I'm not sure if anyone else has had this problem, but a lot of my customers use Polycom M100 software for conducting video conferences on Cisco MCU's. Recently, my company received a new Cisco MCU 4515 with software version 4.5. Almost immediately after the MCU was put online, I started receiving phone calls that the Polycom M100 users were unable to see video from the MCU, but they still received audio. From the MCU, I could see the Polycom M100 user's video and was able to hear audio from their systems. I researched online and found that the issue is with H.264, so on the MCU, disabled the H.264 codec and the Polycom system was able to have video again. The issue was seen using H.323 and SIP. I ended up downgrading the MCU to sw version 4.4.
I put in a ticket with Cisco, and here's the response:
- As you probably already know, Polycomm M100 nor CMA/RealPresence Desktop is not supported by the MCU. I know that Polycom has put a EOL on the M100s, so most likely they will not make any changes to the M100s.
- According to the BU, the MCU is operating to specification, but Polycom has many limitations with the Codian MCU.
- More specifically, when you upgraded from 4.4 to 4.5, there were some new H.264 parameters added. Those parameters is likely due to Polycom’s M100 not being able to cope with the added H.264 parameters.
- Here is a sample SDP parameter line for H.264 main video.
- a=fmtp:126 profile-level-id=42e014;packetization-mode=1;max-mbps=27600;max-fs=3600;max-fps=3000;max-smbps=79000;max-dpb=1380;max-rcmd-nalu-size=196608
- Max-fps (max frame rate), max-dpb (max decoding picture buffer size), max-rcmd-malu-size (max recommend NAL-unity size) are new in the 4.5.
- You cannot control the parameters on the MCU, but you can insert a SIP Proxy in the middle of the signaling path to rewrite all the parameters. However, Cisco does not support this.
- Even though this issue is prevalent for SIP, I can most likely guarantee that there is a comparable change for H323.
- To reinforce that Polycom knows about this, here are some of the Polycom bugs found in their release notes (http://downloads.polycom.com/video/m100/RelNotes_1_0_7.pdf😞
- Interoperability: Codian MCU
CMAD-2272
When placing a SIP call from the Polycom Telepresence m100 to Codian MCU, you get a blank screen on Telepresence m100.
- The BU’s recommendation is to disable H.264 for only those Polycom M100s by using the preconfigured endpoint feature on the MCU, setting a custom codec to exclude H.264. Polycom M100 seems to work well with H.263 video. Their other recommendation is to move away from the M100s only because Polycom nor Cisco’s BU will try to support this.
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