The GstRTPCBuffer helper functions makes it easy to parse and create regular GstBuffer objects that contain compound RTCP packets. These buffers are typically of 'application/x-rtcp' GstCaps.

An RTCP buffer consists of 1 or more GstRTCPPacket structures that you can retrieve with gst_rtcp_buffer_get_first_packet(). GstRTCPPacket acts as a pointer into the RTCP buffer; you can move to the next packet with gst_rtcp_packet_move_to_next().

GST_RTCP_VERSION

#define GST_RTCP_VERSION 2

The supported RTCP version 2.

GST_RTCP_MAX_SDES

#define GST_RTCP_MAX_SDES 255

The maximum text length for an SDES item.

GST_RTCP_MAX_BYE_SSRC_COUNT

#define GST_RTCP_MAX_BYE_SSRC_COUNT   31

The maximum amount of SSRCs in a BYE packet.

GST_RTCP_MAX_RB_COUNT

#define GST_RTCP_MAX_RB_COUNT   31

The maximum amount of Receiver report blocks in RR and SR messages.

GST_RTCP_MAX_SDES_ITEM_COUNT

#define GST_RTCP_MAX_SDES_ITEM_COUNT   31

The maximum amount of SDES items.

GST_RTCP_VALID_MASK

#define GST_RTCP_VALID_MASK (0xc000 | 0x2000 | 0xfe)

Mask for version, padding bit and packet type pair

GST_RTCP_VALID_VALUE

#define GST_RTCP_VALID_VALUE ((GST_RTCP_VERSION << 14) | GST_RTCP_TYPE_SR)

Valid value for the first two bytes of an RTCP packet after applying GST_RTCP_VALID_MASK to them.

enum GstRTCPType

typedef enum
{
  GST_RTCP_TYPE_INVALID = 0,
  GST_RTCP_TYPE_SR      = 200,
  GST_RTCP_TYPE_RR      = 201,
  GST_RTCP_TYPE_SDES    = 202,
  GST_RTCP_TYPE_BYE     = 203,
  GST_RTCP_TYPE_APP     = 204,
  GST_RTCP_TYPE_RTPFB   = 205,
  GST_RTCP_TYPE_PSFB    = 206
} GstRTCPType;

Different RTCP packet types.

GstRTCPPacket

typedef struct {
  GstBuffer   *buffer;
  guint        offset;
} GstRTCPPacket;

Data structure that points to a packet at offset in buffer. The size of the structure is made public to allow stack allocations.

enum GstRTCPSDESType

typedef enum 
{
  GST_RTCP_SDES_INVALID  = -1,
  GST_RTCP_SDES_END      = 0,
  GST_RTCP_SDES_CNAME    = 1,
  GST_RTCP_SDES_NAME     = 2,
  GST_RTCP_SDES_EMAIL    = 3,
  GST_RTCP_SDES_PHONE    = 4,
  GST_RTCP_SDES_LOC      = 5,
  GST_RTCP_SDES_TOOL     = 6,
  GST_RTCP_SDES_NOTE     = 7,
  GST_RTCP_SDES_PRIV     = 8
} GstRTCPSDESType;

Different types of SDES content.

enum GstRTCPFBType

typedef enum
{
  /* generic */
  GST_RTCP_FB_TYPE_INVALID    = 0,
  /* RTPFB types */
  GST_RTCP_RTPFB_TYPE_NACK    = 1,
  /* PSFB types */
  GST_RTCP_PSFB_TYPE_PLI      = 1,
  GST_RTCP_PSFB_TYPE_SLI      = 2,
  GST_RTCP_PSFB_TYPE_RPSI     = 3,
  GST_RTCP_PSFB_TYPE_AFB      = 15
} GstRTCPFBType;

Different types of feedback messages.

