The RPI HDMI to CSI adapter provides a means of interfacing HDMI output from cameras to the Raspberry Pi platform. However, it's important to note that this adapter is not officially supported by the Raspberry Pi Foundation, and as a result, it presents certain challenges and limitations. Here's a concise rundown of these quirks:
Encoder Bitrate Control: One notable issue is the unreliable performance of the encoder bitrate control. This often results in fluctuations like overshoot and undershoot in the bit rate. To mitigate this problem, it is recommended to disable variable bitrate and instead manually set a conservative bitrate, such as 8 MBit/s for MCS3 encoding.
Resolution and Framerate Configuration: Configuring the resolution and framerate through the adapter can be problematic and may even fail in certain instances. To enhance the likelihood of successful configuration, it is advised to set the camera resolution to match exactly the resolution and framerate output by your HDMI source.
Maximum Resolution and Framerate: The Raspberry Pi hardware encoder is constrained to a maximum output of 1080p@30fps or 720p@60fps. Consequently, it's important not to select an HDMI output video signal from your camera that exceeds these limits.
Reliable Adapter Detection: For consistent and reliable detection of the HDMI to CSI adapter during boot, it is crucial to sequence the power supply. In practice, ensure that the OpenHD system is powered on after your HDMI camera. This ensures that the adapter receives a valid HDMI input signal prior to the initialization of the Air Pi system.
While the RPI HDMI to CSI adapter serves as a bridge between HDMI cameras and Raspberry Pi devices, its unofficial nature can lead to these operational quirks. Users seeking to employ this adapter should be aware of these limitations and implement the recommended workarounds for optimal results.
CMOS
Good WDR
$75
Unknown
Good WDR
$75
HDMI cameras require the MMAL Overlay.
To use an HDMI Camera, you need an HDMI-CSI Adapter. These adapters enable you to connect cameras with HDMI outputs, allowing the use of a wider variety of cameras beyond the usual Raspberry Pi camera sensor boards. Depending on the camera, this may result in improved picture quality, including support for features like WDR.
Most small/cheap Toshiba chip boards support up to 1080p25 or 1080p30 HDMI camera resolutions on most Raspberry Pi models. The Raspberry Pi Compute Module boards are technically capable of 1080p60, but the necessary driver change to support 1080p60 has not been implemented yet.
Note: If your camera only supports 1080p60 or 4k60 HDMI output, it will not work with the Toshiba boards.
A latency test was conducted by Bortek using the Auvidea B102 with a GoPro4 camera.
GoPro4
SJcam M10
Canon EOS 700D
Cameras That Do Not Work:
Samsung NX500 (1080p60, framerate too high)
Canon EOS M (1080i, interlaced output is not supported by these adapters)
AliExpress link: DCDZ HDMI CSI-2 Adapter
This adapter is widely used for OpenHD. It's available through AliExpress and Taobao. Users in the U.S. or Europe may experience delays in obtaining them. For those regions, consider the similar geekworm board mentioned below, available on Amazon.
The adapter is compatible with both Raspberry Pi Zero and full-size Raspberry Pi models, setting it apart from other cards.
Available on Amazon in the U.S., this adapter is similar to the DCDZ adapter mentioned above. Amazon store link: Geekworm HDMI CSI2 Adapter Geekworm store link: Geekworm HDMI CSI2 Adapter
The adapter is compatible with full-size Raspberry Pi models.
More info: Auvidea B102
The Auvidea B102 shares similar capabilities with other adapters, but it's only compatible with the Pi Zero.
More info: Auvidea B101
Similar to other adapters, the Auvidea B101 is compatible with full-size Raspberry Pi models. Technical details
More info: Lintest Systems PiCapture HD1
This more complex (and expensive) card supports HDMI like other adapters, as well as analog component input. However, it's unlikely that any drone-worthy camera uses component connections. The adapter includes LEDs to indicate the status of the camera connection.
A drone-specific HDMI camera with onboard recording to MicroSD, WDR support, and a weight of 60g.
Note that some cameras were shipped without HDMI output. The provided link is reported to be the correct HDMI model.