Appsink stops (pauses/freezes) after 2 frames.

[Hjalmar Turesson]

Hi,

I'm trying to write the buffer timestamps (buf.pts) of a webcam steam to a
text file. I use appsink and a little callable function. This works fine
when I stream h.264 (apart from non-monotonical timestamps). But, it fails
if I stream raw or mpeg. I see no errors or warnings, but the stream
freezes/pauses after two frames (i.e. 2 timestamps written to file). When
streaming h.264 h264parse is necessary otherwise it too freezes after 2
frames. I tried using videoparse, but this crashes python, and jpegparse
does not make any difference.

Does anyone have advice?

Scripts (unfortunately not gst-launch since I do not know how to combine
that with the callback)
- - - - - - - - - - - - - - - - - -

Streaming h.264 (WORKS):

class Webcam_ts_h264:

def __init__(self, video_dev='/dev/video0', fps=15):

"""

"""

ts_log_fname = 'ts_test.log'

 self.ts_log = open(ts_log_fname, 'w')

self.ts_log.write('n_buf, buf.pts\n')

self.n_frames = 0

self.pipeline = Gst.Pipeline()

 def on_new_sample(appsink):

"""

Function called from the pipeline by appsink.

Writes the timestampes of frame capture to a log file.

"""

# Get the buffer

smp = appsink.emit('pull-sample')

buf = smp.get_buffer()

self.n_frames += 1

self.ts_log.write('%d,%0.9f\n' %

(self.n_frames, np.float64(1e-9) * buf.pts))

return Gst.FlowReturn.OK


 # Video source:

self.v4l2src = Gst.ElementFactory.make('v4l2src', None)

self.v4l2src.set_property('device', video_dev)

self.v4l2src.set_property('do-timestamp', 'true')

# Formats available from C920 camera:

# 'image/jpeg', 'video/x-h264', 'video/x-raw'

vid_caps = Gst.Caps.from_string('video/x-h264,'

'width=%d,height=%d,'

'framerate=%d/1' % (640, 480, fps))

self.vid_filter = Gst.ElementFactory.make('capsfilter', None)

self.vid_filter.set_property('caps', vid_caps)

self.vid_parse = Gst.ElementFactory.make('h264parse', None)

self.ts_sink = Gst.ElementFactory.make('appsink', None)

# Setting properties of appsink

# Tell sink to emit signals

self.ts_sink.set_property('emit-signals', True)

self.ts_sink.set_property('sync', False) # No sync

# Connect appsink to my function (writing timestamps)

self.ts_sink.connect('new-sample', on_new_sample)


 # Add elements to the pipeline

self.pipeline.add(self.v4l2src)

self.pipeline.add(self.vid_filter)

self.pipeline.add(self.vid_parse)

self.pipeline.add(self.ts_sink)


 # link

self.v4l2src.link(self.vid_filter)

self.vid_filter.link(self.vid_parse)

self.vid_parse.link(self.ts_sink)

 def run(self):

self.pipeline.set_state(Gst.State.PLAYING)


 def quit(self):

self.pipeline.set_state(Gst.State.NULL)

self.ts_log.close()


Streaming raw (FAILS):


class Webcam_ts_raw:

def __init__(self, video_dev='/dev/video0', fps=15):

"""

"""

ts_log_fname = 'ts_test.log'

 self.ts_log = open(ts_log_fname, 'w')

self.ts_log.write('n_buf, buf.pts\n')

self.n_frames = 0

self.pipeline = Gst.Pipeline()

 def on_new_sample(appsink):

"""

Function called from the pipeline by appsink.

Writes the timestampes of frame capture to a log file.

"""

# Get the buffer

smp = appsink.emit('pull-sample')

buf = smp.get_buffer()

self.n_frames += 1

self.ts_log.write('%d,%0.9f\n' %

(self.n_frames, np.float64(1e-9) * buf.pts))

return Gst.FlowReturn.OK


 # Video source:

self.v4l2src = Gst.ElementFactory.make('v4l2src', None)

self.v4l2src.set_property('device', video_dev)

self.v4l2src.set_property('do-timestamp', 'true')

# Formats available from C920 camera:

# 'image/jpeg', 'video/x-h264', 'video/x-raw'

vid_caps = Gst.Caps.from_string('video/x-raw,'

'width=%d,height=%d,'

'framerate=%d/1' % (640, 480, fps))

self.vid_filter = Gst.ElementFactory.make('capsfilter', None)

self.vid_filter.set_property('caps', vid_caps)

#self.vid_parse = Gst.ElementFactory.make('jpegparse', None)

self.ts_sink = Gst.ElementFactory.make('appsink', None)

# Setting properties of appsink

# Tell sink to emit signals

self.ts_sink.set_property('emit-signals', True)

self.ts_sink.set_property('sync', False) # No sync

# Connect appsink to my function (writing timestamps)

self.ts_sink.connect('new-sample', on_new_sample)


 # Add elements to the pipeline

self.pipeline.add(self.v4l2src)

self.pipeline.add(self.vid_filter)

#self.pipeline.add(self.vid_parse)

self.pipeline.add(self.ts_sink)


 # link

self.v4l2src.link(self.vid_filter)

self.vid_filter.link(self.ts_sink)

#self.vid_filter.link(self.vid_parse)

#self.vid_parse.link(self.ts_sink)

 def run(self):

self.pipeline.set_state(Gst.State.PLAYING)


 def quit(self):

self.pipeline.set_state(Gst.State.NULL)

self.ts_log.close()

Best regards,
Hjalmar
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