vdo.ninja/thirdparty/CodecsHandler.js

/*
The MIT License (MIT)

Copyright (c) 2012-2020 [Muaz Khan](https://github.com/muaz-khan)

	Permission is hereby granted, free of charge, to any person obtaining a copy of
	this software and associated documentation files (the "Software"), to deal in
	the Software without restriction, including without limitation the rights to
	use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
	the Software, and to permit persons to whom the Software is furnished to do so,
	subject to the following conditions:

	The above copyright notice and this permission notice shall be included in all
	copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
	FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
	COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
	IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/
// Sourced from: https://cdn.webrtc-experiment.com/CodecsHandler.js
var CodecsHandler = (function() {
    function preferCodec(sdp, codecName) {
        var info = splitLines(sdp);

        if (!info.videoCodecNumbers) {
            return sdp;
        }

        if (codecName === 'vp8' && info.vp8LineNumber === info.videoCodecNumbers[0]) {
            return sdp;
        }

        if (codecName === 'vp9' && info.vp9LineNumber === info.videoCodecNumbers[0]) {
            return sdp;
        }

        if (codecName === 'h264' && info.h264LineNumber === info.videoCodecNumbers[0]) {
            return sdp;
        }

        sdp = preferCodecHelper(sdp, codecName, info);

        return sdp;
    }

    function preferCodecHelper(sdp, codec, info, ignore) {
        var preferCodecNumber = '';

        if (codec === 'vp8') {
            if (!info.vp8LineNumber) {
                return sdp;
            }
            preferCodecNumber = info.vp8LineNumber;
        }

        if (codec === 'vp9') {
            if (!info.vp9LineNumber) {
                return sdp;
            }
            preferCodecNumber = info.vp9LineNumber;
        }

        if (codec === 'h264') {
            if (!info.h264LineNumber) {
                return sdp;
            }

            preferCodecNumber = info.h264LineNumber;
        }

        var newLine = info.videoCodecNumbersOriginal.split('SAVPF')[0] + 'SAVPF ';

        var newOrder = [preferCodecNumber];

        if (ignore) {
            newOrder = [];
        }

        info.videoCodecNumbers.forEach(function(codecNumber) {
            if (codecNumber === preferCodecNumber) return;
            newOrder.push(codecNumber);
        });

        newLine += newOrder.join(' ');

        sdp = sdp.replace(info.videoCodecNumbersOriginal, newLine);
        return sdp;
    }

    function splitLines(sdp) {
        var info = {};
        sdp.split('\n').forEach(function(line) {
            if (line.indexOf('m=video') === 0) {
                info.videoCodecNumbers = [];
                line.split('SAVPF')[1].split(' ').forEach(function(codecNumber) {
                    codecNumber = codecNumber.trim();
                    if (!codecNumber || !codecNumber.length) return;
                    info.videoCodecNumbers.push(codecNumber);
                    info.videoCodecNumbersOriginal = line;
                });
            }

            if (line.indexOf('VP8/90000') !== -1 && !info.vp8LineNumber) {
                info.vp8LineNumber = line.replace('a=rtpmap:', '').split(' ')[0];
            }

            if (line.indexOf('VP9/90000') !== -1 && !info.vp9LineNumber) {
                info.vp9LineNumber = line.replace('a=rtpmap:', '').split(' ')[0];
            }

            if (line.indexOf('H264/90000') !== -1 && !info.h264LineNumber) {
                info.h264LineNumber = line.replace('a=rtpmap:', '').split(' ')[0];
            }
        });

        return info;
    }

    function removeVPX(sdp) {
        var info = splitLines(sdp);

        // last parameter below means: ignore these codecs
        sdp = preferCodecHelper(sdp, 'vp9', info, true);
        sdp = preferCodecHelper(sdp, 'vp8', info, true);

        return sdp;
    }

    function disableNACK(sdp) {
        if (!sdp || typeof sdp !== 'string') {
            throw 'Invalid arguments.';
        }

        sdp = sdp.replace('a=rtcp-fb:126 nack\r\n', '');
        sdp = sdp.replace('a=rtcp-fb:126 nack pli\r\n', 'a=rtcp-fb:126 pli\r\n');
        sdp = sdp.replace('a=rtcp-fb:97 nack\r\n', '');
        sdp = sdp.replace('a=rtcp-fb:97 nack pli\r\n', 'a=rtcp-fb:97 pli\r\n');

        return sdp;
    }

    function prioritize(codecMimeType, peer) {
        if (!peer || !peer.getSenders || !peer.getSenders().length) {
            return;
        }

