Raspberry pi3 and h264_mmal

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cmisip
Posts: 39
Joined: Sun Apr 30, 2017 10:09 pm

Re: Raspberry pi3 and h264_mmal

Post by cmisip » Sat Aug 25, 2018 3:59 pm

I merged the latest changes to the fork's master branch just this morning. Hopefully there will be no issues. The mmal decoder is now native and does not need ffmpeg's h264_mmal decoder. In the future, if ZM starts supporting RGB565, the shared memory requirements per pixel data would save 8 bits. The issue with resolutions not being multiples of 16 or 32 for height and width has been fixed although I was only able to test at 640x360. I dont see the green artifact in the jpeg encodes from this resolution. There are mmal optimizations for zero copy. The motion vector code is integrated into the video capture module as well. I am using it in passthrough mode.

I find that the greatest weakness of the system right now is the necessity to have large ringbuffer in shared memory. I am using 150 frames for the ring buffer size and alarm frame count of 2. This limits the number of cameras that could be used simultaneously. I still get buffer overruns with long events. I think the buffer overruns cause the frames going backward in time issue when replaying the jpegs in zms.

Have Fun.
Chris

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