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/* SPDX-License-Identifier: GPL-3.0-or-later
* Copyright © 2016-2018 The TokTok team.
* Copyright © 2013-2015 Tox project.
*/
#ifndef C_TOXCORE_TOXAV_RTP_H
#define C_TOXCORE_TOXAV_RTP_H
#include "bwcontroller.h"
#include "../toxcore/Messenger.h"
#include "../toxcore/logger.h"
#include <stdbool.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* RTPHeader serialised size in bytes.
*/
#define RTP_HEADER_SIZE 80
/**
* Number of 32 bit padding fields between \ref RTPHeader::offset_lower and
* everything before it.
*/
#define RTP_PADDING_FIELDS 11
/**
* Payload type identifier. Also used as rtp callback prefix.
*/
typedef enum RTP_Type {
RTP_TYPE_AUDIO = 192,
RTP_TYPE_VIDEO = 193,
} RTP_Type;
/**
* A bit mask (up to 64 bits) specifying features of the current frame affecting
* the behaviour of the decoder.
*/
typedef enum RTPFlags {
/**
* Support frames larger than 64KiB. The full 32 bit length and offset are
* set in \ref RTPHeader::data_length_full and \ref RTPHeader::offset_full.
*/
RTP_LARGE_FRAME = 1 << 0,
/**
* Whether the packet is part of a key frame.
*/
RTP_KEY_FRAME = 1 << 1,
} RTPFlags;
struct RTPHeader {
/* Standard RTP header */
unsigned ve: 2; /* Version has only 2 bits! */
unsigned pe: 1; /* Padding */
unsigned xe: 1; /* Extra header */
unsigned cc: 4; /* Contributing sources count */
unsigned ma: 1; /* Marker */
unsigned pt: 7; /* Payload type */
uint16_t sequnum;
uint32_t timestamp;
uint32_t ssrc;
/* Non-standard Tox-specific fields */
/**
* Bit mask of \ref RTPFlags setting features of the current frame.
*/
uint64_t flags;
/**
* The full 32 bit data offset of the current data chunk. The \ref
* offset_lower data member contains the lower 16 bits of this value. For
* frames smaller than 64KiB, \ref offset_full and \ref offset_lower are
* equal.
*/
uint32_t offset_full;
/**
* The full 32 bit payload length without header and packet id.
*/
uint32_t data_length_full;
/**
* Only the receiver uses this field (why do we have this?).
*/
uint32_t received_length_full;
/**
* Data offset of the current part (lower bits).
*/
uint16_t offset_lower;
/**
* Total message length (lower bits).
*/
uint16_t data_length_lower;
};
struct RTPMessage {
/**
* This is used in the old code that doesn't deal with large frames, i.e.
* the audio code or receiving code for old 16 bit messages. We use it to
* record the number of bytes received so far in a multi-part message. The
* multi-part message in the old code is stored in \ref RTPSession::mp.
*/
uint16_t len;
struct RTPHeader header;
uint8_t data[];
};
#define USED_RTP_WORKBUFFER_COUNT 3
/**
* One slot in the work buffer list. Represents one frame that is currently
* being assembled.
*/
struct RTPWorkBuffer {
/**
* Whether this slot contains a key frame. This is true iff
* `buf->header.flags & RTP_KEY_FRAME`.
*/
bool is_keyframe;
/**
* The number of bytes received so far, regardless of which pieces. I.e. we
* could have received the first 1000 bytes and the last 1000 bytes with
* 4000 bytes in the middle still to come, and this number would be 2000.
*/
uint32_t received_len;
/**
* The message currently being assembled.
*/
struct RTPMessage *buf;
};
struct RTPWorkBufferList {
int8_t next_free_entry;
struct RTPWorkBuffer work_buffer[USED_RTP_WORKBUFFER_COUNT];
};
#define DISMISS_FIRST_LOST_VIDEO_PACKET_COUNT 10
typedef int rtp_m_cb(Mono_Time *mono_time, void *cs, struct RTPMessage *msg);
/**
* RTP control session.
*/
typedef struct RTPSession {
uint8_t payload_type;
uint16_t sequnum; /* Sending sequence number */
uint16_t rsequnum; /* Receiving sequence number */
uint32_t rtimestamp;
uint32_t ssrc; // this seems to be unused!?
struct RTPMessage *mp; /* Expected parted message */
struct RTPWorkBufferList *work_buffer_list;
uint8_t first_packets_counter; /* dismiss first few lost video packets */
Messenger *m;
uint32_t friend_number;
BWController *bwc;
void *cs;
rtp_m_cb *mcb;
} RTPSession;
/**
* Serialise an RTPHeader to bytes to be sent over the network.
*
* @param rdata A byte array of length RTP_HEADER_SIZE. Does not need to be
* initialised. All RTP_HEADER_SIZE bytes will be initialised after a call
* to this function.
* @param header The RTPHeader to serialise.
*/
size_t rtp_header_pack(uint8_t *rdata, const struct RTPHeader *header);
/**
* Deserialise an RTPHeader from bytes received over the network.
*
* @param data A byte array of length RTP_HEADER_SIZE.
* @param header The RTPHeader to write the unpacked values to.
*/
size_t rtp_header_unpack(const uint8_t *data, struct RTPHeader *header);
RTPSession *rtp_new(int payload_type, Messenger *m, uint32_t friendnumber,
BWController *bwc, void *cs, rtp_m_cb *mcb);
void rtp_kill(RTPSession *session);
int rtp_allow_receiving(RTPSession *session);
int rtp_stop_receiving(RTPSession *session);
/**
* Send a frame of audio or video data, chunked in \ref RTPMessage instances.
*
* @param session The A/V session to send the data for.
* @param data A byte array of length \p length.
* @param length The number of bytes to send from @p data.
* @param is_keyframe Whether this video frame is a key frame. If it is an
* audio frame, this parameter is ignored.
*/
int rtp_send_data(RTPSession *session, const uint8_t *data, uint32_t length,
bool is_keyframe, const Logger *log);
#ifdef __cplusplus
} // extern "C"
#endif
#endif // C_TOXCORE_TOXAV_RTP_H
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