One more thing on the image signal processor (ISP) in the Fir batch. The i.MX 8M Plus fact sheet says “Dual Camera ISP (2x HD/1x 12MP) HDR, dewarp” and “Up to 375 MP/s”. Usually “2x HD” just means two 720p video streams, but the fact that they got 4K video at 30fps to work tells me that the ISP is more powerful than what NXP is listing in its spec sheet.
Another question is whether we will have free/open drivers to use the hardware encoders for H.264 and H.265 1080p video in the Plus. It is taking quite a while to get support in mainline Linux for the Hantro H1/H2 video decoders in the i.MX 8M Quad, so I wouldn’t be surprised if we have the same problem with the hardware video encoders in the Plus.
What we know is that video encoding on the Librem 5 Evergreen will have to be done in software. Software video encoding is usually done by the CPU and more CPU cores helps, but the four Cortex-A53 cores in the i.MX 8M Quad aren’t very powerful. If some of the encoding work can be passed to the GPU, that will definitely help, since the GPU in the i.MX 8M Quad is decent. Either way, software video encoding in Evergreen is going to use up a lot of battery and generate a lot of heat.
Hopefully we will get an option to do raw video recording, which will take up a lot of space and depends on how fast data can be written to the eMMC or uSD, but it might allow for higher resolution video, because the video encoding processing can be done later. It looks like we are getting Samsung image sensors, but still don’t know the particular model. If we know the model, we can investigate if its mainline Linux driver will provide an option for raw video recording.