Simple question about a Tandberg/Cisco C20 codec

[Andrea Morici]

Hi Guys,

I'd like to ask your valuable advice about a question one of our customers recently raised; here is the long story short:

after his ISP upgraded a Radvision GK, customer experienced no video in, on his C20s, on multi point conferences (video was corrently sent out though).

After an initial troubleshooting, customer was told the issue could lay in the C20 non accepting/negotiating QCIF video protocol (used instead by Radvision equipment and other old stuff possibly joining the conference).

As a solution, ISP suggested to enable via SSH (API commands) the specific protocol (QCIF) on the C20 (which apparently is not enabled by default ... according to ISP support)

Now, as far as I know, C20 already supports QCIF and the should be no need to enable it via specific shell commands !

... moreover there's no reference in the C20 API documentation about such a specific command.

What I suspect is that, from time to time, an old ISDN codec connects to the conference (maybe as first partecipant) and forces somehow the MCU to negotiate some weird codec leading to no video in (... indeed we just went through a troubleshooting session, conneting no less than theree different IP partecipants and we had no issues at all !).

Could you please let me know if I'm wrong and C20 doesn't indeed by default accept QCIF ? ... if so, could you please share me the command to enable it ?

Thanks a lot !

- Andrea

[Tomonori Taniguchi · Accepted solution]

You are correct that C20 support QCIF in default configuration and no need to add any special command to enable it.

Just for sample, below is terminal capset from C20 advantaging what video can be receive and including QCIF with multiple video protocol.

================================================================

H245LO-1 Incoming MESSAGE START

capabilityTableEntryNumber 12,

capability receiveVideoCapability : h263VideoCapability :

{

qcifMPI 1, <== Support for decoding QCIF for H.263

cifMPI 1,

cif4MPI 1,

maxBitRate 20000,

unrestrictedVector FALSE,

arithmeticCoding FALSE,

advancedPrediction FALSE,

pbFrames FALSE,

temporalSpatialTradeOffCapability FALSE,

errorCompensation FALSE,

h263Options

{

capabilityTableEntryNumber 14,

capability receiveVideoCapability : h261VideoCapability :

{

qcifMPI 1, <== Support for decoding QCIF for H.261

cifMPI 1,

temporalSpatialTradeOffCapability FALSE,

maxBitRate 19200,

stillImageTransmission TRUE

capabilityTableEntryNumber 18,

capability receiveVideoCapability : extendedVideoCapability :

h263VideoCapability :

{

qcifMPI 1, <== Support for decoding QCIF for H.263+

cifMPI 1,

cif4MPI 1,

maxBitRate 20000,

unrestrictedVector FALSE,

arithmeticCoding FALSE,

advancedPrediction FALSE,

pbFrames FALSE,

temporalSpatialTradeOffCapability FALSE,

errorCompensation FALSE

================================================================

Although using QCIF with C20 is bit wasting capability of C20 video processing power, but interesting to understand why Radvision GK software upgrade introduce one-way video issue.

Application log from C20 will definitely help to identify or at least narrow down the root cause of this.

[Tomonori Taniguchi]

For taking H323 call trace log from C20, please refer Endpoint Technical Handbook which available at https://supportforums.cisco.com/docs/DOC-15643.

Step for taking H.323 call trace log is on page 16.

[Andrea Morici]

Hi Tomonori,

thanks a lot for your confirm and suggestions, really appreciated !

So, as I was suspecting, C20 comes already with QCIF support, out of the box.

I saw you also pointed us to the docs explaining how to enable detailed traces on C20, should we need to delve further into this ... thanks for this hint as well !

What to say ? ... great help, no other way to put it :-)

Take care and see you !

- Andrea