Transcoding Resources

The computing resources used to transcode media come in one of three forms. When deploying an SBC image, only one of these transcoding resource types may be used per system.

The forms of transcoding resources are:

Hardware-based transcoding for physical SBC platforms
Software-based transcoding for vSBC platforms
Artesyn PCIe card-based transcoding for vSBC platforms.

See the Transcoding Support section in the Release Notes for a list of the codecs supported by each of the 3 resource types, and any limitations.

Hardware-based Transcoding Resources

Acme Packet hardware is provisioned with DSP resources that enable transcoding on the Oracle Communications Session Border Controller. Transcoding capacity depends on the codecs in-use and the number of transcoding modules installed in the system. Capacity scales linearly with each additional transcoding module installed. The number of DSP modules that can be installed is platform-dependent.

Acme Packet 6300 and 6350: maximum of 48 DSP modules per system; 1 or 2 (24 DSP) TCUs may be installed in each system
Acme Packet 4600: maximum of 12 DSP modules
Acme Packet 3900: maximum of 5 DSP modules

Transcodable Codecs

Refer to the Release Notes' Transcoding Support topic for a list of the transcodable codecs in this release and which platforms they are supported on. The codec names listed in the table in the Release Notes reflect the default media profiles for their given names.

When creating an override media profile for a codec, the system ignores case sensitivity. Also, GSM = GSM-FR.

Transcodable Codec Details

The following table lists the supported codecs, bit rates, RTP payload type, default ptime, and supported ptimes. See the Release Notes for which transcoding platforms support specific codecs.

Codec	Supported Bit Rate (kbps)	RTP Payload Type	Default Ptime (ms)	Supported Ptime (ms)
G.711 PCMU	64	0	20	10, 20, 30, 40, 50, 60
G.711 PCMA	64	8	20	10, 20, 30, 40, 50, 60
G.722	48, 56, 64	9	20	10, 20, 30, 40 For Acme Packet 1100, 3900 and virtual platforms, supported Ptimes include 20 and 40 only
G.723.1	5.3, 6.3	4	30	30, 60, 90
G.726	16, 24, 32, 40	2, 96-127	20	10, 20, 30, 40, 50
iLBC	13.33	96-127	20	20, 30, 40, 60
iLBC	15.2	96-127	30	20, 30, 40, 60
G.729/A/B	8	18	20	10, 20, 30, 40, 50, 60, 70, 80, 90
AMR	4.75, 5.15, 5.90, 6.70, 7.40, 7.95, 10.2, 12.2	96-127	20	20, 40, 60, 80, 100
AMR-WB (G.722.2)	6.6, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05, 23.85	96-127	20	20, 40, 60, 80, 100
GSM FR	13	3	20	20
T.38	4.8, 9.6, 14.4	N/A		10, 20, 30
Opus	48	104	20	10, 20, 40, 60, 80, 100
EVRC	0.8, 4.0, 8.55	96-127	20	20, 40, 60
EVRC0	0.8, 4.0, 8.55	96-127	20	20
EVRC1	4.0, 8.55	96-127	20	20
EVRCB	0.8, 2.0, 4.0, 8.55	96-127	20	20
EVRCB0	0.8, 2.0, 4.0, 8.55	96-127	20	20
EVRCB1	4.0, 8.55	96-127	20	20
SILK	6.0 to 40	96-127	20	20, 40, 60, 80, 100

Note:

If you set the value for the transcoding capacity as 0, then SBC considers the transcoding capacity as unlimited. But if you set the value greater than zero, Oracle Communications Session Border Controller considers the transcoding capacity as maximum license capacity. This is applicable for all supporting transcoding codecs.

See the EVS Supported Options section for EVS information.

See theSILK Codec Transcoding Support section for SILK information.

T.38 FAX Support

The Oracle Communications Session Border Controller (SBC) supports T.38 FAX relay (Version 0) conversion to T.30 over G.711 and supports FAX modulation schemes up to 14400 kbps V.17. The SBC does not support V.34 modulation, at this time.

Software-based transcoding

The Oracle Communications Session Border Controller supports media transcoding on virtual platforms. Refer to the Transcoding Support section of the Release Notes for the list of codecs which may be transcoded with software-based transcoding resources.

Transcoding is the process of converting voice audio streams from one encoding format (codec) to another. In addition to conversion between codecs, the Oracle Communications Session Border Controller can also reframe compressed audio streams from one packet size to another (e.g. 10ms G.729 reframed to 30ms G.729) according to packetization times specified in session establishment. The Oracle Communications Session Border Controller may then convert between any supported codecs and frame size combination to another supported codec and frame size combination.

Software-based transcoding is configured identically to hardware-based transcoding, and is invoked when codec policies are configured but no transcoding hardware is recognized in the system.

Software-based transcoding alarms and traps

SNMP Traps

The apSysMgmtGroupTrap trap is sent with the MIB OID apSysXCodeG729Capacity to alert you of high G.729 Royalty codec usage. This MIB object is defined in ap-smgmt.mib. It is sent when utilization rises above 95% of licensed capacity. It is cleared when utilization falls below 80% of licensed capacity. The MIB object appears as:

apSysXCodeG729Capacity OBJECT-TYPE
        SYNTAX          SysMgmtPercentage
        MAX-ACCESS      read-only
        STATUS          current
        DESCRIPTION	
                "The percentage of licensed G729 transcoding utilization"
        ::= { apSysMgmtMIBGeneralObjects 35 }

Alarms

The G729 transcoding utilization alarm is triggered when utilization rises above 95% of licensed capacity. It is cleared when utilization falls below 80% of licensed capacity. The alarm appears as follows on the ACLI:

ID      Task      Severity      First Occurred          Last Occurred
131159  527739792       6       2011-10-11 10:11:49     2011-10-11 10:11:49
Count   Description
1       G729 Transcoding capacity at  97 (over threshold of 95)

Debugging log files

The log.media log file records host based transcoding events based upon logging level.

PCIe Transcoding Accelerator Cards

PCIe transcoding accelerator cards enable high-density media processing using the same DSP hardware as physical Acme Packet platform hardware-based transcoding. A PCIe transcoding accelerator card in conjunction with a vSBC provides functional parity with engineered SBC platforms.

PCIe transcoding accelerator cards work seamlessly with vSBCs, once initialized and recognized by the hypervisor. In this way there are no unique configuration or maintenance tasks to be aware of.
Provisioning any transcoding cores for software-based transcoding is incompatible with a PCIe card.
If the PCIe transcoding accelerator card fails after the SBC starts, an alarm is raised and the system is rebooted.
When vSBCs are configured in a redundant pair, both systems must have the same population of PCIe cards and installed DSPs.

Refer to the Release Notes document for all system prerequisites and limitation. Check My Oracle Support for the latest application notes on how to initialize PCIe cards on supported hypervisors.