toxcore/toxav/toxav.h

/* toxav.h
 * 
 * Copyright (C) 2013-2015 Tox project All Rights Reserved.
 *
 * This file is part of Tox.
 *
 * Tox is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Tox is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Tox. If not, see <http://www.gnu.org/licenses/>.
 * 
 */

#ifndef TOXAV_H
#define TOXAV_H

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

/** \page av Public audio/video API for Tox clients.
 * 
 * This API can handle multiple calls. Each call has its state, in very rare
 * occasions the library can change the state of the call without apps knowledge.
 * 
 */
/** \subsection events Events and callbacks
 *
 * As in Core API, events are handled by callbacks. One callback can be 
 * registered per event. All events have a callback function type named 
 * `toxav_{event}_cb` and a function to register it named `toxav_callback_{event}`.
 * Passing a NULL callback will result in no callback being registered for that 
 * event. Only one callback per event can be registered, so if a client needs 
 * multiple event listeners, it needs to implement the dispatch functionality 
 * itself. Unlike Core API, lack of some event handlers will cause the the 
 * library to drop calls before they are started. Hanging up call from a 
 * callback causes undefined behaviour.
 * 
 */
/** \subsection threading Threading implications
 *
 * Unlike the Core API, this API is fully thread-safe. The library will ensure
 * the proper synchronization of parallel calls. 
 * 
 * A common way to run ToxAV (multiple or single instance) is to have a thread,
 * separate from tox instance thread, running a simple toxav_iterate loop, 
 * sleeping for toxav_iteration_interval * milliseconds on each iteration.
 *
 * An important thing to note is that events are triggered from both tox and
 * toxav thread (see above). Audio and video receive frame events are triggered
 * from toxav thread while all the other events are triggered from tox thread.
 * 
 * Tox thread has priority with mutex mechanisms. Any api function can
 * fail if mutexes are held by tox thread in which case they will set SYNC
 * error code.
 */
/**
 * External Tox type.
 */
#ifndef TOX_DEFINED
#define TOX_DEFINED
typedef struct Tox Tox;
#endif /* TOX_DEFINED */

/**
 * ToxAV.
 */
/**
 * The ToxAV instance type. Each ToxAV instance can be bound to only one Tox
 * instance, and Tox instance can have only one ToxAV instance. One must make
 * sure to close ToxAV instance prior closing Tox instance otherwise undefined
 * behaviour occurs. Upon closing of ToxAV instance, all active calls will be 
 * forcibly terminated without notifying peers.
 * 
 */
#ifndef TOXAV_DEFINED
#define TOXAV_DEFINED
typedef struct ToxAV ToxAV;
#endif /* TOXAV_DEFINED */


/*******************************************************************************
 *
 * :: API version
 *
 ******************************************************************************/
/**
 * The major version number. Incremented when the API or ABI changes in an
 * incompatible way.
 */
#define TOXAV_VERSION_MAJOR               0u

/**
 * The minor version number. Incremented when functionality is added without
 * breaking the API or ABI. Set to 0 when the major version number is
 * incremented.
 */
#define TOXAV_VERSION_MINOR               0u

/**
 * The patch or revision number. Incremented when bugfixes are applied without
 * changing any functionality or API or ABI.
 */
#define TOXAV_VERSION_PATCH               0u

/**
 * A macro to check at preprocessing time whether the client code is compatible
 * with the installed version of ToxAV.
 */
#define TOXAV_VERSION_IS_API_COMPATIBLE(MAJOR, MINOR, PATCH)        \
  (TOXAV_VERSION_MAJOR == MAJOR &&                                \
   (TOXAV_VERSION_MINOR > MINOR ||                                \
    (TOXAV_VERSION_MINOR == MINOR &&                              \
     TOXAV_VERSION_PATCH >= PATCH)))

/**
 * A macro to make compilation fail if the client code is not compatible with
 * the installed version of ToxAV.
 */
#define TOXAV_VERSION_REQUIRE(MAJOR, MINOR, PATCH)                \
  typedef char toxav_required_version[TOXAV_IS_COMPATIBLE(MAJOR, MINOR, PATCH) ? 1 : -1]

/**
 * A convenience macro to call toxav_version_is_compatible with the currently
 * compiling API version.
 */
#define TOXAV_VERSION_IS_ABI_COMPATIBLE()                         \
  toxav_version_is_compatible(TOXAV_VERSION_MAJOR, TOXAV_VERSION_MINOR, TOXAV_VERSION_PATCH)

