Can --dvr-framerate be an optional parameter?

[zhouruixi]

Why --dvr-framerate parameter must required? Can we just get the frame rate from the video stream?The FPS shows in OSD is the FPS I set in IPC.

[luastoned]

It could be that you fly with 120/60 but want the recording to be 60 or even 30 fps.. but I think it should be a solid default.

[zhouruixi]

It could be that you fly with 120/60 but want the recording to be 60 or even 30 fps.. but I think it should be a solid default.

--dvr-framerate does not change the frame rate of the video Correctly.

• If I set the fps to 60 on IPC, and set --dvr-framerate to 30, the original frame rate of the record video is: 60.000 FPS, and the frame rate is: 30.000 FPS. The video plays at half its normal speed( 30/60=1/2).
• If I set the fps to 30 on IPC, and set --dvr-framerate to 60, the original frame rate of the record video is: 30.000 FPS, and the frame rate is: 60.000 FPS. The video plays at twice its normal speed( 60/30=2).
  The video plays at twice the normal speed

I think:

• If don't use --dvr-framerate parameter: record according to the original video fps.
• If use this parameter: record according to the parameter setting. We first need to fix the speed problem I mentioned above.

[seriyps]

The FPS shows in OSD is the FPS I set in IPC.

This FPS is calculated by literally counting the number of received frames:

PixelPilot_rk/src/main.cpp

Line 309 in dbf3f88

osd_vars.current_framerate = frame_counter*(1000/osd_vars.refresh_frequency_ms);

And the way FPS you specify in commandline is used is quite interesting: for each frame it represents a duration of this frame and current DVR assumes that FPS is constant:

PixelPilot_rk/src/dvr.cpp

Line 158 in dbf3f88

auto res = mp4_h26x_write_nal(mp4wr, frame->data(), frame->size(), 90000/video_framerate);

I think what we can do is to rely on Radxa's clock and just measure the time between frames and write it as frame duration to each individual frame? It's not 100% clear if it's ok to have non-fixed duration. Probably ok, otherwise why would we tag each frame with duration =)