chromium/media/formats/common/opus_constants.h

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_FORMATS_COMMON_OPUS_CONSTANTS_H_
#define MEDIA_FORMATS_COMMON_OPUS_CONSTANTS_H_

#include <stdint.h>

namespace media {

// The Opus specification is part of IETF RFC 6716:
// http://tools.ietf.org/html/rfc6716

// Opus Extra Data contents:
// - "OpusHead" magic signature (64 bits)
// - version number (8 bits)
// - Channels C (8 bits)
// - Pre-skip (16 bits)
// - Sampling rate (32 bits)
// - Gain in dB (16 bits, S7.8)
// - Mapping (8 bits, 0=single stream (mono/stereo) 1=Vorbis mapping,
//            2..254: reserved, 255: multistream with no mapping)
//
// - if (mapping != 0)
//    - N = total number of streams (8 bits)
//    - M = number of paired streams (8 bits)
//    - C times channel origin
//         - if (C<2*M)
//            - stream = byte/2
//            - if (byte&0x1 == 0)
//                - left
//              else
//                - right
//         - else
//            - stream = byte-M

enum { … };

// Opus internal to Vorbis channel order mapping written in the header.
extern const uint8_t kOpusVorbisChannelMap[OPUS_MAX_VORBIS_CHANNELS]
                                          [OPUS_MAX_VORBIS_CHANNELS];

}  // namespace media

#endif  // MEDIA_FORMATS_COMMON_OPUS_CONSTANTS_H_