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Cisco Bug: CSCub15815 - Improvement of forbidden zero bit filter

Last Modified

Aug 06, 2018

Products (13)

  • Cisco TelePresence MCU 4500 Series
  • Cisco TelePresence MCU 4520
  • Cisco TelePresence MCU 4505
  • Cisco TelePresence MCU 4510
  • Cisco TelePresence MCU 4205
  • Cisco TelePresence MCU 4215
  • Cisco TelePresence MCU 4220
  • Cisco TelePresence MCU MSE 8420
  • Cisco TelePresence MCU MSE 8510
  • Cisco TelePresence MCU 4203
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Known Affected Releases

4.3(2.18) unspecified

Description (partial)

Symptom: The H.264 NAL-U header contains a parameter known as forbidden zero bit (1st bit of the 1-byte header). According to H.264 spec, this valud shall always be 0. 
In certain cases we have seen endpoints sending corrupt bit-stream where this bit is incorrectly set to 1 (e.g. MXP bug 133005). When this error is detected, the MCU 4.3(2.18) software reports the following error in the console output: 

DSP(00002002) : os_error:VRX h264 compose error = 0x3 (vrx->last_error = 0x0),
frame_size = 48, start=0x32, finish=0x35

There are plans to make improvements of this detection mechanism in MCU 4.4. Raising this bug to track those changes.

Condition: When MCU is receiving corrupt bit-stream from devices where H.264 forbidden zero bit is set to 1 (it should not be anything other than 0).
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