/**
 * Return the major version number of the library. Can be used to display the
 * ToxAV library version or to check whether the client is compatible with the
 * dynamically linked version of ToxAV.
 */
uint32_t toxav_version_major(void);

/**
 * Return the minor version number of the library.
 */
uint32_t toxav_version_minor(void);

/**
 * Return the patch number of the library.
 */
uint32_t toxav_version_patch(void);

/**
 * Return whether the compiled library version is compatible with the passed
 * version numbers.
 */
bool toxav_version_is_compatible(uint32_t major, uint32_t minor, uint32_t patch);


/*******************************************************************************
 * 
 * :: Creation and destruction
 *
 ******************************************************************************/
typedef enum TOXAV_ERR_NEW {
  /**
   * The function returned successfully.
   */
  TOXAV_ERR_NEW_OK,
  /**
   * One of the arguments to the function was NULL when it was not expected.
   */
  TOXAV_ERR_NEW_NULL,
  /**
   * Memory allocation failure while trying to allocate structures required for
   * the A/V session.
   */
  TOXAV_ERR_NEW_MALLOC,
  /**
   * Attempted to create a second session for the same Tox instance.
   */
  TOXAV_ERR_NEW_MULTIPLE,
} TOXAV_ERR_NEW;

/**
 * Start new A/V session. There can only be only one session per Tox instance.
 */
ToxAV *toxav_new(Tox *tox, TOXAV_ERR_NEW *error);

/**
 * Releases all resources associated with the A/V session.
 *
 * If any calls were ongoing, these will be forcibly terminated without
 * notifying peers. After calling this function, no other functions may be
 * called and the av pointer becomes invalid.
 */
void toxav_kill(ToxAV *toxAV);

/**
 * Returns the Tox instance the A/V object was created for.
 */
Tox *toxav_get_tox(const ToxAV *toxAV);


/*******************************************************************************
 * 
 * :: A/V event loop
 *
 ******************************************************************************/
/**
 * Returns the interval in milliseconds when the next toxav_iterate call should
 * be. If no call is active at the moment, this function returns 200.
 */
uint32_t toxav_iteration_interval(const ToxAV *toxAV);

/**
 * Main loop for the session. This function needs to be called in intervals of
 * toxav_iteration_interval() milliseconds. It is best called in the separate 
 * thread from tox_iterate.
 */
void toxav_iterate(ToxAV *toxAV);


/*******************************************************************************
 * 
 * :: Call setup
 *
 ******************************************************************************/
typedef enum TOXAV_ERR_CALL {
  /**
   * The function returned successfully.
   */
  TOXAV_ERR_CALL_OK,
  /**
   * A resource allocation error occurred while trying to create the structures
   * required for the call.
   */
  TOXAV_ERR_CALL_MALLOC,
  /**
   * Synchronization error occurred.
   */
  TOXAV_ERR_CALL_SYNC,
  /**
   * The friend number did not designate a valid friend.
   */
  TOXAV_ERR_CALL_FRIEND_NOT_FOUND,
  /**
   * The friend was valid, but not currently connected.
   */
  TOXAV_ERR_CALL_FRIEND_NOT_CONNECTED,
  /**
   * Attempted to call a friend while already in an audio or video call with
   * them.
   */
  TOXAV_ERR_CALL_FRIEND_ALREADY_IN_CALL,
  /**
   * Audio or video bit rate is invalid.
   */
  TOXAV_ERR_CALL_INVALID_BIT_RATE,
} TOXAV_ERR_CALL;

/**
 * Call a friend. This will start ringing the friend.
 *
 * It is the client's responsibility to stop ringing after a certain timeout,
 * if such behaviour is desired. If the client does not stop ringing, the
 * library will not stop until the friend is disconnected. Audio and video 
 * receiving are both enabled by default.
 *
 * @param friend_number The friend number of the friend that should be called.
 * @param audio_bit_rate Audio bit rate in Kb/sec. Set this to 0 to disable
 * audio sending.
 * @param video_bit_rate Video bit rate in Kb/sec. Set this to 0 to disable
 * video sending.
 */
bool toxav_call(ToxAV *toxAV, uint32_t friend_number, uint32_t audio_bit_rate,
                uint32_t video_bit_rate, TOXAV_ERR_CALL *error);

