1 /* 2 * Copyright (c) 2019 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef API_AUDIO_CODECS_OPUS_AUDIO_DECODER_MULTI_CHANNEL_OPUS_CONFIG_H_ 12 #define API_AUDIO_CODECS_OPUS_AUDIO_DECODER_MULTI_CHANNEL_OPUS_CONFIG_H_ 13 14 #include <vector> 15 16 namespace webrtc { 17 struct AudioDecoderMultiChannelOpusConfig { 18 // The number of channels that the decoder will output. 19 int num_channels; 20 21 // Number of mono or stereo encoded Opus streams. 22 int num_streams; 23 24 // Number of channel pairs coupled together, see RFC 7845 section 25 // 5.1.1. Has to be less than the number of streams. 26 int coupled_streams; 27 28 // Channel mapping table, defines the mapping from encoded streams to output 29 // channels. See RFC 7845 section 5.1.1. 30 std::vector<unsigned char> channel_mapping; 31 IsOkAudioDecoderMultiChannelOpusConfig32 bool IsOk() const { 33 if (num_channels < 0 || num_streams < 0 || coupled_streams < 0) { 34 return false; 35 } 36 if (num_streams < coupled_streams) { 37 return false; 38 } 39 if (channel_mapping.size() != static_cast<size_t>(num_channels)) { 40 return false; 41 } 42 43 // Every mono stream codes one channel, every coupled stream codes two. This 44 // is the total coded channel count: 45 const int max_coded_channel = num_streams + coupled_streams; 46 for (const auto& x : channel_mapping) { 47 // Coded channels >= max_coded_channel don't exist. Except for 255, which 48 // tells Opus to put silence in output channel x. 49 if (x >= max_coded_channel && x != 255) { 50 return false; 51 } 52 } 53 54 if (num_channels > 255 || max_coded_channel >= 255) { 55 return false; 56 } 57 return true; 58 } 59 }; 60 61 } // namespace webrtc 62 63 #endif // API_AUDIO_CODECS_OPUS_AUDIO_DECODER_MULTI_CHANNEL_OPUS_CONFIG_H_ 64