How to measure the total latency?

Hi~ Badri

Now i'm also measuring the total latency.  My chain is cap+sclr+nsf+encode. But I don't know what you have said in this post.

Can I use the function Vsys_printDetailedStatistics() to get the info. what's the print info function name in HDVPSS?

Is the print info "LATENCY MAX/MIN" is the true latency?  And the sum is the total latency?

thx~

Are you using DVR RDK 3.5 ? If so measure total latency of cap+sclr+nsf+encode as below:

1. Get encoded frame using Venc_getBitstreamBuffer(&fullBufList, 0);

2.   VCODEC_BITSBUF_S *pBuf = &fullBufList.bitsBuf[i]     

      latency = Avsync_getWallTime() - (((UInt64)pBuf->upperTimeStamp << 32) |  (UInt64)pBuf->lowerTimeStamp);

This will give total latency in msec from capture to when the frame is received using Venc_getBitstreamBuffer

Badri

thanks for your reply

But I'm using DVR RDK 3.0  .  can I get the lotal latency ?

Badri,

I also want to know if I can just use the print info by  VcapVenc_printStatistics?

Is the sum of the " Latency (MAX/MIN)" of each link a precise total latency?

On RDK 3.0 you will get approx. latency +-16ms since timestamp is not set by the capture driver at point of capture but instead set based on capture frame number which is not correct. Sum of latency should not be done. Latency at each link indicates latency from capture to that link. So if you have cap+nsf+scalar_enc latency of scaler includes latency of nsf also.Similarly enc latency includes scalar latency.

Badri

below is my print info

Badri,

1.   I don't konw the meaning of  "Latency at each link indicates latency from capture to that link. So if you have cap+nsf+scalar_enc latency of scaler includes latency of nsf also.Similarly enc latency includes scalar latency." upstaris I have posted my cap info . The nsf latency is 13/14. But the dis latency is 12/20. and it doesn't "include".

2. as you have said before, I still can use the "

1. Get encoded frame using Venc_getBitstreamBuffer(&fullBufList, 0);
2. VCODEC_BITSBUF_S *pBuf = &fullBufList.bitsBuf[i]
latency = Avsync_getWallTime() - (((UInt64)pBuf->upperTimeStamp << 32) | (UInt64)pBuf->lowerTimeStamp);"

but I don't know how to use definitely. where should I add these sentences. Could you point it in detail?

Thx

From the logs the latency in your case is Cap -> Encode Min = 12ms , Max = 20 ms latency. To receive the frame on A8 there could be additional 8ms latency so total latency in your case is 20/28 ms. 

Badri,

Thank you for your reply. 

And I also want to know my "cap+sclr+nsf" latency.

the print info said " 1482251: DISPLAY: HDDAC(BP0) : 71 fps, Latency (Min / Max) = ( 0 / 14 ), Callback Interval (Min / Max) = ( 13 / 14 )"

Is my "cap+sclr+nsf" latency 13/14(min/max)? 

regards,

oguri

Cap+sclr+nsf latency is

Minimum = 4 to 10 ms

Max = 9 to 18 ms.