What is the alignment capability in video/x-h264

Tim Müller tim at centricular.com
Sat Feb 22 09:12:46 PST 2014

On Sat, 2014-02-22 at 04:47 -0800, pfarmer wrote:

> > 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).

Well, the output of x264enc is always also NALU aligned, since AU
alignment is a subset of NALU alignment. Where does it make a difference
for you? Is it just about the caps, or something else? The only
difference I can think of is that if you could get the encoder to output
a partial frame already you have marginally lower latency. Whether x264
actually supports that, I don't know (but didn't check). Most encoders

>  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. 

There was parsing done inside ffdec_h264, now parsing is done in
h264parse. Why not just put an h264parse in front of avdec_h264? Is it
about parsing overhead, or caps or.. ? 


Tim Müller, Centricular Ltd - http://www.centricular.com

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