[x264-devel] libx264 encoding parameters that influence SPS andPPS

[declan harrison]

On Mon, Sep 20, 2010 at 11:31 PM, Jason Garrett-Glaser
<darkshikari at gmail.com> wrote:
> On Mon, Sep 20, 2010 at 2:57 PM,  <harrison.declan at gmail.com> wrote:
>> Hi jason
>>
>> Do you think exposing the libx264 parameter sps-id in ffmpeg would be of general use?
>
> Yes.  Patches welcome.  Send it to the ffmpeg-devel ML.
Hi Jason

I noticed a problem in what Im doing with supplying multiple SPS/PPS
for  video content during playback over network based I/O. File based
I/O is fine.

For example if I use VLC to playback one of these videos files that I
have created, then theres no problems whatever, the player is able to
switch to playing the 2nd part of the video content, this is were the
content is file based.

Now for the exact same video but this time as I create the content and
send it over the network (over HTTP) to VLC the player is using
network based I/O the player freezes completely on when the 2nd part
of the video content arrives; and then buffers up all the rest of the
video content before playing. When it resumes playing it does do
without a problem.  The debugger in VLC complains about the number of
"reference frames exceeds max".  Now if I captured this exact same
video as client downloads over network and save as a file and playback
to VLC it has no problems or complaints.

That indicates to me that the player is able to seek forward using
file based I/O to get the frame it wants but is unable to do when
using network based I/O and therefore buffers up all the content
before continuing to play.  Well thats what I suspect as I'm not 100%
sure.

So I assumed that the problem was that I might have transitioned on a
non-key packet (which it was) so then I ensured that as soon as I
transition I force the next packet output to be a complete keyframe.
However this doesnt solve it and the problem still exists.

You any ideas what the root cause of the problem is when doing this
over a network that doesnt occur when using file based I/O.

Running through H264Visa, around frame 400 I see that the switch
occurs and I see that the Picture No and Decoding No can get out of
sync by 1. Also the MaxFPS changes to 2000(from 50) and Aspect Ratio
changes to Unspecified (from 1:1) and Timing Type changes to Variable
(from Fixed).

Not sure why or if these parameters cause the problem I see over the network.

Any suggestions I could try out or ideas why this isnt playing back
over the network

Thanks
Declan