the bytestream format. This comprises of: <6 bytes avcC atom> + <SPS> + <1 byte indicating Number of PPS present> + <PPS> + <PPS> + .... In the avcC atom the 2 Least Significant Bits of the 5th Byte corresponds to the (NumBytesInNalUnit -1). So to get the NumBytesInNalUnit (Length of Length of NAL): length_of_length = (<5th Byte of "codec_data"> & 0x3) + 1 <div class="im"> vineeth wrote: > > Also, is it possible to configure qtdemux to give Nal units with NAL > prefix ( Annex-B of *14496-10* standard) > </div>AFAIK configuration is not possible. Regards, Sandeep Prakash <a href="http://sandeepprakash.homeip.net" target="_blank">http://sandeepprakash.homeip.net</a> -- View this message in context: <a href="http://gstreamer-devel.966125.n4.nabble.com/qtdemux-nal-slice-size-tp2535442p2536285.html" target="_blank">http://gstreamer-devel.966125.n4.nabble.com/qtdemux-nal-slice-size-tp2535442p2536285.html</a> Sent from the GStreamer-devel mailing list archive at Nabble.com. ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing <a href="http://p.sf.net/sfu/novell-sfdev2dev" target="_blank">http://p.sf.net/sfu/novell-sfdev2dev</a> _______________________________________________ gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.sourceforge.net">gstreamer-devel@lists.sourceforge.net</a> <a href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel" target="_blank">https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</a> </blockquote></div>