SaLoopBackFbDev varying frame rate depending on total number of frames

_Ralph_

As title, I am running the SaLoopBackFbDev demo to do frame counting on VIP0.

I am finding that the frame rate varies depending on how many frames of video are captured by the V4L2 driver. I should point out that I have modified the program so that the time lapse is calculated _not_ including the fwrite call, as it is by default.

Here are some values that I'm getting:

Number of frames Frame rate

1000 62

10000 56

20000 56

Any ideas why this is happening?

Thanks,

Ralph

over 13 years ago

0 HardikShah over 13 years ago

TI__Mastermind 20245 points

Hi,

This is because of rounding error. You must run for more than 5000 frames to get actual fps. FPS you get for 10000 and 20000 are ok. There is a issue with V4L2 capture driver and FBDEV that fps is coming to only 56 and not 60.

Regards,

Hardik Shah

0 _Ralph_ over 13 years ago in reply to HardikShah

Guru 10685 points

HardikShah said:
There is a issue with V4L2 capture driver and FBDEV that fps is coming to only 56 and not 60.

What do you mean by this? What is the issue? Do other people see this too?

Thanks,

Ralph

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SaLoopBackFbDev varying frame rate depending on total number of frames