The poll() function is don't work on saLoopBack.

shinji miki

Hi.

I use "l4v2" on ti-ezsdk_dm816x-evm_5_03_01_15.

I changed saLoopBack.c

Before calling ioctl(capt.fd, VIDIOC_DQBUF, &capt.buf),
I tried to check whether data is prepared using poll(). 

However, poll() returns timeout. 

The poll() function is don't work on saLoopBack.

Is there any means to check that capture data is prepared? 

Regards,
Miki Shinji.

over 13 years ago

0 HardikShah over 13 years ago

TI__Mastermind 20245 points

Hi,

Poll is not implemented for V4L2 capture. Any specific need for poll method.

Regards,

Hardik Shah

0 shinji miki over 13 years ago in reply to HardikShah

Intellectual 285 points

Hi.

Thank you for reply.

Is there another means to check that capture data is prepared? 

I want check for no video signal.

Regards,
Miki Shinji.

0 HardikShah over 13 years ago in reply to shinji miki

TI__Mastermind 20245 points

Hi,

You can call ioctl VIDIOC_S_DV_PRESET, it will let you know the resolution detected else it will show you error.

Regards,

Hardik Shah

0 shinji miki over 13 years ago in reply to HardikShah

Intellectual 285 points

Hi.

My situation is

(1)There is a normal video signal at the time of the start of a program. 
(2)A video signal is lost while running a program. 

I would like to detect that the video signal was lost on the way. 

Can ioctl (VIDIOC_S_DV_PRESET) be called in a loop ?

Regards,

Miki　Shinji.

0 HardikShah over 13 years ago in reply to shinji miki

TI__Mastermind 20245 points

Ok,

I got your problem. Unfortunately you cant call VIDIOC_s_DV_PRESET once streaming is started. Let me see how difficult is to add that.

Regards,

Hardik Shah

0 shinji miki over 13 years ago in reply to HardikShah

Intellectual 285 points

Hi.

My problem was solved. 

NON_BLOCK flag is added, when a capture device is open. 

ioctl( VIDIOC_DQBUF ) measures the period set to EAGAIN. 

thank you.

Miki Shinji.

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The poll() function is don't work on saLoopBack.