        if (!codecMimeType || typeof codecMimeType !== 'string') {
            throw 'Invalid arguments.';
        }

        peer.getSenders().forEach(function(sender) {
            var params = sender.getParameters();
            for (var i = 0; i < params.codecs.length; i++) {
                if (params.codecs[i].mimeType == codecMimeType) {
                    params.codecs.unshift(params.codecs.splice(i, 1));
                    break;
                }
            }
            sender.setParameters(params);
        });
    }

    function removeNonG722(sdp) {
        return sdp.replace(/m=audio ([0-9]+) RTP\/SAVPF ([0-9 ]*)/g, 'm=audio $1 RTP\/SAVPF 9');
    }

    function setBAS(sdp, bandwidth, isScreen) {
        if (!bandwidth) {
            return sdp;
        }

        if (typeof isFirefox !== 'undefined' && isFirefox) {
            return sdp;
        }

        if (isScreen) {
            if (!bandwidth.screen) {
                console.warn('It seems that you are not using bandwidth for screen. Screen sharing is expected to fail.');
            } else if (bandwidth.screen < 300) {
                console.warn('It seems that you are using wrong bandwidth value for screen. Screen sharing is expected to fail.');
            }
        }

        // if screen; must use at least 300kbs
        if (bandwidth.screen && isScreen) {
            sdp = sdp.replace(/b=AS([^\r\n]+\r\n)/g, '');
            sdp = sdp.replace(/a=mid:video\r\n/g, 'a=mid:video\r\nb=AS:' + bandwidth.screen + '\r\n');
        }

        // remove existing bandwidth lines
        if (bandwidth.audio || bandwidth.video) {
            sdp = sdp.replace(/b=AS([^\r\n]+\r\n)/g, '');
        }

        if (bandwidth.audio) {
            sdp = sdp.replace(/a=mid:audio\r\n/g, 'a=mid:audio\r\nb=AS:' + bandwidth.audio + '\r\n');
        }

        if (bandwidth.screen) {
            sdp = sdp.replace(/a=mid:video\r\n/g, 'a=mid:video\r\nb=AS:' + bandwidth.screen + '\r\n');
        } else if (bandwidth.video) {
            sdp = sdp.replace(/a=mid:video\r\n/g, 'a=mid:video\r\nb=AS:' + bandwidth.video + '\r\n');
        }

        return sdp;
    }

    // Find the line in sdpLines that starts with |prefix|, and, if specified,
    // contains |substr| (case-insensitive search).
    function findLine(sdpLines, prefix, substr) {
        return findLineInRange(sdpLines, 0, -1, prefix, substr);
    }

    // Find the line in sdpLines[startLine...endLine - 1] that starts with |prefix|
    // and, if specified, contains |substr| (case-insensitive search).
    function findLineInRange(sdpLines, startLine, endLine, prefix, substr) {
        var realEndLine = endLine !== -1 ? endLine : sdpLines.length;
        for (var i = startLine; i < realEndLine; ++i) {
            if (sdpLines[i].indexOf(prefix) === 0) {
                if (!substr ||
                    sdpLines[i].toLowerCase().indexOf(substr.toLowerCase()) !== -1) {
                    return i;
                }
            }
        }
        return null;
    }

    // Gets the codec payload type from an a=rtpmap:X line.
    function getCodecPayloadType(sdpLine) {
        var pattern = new RegExp('a=rtpmap:(\\d+) \\w+\\/\\d+');
        var result = sdpLine.match(pattern);
        return (result && result.length === 2) ? result[1] : null;
    }

    function setVideoBitrates(sdp, params) {
        params = params || {};
        var xgoogle_min_bitrate = params.min;
        var xgoogle_max_bitrate = params.max;

        var sdpLines = sdp.split('\r\n');

        // VP8
        var vp8Index = findLine(sdpLines, 'a=rtpmap', 'VP8/90000');
        var vp8Payload;
        if (vp8Index) {
            vp8Payload = getCodecPayloadType(sdpLines[vp8Index]);
        }

        if (!vp8Payload) {
            return sdp;
        }

        var rtxIndex = findLine(sdpLines, 'a=rtpmap', 'rtx/90000');
        var rtxPayload;
        if (rtxIndex) {
            rtxPayload = getCodecPayloadType(sdpLines[rtxIndex]);
        }