/**
 * The function type for the call callback.
 * 
 * @param friend_number The friend number from which the call is incoming.
 * @param audio_enabled True if friend is sending audio.
 * @param video_enabled True if friend is sending video.
 */
typedef void toxav_call_cb(ToxAV *toxAV, uint32_t friend_number, bool audio_enabled,
                           bool video_enabled, void *user_data);

/**
 * Set the callback for the `call` event. Pass NULL to unset.
 *
 */
void toxav_callback_call(ToxAV *toxAV, toxav_call_cb *callback, void *user_data);

typedef enum TOXAV_ERR_ANSWER {
  /**
   * The function returned successfully.
   */
  TOXAV_ERR_ANSWER_OK,
  /**
   * Synchronization error occurred.
   */
  TOXAV_ERR_ANSWER_SYNC,
  /**
   * Failed to initialize codecs for call session. Note that codec initiation
   * will fail if there is no receive callback registered for either audio or
   * video.
   */
  TOXAV_ERR_ANSWER_CODEC_INITIALIZATION,
  /**
   * The friend number did not designate a valid friend.
   */
  TOXAV_ERR_ANSWER_FRIEND_NOT_FOUND,
  /**
   * The friend was valid, but they are not currently trying to initiate a call.
   * This is also returned if this client is already in a call with the friend.
   */
  TOXAV_ERR_ANSWER_FRIEND_NOT_CALLING,
  /**
   * Audio or video bit rate is invalid.
   */
  TOXAV_ERR_ANSWER_INVALID_BIT_RATE,
} TOXAV_ERR_ANSWER;

/**
 * Accept an incoming call.
 *
 * If answering fails for any reason, the call will still be pending and it is
 * possible to try and answer it later. Audio and video receiving are both
 * enabled by default.
 *
 * @param friend_number The friend number of the friend that is calling.
 * @param audio_bit_rate Audio bit rate in Kb/sec. Set this to 0 to disable
 * audio sending.
 * @param video_bit_rate Video bit rate in Kb/sec. Set this to 0 to disable
 * video sending.
 */
bool toxav_answer(ToxAV *toxAV, uint32_t friend_number, uint32_t audio_bit_rate, uint32_t video_bit_rate, TOXAV_ERR_ANSWER *error);


/*******************************************************************************
 * 
 * :: Call state graph
 *
 ******************************************************************************/
enum TOXAV_FRIEND_CALL_STATE {
  /**
   * Set by the AV core if an error occurred on the remote end or if friend 
   * timed out. This is the final state after which no more state
   * transitions can occur for the call. This call state will never be triggered
   * in combination with other call states.
   */
  TOXAV_FRIEND_CALL_STATE_ERROR = 1,
  /**
   * The call has finished. This is the final state after which no more state
   * transitions can occur for the call. This call state will never be 
   * triggered in combination with other call states.
   */
  TOXAV_FRIEND_CALL_STATE_FINISHED = 2,
  /**
   * The flag that marks that friend is sending audio.
   */
  TOXAV_FRIEND_CALL_STATE_SENDING_A = 4,
  /**
   * The flag that marks that friend is sending video.
   */
  TOXAV_FRIEND_CALL_STATE_SENDING_V = 8,
  /**
   * The flag that marks that friend is receiving audio.
   */
  TOXAV_FRIEND_CALL_STATE_ACCEPTING_A = 16,
  /**
   * The flag that marks that friend is receiving video.
   */
  TOXAV_FRIEND_CALL_STATE_ACCEPTING_V = 32,
};

/**
 * The function type for the call_state callback.
 *
 * @param friend_number The friend number for which the call state changed.
 * @param state The bitmask of the new call state which is guaranteed to be
 * different than the previous state. The state is set to 0 when the call is
 * paused. The bitmask represents all the activities currently performed by the
 * friend.
 */
typedef void toxav_call_state_cb(ToxAV *toxAV, uint32_t friend_number, uint32_t state, void *user_data);

/**
 * Set the callback for the `call_state` event. Pass NULL to unset.
 *
 */
void toxav_callback_call_state(ToxAV *toxAV, toxav_call_state_cb *callback, void *user_data);

