i.MX ProcessorsのトピックRe: Less frame rate when used 2 buffers

Less frame rate when used 2 buffers

titusstalin — Thu, 26 Oct 2017 07:47:11 GMT

Hello,

I have used the OV5640 MIPI camera with i.MX6 platform and using prebuilt i.MX BSP binaries.

Getting less frame rates when using 2 buffers (VIDIOC_REQBUFS) and able to see the higher or actual frame rate if I use 3 or more buffers.

What could be reason for this behavior ?

Re: Less frame rate when used 2 buffers

igorpadykov — Thu, 26 Oct 2017 10:52:03 GMT

Hi Titus

usually several circle buffers are used: one is filled with sensor data, others are

processed in chain by application. Two buffers are min. number: one is filling with sensor data,

other is processed by application, after that they are changed in places. Two buffers may require

more overheads and underrun may happens, when sensor data was not ready when other

buffer was already emptied by application. Three or more buffers allows more flexible

timings and do not require strict synchronization as in case two buffers.

Best regards
igor
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Re: Less frame rate when used 2 buffers

titusstalin — Fri, 27 Oct 2017 12:44:41 GMT

Thanks Igor.

I too suspected the same.

And generic v4l2 application uses buffer count as 4. (min)