Prosody RTP processing: API: sm_vmprx_config_codec_evrc

Prototype Definition

int sm_vmprx_config_codec_evrc(struct sm_vmprx_codec_evrc_parms *codecp)

Parameters

a structure of the following type:

typedef struct sm_vmprx_codec_evrc_parms {
	tSMVMPrxId vmprx;					/* in */
	tSM_INT payload_type;					/* in */
	tSM_INT post_filter;					/* in */
	enum kSMEVRCRTPMode {
		kSMEVRCRTPModeHeaderless,
		kSMEVRCRTPModeRFC2658,
		kSMEVRCRTPModeRFC3558,
	} rtp_mode;						/* in */
	enum kSMPLCMode plc_mode;				/* in */
} SM_VMPRX_CODEC_EVRC_PARMS;

Description

Configures the VMP[rx] to use the Enhanced Variable Rate Codec (EVRC), setting the payload type mapping to payload_type. This supersedes any previous mapping that was in effect for this codec.

If the call completes successfully, RTP packets arriving at the VMP[rx] with a payload type that matches the specified payload type will be decoded using this codec.

This requires the module evrc to have been downloaded.

Fields

vmprx

The VMP[rx] to which to add the 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.

post_filter

Configures whether or not to use a post-filter. It is used if this value is non-zero.

rtp_mode

Selects the RTP format for this codec. There are two commonly-used specifications for how to pack the the encoded data into an RTP packet. One of these values:

kSMEVRCRTPModeHeaderless: Encodes the bitstream as raw encoded bytes, with no headers. This requires that there is only one frame per packet.
kSMEVRCRTPModeRFC2658: Encodes the bitstream as specified in IETF RFC 2658. The header is one byte. This specification only allows for one frame per packet.
kSMEVRCRTPModeRFC3558: Encodes the bitstream as specified in IETF RFC 3558. The header is two bytes, plus one byte for every two frames in the packet.

plc_mode

Configures packet loss concealment for this codec. Note the codec implementation may not allow PLC to be disabled. One of these values:

kSMPLCModeDisabled: PLC Disabled
kSMPLCModeEnabled: PLC Enabled

Returns

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

ERR_SM_DEVERR - device error

This function is part of the Prosody RTP processing API.