/*******************************************************************************
 * 
 * :: Call control
 *
 ******************************************************************************/
typedef enum TOXAV_CALL_CONTROL {
  /**
   * Resume a previously paused call. Only valid if the pause was caused by this
   * client, if not, this control is ignored. Not valid before the call is accepted.
   */
  TOXAV_CALL_CONTROL_RESUME,
  /**
   * Put a call on hold. Not valid before the call is accepted.
   */
  TOXAV_CALL_CONTROL_PAUSE,
  /**
   * Reject a call if it was not answered, yet. Cancel a call after it was
   * answered.
   */
  TOXAV_CALL_CONTROL_CANCEL,
  /**
   * Request that the friend stops sending audio. Regardless of the friend's
   * compliance, this will cause the audio_receive_frame event to stop being
   * triggered on receiving an audio frame from the friend.
   */
  TOXAV_CALL_CONTROL_MUTE_AUDIO,
  /**
   * Calling this control will notify client to start sending audio again.
   */
  TOXAV_CALL_CONTROL_UNMUTE_AUDIO,
  /**
   * Request that the friend stops sending video. Regardless of the friend's
   * compliance, this will cause the video_receive_frame event to stop being
   * triggered on receiving a video frame from the friend.
   */
  TOXAV_CALL_CONTROL_HIDE_VIDEO,
  /**
   * Calling this control will notify client to start sending video again.
   */
  TOXAV_CALL_CONTROL_SHOW_VIDEO,
} TOXAV_CALL_CONTROL;

typedef enum TOXAV_ERR_CALL_CONTROL {
  /**
   * The function returned successfully.
   */
  TOXAV_ERR_CALL_CONTROL_OK,
  /**
   * Synchronization error occurred.
   */
  TOXAV_ERR_CALL_CONTROL_SYNC,
  /**
   * The friend_number passed did not designate a valid friend.
   */
  TOXAV_ERR_CALL_CONTROL_FRIEND_NOT_FOUND,
  /**
   * This client is currently not in a call with the friend. Before the call is
   * answered, only CANCEL is a valid control.
   */
  TOXAV_ERR_CALL_CONTROL_FRIEND_NOT_IN_CALL,
  /**
   * Happens if user tried to pause an already paused call or if trying to
   * resume a call that is not paused.
   */
  TOXAV_ERR_CALL_CONTROL_INVALID_TRANSITION,
} TOXAV_ERR_CALL_CONTROL;

/**
 * Sends a call control command to a friend.
 *
 * @param friend_number The friend number of the friend this client is in a call
 * with.
 * @param control The control command to send.
 *
 * @return true on success.
 */
bool toxav_call_control(ToxAV *toxAV, uint32_t friend_number, TOXAV_CALL_CONTROL control, TOXAV_ERR_CALL_CONTROL *error);


/*******************************************************************************
 * 
 * :: Controlling bit rates
 *
 ******************************************************************************/
typedef enum TOXAV_ERR_BIT_RATE_SET {
  /**
   * The function returned successfully.
   */
  TOXAV_ERR_BIT_RATE_SET_OK,
  /**
   * Synchronization error occurred.
   */
  TOXAV_ERR_BIT_RATE_SET_SYNC,
  /**
   * The audio bit rate passed was not one of the supported values.
   */
  TOXAV_ERR_BIT_RATE_SET_INVALID_AUDIO_BIT_RATE,
  /**
   * The video bit rate passed was not one of the supported values.
   */
  TOXAV_ERR_BIT_RATE_SET_INVALID_VIDEO_BIT_RATE,
  /**
   * The friend_number passed did not designate a valid friend.
   */
  TOXAV_ERR_BIT_RATE_SET_FRIEND_NOT_FOUND,
  /**
   * This client is currently not in a call with the friend.
   */
  TOXAV_ERR_BIT_RATE_SET_FRIEND_NOT_IN_CALL,
} TOXAV_ERR_BIT_RATE_SET;

/**
 * Set the bit rate to be used in subsequent audio/video frames.
 *
 * @param friend_number The friend number of the friend for which to set the
 * bit rate.
 * @param audio_bit_rate The new audio bit rate in Kb/sec. Set to 0 to disable
 * audio sending. Set to -1 to leave unchanged.
 * @param video_bit_rate The new video bit rate in Kb/sec. Set to 0 to disable
 * video sending. Set to -1 to leave unchanged.
 * 
 */
bool toxav_bit_rate_set(ToxAV *toxAV, uint32_t friend_number, int32_t audio_bit_rate,
                        int32_t video_bit_rate, TOXAV_ERR_BIT_RATE_SET *error);

