93 lines
3.4 KiB
Mathematica
93 lines
3.4 KiB
Mathematica
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/*
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* Copyright 2015 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#import "ARDSDPUtils.h"
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#import "WebRTC/RTCLogging.h"
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#import "WebRTC/RTCSessionDescription.h"
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@implementation ARDSDPUtils
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+ (RTCSessionDescription *)
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descriptionForDescription:(RTCSessionDescription *)description
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preferredVideoCodec:(NSString *)codec {
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NSString *sdpString = description.sdp;
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NSString *lineSeparator = @"\n";
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NSString *mLineSeparator = @" ";
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// Copied from PeerConnectionClient.java.
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// TODO(tkchin): Move this to a shared C++ file.
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NSMutableArray *lines =
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[NSMutableArray arrayWithArray:
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[sdpString componentsSeparatedByString:lineSeparator]];
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NSInteger mLineIndex = -1;
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NSString *codecRtpMap = nil;
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// a=rtpmap:<payload type> <encoding name>/<clock rate>
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// [/<encoding parameters>]
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NSString *pattern =
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[NSString stringWithFormat:@"^a=rtpmap:(\\d+) %@(/\\d+)+[\r]?$", codec];
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NSRegularExpression *regex =
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[NSRegularExpression regularExpressionWithPattern:pattern
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options:0
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error:nil];
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for (NSInteger i = 0; (i < lines.count) && (mLineIndex == -1 || !codecRtpMap);
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++i) {
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NSString *line = lines[i];
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if ([line hasPrefix:@"m=video"]) {
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mLineIndex = i;
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continue;
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}
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NSTextCheckingResult *codecMatches =
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[regex firstMatchInString:line
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options:0
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range:NSMakeRange(0, line.length)];
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if (codecMatches) {
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codecRtpMap =
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[line substringWithRange:[codecMatches rangeAtIndex:1]];
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continue;
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}
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}
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if (mLineIndex == -1) {
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RTCLog(@"No m=video line, so can't prefer %@", codec);
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return description;
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}
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if (!codecRtpMap) {
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RTCLog(@"No rtpmap for %@", codec);
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return description;
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}
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NSArray *origMLineParts =
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[lines[mLineIndex] componentsSeparatedByString:mLineSeparator];
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if (origMLineParts.count > 3) {
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NSMutableArray *newMLineParts =
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[NSMutableArray arrayWithCapacity:origMLineParts.count];
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NSInteger origPartIndex = 0;
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// Format is: m=<media> <port> <proto> <fmt> ...
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[newMLineParts addObject:origMLineParts[origPartIndex++]];
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[newMLineParts addObject:origMLineParts[origPartIndex++]];
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[newMLineParts addObject:origMLineParts[origPartIndex++]];
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[newMLineParts addObject:codecRtpMap];
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for (; origPartIndex < origMLineParts.count; ++origPartIndex) {
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if (![codecRtpMap isEqualToString:origMLineParts[origPartIndex]]) {
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[newMLineParts addObject:origMLineParts[origPartIndex]];
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}
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}
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NSString *newMLine =
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[newMLineParts componentsJoinedByString:mLineSeparator];
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[lines replaceObjectAtIndex:mLineIndex
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withObject:newMLine];
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} else {
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RTCLogWarning(@"Wrong SDP media description format: %@", lines[mLineIndex]);
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}
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NSString *mangledSdpString = [lines componentsJoinedByString:lineSeparator];
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return [[RTCSessionDescription alloc] initWithType:description.type
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sdp:mangledSdpString];
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}
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@end
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