Add python rtc server

python/README.rst

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+Audio, video and data channel server
+====================================
+
+This example illustrates establishing audio, video and a data channel with a
+browser. It also performs some image processing on the video frames using
+OpenCV.
+
+Running
+-------
+
+First install the required packages:
+
+.. code-block:: console
+
+    $ pip install aiohttp aiortc opencv-python
+
+When you start the example, it will create an HTTP server which you
+can connect to from your browser:
+
+.. code-block:: console
+
+    $ python server.py
+
+You can then browse to the following page with your browser:
+
+http://127.0.0.1:8080
+
+Once you click `Start` the browser will send the audio and video from its
+webcam to the server.
+
+The server will play a pre-recorded audio clip and send the received video back
+to the browser, optionally applying a transform to it.
+
+In parallel to media streams, the browser sends a 'ping' message over the data
+channel, and the server replies with 'pong'.
+
+Additional options
+------------------
+
+If you want to enable verbose logging, run:
+
+.. code-block:: console
+
+    $ python server.py -v
+
+Credits
+-------
+
+The audio file "demo-instruct.wav" was borrowed from the Asterisk
+project. It is licensed as Creative Commons Attribution-Share Alike 3.0:
+
+https://wiki.asterisk.org/wiki/display/AST/Voice+Prompts+and+Music+on+Hold+License

