STM32N6 camera code roadmap (DCMIPP -> VENC -> x) ?

[svogl]

Dear all,

we're creating a camera application and have successfully run and modified some of the demos available. ( State at time of writing: 800x600 30 fps full-frame encoding to SDCard).

We have full-frame double-buffering code running but this is consuming extensive memory; from the documentation I saw that there is a hardware-linked mode available chaining DCMIPP and VENC cores. From the code, I see there is one implementation in VENC_USB example.

The camera and venc middlewares on github miss the slice aka "HW Handshake mode" so I wonder which code-base is recent and will be supported in the future, especially as CubeMX does not (yet) support VENC configuration.

We're trying to go beyond a proof of concept, so I'd like to base our project on a maintained code-base but that is hard to spot, could you give some indications?
Many thanks,

Simon

[FBL]

Hi @svogl 

In your case, I would suggest this example firmware for SDCard recording.  Can you provide more details about : the slice aka "HW Handshake mode" issue?

[svogl]

hi @FBL ,

apparently, the VENC_USB example implements a mode that links dcmipp line interrupts to the venc encoder interrupts, which reduces the amount of internal RAM needed significantly (from full frames to multiples of 16 lines == macroblock sizes).

This code is not present anywhere else but would be needed to support higher resolutions. I have successfully modified the VENC_SDCard_ThreadX example to run with 800x600 pixels, which is about the maximum before hitting memory limits (n.b. that the VENC encoder library internally needs another full frame for reference >= 1.01MB in best case - I have these in PSRAM already but I start seeing timing-related artifacts in the encoded h264 stream).

Maybe you can check with the camera development team what is on the roadmap?

Simon

[FBL]

Hi @svogl again, 

Thank you for the heads up! Would you make sure to use latest CubeN6 version provided on GitHub. I found updates in latest version to correct PSRAM initialization in VENC_USB application and enhance VENC_SDCard application to support resolution changes.

[svogl]

thanks for the update, will check the latest state there.

Side-question: Is there a CubeMX config file available for one of the examples? It would be helpful to get access to the clock tree etc. in an ordered way.

[FBL]

Hi @svogl 

Unfortunately, VideoEncoder_EWL middleware is not supported as of now using CubeMX.

[svogl]

Hi @FBL , 

I finally had some time to start with the latest VENC code. The VENC_SDCard_ThreadX example does not compile (Linux) due to an absolute Windoes path in the project settings, I posted a PR here:

https://github.com/STMicroelectronics/STM32CubeN6/pull/13

--> the same applies to other projects.

both VENC_SDCard and the threadx exmaples crash in under a second. In which configuration have these been tested?
Simon 

[svogl]

And after upgrading to the latest STMCubeIDE version (2.1.0), stricter type checks caused an error in the venc code - there's a PR fixing this:

https://github.com/STMicroelectronics/STM32CubeN6/pull/14