This FAQ was generated from the following discussion: Black line on the Output from the ADV7282-M
Our back end process can't do I2P process,I disabled ADV7282-M I2P function,
A balck line shown in a field.
You can get video(3.0MB) from following address link:
Local Analog engineer Bob Gao sent me some pictures.It showed that image had 507 lines whether ADV7282-M output BT656-3 or BT656-4 format based 480P.
Everything is normal in free-run mode,but there is a black line at botton of image when using a extern analog camera,DVD device or TV Pattern generator.I want to make sure that if this issue has occurred after I2P process.Register 0x12 states that sometimes the ADV7282-M receives CVBS video of non-standard horizontal line length,so an error occurred during the I2P process.
How can I confirm?
Could you recreate this issue in the lab?
I think it is difficult to implement a detection mechanism in back end processor.
I'am checking it,thanks!
Hello Yuanyuan Guo,
Thanks for reading those registers. Register 0x12 states that sometimes the ADV7282-M receives CVBS video of non-standard horizontal line length. This may be related to your issue.
You may be correct in this issue being due to a screen resolution issue. I will run some experiments in the lab to see if I can recreate your issue.
Note that when a CVBS source is disconnected from the ADV7282-M it will output a few frames of video of non-standard length (i.e. greater than 576 lines lines of video) until it enters free-run mode. These non-standard line lengths can sometimes cause input buffers on the MIPI receiving device to overflow.
I would advise implementing a line counter or similar control loop, to prevent issues in your back end processor.
I think this may be parameters settings issue, I did a set of experiments as follows:
In order for the receiver to correctly receive video data, It is necessary to tell the szie of video data,also included video data + blanking data in platform side(receiver).
ADV7282-M output format video data video data + blanking data test results
BT656-4 1440x487 1728x525 Images is displayed correctly(no 10lines dark and a black line) ,but a error is receiver has received the 507 lines.
BT656-4 1440x507 1728x525 there is a black line at botton of image,no any software error
BT656-3 1440x487 1728x525 more than 10 dark lines at top of image,and a error is receiver has received the 507 lines
BT656-3 1440x507 1728x525 10 dark lines at botton of image,no any software error
Image is displayed correctly in the first set of experiments,and only has a software error.
The ADV7282-M outputs 487 lines of video in BT656-4 progressive NTSC mode,Why receiver does receive is 507 lines? I initialize ADV7282-M wiht parameters of "I2P AUTODETECT CVBS Single Ended In Ain 1, 480p/576p MIPI Out", Is it related to this settings?