Since 0.10.23

gst_rtcp_buffer_new_take_data ()

GstBuffer*          gst_rtcp_buffer_new_take_data       (gpointer data,
                                                         guint len);

Create a new buffer and set the data and size of the buffer to data and len respectively. data will be freed when the buffer is unreffed, so this function transfers ownership of data to the new buffer.

gst_rtcp_buffer_new_copy_data ()

GstBuffer*          gst_rtcp_buffer_new_copy_data       (gpointer data,
                                                         guint len);

Create a new buffer and set the data to a copy of len bytes of data and the size to len. The data will be freed when the buffer is freed.

gst_rtcp_buffer_validate_data ()

gboolean            gst_rtcp_buffer_validate_data       (guint8 *data,
                                                         guint len);

Check if the data and size point to the data of a valid RTCP (compound) packet. Use this function to validate a packet before using the other functions in this module.

gst_rtcp_buffer_validate ()

gboolean            gst_rtcp_buffer_validate            (GstBuffer *buffer);

Check if the data pointed to by buffer is a valid RTCP packet using gst_rtcp_buffer_validate_data().

gst_rtcp_buffer_new ()

GstBuffer*          gst_rtcp_buffer_new                 (guint mtu);

Create a new buffer for constructing RTCP packets. The packet will have a maximum size of mtu.

gst_rtcp_buffer_end ()

void                gst_rtcp_buffer_end                 (GstBuffer *buffer);

Finish buffer after being constructured. This function is usually called after gst_rtcp_buffer_new() and after adding the RTCP items to the new buffer.

The function adjusts the size of buffer with the total length of all the added packets.

gst_rtcp_buffer_get_packet_count ()

guint               gst_rtcp_buffer_get_packet_count    (GstBuffer *buffer);

Get the number of RTCP packets in buffer.

gst_rtcp_buffer_get_first_packet ()

gboolean            gst_rtcp_buffer_get_first_packet    (GstBuffer *buffer,
                                                         GstRTCPPacket *packet);

Initialize a new GstRTCPPacket pointer that points to the first packet in buffer.

gst_rtcp_packet_move_to_next ()

gboolean            gst_rtcp_packet_move_to_next        (GstRTCPPacket *packet);

Move the packet pointer packet to the next packet in the payload. Use gst_rtcp_buffer_get_first_packet() to initialize packet.

gst_rtcp_buffer_add_packet ()

gboolean            gst_rtcp_buffer_add_packet          (GstBuffer *buffer,
                                                         GstRTCPType type,
                                                         GstRTCPPacket *packet);

Add a new packet of type to buffer. packet will point to the newly created packet.

gst_rtcp_packet_remove ()

gboolean            gst_rtcp_packet_remove              (GstRTCPPacket *packet);

Removes the packet pointed to by packet and moves pointer to the next one

gst_rtcp_packet_get_padding ()

gboolean            gst_rtcp_packet_get_padding         (GstRTCPPacket *packet);

Get the packet padding of the packet pointed to by packet.

gst_rtcp_packet_get_count ()

guint8              gst_rtcp_packet_get_count           (GstRTCPPacket *packet);

Get the count field in packet.

gst_rtcp_packet_get_type ()

GstRTCPType         gst_rtcp_packet_get_type            (GstRTCPPacket *packet);

Get the packet type of the packet pointed to by packet.

gst_rtcp_packet_get_length ()

guint16             gst_rtcp_packet_get_length          (GstRTCPPacket *packet);

Get the length field of packet. This is the length of the packet in 32-bit words minus one.

gst_rtcp_packet_sr_get_sender_info ()

void                gst_rtcp_packet_sr_get_sender_info  (GstRTCPPacket *packet,
                                                         guint32 *ssrc,
                                                         guint64 *ntptime,
                                                         guint32 *rtptime,
                                                         guint32 *packet_count,
                                                         guint32 *octet_count);

Parse the SR sender info and store the values.

gst_rtcp_packet_sr_set_sender_info ()

void                gst_rtcp_packet_sr_set_sender_info  (GstRTCPPacket *packet,
                                                         guint32 ssrc,
                                                         guint64 ntptime,
                                                         guint32 rtptime,
                                                         guint32 packet_count,
                                                         guint32 octet_count);

Set the given values in the SR packet packet.

gst_rtcp_packet_rr_get_ssrc ()

guint32             gst_rtcp_packet_rr_get_ssrc         (GstRTCPPacket *packet);

Get the ssrc field of the RR packet.

