Hi, my app need to decode multiple video streams simultaneously, so does rpi4 support the creation of multiple video decoders?

Yes, you can. Running multiple instances of omxplayer with different rendering co-ords will do that for you, but it'll be equally happy whether it's one program or multiple.
Just remember that the hardware spec is nominally 1080p30 for all your streams combined, although it can handle 1080p60 (489600 macroblocks/s).

OpenMAX is considered deprecated as an API. Please look at MMAL or the V4L2 stateful decoder API.

Software Engineer at Raspberry Pi Ltd. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

6by9 wrote: ↑

Mon May 24, 2021 4:37 pm

OpenMAX is considered deprecated as an API. Please look at MMAL or the V4L2 stateful decoder API.

thanks,so where can i get the documents about MMAL or V4L2?

italiansc wrote: ↑

Tue May 25, 2021 2:43 am

6by9 wrote: ↑

Mon May 24, 2021 4:37 pm

OpenMAX is considered deprecated as an API. Please look at MMAL or the V4L2 stateful decoder API.

thanks,so where can i get the documents about MMAL or V4L2?

MMAL docs are in the headers as Doxygen markup. Someone is hosting a rendering of it at http://www.jvcref.com/files/PI/documentation/html/ Examples in https://github.com/raspberrypi/userland ... t/examples (ignore example_graph - I've never understood it!)

V4L2 spec is at https://www.kernel.org/doc/html/latest/ ... coder.html. FFmpeg and GStreamer have implementations that use it. Note that V4L2 does specify that you are meant to feed in one NAL per buffer, which requires bitstream parsing. It is likely to work without, but is less optimal.

Software Engineer at Raspberry Pi Ltd. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

6by9 wrote: ↑

Tue May 25, 2021 7:53 am

italiansc wrote: ↑

Tue May 25, 2021 2:43 am

6by9 wrote: ↑

Mon May 24, 2021 4:37 pm

OpenMAX is considered deprecated as an API. Please look at MMAL or the V4L2 stateful decoder API.

thanks,so where can i get the documents about MMAL or V4L2?

MMAL docs are in the headers as Doxygen markup. Someone is hosting a rendering of it at http://www.jvcref.com/files/PI/documentation/html/ Examples in https://github.com/raspberrypi/userland ... t/examples (ignore example_graph - I've never understood it!)

V4L2 spec is at https://www.kernel.org/doc/html/latest/ ... coder.html. FFmpeg and GStreamer have implementations that use it. Note that V4L2 does specify that you are meant to feed in one NAL per buffer, which requires bitstream parsing. It is likely to work without, but is less optimal.

Thanks, I decide to use V4L2 through FFmpeg or GStreamer API,so which one support better do you think? For developping a net stream player app,which one should I use?

italiansc wrote: ↑

Tue May 25, 2021 10:42 am

Thanks, I decide to use V4L2 through FFmpeg or GStreamer API,so which one support better do you think? For developping a net stream player app,which one should I use?

Personally I prefer GStreamer, but it's largely down to personal preference. They can both largely do the same things, although FFmpeg typically doesn't have a way to render to the screen (vout filters are a bit of a funny one). Then again I haven't looked the full set of options on GST's kmssink for setting the display region.

Software Engineer at Raspberry Pi Ltd. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

Hi, 6by9:

Which version of gstreamer support all hardware codecs(include encoder) on rpi4? Does v1.14.4 from repo meat the requirements?