/**
 * The function type for the bit_rate_status callback. The event is triggered
 * when the network becomes too saturated for current bit rates at which 
 * point core suggests new bit rates.
 * 
 * @param friend_number The friend number of the friend for which to set the
 * bit rate.
 * @param audio_bit_rate Suggested maximum audio bit rate in Kb/sec.
 * @param video_bit_rate Suggested maximum video bit rate in Kb/sec.
 */
typedef void toxav_bit_rate_status_cb(ToxAV *toxAV, uint32_t friend_number, uint32_t audio_bit_rate, uint32_t video_bit_rate, void *user_data);

/**
 * Set the callback for the `bit_rate_status` event. Pass NULL to unset.
 *
 */
void toxav_callback_bit_rate_status(ToxAV *toxAV, toxav_bit_rate_status_cb *callback, void *user_data);


/*******************************************************************************
 * 
 * :: A/V sending
 *
 ******************************************************************************/
typedef enum TOXAV_ERR_SEND_FRAME {
  /**
   * The function returned successfully.
   */
  TOXAV_ERR_SEND_FRAME_OK,
  /**
   * In case of video, one of Y, U, or V was NULL. In case of audio, the samples
   * data pointer was NULL.
   */
  TOXAV_ERR_SEND_FRAME_NULL,
  /**
   * The friend_number passed did not designate a valid friend.
   */
  TOXAV_ERR_SEND_FRAME_FRIEND_NOT_FOUND,
  /**
   * This client is currently not in a call with the friend.
   */
  TOXAV_ERR_SEND_FRAME_FRIEND_NOT_IN_CALL,
  /**
   * Synchronization error occurred.
   */
  TOXAV_ERR_SEND_FRAME_SYNC,
  /**
   * One of the frame parameters was invalid. E.g. the resolution may be too
   * small or too large, or the audio sampling rate may be unsupported.
   */
  TOXAV_ERR_SEND_FRAME_INVALID,
  /**
   * Either friend turned off audio or video receiving or we turned off sending
   * for the said payload.
   */
  TOXAV_ERR_SEND_FRAME_PAYLOAD_TYPE_DISABLED,
  /**
   * Failed to push frame through rtp interface.
   */
  TOXAV_ERR_SEND_FRAME_RTP_FAILED,
} TOXAV_ERR_SEND_FRAME;

/**
 * Send an audio frame to a friend.
 *
 * The expected format of the PCM data is: [s1c1][s1c2][...][s2c1][s2c2][...]...
 * Meaning: sample 1 for channel 1, sample 1 for channel 2, ...
 * For mono audio, this has no meaning, every sample is subsequent. For stereo,
 * this means the expected format is LRLRLR... with samples for left and right
 * alternating.
 *
 * @param friend_number The friend number of the friend to which to send an
 * audio frame.
 * @param pcm An array of audio samples. The size of this array must be
 * sample_count * channels.
 * @param sample_count Number of samples in this frame. Valid numbers here are
 * ((sample rate) * (audio length) / 1000), where audio length can be
 * 2.5, 5, 10, 20, 40 or 60 millseconds.
 * @param channels Number of audio channels. Supported values are 1 and 2.
 * @param sampling_rate Audio sampling rate used in this frame. Valid sampling
 * rates are 8000, 12000, 16000, 24000, or 48000.
 */
bool toxav_audio_send_frame(ToxAV *toxAV, uint32_t friend_number, const int16_t *pcm, 
                            size_t sample_count, uint8_t channels, uint32_t sampling_rate,
                            TOXAV_ERR_SEND_FRAME *error);

/**
 * Send a video frame to a friend.
 *
 * Y - plane should be of size: height * width
 * U - plane should be of size: (height/2) * (width/2)
 * V - plane should be of size: (height/2) * (width/2)
 *
 * @param friend_number The friend number of the friend to which to send a video
 * frame.
 * @param width Width of the frame in pixels.
 * @param height Height of the frame in pixels.
 * @param y Y (Luminance) plane data.
 * @param u U (Chroma) plane data.
 * @param v V (Chroma) plane data.
 */
bool toxav_video_send_frame(ToxAV *toxAV, uint32_t friend_number, uint16_t width, 
                            uint16_t height, const uint8_t *y, const uint8_t *u, const uint8_t *v, 
                            TOXAV_ERR_SEND_FRAME *error);


