Video sync via GstClock

[Andreas Rödig]

Hi Marc,

yes your script seems what i want.

I try it in c, but i can not get videos in sync.
I got very good hints from your script (base_time and so on...), but 
finally it doesn't has any effect.

Here is what i do:
Server:
netclock=gst_pipeline_get_clock((GstPipeline*)pipeline);
gst_pipeline_use_clock((GstPipeline*)pipeline,netclock);
basetime = gst_clock_get_time(netclock);
provider=gst_net_time_provider_new(netclock, "192.168.1.69", 5637);
gst_pipeline_set_new_stream_time((GstPipeline*)pipeline,GST_CLOCK_TIME_NONE);
gst_element_set_start_time(pipeline,basetime);
gst_element_set_state(GST_ELEMENT(pipeline), GST_STATE_PLAYING);

Client (basetime comes over network):
gst_pipeline_set_new_stream_time((GstPipeline*)pipeline,GST_CLOCK_TIME_NONE);
netclock =  gst_net_client_clock_new(NULL, "192.168.1.69", 5637, 
(GstClockTime)position);
gst_element_set_start_time(pipeline,position);
gst_pipeline_use_clock((GstPipeline*)pipeline,netclock);
gst_element_set_state(GST_ELEMENT(pipeline), GST_STATE_PLAYING);

Do i miss something?

Thanks,
Andreas Rödig


Am 12.03.2013 17:57, schrieb Marc Leeman:
> I think these were the scripts I used for the demo (the devices are
> powered off, so I cannot check atm).
>
> the setup was a 2x2 of Blood and Chrome
>
> the top left was the original and the three others were files that
> were converted with some effect of videoconvert (sepia, xray, ...).
>
> These files were all stored on the HDDs driving the monitor (4
> monitors, 4 devices (AD10)). Oh, and the files are TS, I had an issue
> with MKV but not yet look into it as to why.
>
> marc at drd1812:~$ cat play-master-file.py
> #!/usr/bin/env python
>
> import sys
>
> import pygst
> pygst.require('0.10')
> import gst
>
> def main(args):
>      _, uri, port, crop = args
>      port = int(port)
>      crop = crop.split(':')
>
>      # make the pipeline
>      # pipeline = gst.element_factory_make("playbin2", "player")
>      # pipeline.set_property("uri", uri)
>
>      # gstline = "filesrc name=src ! decodebin ! videocrop left=%s
> right=%s top=%s bottom=%s ! autovideosink" % (crop[0], crop[1],
> crop[2], crop[3])
>      # make pipeline more explicit for older code (require parser)
>      gstline = "filesrc name=src ! mpegtsdemux ! mpeg4videoparse !
> ffdec_mpeg4 ! videocrop left=%s right=%s top=%s bottom=%s !
> timeoverlay ! ffmpegcolorspace ! videoscale !
> video/x-raw-rgb,height=1200,width=1920 ! ximagesink" % (crop[0],
> crop[1], crop[2], crop[3])
>      print gstline
>
>      pipeline = gst.parse_launch (gstline)
>      pipeline.get_by_name('src').set_uri(uri) # uri interface
>
>      # make sure some other clock isn't autoselected
>      clock = pipeline.get_clock()
>      print 'Using clock: ', clock
>      pipeline.use_clock(clock)
>
>      # this will start a server listening on a UDP port
>      clock_provider = gst.NetTimeProvider(clock, None, port)
>
>      # we explicitly manage our base time
>      base_time = clock.get_time()
>      print ('Start slave as: python ./play-slave.py %s [IP] %d %s:%s:%s:%s %d'
>             % (uri, port, crop[0], crop[1], crop[2], crop[3], base_time))
>
>      # disable the pipeline's management of base_time -- we're going
>      # to set it ourselves.
>      pipeline.set_new_stream_time(gst.CLOCK_TIME_NONE)
>      pipeline.set_base_time(base_time)
>
>      # now we go :)
>      pipeline.set_state(gst.STATE_PLAYING)
>
>      # wait until things stop
>      pipeline.get_bus().poll(gst.MESSAGE_EOS | gst.MESSAGE_ERROR, -1)
>      pipeline.set_state(gst.STATE_NULL)
>
> if __name__ == '__main__':
>      main(sys.argv)
>
>
> slave:
>
> marc at drd1812:~$ cat play-slave-file.py
> #!/usr/bin/env python
>
> import sys
>
> import pygst
> pygst.require('0.10')
> import gst
>
> def main(args):
>      _, uri, ip, port, crop, base_time = args
>      port, base_time, crop= int(port), int(base_time), crop.split(':')
>
>      # make the pipeline
>      # pipeline = gst.element_factory_make("playbin2", "player")
>      # pipeline.set_property("uri", uri)
>
>      # gstline = "filesrc name=src ! decodebin ! videocrop left=%s
> right=%s top=%s bottom=%s ! autovideosink" % (crop[0], crop[1],
> crop[2], crop[3])
>      # make pipeline more explicit for older code (require parser)
>      gstline = "filesrc name=src ! mpegtsdemux ! mpeg4videoparse !
> ffdec_mpeg4 ! videocrop left=%s right=%s top=%s bottom=%s !
> timeoverlay ! ffmpegcolorspace ! videoscale !
> video/x-raw-rgb,height=1200,width=1920 ! ximagesink" % (crop[0],
> crop[1], crop[2], crop[3])
>      print gstline
>
>      pipeline = gst.parse_launch (gstline)
>      pipeline.get_by_name('src').set_uri(uri) # uri interface
>      # disable the pipeline's management of base_time -- we're going
>      # to set it ourselves.
>      pipeline.set_new_stream_time(gst.CLOCK_TIME_NONE)
>
>      # make a clock slaving to the network
>      clock = gst.NetClientClock(None, ip, port, base_time)
>
>      # use it in the pipeline
>      pipeline.set_base_time(base_time)
>      pipeline.use_clock(clock)
>
>      # now we go :)
>      pipeline.set_state(gst.STATE_PLAYING)
>
>      # wait until things stop
>      pipeline.get_bus().poll(gst.MESSAGE_EOS | gst.MESSAGE_ERROR, -1)
>      pipeline.set_state(gst.STATE_NULL)
>
> if __name__ == '__main__':
>      main(sys.argv)
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