Transcoding Configuration

Overview

Transcoding is a process that converts a media stream encoded with one algorithm to another using Digital Signal Processors (DSPs). For example, a media stream encoded using OPUS may be decoded and re-encoded (transcoded) using G.711.


Note

In high availability configurations, checkpoint for transcoded calls require both the standby system and its DSPs to be ready when a call begins. Calls that are set up before the standby resources are ready will not be maintained on failover.

LTI based Transcoding

  • Internal API is used to access Digital Signal Processor (DSP) resources for transcoding.

  • Transcoding resources (DSPFARM) and CUBE must be on the same platform.

  • Only DSPFARM profile configuration is required. Skinny Client Control Protocol (SCCP) configuration is not required.

  • No TCP socket is opened and no registration is used.

  • DSPFARM profile is associated to application type CUBE.
    Device(config)# dspfarm profile 1 transcode
Device(config-dspfarm-profile)# associate application CUBE

  • DSPs are not used for encryption with IOS XE. As all media is encrypted or decrypted as it leaves or enters the platform, transcoding may be used for any combination of RTP-RTP, RTP-SRTP, or SRTP-SRTP calls.


Note
The following support LTI-based transcoding:

  • Cisco Aggregated Services Routers 1000 Series (ASR 1K)

  • Cisco 4000 Series-Integrated Services Routers (ISR G3)

  • Cisco 8200 Catalyst Edge Series

  • Cisco 8300 Catalyst Edge Series

Limitations

  • Video transcoding is not supported. This document only refers to transcoding for CUBE B2BUA calls. Refer to System Configuration Guide for Cisco Unified Communications Manager for UCM MTP details.

  • SCCP-based transcoding is not supported with IOS XE releases.

  • Transcoding cannot be used for SRTP-Passthrough calls or when pass-thru content SDP is enabled.

Configure LTI-Based Transcoding


Note

  • Opus transcoding is only supported by PVDM4 modules.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. voice-card voice-interface-slot-number
  4. dsp services dspfarm
  5. exit
  6. dspfarm profile profile-identifier transcode
  7. codec codec
  8. maximum sessions sessions
  9. associate application CUBE
  10. no shutdown

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Device> configure terminal

Enters global configuration mode.

Step 3

voice-card voice-interface-slot-number

Example:

Device(config)# voice-card 0/2

Configures a voice card and enters voice-card configuration mode.

Step 4

dsp services dspfarm

Enable voice-only DSP services on the Voice Card.

Step 5

exit

Exits the voice-card configuration mode.

Step 6

dspfarm profile profile-identifier transcode

Example:

Device(config)# dspfarm profile 2 transcode
Enters a DSP farm profile configuration mode and defines a profile for DSP farm services.

  • profile-identifier - Number that uniquely identifies a profile. Range: 1–65535.

  • transcode - Enables profile for transcoding.

Step 7

codec codec

Example:

Device(config-dspfarm-profile)# codec opus
Add a list of codecs that you wish to transcode.

Step 8

maximum sessions sessions

Configures maximum number of transcoding sessions.

Step 9

associate application CUBE

Configures an application to the profile for LTI-based transcoding.

Step 10

no shutdown

Example:

Device (config-dsp-farm-profile) # no shutdown
Allocates DSP resources and associates with the application.

Configuration Examples for LTI Based Transcoding

Example: LTI-based Transcoding


! Enabling dspfarm services under voice-card
Device(config)# voice-card 0/2
Device(config-voicecard)# dsp services dspfarm
Device(config-voicecard)# exit
! Configuring dspfarm profile
Device(config)# dspfarm profile 2 transcode
Device(config-dspfarm-profile)# codec g729abr8
Device(config-dspfarm-profile)# codec g729ar8
Device(config-dspfarm-profile)# codec g711alaw
Device(config-dspfarm-profile)# codec g711ulaw
Device(config-dspfarm-profile)# codec g722-64
Device(config-dspfarm-profile)# codec opus
Device(config-dspfarm-profile)# maximum sessions 10
Device(config-dspfarm-profile)# associate application CUBE
Device(config-dspfarm-profile)# no shutdown

Verify Configuration

Device#show dspfarm profile   
 Profile ID = 2, Service = TRANSCODING, Resource ID = 2   
 Profile Service Mode : Non Secure 
 Profile Admin State : UP 
 Profile Operation State : ACTIVE 
 Application : CUBE   Status : ASSOCIATED 
 Resource Provider : FLEX_DSPRM   Status : UP 
 Total Number of Resources Configured : 10 
 Total Number of Resources Available : 10 
 Total Number of Resources Out of Service : 0 
 Total Number of Resources Active : 0
 Codec Configuration: num_of_codecs:6 
 Codec : opus, Maximum Packetization Period : 120 
 Codec : g722-64, Maximum Packetization Period : 30 
 Codec : g711ulaw, Maximum Packetization Period : 30 
 Codec : g711alaw, Maximum Packetization Period : 30 
 Codec : g729ar8, Maximum Packetization Period : 60 
 Codec : g729abr8, Maximum Packetization Period : 60
Device#

VoIP Trace Logging

VoIP Trace is used for event logging and debugging of VoIP parameters. Using the VoIP Trace framework, the following information is recorded for transcoded calls at CUBE:

  • Reservation

  • Association

  • Disassociation

The following is a sample output for VoIP Trace logging specific to transcoded calls at CUBE: 

Apr 16 11:32:42.910: //63/32191ED78080/CUBE_VT/SIP/API: ccsip_xcoder_reserve (0)
Apr 16 11:32:42.926: //63/32191ED78080/CUBE_VT/SIP/API: ccsip_xcoder_associate (0)
Apr 16 11:32:42.942: //63/32191ED78080/CUBE_VT/SIP/API: ccsip_xcoder_disassociate (0)
Apr 16 11:32:42.946: //62/32191ED78080/CUBE_VT/SIP/API: ccsip_xcoder_disassociate (-1)
Apr 16 11:32:42.948: //63/32191ED78080/CUBE_VT/SIP/API: ccsip_xcoder_disassociate_success (0)
Apr 16 11:32:43.910: //66/32191ED78080/CUBE_VT/SIP/API: ccsip_xcoder_reserve (-1)
Apr 16 11:32:44.926: //66/32191ED78080/CUBE_VT/SIP/API: ccsip_xcoder_associate (-1)