webrtc: bandwidth usage in chrome m39 about rtcmulticonnection HOT 5 OPEN

connection.processSdp = function(sdp) {
    sdp = sdp.replace(/a=mid:audio\r\n/g, 'a=mid:audio\r\na=fmtp:111 x-google-min-bitrate=50; x-google-max-bitrate=50\r\n');
    return sdp;
};

connection.processSdp = function (sdp) {
    sdp = addStereo(sdp);
    return sdp;
};

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

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

    // Find the payload in fmtp line.
    var fmtpLineIndex = findLine(sdpLines, 'a=fmtp:' + opusPayload.toString());
    if (fmtpLineIndex === null) {
        return sdp;
    }

    // Append stereo=1 to fmtp line.
    // added maxaveragebitrate here; about 50 kbits/s
    // added stereo=1 here for stereo audio
    // x-google-min-bitrate=50; x-google-max-bitrate=50
    sdpLines[fmtpLineIndex] = sdpLines[fmtpLineIndex].concat('; stereo=1; maxaveragebitrate=' + (50 * 1024) + '; x-google-min-bitrate=50; x-google-max-bitrate=50');

    sdp = sdpLines.join('\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;
}

connection.processSdp = function(sdp) {
    return addVideoBandwidth(sdp);
};

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

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

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

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

    return sdp;
}

function findLine(sdpLines, prefix, substr) {
    return findLineInRange(sdpLines, 0, -1, prefix, substr);
}

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;
}

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;
}