/*******************************************************************************
 * 
 * :: A/V receiving
 *
 ******************************************************************************/
/**
 * The function type for the audio_receive_frame callback. The callback can be
 * called multiple times per single iteration depending on the amount of queued
 * frames in the buffer. The received format is the same as in send function.
 * 
 * @param friend_number The friend number of the friend who sent an audio frame.
 * @param pcm An array of audio samples (sample_count * channels elements).
 * @param sample_count The number of audio samples per channel in the PCM array.
 * @param channels Number of audio channels.
 * @param sampling_rate Sampling rate used in this frame.
 *
 */
typedef void toxav_audio_receive_frame_cb(ToxAV *toxAV, uint32_t friend_number, const int16_t *pcm,
                                          size_t sample_count, uint8_t channels, uint32_t sampling_rate,
                                          void *user_data);

/**
 * Set the callback for the `audio_receive_frame` event. Pass NULL to unset.
 *
 */
void toxav_callback_audio_receive_frame(ToxAV *toxAV, toxav_audio_receive_frame_cb *callback, void *user_data);

/**
 * The function type for the video_receive_frame callback.
 *
 * @param friend_number The friend number of the friend who sent a video frame.
 * @param width Width of the frame in pixels.
 * @param height Height of the frame in pixels.
 * @param y 
 * @param u 
 * @param v Plane data.
 *          The size of plane data is derived from width and height where
 *          Y = MAX(width, abs(ystride)) * height, 
 *          U = MAX(width/2, abs(ustride)) * (height/2) and 
 *          V = MAX(width/2, abs(vstride)) * (height/2).
 * @param ystride
 * @param ustride
 * @param vstride Strides data. Strides represent padding for each plane
 *                that may or may not be present. You must handle strides in
 *                your image processing code. Strides are negative if the 
 *                image is bottom-up hence why you MUST abs() it when
 *                calculating plane buffer size.
 */
typedef void toxav_video_receive_frame_cb(ToxAV *toxAV, uint32_t friend_number, uint16_t width, 
                                          uint16_t height, const uint8_t *y, const uint8_t *u, const uint8_t *v,
                                          int32_t ystride, int32_t ustride, int32_t vstride, void *user_data);

/**
 * Set the callback for the `video_receive_frame` event. Pass NULL to unset.
 *
 */
void toxav_callback_video_receive_frame(ToxAV *toxAV, toxav_video_receive_frame_cb *callback, void *user_data);

/**
 * NOTE Compatibility with old toxav group calls TODO remove
 */
/* Create a new toxav group.
 *
 * return group number on success.
 * return -1 on failure.
 *
 * Audio data callback format:
 *   audio_callback(Tox *tox, int groupnumber, int peernumber, const int16_t *pcm, unsigned int samples, uint8_t channels, unsigned int sample_rate, void *userdata)
 *
 * Note that total size of pcm in bytes is equal to (samples * channels * sizeof(int16_t)).
 */
int toxav_add_av_groupchat(Tox *tox, void (*audio_callback)(void*, int, int, const int16_t *, unsigned int, uint8_t,
                           unsigned int, void *), void *userdata);

/* Join a AV group (you need to have been invited first.)
 *
 * returns group number on success
 * returns -1 on failure.
 *
 * Audio data callback format (same as the one for toxav_add_av_groupchat()):
 *   audio_callback(Tox *tox, int groupnumber, int peernumber, const int16_t *pcm, unsigned int samples, uint8_t channels, unsigned int sample_rate, void *userdata)
 *
 * Note that total size of pcm in bytes is equal to (samples * channels * sizeof(int16_t)).
 */
int toxav_join_av_groupchat(Tox *tox, int32_t friendnumber, const uint8_t *data, uint16_t length,
                            void (*audio_callback)(void*, int, int, const int16_t *, unsigned int, uint8_t, unsigned int, void *), void *userdata);

/* Send audio to the group chat.
 *
 * return 0 on success.
 * return -1 on failure.
 *
 * Note that total size of pcm in bytes is equal to (samples * channels * sizeof(int16_t)).
 *
 * Valid number of samples are ((sample rate) * (audio length (Valid ones are: 2.5, 5, 10, 20, 40 or 60 ms)) / 1000)
 * Valid number of channels are 1 or 2.
 * Valid sample rates are 8000, 12000, 16000, 24000, or 48000.
 *
 * Recommended values are: samples = 960, channels = 1, sample_rate = 48000
 */
int toxav_group_send_audio(Tox *tox, int groupnumber, const int16_t *pcm, unsigned int samples, uint8_t channels,
                           unsigned int sample_rate);

#ifdef __cplusplus
}
#endif
#endif /* TOXAV_H */