What is the alignment capability in video/x-h264

[pfarmer]

On 02/19/2014 06:37 PM, Tim Müller [via GStreamer-devel] wrote:
> On Wed, 2014-02-05 at 05:38 -0800, pfarmer wrote:
>
> Hi,
>
> > Thank you very much!
> >
> > That was a very helpful information!
> >
> > Just as an information:
> >
> > These are the caps as reported by testing with fakesrc/fakesink and
> > video/x-h264 capsfilter
> >
> > stream-format:byte-stream || stream-format:avc
> > au | nal || : au | nal
> >
> > gsteamer-1.0
> >   x264enc: y | n || y | n
> >   rtph264pay: y | y || y | n
> >   rtph264depay:  y | y || y | n
> >   avdec_h264: y | n || n | n
> >
> > So it seems that nal alignment is not (not yet) possible with the
> > gstreamer-1.0 implementations (v1.2.0 Ubuntu 64 13.10)
>
> What's not "possible" exactly?
It is not possible to output NALU aligned buffers from the x264enc 
element (as it wasn't in gstreamer0.10 either). It is also not possible 
to give NALU aligned buffers to the avdec_h264 element.
The reason is that I want to built my own packetizer for another 
transport protocol. For this, it would be sufficient/easier to get the 
NALUS directly.

>
> > gsteamer-0.10
> >   x264enc: y | n || y |  n
> >   rtph264pay:  y | y || y | y
> >   rtph264depay: y | y || n | n
> >   ffdec_h264: y | y || y | y
> >
> > I have not yet examined the source code if it is only a caps filtering
> > problem or if the functionality is really not implemented.
>
> AVC is always au-aligned, so anything else doesn't make sense there. In
> 1.0 we generally require parser before decoders now, which explains the
> change in avdec_h264.
>
Yes, true: It makes not much sense that avc is NALU aligned. AVC is the 
box type avcC (Advanced Video Coding Configuration Box) of ISO/IEC 
14496-15:2004, if I understood it correctly. Thus it is adding some sort 
of container format to find the various NALUs in one gst-buffer.



>  Cheers
>   -Tim
>
> -- 
> Tim Müller, Centricular Ltd - http://www.centricular.com
>
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email] </user/SendEmail.jtp?type=node&node=4665370&i=0>
> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
>
> ------------------------------------------------------------------------
> If you reply to this email, your message will be added to the 
> discussion below:
> http://gstreamer-devel.966125.n4.nabble.com/What-is-the-alignment-capability-in-video-x-h264-tp4665044p4665370.html 
>
> To start a new topic under GStreamer-devel, email 
> ml-node+s966125n966125h77 at n4.nabble.com
> To unsubscribe from GStreamer-devel, click here 
> <http://gstreamer-devel.966125.n4.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=966125&code=ZmxhY29uZUBnbXguZGV8OTY2MTI1fDY2NTk5NjY2OQ==>.
> NAML 
> <http://gstreamer-devel.966125.n4.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml> 
>





--
View this message in context: http://gstreamer-devel.966125.n4.nabble.com/What-is-the-alignment-capability-in-video-x-h264-tp4665044p4665436.html
Sent from the GStreamer-devel mailing list archive at Nabble.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/gstreamer-devel/attachments/20140222/fed766ce/attachment.html>