2009-07-14 06:21:09     ADV7183B ITU-R BT.656 PPI Driver Resolution

Document created by Aaronwu Employee on Aug 16, 2013
Version 1Show Document
  • View in full screen mode

2009-07-14 06:21:09     ADV7183B ITU-R BT.656 PPI Driver Resolution

Samuel Ayet (SPAIN)

Message: 77202   






We are developing a Video Over IP system based on a BF537 @ CCLK = 525MHz, SCLK=131.5MHz with a ADV7183B Daughter Board running ffmpeg that captures the video from a CVBS (input CVBS is mandatory in out project) camera and then compress it (MPEG4) and send it to the destination point (another Blackfin runnign MPlayer).


We are facing the problem that with the ADV7183B (CBVS Digitalizer) that outputs ITU-R BT.656 video format we only can capture digital video at 720x288 pixels. With this resolution, we are having troubles when we try to achieve the fps we want (min of 15fps) and we don't need more resolution than 352x288 (CIF). So here we are working, reduciong the resolution of the BT.656 Driver. Firs of all, we tried to crop the 720x288 pixels into CIF resolution (when we was trying to make Video Calls with Linphone) but we don't have any success, and now, we want to capture BT.656 in CIF resolution with ffmpeg or vlc therefore we will be able to achieve the fps with a CIF resolution.


And now we are lost because we don't know exactly how to reduce the resolution of the captured video and what is the flow of the video captured on the Blackfin (V4L, blackfin_cam...). Maybe, will I have to change some configuration of the PPI?


Please let me know where can we get some information of what to do or what should we do to achieve what we want.




Thank you!


Best Regards!






2009-07-14 19:44:43     Re: ADV7183B ITU-R BT.656 PPI Driver Resolution


Message: 77270   




You should be able to modify the PPI driver to decimate things. Did you try that?






2009-07-15 05:41:15     Re: ADV7183B ITU-R BT.656 PPI Driver Resolution

Michael Hennerich (GERMANY)

Message: 77329    Decimating by means of cropping doesn't work for ITU-R 656 Modes.

- However you could switch to 2/3 External Framesyc Mode,

and crop the area of interest using PPI_DELAY and a reduced PPI_COUNT







2009-07-15 06:02:46     Re: ADV7183B ITU-R BT.656 PPI Driver Resolution

Samuel Ayet (SPAIN)

Message: 77333   


Hi Robin,


No, I only have tryed to capture frames at 720x288 and then crop once I have the frame in memory but without any success because I didn´t use DMA to crop it.


I don´t know exactly what to change in the PPI driver. Should I change it in the blackfin_cam? I have read the PPI chapter of the HW reference Manual of the BF537, What should I change? The mode of the PPI? The PPI_FRAME MMR?  I think I will have to change the PPI_FRAME MMR and the configuration of the 2D DMA (width and height), is it ok?