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/*
* Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef API_AUDIO_CHANNEL_LAYOUT_H_
#define API_AUDIO_CHANNEL_LAYOUT_H_
namespace webrtc {
// This file is derived from Chromium's base/channel_layout.h.
// Enumerates the various representations of the ordering of audio channels.
// Logged to UMA, so never reuse a value, always add new/greater ones!
enum ChannelLayout {
CHANNEL_LAYOUT_NONE = 0,
CHANNEL_LAYOUT_UNSUPPORTED = 1,
// Front C
CHANNEL_LAYOUT_MONO = 2,
// Front L, Front R
CHANNEL_LAYOUT_STEREO = 3,
// Front L, Front R, Back C
CHANNEL_LAYOUT_2_1 = 4,
// Front L, Front R, Front C
CHANNEL_LAYOUT_SURROUND = 5,
// Front L, Front R, Front C, Back C
CHANNEL_LAYOUT_4_0 = 6,
// Front L, Front R, Side L, Side R
CHANNEL_LAYOUT_2_2 = 7,
// Front L, Front R, Back L, Back R
CHANNEL_LAYOUT_QUAD = 8,
// Front L, Front R, Front C, Side L, Side R
CHANNEL_LAYOUT_5_0 = 9,
// Front L, Front R, Front C, LFE, Side L, Side R
CHANNEL_LAYOUT_5_1 = 10,
// Front L, Front R, Front C, Back L, Back R
CHANNEL_LAYOUT_5_0_BACK = 11,
// Front L, Front R, Front C, LFE, Back L, Back R
CHANNEL_LAYOUT_5_1_BACK = 12,
// Front L, Front R, Front C, Side L, Side R, Back L, Back R
CHANNEL_LAYOUT_7_0 = 13,
// Front L, Front R, Front C, LFE, Side L, Side R, Back L, Back R
CHANNEL_LAYOUT_7_1 = 14,
// Front L, Front R, Front C, LFE, Side L, Side R, Front LofC, Front RofC
CHANNEL_LAYOUT_7_1_WIDE = 15,
// Stereo L, Stereo R
CHANNEL_LAYOUT_STEREO_DOWNMIX = 16,
// Stereo L, Stereo R, LFE
CHANNEL_LAYOUT_2POINT1 = 17,
// Stereo L, Stereo R, Front C, LFE
CHANNEL_LAYOUT_3_1 = 18,
// Stereo L, Stereo R, Front C, Rear C, LFE
CHANNEL_LAYOUT_4_1 = 19,
// Stereo L, Stereo R, Front C, Side L, Side R, Back C
CHANNEL_LAYOUT_6_0 = 20,
// Stereo L, Stereo R, Side L, Side R, Front LofC, Front RofC
CHANNEL_LAYOUT_6_0_FRONT = 21,
// Stereo L, Stereo R, Front C, Rear L, Rear R, Rear C
CHANNEL_LAYOUT_HEXAGONAL = 22,
// Stereo L, Stereo R, Front C, LFE, Side L, Side R, Rear Center
CHANNEL_LAYOUT_6_1 = 23,
// Stereo L, Stereo R, Front C, LFE, Back L, Back R, Rear Center
CHANNEL_LAYOUT_6_1_BACK = 24,
// Stereo L, Stereo R, Side L, Side R, Front LofC, Front RofC, LFE
CHANNEL_LAYOUT_6_1_FRONT = 25,
// Front L, Front R, Front C, Side L, Side R, Front LofC, Front RofC
CHANNEL_LAYOUT_7_0_FRONT = 26,
// Front L, Front R, Front C, LFE, Back L, Back R, Front LofC, Front RofC
CHANNEL_LAYOUT_7_1_WIDE_BACK = 27,
// Front L, Front R, Front C, Side L, Side R, Rear L, Back R, Back C.
CHANNEL_LAYOUT_OCTAGONAL = 28,
// Channels are not explicitly mapped to speakers.
CHANNEL_LAYOUT_DISCRETE = 29,
// Front L, Front R, Front C. Front C contains the keyboard mic audio. This
// layout is only intended for input for WebRTC. The Front C channel
// is stripped away in the WebRTC audio input pipeline and never seen outside
// of that.
CHANNEL_LAYOUT_STEREO_AND_KEYBOARD_MIC = 30,
// Front L, Front R, Side L, Side R, LFE
CHANNEL_LAYOUT_4_1_QUAD_SIDE = 31,
// Actual channel layout is specified in the bitstream and the actual channel
// count is unknown at Chromium media pipeline level (useful for audio
// pass-through mode).
CHANNEL_LAYOUT_BITSTREAM = 32,
// Max value, must always equal the largest entry ever logged.
CHANNEL_LAYOUT_MAX = CHANNEL_LAYOUT_BITSTREAM
};
// Note: Do not reorder or reassign these values; other code depends on their
// ordering to operate correctly. E.g., CoreAudio channel layout computations.
enum Channels {
LEFT = 0,
RIGHT,
CENTER,
LFE,
BACK_LEFT,
BACK_RIGHT,
LEFT_OF_CENTER,
RIGHT_OF_CENTER,
BACK_CENTER,
SIDE_LEFT,
SIDE_RIGHT,
CHANNELS_MAX =
SIDE_RIGHT, // Must always equal the largest value ever logged.
};
// The maximum number of concurrently active channels for all possible layouts.
// ChannelLayoutToChannelCount() will never return a value higher than this.
constexpr int kMaxConcurrentChannels = 8;
// Returns the expected channel position in an interleaved stream. Values of -1
// mean the channel at that index is not used for that layout. Values range
// from 0 to ChannelLayoutToChannelCount(layout) - 1.
int ChannelOrder(ChannelLayout layout, Channels channel);
// Returns the number of channels in a given ChannelLayout.
int ChannelLayoutToChannelCount(ChannelLayout layout);
// Given the number of channels, return the best layout,
// or return CHANNEL_LAYOUT_UNSUPPORTED if there is no good match.
ChannelLayout GuessChannelLayout(int channels);
// Returns a string representation of the channel layout.
const char* ChannelLayoutToString(ChannelLayout layout);
} // namespace webrtc
#endif // API_AUDIO_CHANNEL_LAYOUT_H_
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