gst_rtcp_packet_rr_set_ssrc ()

void                gst_rtcp_packet_rr_set_ssrc         (GstRTCPPacket *packet,
                                                         guint32 ssrc);

Set the ssrc field of the RR packet.

gst_rtcp_packet_get_rb_count ()

guint               gst_rtcp_packet_get_rb_count        (GstRTCPPacket *packet);

Get the number of report blocks in packet.

gst_rtcp_packet_get_rb ()

void                gst_rtcp_packet_get_rb              (GstRTCPPacket *packet,
                                                         guint nth,
                                                         guint32 *ssrc,
                                                         guint8 *fractionlost,
                                                         gint32 *packetslost,
                                                         guint32 *exthighestseq,
                                                         guint32 *jitter,
                                                         guint32 *lsr,
                                                         guint32 *dlsr);

Parse the values of the nth report block in packet and store the result in the values.

gst_rtcp_packet_add_rb ()

gboolean            gst_rtcp_packet_add_rb              (GstRTCPPacket *packet,
                                                         guint32 ssrc,
                                                         guint8 fractionlost,
                                                         gint32 packetslost,
                                                         guint32 exthighestseq,
                                                         guint32 jitter,
                                                         guint32 lsr,
                                                         guint32 dlsr);

Add a new report block to packet with the given values.

gst_rtcp_packet_set_rb ()

void                gst_rtcp_packet_set_rb              (GstRTCPPacket *packet,
                                                         guint nth,
                                                         guint32 ssrc,
                                                         guint8 fractionlost,
                                                         gint32 packetslost,
                                                         guint32 exthighestseq,
                                                         guint32 jitter,
                                                         guint32 lsr,
                                                         guint32 dlsr);

Set the nth new report block in packet with the given values.

Note: Not implemented.

gst_rtcp_packet_sdes_get_item_count ()

guint               gst_rtcp_packet_sdes_get_item_count (GstRTCPPacket *packet);

Get the number of items in the SDES packet packet.

gst_rtcp_packet_sdes_first_item ()

gboolean            gst_rtcp_packet_sdes_first_item     (GstRTCPPacket *packet);

Move to the first SDES item in packet.

gst_rtcp_packet_sdes_next_item ()

gboolean            gst_rtcp_packet_sdes_next_item      (GstRTCPPacket *packet);

Move to the next SDES item in packet.

gst_rtcp_packet_sdes_get_ssrc ()

guint32             gst_rtcp_packet_sdes_get_ssrc       (GstRTCPPacket *packet);

Get the SSRC of the current SDES item.

gst_rtcp_packet_sdes_first_entry ()

gboolean            gst_rtcp_packet_sdes_first_entry    (GstRTCPPacket *packet);

Move to the first SDES entry in the current item.

gst_rtcp_packet_sdes_next_entry ()

gboolean            gst_rtcp_packet_sdes_next_entry     (GstRTCPPacket *packet);

Move to the next SDES entry in the current item.

gst_rtcp_packet_sdes_get_entry ()

gboolean            gst_rtcp_packet_sdes_get_entry      (GstRTCPPacket *packet,
                                                         GstRTCPSDESType *type,
                                                         guint8 *len,
                                                         guint8 **data);

Get the data of the current SDES item entry. type (when not NULL) will contain the type of the entry. data (when not NULL) will point to len bytes.

When type refers to a text item, data will point to a UTF8 string. Note that this UTF8 string is NOT null-terminated. Use gst_rtcp_packet_sdes_copy_entry() to get a null-termined copy of the entry.

gst_rtcp_packet_sdes_copy_entry ()

gboolean            gst_rtcp_packet_sdes_copy_entry     (GstRTCPPacket *packet,
                                                         GstRTCPSDESType *type,
                                                         guint8 *len,
                                                         guint8 **data);

This function is like gst_rtcp_packet_sdes_get_entry() but it returns a null-terminated copy of the data instead. use g_free() after usage.

gst_rtcp_packet_sdes_add_item ()

gboolean            gst_rtcp_packet_sdes_add_item       (GstRTCPPacket *packet,
                                                         guint32 ssrc);

Add a new SDES item for ssrc to packet.

