def on_new_webcam_sample(self, appsink: GstApp.AppSink) -> Gst.FlowReturn:
if appsink.is_eos():
return Gst.FlowReturn.OK
sample: Gst.Sample = appsink.try_pull_sample(0.5)
buffer: Gst.Buffer = sample.get_buffer()
caps: Gst.Caps = sample.get_caps()
# This Pythonic usage is thank to python3-gst
struct: Gst.Structure = caps[0]
width = struct['width']
height = struct['height']
success, mapinfo = buffer.map(
Gst.MapFlags.READ) # type: bool, Gst.MapInfo
if not success:
logger.error('Failed to get mapinfo.')
return Gst.FlowReturn.ERROR
# In Gstreamer 1.18, Gst.MapInfo.data is memoryview instead of bytes
imgdata = mapinfo.data.tobytes() if isinstance(
mapinfo.data, memoryview) else mapinfo.data
img = zbar.Image(width, height, 'Y800', imgdata)
n = self.zbar_scanner.scan(img)
logger.debug('Any QR code?: {}', n)
if not n:
return Gst.FlowReturn.OK
# Found QR code in webcam screenshot
logger.debug('Emulate pressing Pause button')
self.btn_pause.set_active(True)
self.display_result(img.symbols)
return Gst.FlowReturn.OK
def on_new_webcam_sample(self, appsink: GstApp.AppSink) -> Gst.FlowReturn:
if appsink.is_eos():
return Gst.FlowReturn.OK
sample: Gst.Sample = appsink.try_pull_sample(0.5)
buffer: Gst.Buffer = sample.get_buffer()
caps: Gst.Caps = sample.get_caps()
# This Pythonic usage is thank to python3-gst
struct: Gst.Structure = caps[0]
width = struct['width']
height = struct['height']
success, mapinfo = buffer.map(
Gst.MapFlags.READ) # type: bool, Gst.MapInfo
if not success:
logger.error('Failed to get mapinfo.')
return Gst.FlowReturn.ERROR
img = zbar.Image(width, height, 'Y800', mapinfo.data)
n = self.zbar_scanner.scan(img)
logger.debug('Any QR code?: {}', n)
if not n:
return Gst.FlowReturn.OK
# Found QR code in webcam screenshot
logger.debug('Emulate pressing Pause button')
self.btn_pause.set_active(True)
try:
sym = next(iter(img.symbols))
except StopIteration:
logger.error(
'Something wrong. Failed to extract symbol from zbar image!')
return Gst.FlowReturn.ERROR
logger.info('QR type: {}', sym.type)
logger.info('Decoded string: {}', sym.data)
self.raw_result_buffer.set_text(sym.data)
return Gst.FlowReturn.OK
def _on_buffer(self, sink: GstApp.AppSink,
data: typ.Any) -> Gst.FlowReturn:
"""Callback on 'new-sample' signal"""
# Emit 'pull-sample' signal
# https://lazka.github.io/pgi-docs/GstApp-1.0/classes/AppSink.html#GstApp.AppSink.signals.pull_sample
sample = sink.emit("pull-sample")
if isinstance(sample, Gst.Sample):
self._queue.put(self._extract_buffer(sample))
self._counter += 1
return Gst.FlowReturn.OK
self.log.error(
"Error : Not expected buffer type: %s != %s. %s",
type(sample),
Gst.Sample,
self,
)
return Gst.FlowReturn.ERROR