class Snapshot(cyclone.web.RequestHandler):

    @defer.inlineCallbacks

    def post(self):

        # save next pic

        # return /snapshot/path

        try:

            snapshotDir = 'todo'

            outputFilename = yield self.settings.gui.snapshot()

            assert outputFilename.startswith(snapshotDir)

            out = networking.vidref.path(

                "snapshot/%s" % outputFilename[len(snapshotDir):].lstrip('/'))

            self.write(json.dumps({'snapshot': out}))

            self.set_header("Location", out)

            self.set_status(303)

        except Exception:

            import traceback

            traceback.print_exc()

            raise

pipeline = videorecorder.GstSource(

class Live(cyclone.websocket.WebSocketHandler):

    def connectionMade(self, *args, **kwargs):

        pipeline.liveImages.subscribe(on_next=self.onFrame)

        stats.liveClients += 1

    def connectionLost(self, reason):

        #self.subj.dispose()

        stats.liveClients -= 1

    def onFrame(self, cf: videorecorder.CaptureFrame):

        if cf is None: return

        stats.liveWebsocketFrameFps.mark()

        self.sendMessage(

            json.dumps({

                'jpeg': base64.b64encode(cf.asJpeg()).decode('ascii'),

                'description': f't={cf.t}',

            }))

        # should be a little queue to miss fewer frames

        t1 = time.time()

        while self.nextImg is None:

            time.sleep(.015)

        stats.waitForNextImg = time.time() - t1

        cf, self.nextImg = self.nextImg, None

        self.frameMap.write(f'video {video_time_secs:g} = song {cf.t:g}\n')

        self.currentClipFrameCount += 1

        return numpy.asarray(cf.img)

class GstSource:

    def __init__(self, dev):

        """

        make new gst pipeline

        """

        Gst.init(None)

        self.musicTime = MusicTime(pollCurvecalc=False)

        self.liveImages: BehaviorSubject = BehaviorSubject(

            None)  # stream of Optional[CaptureFrame]

        log.info("new pipeline using device=%s" % dev)

        # using videocrop breaks the pipeline, may be this issue

        # https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/issues/732

        pipeStr = (

            f" ! videoconvert"

            f" ! appsink emit-signals=true max-buffers=1 drop=true name=end0 caps=video/x-raw,format=RGB,width={size[0]},height={size[1]}"

        )

        log.info("pipeline: %s" % pipeStr)

        self.pipe = Gst.parse_launch(pipeStr)

        self.setupPipelineError(self.pipe, self.onError)

        self.appsink = self.pipe.get_by_name('end0')

        self.appsink.connect('new-sample', self.new_sample)

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

        log.info('gst pipeline is recording video')

    def new_sample(self, appsink):

        try:

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

            caps = sample.get_caps()

            buf = sample.get_buffer()

            (result, mapinfo) = buf.map(Gst.MapFlags.READ)

            try:

                img = PIL.Image.frombytes(

                    'RGB', (caps.get_structure(0).get_value('width'),

                            caps.get_structure(0).get_value('height')),

                    mapinfo.data)

                img = self.crop(img)

            finally:

                buf.unmap(mapinfo)

            # could get gst's frame time and pass it to getLatest

            latest = self.musicTime.getLatest()

            if 'song' in latest:

                stats.queueGstFrameFps.mark()

                self.liveImages.on_next(

                    CaptureFrame(img=img,

                                 song=Song(latest['song']),

                                 t=latest['t'],

                                 isPlaying=latest['playing']))

        except Exception:

            traceback.print_exc()

        return Gst.FlowReturn.OK

    @stats.crop.time()

    def crop(self, img):

    def setupPipelineError(self, pipe, cb):

        bus = pipe.get_bus()

        def onBusMessage(bus, msg):

            print('nusmsg', msg)

            if msg.type == Gst.MessageType.ERROR:

                _, txt = msg.parse_error()

                cb(txt)

            return True

        # not working; use GST_DEBUG=4 to see errors

        bus.add_watch(0, onBusMessage)

        bus.connect('message', onBusMessage)

    def onError(self, messageText):

        if ('v4l2src' in messageText and

            ('No such file or directory' in messageText or

             'Resource temporarily unavailable' in messageText or

             'No such device' in messageText)):

            log.error(messageText)

            os.abort()

        else: