modules/audio_coding/codecs/opus/opus_interface.h

/*
 *  Copyright (c) 2012 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 MODULES_AUDIO_CODING_CODECS_OPUS_OPUS_INTERFACE_H_
#define MODULES_AUDIO_CODING_CODECS_OPUS_OPUS_INTERFACE_H_

#include <stddef.h>

#include "typedefs.h"

#ifdef __cplusplus
extern "C" {
#endif

// Opaque wrapper types for the codec state.
typedef struct WebRtcOpusEncInst OpusEncInst;
typedef struct WebRtcOpusDecInst OpusDecInst;

/****************************************************************************
 * WebRtcOpus_EncoderCreate(...)
 *
 * This function create an Opus encoder.
 *
 * Input:
 *      - channels           : number of channels.
 *      - application        : 0 - VOIP applications.
 *                                 Favor speech intelligibility.
 *                             1 - Audio applications.
 *                                 Favor faithfulness to the original input.
 *
 * Output:
 *      - inst               : a pointer to Encoder context that is created
 *                             if success.
 *
 * Return value              : 0 - Success
 *                            -1 - Error
 */
int16_t WebRtcOpus_EncoderCreate(OpusEncInst** inst,
                                 size_t channels,
                                 int32_t application);

int16_t WebRtcOpus_EncoderFree(OpusEncInst* inst);

/****************************************************************************
 * WebRtcOpus_Encode(...)
 *
 * This function encodes audio as a series of Opus frames and inserts
 * it into a packet. Input buffer can be any length.
 *
 * Input:
 *      - inst                  : Encoder context
 *      - audio_in              : Input speech data buffer
 *      - samples               : Samples per channel in audio_in
 *      - length_encoded_buffer : Output buffer size
 *
 * Output:
 *      - encoded               : Output compressed data buffer
 *
 * Return value                 : >=0 - Length (in bytes) of coded data
 *                                -1 - Error
 */
int WebRtcOpus_Encode(OpusEncInst* inst,
                      const int16_t* audio_in,
                      size_t samples,
                      size_t length_encoded_buffer,
                      uint8_t* encoded);

/****************************************************************************
 * WebRtcOpus_SetBitRate(...)
 *
 * This function adjusts the target bitrate of the encoder.
 *
 * Input:
 *      - inst               : Encoder context
 *      - rate               : New target bitrate
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_SetBitRate(OpusEncInst* inst, int32_t rate);

/****************************************************************************
 * WebRtcOpus_SetPacketLossRate(...)
 *
 * This function configures the encoder's expected packet loss percentage.
 *
 * Input:
 *      - inst               : Encoder context
 *      - loss_rate          : loss percentage in the range 0-100, inclusive.
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_SetPacketLossRate(OpusEncInst* inst, int32_t loss_rate);

/****************************************************************************
 * WebRtcOpus_SetMaxPlaybackRate(...)
 *
 * Configures the maximum playback rate for encoding. Due to hardware
 * limitations, the receiver may render audio up to a playback rate. Opus
 * encoder can use this information to optimize for network usage and encoding
 * complexity. This will affect the audio bandwidth in the coded audio. However,
 * the input/output sample rate is not affected.
 *
 * Input:
 *      - inst               : Encoder context
 *      - frequency_hz       : Maximum playback rate in Hz.
 *                             This parameter can take any value. The relation
 *                             between the value and the Opus internal mode is
 *                             as following:
 *                             frequency_hz <= 8000           narrow band
 *                             8000 < frequency_hz <= 12000   medium band
 *                             12000 < frequency_hz <= 16000  wide band
 *                             16000 < frequency_hz <= 24000  super wide band
 *                             frequency_hz > 24000           full band
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_SetMaxPlaybackRate(OpusEncInst* inst, int32_t frequency_hz);

/* TODO(minyue): Check whether an API to check the FEC and the packet loss rate
 * is needed. It might not be very useful since there are not many use cases and
 * the caller can always maintain the states. */

/****************************************************************************
 * WebRtcOpus_EnableFec()
 *
 * This function enables FEC for encoding.
 *
 * Input:
 *      - inst               : Encoder context
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_EnableFec(OpusEncInst* inst);

/****************************************************************************
 * WebRtcOpus_DisableFec()
 *
 * This function disables FEC for encoding.
 *
 * Input:
 *      - inst               : Encoder context
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_DisableFec(OpusEncInst* inst);

/****************************************************************************
 * WebRtcOpus_EnableDtx()
 *
 * This function enables Opus internal DTX for encoding.
 *
 * Input:
 *      - inst               : Encoder context
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_EnableDtx(OpusEncInst* inst);

/****************************************************************************
 * WebRtcOpus_DisableDtx()
 *
 * This function disables Opus internal DTX for encoding.
 *
 * Input:
 *      - inst               : Encoder context
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_DisableDtx(OpusEncInst* inst);

/****************************************************************************
 * WebRtcOpus_EnableCbr()
 *
 * This function enables CBR for encoding.
 *
 * Input:
 *      - inst               : Encoder context
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_EnableCbr(OpusEncInst* inst);

/****************************************************************************
 * WebRtcOpus_DisableCbr()
 *
 * This function disables CBR for encoding.
 *
 * Input:
 *      - inst               : Encoder context
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_DisableCbr(OpusEncInst* inst);

/*
 * WebRtcOpus_SetComplexity(...)
 *
 * This function adjusts the computational complexity. The effect is the same as
 * calling the complexity setting of Opus as an Opus encoder related CTL.
 *
 * Input:
 *      - inst               : Encoder context
 *      - complexity         : New target complexity (0-10, inclusive)
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_SetComplexity(OpusEncInst* inst, int32_t complexity);

/*
 * WebRtcOpus_SetForceChannels(...)
 *
 * If the encoder is initialized as a stereo encoder, Opus will by default
 * decide whether to encode in mono or stereo based on the bitrate. This
 * function overrules the previous setting, and forces the encoder to encode
 * in auto/mono/stereo.
 *
 * If the Encoder is initialized as a mono encoder, and one tries to force
 * stereo, the function will return an error.
 *
 * Input:
 *      - inst               : Encoder context
 *      - num_channels       : 0 - Not forced
 *                             1 - Mono
 *                             2 - Stereo
 *
 * Return value              :  0 - Success
 *                             -1 - Error
 */
int16_t WebRtcOpus_SetForceChannels(OpusEncInst* inst, size_t num_channels);

int16_t WebRtcOpus_DecoderCreate(OpusDecInst** inst, size_t channels);
int16_t WebRtcOpus_DecoderFree(OpusDecInst* inst);

/****************************************************************************
 * WebRtcOpus_DecoderChannels(...)
 *
 * This function returns the number of channels created for Opus decoder.
 */
size_t WebRtcOpus_DecoderChannels(OpusDecInst* inst);

/****************************************************************************
 * WebRtcOpus_DecoderInit(...)
 *
 * This function resets state of the decoder.
 *
 * Input:
 *      - inst               : Decoder context
 */
void WebRtcOpus_DecoderInit(OpusDecInst* inst);

/****************************************************************************
 * WebRtcOpus_Decode(...)
 *
 * This function decodes an Opus packet into one or more audio frames at the
 * ACM interface's sampling rate (32 kHz).
 *
 * Input:
 *      - inst               : Decoder context
 *      - encoded            : Encoded data
 *      - encoded_bytes      : Bytes in encoded vector
 *
 * Output:
 *      - decoded            : The decoded vector
 *      - audio_type         : 1 normal, 2 CNG (for Opus it should
 *                             always return 1 since we're not using Opus's
 *                             built-in DTX/CNG scheme)
 *
 * Return value              : >0 - Samples per channel in decoded vector
 *                             -1 - Error
 */
int WebRtcOpus_Decode(OpusDecInst* inst, const uint8_t* encoded,
                      size_t encoded_bytes, int16_t* decoded,
                      int16_t* audio_type);

/****************************************************************************
 * WebRtcOpus_DecodePlc(...)
 *
 * This function processes PLC for opus frame(s).
 * Input:
 *        - inst                  : Decoder context
 *        - number_of_lost_frames : Number of PLC frames to produce
 *
 * Output:
 *        - decoded               : The decoded vector
 *
 * Return value                   : >0 - number of samples in decoded PLC vector
 *                                  -1 - Error
 */
int WebRtcOpus_DecodePlc(OpusDecInst* inst, int16_t* decoded,
                         int number_of_lost_frames);

/****************************************************************************
 * WebRtcOpus_DecodeFec(...)
 *
 * This function decodes the FEC data from an Opus packet into one or more audio
 * frames at the ACM interface's sampling rate (32 kHz).
 *
 * Input:
 *      - inst               : Decoder context
 *      - encoded            : Encoded data
 *      - encoded_bytes      : Bytes in encoded vector
 *
 * Output:
 *      - decoded            : The decoded vector (previous frame)
 *
 * Return value              : >0 - Samples per channel in decoded vector
 *                              0 - No FEC data in the packet
 *                             -1 - Error
 */
int WebRtcOpus_DecodeFec(OpusDecInst* inst, const uint8_t* encoded,
                         size_t encoded_bytes, int16_t* decoded,
                         int16_t* audio_type);

/****************************************************************************
 * WebRtcOpus_DurationEst(...)
 *
 * This function calculates the duration of an opus packet.
 * Input:
 *        - inst                 : Decoder context
 *        - payload              : Encoded data pointer
 *        - payload_length_bytes : Bytes of encoded data
 *
 * Return value                  : The duration of the packet, in samples per
 *                                 channel.
 */
int WebRtcOpus_DurationEst(OpusDecInst* inst,
                           const uint8_t* payload,
                           size_t payload_length_bytes);

/****************************************************************************
 * WebRtcOpus_PlcDuration(...)
 *
 * This function calculates the duration of a frame returned by packet loss
 * concealment (PLC).
 *
 * Input:
 *        - inst                 : Decoder context
 *
 * Return value                  : The duration of a frame returned by PLC, in
 *                                 samples per channel.
 */
int WebRtcOpus_PlcDuration(OpusDecInst* inst);

/* TODO(minyue): Check whether it is needed to add a decoder context to the
 * arguments, like WebRtcOpus_DurationEst(...). In fact, the packet itself tells
 * the duration. The decoder context in WebRtcOpus_DurationEst(...) is not used.
 * So it may be advisable to remove it from WebRtcOpus_DurationEst(...). */

/****************************************************************************
 * WebRtcOpus_FecDurationEst(...)
 *
 * This function calculates the duration of the FEC data within an opus packet.
 * Input:
 *        - payload              : Encoded data pointer
 *        - payload_length_bytes : Bytes of encoded data
 *
 * Return value                  : >0 - The duration of the FEC data in the
 *                                 packet in samples per channel.
 *                                  0 - No FEC data in the packet.
 */
int WebRtcOpus_FecDurationEst(const uint8_t* payload,
                              size_t payload_length_bytes);

/****************************************************************************
 * WebRtcOpus_PacketHasFec(...)
 *
 * This function detects if an opus packet has FEC.
 * Input:
 *        - payload              : Encoded data pointer
 *        - payload_length_bytes : Bytes of encoded data
 *
 * Return value                  : 0 - the packet does NOT contain FEC.
 *                                 1 - the packet contains FEC.
 */
int WebRtcOpus_PacketHasFec(const uint8_t* payload,
                            size_t payload_length_bytes);

#ifdef __cplusplus
}  // extern "C"
#endif

#endif  // MODULES_AUDIO_CODING_CODECS_OPUS_OPUS_INTERFACE_H_