Anyone doing field rate capture bt.656 on i.MX6

[jamiew]

Hello All

Has anyone been able to capture composite PAL video at 50 fields per second rather than 25 frames per second? I am using bt.656 over the MIPI CSI IPU route into the i.MX6 on within the Yocto/V4L2 environment. So ideally mxc_v4l2_capture would send through each field to my V4L2 code as it arrived from the MIPI interface rather than combining them into one frame which introduces a significant delay.

Thanks in advance

Jamie

[art · Accepted solution]

Seems that you have to configure your video capture driver to the Progressive mode rather than the Interlaced one and specify the Frame Height to the half of the original value. For details, please refer to the attached Application Note.

Have a great day,
Artur

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[jamiew]

Hello

Any ideas on how to get which field we are on? eg set a bit for top/bottom or odd/even

Thanks

[art]

The odd/even field attribute should be captured in the field header.

[jamiew]

Thanks, can I get at the field header from drivers/media/video/mxc/capture/mxc_v4l2_capture.c?

[jamiew]

Hi Artur

Thanks for your reply. I am now capturing fields. But at frame rate not field rate. It seems that the first field of each frame is sent.

What do you think I should set IPU_CSI_SENS_FRM_SIZE to? if it was 720x625 when using 720x576 for IPU_CSI_ACT_FRM_SIZE should it still be set to 720x625 when IPU_CSI_ACT_FRM_SIZE is 720x288?

Not sure what to do about the top field having 22 blank lines and the bottom 23 (table 2-3 in the pdf above)

Thanks

[jamiew]

FRM_SIZE should be 720x313