        if (!rtxIndex) {
            return sdp;
        }

        var rtxFmtpLineIndex = findLine(sdpLines, 'a=fmtp:' + rtxPayload.toString());
        if (rtxFmtpLineIndex !== null) {
            var appendrtxNext = '\r\n';
            appendrtxNext += 'a=fmtp:' + vp8Payload + ' x-google-min-bitrate=' + (xgoogle_min_bitrate || '228') + '; x-google-max-bitrate=' + (xgoogle_max_bitrate || '228');
            sdpLines[rtxFmtpLineIndex] = sdpLines[rtxFmtpLineIndex].concat(appendrtxNext);
            sdp = sdpLines.join('\r\n');
        }

        return sdp;
    }

    function setOpusAttributes(sdp, params) {
        params = params || {};

        var sdpLines = sdp.split('\r\n');

        // Opus
        var opusIndex = findLine(sdpLines, 'a=rtpmap', 'opus/48000');
        var opusPayload;
        if (opusIndex) {
            opusPayload = getCodecPayloadType(sdpLines[opusIndex]);
        }

        if (!opusPayload) {
            return sdp;
        }

        var opusFmtpLineIndex = findLine(sdpLines, 'a=fmtp:' + opusPayload.toString());
        if (opusFmtpLineIndex === null) {
            return sdp;
        }

        var appendOpusNext = '';
        appendOpusNext += '; stereo=' + (typeof params.stereo != 'undefined' ? params.stereo : '1');
        appendOpusNext += '; sprop-stereo=' + (typeof params['sprop-stereo'] != 'undefined' ? params['sprop-stereo'] : '1');

        if (typeof params.maxaveragebitrate != 'undefined') {
            appendOpusNext += '; maxaveragebitrate=' + (params.maxaveragebitrate || 128 * 1024 * 8);
        }

        if (typeof params.maxplaybackrate != 'undefined') {
            appendOpusNext += '; maxplaybackrate=' + (params.maxplaybackrate || 128 * 1024 * 8);
        }

        if (typeof params.cbr != 'undefined') {
            appendOpusNext += '; cbr=' + (typeof params.cbr != 'undefined' ? params.cbr : '1');
        }

        if (typeof params.useinbandfec != 'undefined') {
            appendOpusNext += '; useinbandfec=' + params.useinbandfec;
        }

        if (typeof params.usedtx != 'undefined') {
            appendOpusNext += '; usedtx=' + params.usedtx;
        }

        if (typeof params.maxptime != 'undefined') {
            appendOpusNext += '\r\na=maxptime:' + params.maxptime;
        }

        sdpLines[opusFmtpLineIndex] = sdpLines[opusFmtpLineIndex].concat(appendOpusNext);

        sdp = sdpLines.join('\r\n');
        return sdp;
    }

    // forceStereoAudio => via webrtcexample.com
    // requires getUserMedia => echoCancellation:false
    function forceStereoAudio(sdp) {
        var sdpLines = sdp.split('\r\n');
        var fmtpLineIndex = null;
        for (var i = 0; i < sdpLines.length; i++) {
            if (sdpLines[i].search('opus/48000') !== -1) {
                var opusPayload = extractSdp(sdpLines[i], /:(\d+) opus\/48000/i);
                break;
            }
        }
        for (var i = 0; i < sdpLines.length; i++) {
            if (sdpLines[i].search('a=fmtp') !== -1) {
                var payload = extractSdp(sdpLines[i], /a=fmtp:(\d+)/);
                if (payload === opusPayload) {
                    fmtpLineIndex = i;
                    break;
                }
            }
        }
        if (fmtpLineIndex === null) return sdp;
        sdpLines[fmtpLineIndex] = sdpLines[fmtpLineIndex].concat('; stereo=1; sprop-stereo=1');
        sdp = sdpLines.join('\r\n');
        return sdp;
    }

    return {
        removeVPX: removeVPX,
        disableNACK: disableNACK,
        prioritize: prioritize,
        removeNonG722: removeNonG722,
        setApplicationSpecificBandwidth: function(sdp, bandwidth, isScreen) {
            return setBAS(sdp, bandwidth, isScreen);
        },
        setVideoBitrates: function(sdp, params) {
            return setVideoBitrates(sdp, params);
        },
        setOpusAttributes: function(sdp, params) {
            return setOpusAttributes(sdp, params);
        },
        preferVP9: function(sdp) {
            return preferCodec(sdp, 'vp9');
        },
        preferCodec: preferCodec,
        forceStereoAudio: forceStereoAudio
    };
})();

// backward compatibility
window.BandwidthHandler = CodecsHandler;