Tuesday, October 30, 2007

CC error

Two weeks a go I was in a meeting – the issue was about CC error , since no one really knew what is "cc error" , I was asked to figure out what is CC error , well … this was a task with no real information in hand , actually I knew its something to do with video multicasting , so I was looking for some clue about cc error in UDP/RTP header , but ,,, found basically nothing , the problem was I did not know what 'cc' stands for . Then I assumed that may be CC error is related to the MPEG-2 frame - ..ha ha … yha I was correct , cc = 'continuity counter' …. so the cc error is "continuity counter error" , this is used for keeping a track of the sequence of the MPEG-2 frames , and if you are seeing "cc error" at the clients end when you are using some video stream analyzer like "IQmedia" , the error can be mainly due to ,

1) one packet repeat more than twice

2) packets out of sequence

3) packet loss

each UDP packet of 1316 bytes carry 7 MPEG-2 frames of 188bytes each – each MPEG-2 frames has 4 byte header and the last byte is for continuity counter .

ETH

IP

UDP

FR-1

FR-2

FR-3

FR-4

FR-5

FR-6

FR-7

Eth…

Frame – 1 (FR-1)

SYN(8)

TEI(1)

PUSI(1)

TP(1)

PID(13)

TSC(2)

AF(2)

CC (4)

Video

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