Raspberry Pi HDMI to Composite Converter
Blair Vidakovich wrote 01/10/2019 at 13:14 • 0 pointsWould it be somehow possible to use a Pi 3+ to convert input HDMI to composite video?
...asking for a friend.
I don't mind if it's software conversion, or a bit laggy!
I may just resort to buying a cheap $6 box from Alibaba.
I am very low on money, and all I have is my pi!
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"HDMI2AV" on AliExpress, $5 delivered?
On the interesting side of things, Lontium Semiconductor makes interesting format conversion chips for HDMI -> X, giving you at least a route to VGA.
http://www.lontiumsemi.com/?list-1537.html
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what i mean is, could i take the HDMI output from my xbox, and use the Pi to convert it to composite :-)
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Hi. not a chance, I'm afraid. The pi's HDMI is output only, and the GPIOS are not nearly fast enough. HDMI to composite converters use dedicated fast chips, and homebrew stuff would use FPGAs. No way you could do it with a pi.
If it's an xbox one, there's a possibility you could stream to the pi over the network. https://www.reddit.com/r/raspberry_pi/comments/5w2wjg/xbox_one_streaming_on_raspberry_pi_using_windows/
I think you'd be better off buying the converter though. or search around for a cheap second-hand HDMI TV to buy locally. I've seen 720p LCD TVS going for under 20 dollars in our area...
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I'm ashamed to only realize it now but to be precise, the Raspberry Pi does have both peripheral and hardware acceleration capabilities to do HDMI to composite conversion, albeit somewhat exotic:
* the camera serial interface (MIPI CSI-2)
* hardware accelerated video processing
The catch however is the digital format conversion due to licensing and performance requirements.
https://www.youtube.com/watch?v=3dCWq0fS5Qw
Oddly enough, some dedicated silicon exists, probably a lower density FPGA or straight ASIC close to the IP shown in the video.
https://www.mouser.de/datasheet/2/864/B10x_technical_reference_1.4-1130369.pdf
with the display interface (DSI) side being investigated and reverse engineered in the community I would be delighted to learn that this exists somewhere or thrilled to see it happen in the future.
ps. a two-chip solution is also possible ... but still the $5 AliExpress thing will be way cheaper.
TDA9975A
Triple 10-bit video converter and HDMI receiver interface with digital processing
https://4donline.ihs.com/images/VipMasterIC/IC/PHGL/PHGLS15871/PHGLS15871-1.pdf
2.7 V to 5.5 V RGB-to-NTSC/PAL Encode
https://www.analog.com/media/en/technical-documentation/data-sheets/ad723.pdf
pps.
https://hackaday.io/project/19480-raspberry-pi-camera-v21-reversed/log/53217-pi-camera-driver-makes-deal-with-the-devil
https://twitter.com/marcan42/status/1088703260179914752
HMAC-SHA256 key for the secret authentication chip: 0d48bfb7fd81bb7fe9a24b1df9653a185f9d438aac819afe1672a77afca451a4.
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the pi already has composite video output, nothing extra is needed (maybe a cable for a pi3)
https://www.youtube.com/watch?v=YHxrnVOl0b4
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