python/client.js

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+// get DOM elements
+var dataChannelLog = document.getElementById('data-channel'),
+    iceConnectionLog = document.getElementById('ice-connection-state'),
+    iceGatheringLog = document.getElementById('ice-gathering-state'),
+    signalingLog = document.getElementById('signaling-state');
+
+// peer connection
+var pc = null;
+
+// data channel
+var dc = null, dcInterval = null;
+
+function createPeerConnection() {
+    var config = {
+        sdpSemantics: 'unified-plan'
+    };
+
+    if (document.getElementById('use-stun').checked) {
+        config.iceServers = [{ urls: ['stun:stun.l.google.com:19302'] }];
+    }
+
+    pc = new RTCPeerConnection(config);
+
+    // register some listeners to help debugging
+    pc.addEventListener('icegatheringstatechange', () => {
+        iceGatheringLog.textContent += ' -> ' + pc.iceGatheringState;
+    }, false);
+    iceGatheringLog.textContent = pc.iceGatheringState;
+
+    pc.addEventListener('iceconnectionstatechange', () => {
+        iceConnectionLog.textContent += ' -> ' + pc.iceConnectionState;
+    }, false);
+    iceConnectionLog.textContent = pc.iceConnectionState;
+
+    pc.addEventListener('signalingstatechange', () => {
+        signalingLog.textContent += ' -> ' + pc.signalingState;
+    }, false);
+    signalingLog.textContent = pc.signalingState;
+
+    // connect audio / video
+    pc.addEventListener('track', (evt) => {
+        if (evt.track.kind == 'video')
+            document.getElementById('video').srcObject = evt.streams[0];
+        else
+            document.getElementById('audio').srcObject = evt.streams[0];
+    });
+
+    return pc;
+}
+
+function enumerateInputDevices() {
+    const populateSelect = (select, devices) => {
+        let counter = 1;
+        devices.forEach((device) => {
+            const option = document.createElement('option');
+            option.value = device.deviceId;
+            option.text = device.label || ('Device #' + counter);
+            select.appendChild(option);
+            counter += 1;
+        });
+    };
+
+    navigator.mediaDevices.enumerateDevices().then((devices) => {
+        populateSelect(
+            document.getElementById('audio-input'),
+            devices.filter((device) => device.kind == 'audioinput')
+        );
+        populateSelect(
+            document.getElementById('video-input'),
+            devices.filter((device) => device.kind == 'videoinput')
+        );
+    }).catch((e) => {
+        alert(e);
+    });
+}
+
+function negotiate() {
+    return pc.createOffer().then((offer) => {
+        return pc.setLocalDescription(offer);
+    }).then(() => {
+        // wait for ICE gathering to complete
+        return new Promise((resolve) => {
+            if (pc.iceGatheringState === 'complete') {
+                resolve();
+            } else {
+                function checkState() {
+                    if (pc.iceGatheringState === 'complete') {
+                        pc.removeEventListener('icegatheringstatechange', checkState);
+                        resolve();
+                    }
+                }
+                pc.addEventListener('icegatheringstatechange', checkState);
+            }
+        });
+    }).then(() => {
+        var offer = pc.localDescription;
+        var codec;
+
+        codec = document.getElementById('audio-codec').value;
+        if (codec !== 'default') {
+            offer.sdp = sdpFilterCodec('audio', codec, offer.sdp);
+        }
+
+        codec = document.getElementById('video-codec').value;
+        if (codec !== 'default') {
+            offer.sdp = sdpFilterCodec('video', codec, offer.sdp);
+        }
+
+        document.getElementById('offer-sdp').textContent = offer.sdp;
+        return fetch('/offer', {
+            body: JSON.stringify({
+                sdp: offer.sdp,
+                type: offer.type,
+                video_transform: document.getElementById('video-transform').value
+            }),
+            headers: {
+                'Content-Type': 'application/json'
+            },
+            method: 'POST'
+        });
+    }).then((response) => {
+        return response.json();
+    }).then((answer) => {
+        document.getElementById('answer-sdp').textContent = answer.sdp;
+        return pc.setRemoteDescription(answer);
+    }).catch((e) => {
+        alert(e);
+    });
+}
+
+function start() {
+    document.getElementById('start').style.display = 'none';
+
+    pc = createPeerConnection();
+
+    var time_start = null;
+
+    const current_stamp = () => {
+        if (time_start === null) {
+            time_start = new Date().getTime();
+            return 0;
+        } else {
+            return new Date().getTime() - time_start;
+        }
+    };
+
+    if (document.getElementById('use-datachannel').checked) {
+        var parameters = JSON.parse(document.getElementById('datachannel-parameters').value);
+
+        dc = pc.createDataChannel('chat', parameters);
+        dc.addEventListener('close', () => {
+            clearInterval(dcInterval);
+            dataChannelLog.textContent += '- close\n';
+        });
+        dc.addEventListener('open', () => {
+            dataChannelLog.textContent += '- open\n';
+            dcInterval = setInterval(() => {
+                var message = 'ping ' + current_stamp();
+                dataChannelLog.textContent += '> ' + message + '\n';
+                dc.send(message);
+            }, 1000);
+        });
+        dc.addEventListener('message', (evt) => {
+            dataChannelLog.textContent += '< ' + evt.data + '\n';
+
+            if (evt.data.substring(0, 4) === 'pong') {
+                var elapsed_ms = current_stamp() - parseInt(evt.data.substring(5), 10);
+                dataChannelLog.textContent += ' RTT ' + elapsed_ms + ' ms\n';
+            }
+        });
+    }
+
+    // Build media constraints.
+
+    const constraints = {
+        audio: false,
+        video: false
+    };
+
+    if (document.getElementById('use-audio').checked) {
+        const audioConstraints = {};
+
+        const device = document.getElementById('audio-input').value;
+        if (device) {
+            audioConstraints.deviceId = { exact: device };
+        }
+
+        constraints.audio = Object.keys(audioConstraints).length ? audioConstraints : true;
+    }
+
+    if (document.getElementById('use-video').checked) {
+        const videoConstraints = {};
+
+        const device = document.getElementById('video-input').value;
+        if (device) {
+            videoConstraints.deviceId = { exact: device };
+        }
+
+        const resolution = document.getElementById('video-resolution').value;
+        if (resolution) {
+            const dimensions = resolution.split('x');
+            videoConstraints.width = parseInt(dimensions[0], 0);
+            videoConstraints.height = parseInt(dimensions[1], 0);
+        }
+
+        constraints.video = Object.keys(videoConstraints).length ? videoConstraints : true;
+    }
+
+    // Acquire media and start negociation.
+
+    if (constraints.audio || constraints.video) {
+        if (constraints.video) {
+            document.getElementById('media').style.display = 'block';
+        }
+        navigator.mediaDevices.getUserMedia(constraints).then((stream) => {
+            stream.getTracks().forEach((track) => {
+                pc.addTrack(track, stream);
+            });
+            return negotiate();
+        }, (err) => {
+            alert('Could not acquire media: ' + err);
+        });
+    } else {
+        negotiate();
+    }
+
+    document.getElementById('stop').style.display = 'inline-block';
+}
+
+function stop() {
+    document.getElementById('stop').style.display = 'none';
+
+    // close data channel
+    if (dc) {
+        dc.close();
+    }
+
+    // close transceivers
+    if (pc.getTransceivers) {
+        pc.getTransceivers().forEach((transceiver) => {
+            if (transceiver.stop) {
+                transceiver.stop();
+            }
+        });
+    }
+
+    // close local audio / video
+    pc.getSenders().forEach((sender) => {
+        sender.track.stop();
+    });
+
+    // close peer connection
+    setTimeout(() => {
+        pc.close();
+    }, 500);
+}
+
+function sdpFilterCodec(kind, codec, realSdp) {
+    var allowed = []
+    var rtxRegex = new RegExp('a=fmtp:(\\d+) apt=(\\d+)\r$');
+    var codecRegex = new RegExp('a=rtpmap:([0-9]+) ' + escapeRegExp(codec))
+    var videoRegex = new RegExp('(m=' + kind + ' .*?)( ([0-9]+))*\\s*$')
+
+    var lines = realSdp.split('\n');
+
+    var isKind = false;
+    for (var i = 0; i < lines.length; i++) {
+        if (lines[i].startsWith('m=' + kind + ' ')) {
+            isKind = true;
+        } else if (lines[i].startsWith('m=')) {
+            isKind = false;
+        }
+
+        if (isKind) {
+            var match = lines[i].match(codecRegex);
+            if (match) {
+                allowed.push(parseInt(match[1]));
+            }
+
+            match = lines[i].match(rtxRegex);
+            if (match && allowed.includes(parseInt(match[2]))) {
+                allowed.push(parseInt(match[1]));
+            }
+        }
+    }
+
+    var skipRegex = 'a=(fmtp|rtcp-fb|rtpmap):([0-9]+)';
+    var sdp = '';
+
+    isKind = false;
+    for (var i = 0; i < lines.length; i++) {
+        if (lines[i].startsWith('m=' + kind + ' ')) {
+            isKind = true;
+        } else if (lines[i].startsWith('m=')) {
+            isKind = false;
+        }
+
+        if (isKind) {
+            var skipMatch = lines[i].match(skipRegex);
+            if (skipMatch && !allowed.includes(parseInt(skipMatch[2]))) {
+                continue;
+            } else if (lines[i].match(videoRegex)) {
+                sdp += lines[i].replace(videoRegex, '$1 ' + allowed.join(' ')) + '\n';
+            } else {
+                sdp += lines[i] + '\n';
+            }
+        } else {
+            sdp += lines[i] + '\n';
+        }
+    }
+
+    return sdp;
+}
+
+function escapeRegExp(string) {
+    return string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'); // $& means the whole matched string
+}
+
+enumerateInputDevices();