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| Digital FPV video for drone racing |
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| ogden:
--- Quote from: Marco on January 20, 2019, 09:13:29 pm ---Why not try to build a system which can sync the transmitter and receiver and sends an image as uncompressed PCM YUV before even worrying about compression? --- End quote --- Why not use video camera that provides compressed digital video output? Any inter-frame compressor like h.264 or MPEG will barely help for FPV drone video. FPV video stream is not like hollywood movie /w fixed camera, every next frame differ too much. |
| Marco:
--- Quote from: ogden on January 20, 2019, 09:33:57 pm ---Any inter-frame compressor like h.264 or MPEG will barely help for FPV drone video. --- End quote --- H.264 720p will go a bit fuzzy during motion at 2 Mbps, MJPEG will just look like utter trash non stop. |
| ogden:
--- Quote from: Marco on January 20, 2019, 10:24:10 pm --- --- Quote from: ogden on January 20, 2019, 09:33:57 pm ---Any inter-frame compressor like h.264 or MPEG will barely help for FPV drone video. --- End quote --- H.264 720p will go a bit fuzzy during motion at 2 Mbps, MJPEG will just look like utter trash non stop. --- End quote --- MJPEG is jpeg still of each video frame. Better you explain how exactly and why MJPEG will look like utter trash. I am all ears. [edit] Oh, you mean - at same video stream bitrate. Yes, I agree in such case. |
| Marco:
--- Quote from: hexahedron on January 20, 2019, 09:21:25 pm ---I guess the next logical step will be to purchase a beefy microcontroller of some sort. Any recommendations? --- End quote --- I'd try to find a SBC, but you have somewhat restrictive requirements. Light weight, I assume you want parallel CSI (for the cheap 720P60 cameras like OV5647), you'll need sufficient GPIO and a DMA engine which can push data to it for your DAC (I don't think Allwinner chips can do this for instance and Raspberry Pi was very slow with DMA AFAIR). As I said before, maybe something based on iMX6UL or iMX6ULL? On the receiver the weight won't matter, but there you have to be able to attach a relatively fast ADC ... also as I said, if you use the standard receiver modules like RX5808, you'll still need to downconvert it to baseband. PS. you could also only use the SBC for interfacing with the camera and compression, and then SPI the bitstream to a microcontroller and let that handle the DAC. |
| Kilrah:
--- Quote from: ogden on January 20, 2019, 09:33:57 pm ---Why not use video camera that provides compressed digital video output? --- End quote --- Because latency from the onboard, non latency-optimized encoder is almost guaranteed to be terribly inappropriate. --- Quote from: ogden on January 20, 2019, 09:33:57 pm ---FPV video stream is not like hollywood movie /w fixed camera, every next frame differ too much. --- End quote --- Correct. |
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