Prosody RTP processing: API: sm_vmptx_config_codec_rttext

Prototype Definition

int sm_vmptx_config_codec_rttext(struct sm_vmptx_codec_rttext_parms *codecp)

Parameters

*codecp
a structure of the following type: 
typedef struct sm_vmptx_codec_rttext_parms {
	tSMVMPtxId vmptx;					/* in */
	tSM_INT payload_type;					/* in */
	tSM_INT redundant_payload_type;				/* in */
	tSM_INT redundancy_level;				/* in */
	tSM_INT buffer_time;					/* in */
	tSM_INT idle_time;					/* in */
} SM_VMPTX_CODEC_RTTEXT_PARMS;

Description

Configures a VMP[tx] to be able to send real-time text.

The packet format is described in IETF RFC 4103.

A VMP[tx] that is configured to use this codec will expect to be provided with octet data rather than audio. As such it will normally be connected to a channel configured for data communitcations with the raw protocol and no encoding. The data written to the channel must be 32 bit values, presented as 4 octets with the least significant octet first. The values should correspond to UCS4 characters.

The firmware does not attempt to ensure that composite character sequences are sent in the same packet. However, there is usually only a small number of characters in each call to smdc_tx_data() and these blocks are normally sent in a single packet.

This requires the module rttext to have been downloaded.

Fields

vmptx
The VMP[tx] to which to add this codec
payload_type
The payload type identifer to use with this codec (see IETF RFC 3550 section 13). Supplying a value of -1 will remove any payload type configuration from the codec preventing its use.
redundant_payload_type
The payload type identifer to use with this codec (see IETF RFC 3550 section 13) for redundant data packets. Supplying a value of -1 will prevent redundancy being used.
redundancy_level
The number of redundant payloads per packet. If zero is specified, the default of 2 is used. To disable redundancy, set redundant_payload_type to -1.
buffer_time
The time in milliseconds that text may be buffered for before being transmitted.
idle_time
The time in milliseconds before an empty block is sent.

Returns

0 if call completed successfully, otherwise a standard error such as:

This function is part of the Prosody RTP processing API.