gst_rtcp_packet_sdes_add_entry ()

gboolean            gst_rtcp_packet_sdes_add_entry      (GstRTCPPacket *packet,
                                                         GstRTCPSDESType type,
                                                         guint8 len,
                                                         const guint8 *data);

Add a new SDES entry to the current item in packet.

gst_rtcp_packet_bye_get_ssrc_count ()

guint               gst_rtcp_packet_bye_get_ssrc_count  (GstRTCPPacket *packet);

Get the number of SSRC fields in packet.

gst_rtcp_packet_bye_get_nth_ssrc ()

guint32             gst_rtcp_packet_bye_get_nth_ssrc    (GstRTCPPacket *packet,
                                                         guint nth);

Get the nth SSRC of the BYE packet.

gst_rtcp_packet_bye_add_ssrc ()

gboolean            gst_rtcp_packet_bye_add_ssrc        (GstRTCPPacket *packet,
                                                         guint32 ssrc);

Add ssrc to the BYE packet.

gst_rtcp_packet_bye_add_ssrcs ()

gboolean            gst_rtcp_packet_bye_add_ssrcs       (GstRTCPPacket *packet,
                                                         guint32 *ssrc,
                                                         guint len);

Adds len SSRCs in ssrc to BYE packet.

gst_rtcp_packet_bye_get_reason_len ()

guint8              gst_rtcp_packet_bye_get_reason_len  (GstRTCPPacket *packet);

Get the length of the reason string.

gst_rtcp_packet_bye_get_reason ()

gchar*              gst_rtcp_packet_bye_get_reason      (GstRTCPPacket *packet);

Get the reason in packet.

gst_rtcp_packet_bye_set_reason ()

gboolean            gst_rtcp_packet_bye_set_reason      (GstRTCPPacket *packet,
                                                         const gchar *reason);

Set the reason string to reason in packet.

gst_rtcp_packet_fb_get_type ()

GstRTCPFBType       gst_rtcp_packet_fb_get_type         (GstRTCPPacket *packet);

Get the feedback message type of the FB packet.

Since 0.10.23

gst_rtcp_packet_fb_set_type ()

void                gst_rtcp_packet_fb_set_type         (GstRTCPPacket *packet,
                                                         GstRTCPFBType type);

Set the feedback message type of the FB packet.

Since 0.10.23

gst_rtcp_packet_fb_get_sender_ssrc ()

guint32             gst_rtcp_packet_fb_get_sender_ssrc  (GstRTCPPacket *packet);

Get the sender SSRC field of the RTPFB or PSFB packet.

Since 0.10.23

gst_rtcp_packet_fb_set_sender_ssrc ()

void                gst_rtcp_packet_fb_set_sender_ssrc  (GstRTCPPacket *packet,
                                                         guint32 ssrc);

Set the sender SSRC field of the RTPFB or PSFB packet.

Since 0.10.23

gst_rtcp_packet_fb_get_media_ssrc ()

guint32             gst_rtcp_packet_fb_get_media_ssrc   (GstRTCPPacket *packet);

Get the media SSRC field of the RTPFB or PSFB packet.

Since 0.10.23

gst_rtcp_packet_fb_set_media_ssrc ()

void                gst_rtcp_packet_fb_set_media_ssrc   (GstRTCPPacket *packet,
                                                         guint32 ssrc);

Set the media SSRC field of the RTPFB or PSFB packet.

Since 0.10.23

gst_rtcp_ntp_to_unix ()

guint64             gst_rtcp_ntp_to_unix                (guint64 ntptime);

Converts an NTP time to UNIX nanoseconds. ntptime can typically be the NTP time of an SR RTCP message and contains, in the upper 32 bits, the number of seconds since 1900 and, in the lower 32 bits, the fractional seconds. The resulting value will be the number of nanoseconds since 1970.

gst_rtcp_unix_to_ntp ()

guint64             gst_rtcp_unix_to_ntp                (guint64 unixtime);

Converts a UNIX timestamp in nanoseconds to an NTP time. The caller should pass a value with nanoseconds since 1970. The NTP time will, in the upper 32 bits, contain the number of seconds since 1900 and, in the lower 32 bits, the fractional seconds. The resulting value can be used as an ntptime for constructing SR RTCP packets.