LINux on MOBile

This morning, while in the process of a lengthy sunday-morning wake-up process, I figured: Let's see if I can't get that PinePhone video recording script I downloaded recently to work on postmarketOS. After being successful, I felt that documenting how I did this might be helpful.

Just to be clear: This article is about the AllWinner A64 powered original PinePhone, NOT the PinePhone Pro

The issue at hand

PinePhone video recording? Why would you want that? I don't really know either. On the other hand, it somewhat upset ¹ me when I read the title of a recent reddit post on the topic: When are they going to add video recording to the default OS? It’s ridiculous it can’t take video out of the box 📦.

I knew that people had managed to record video with the PinePhone before, but personally I had never bothered. I had downloaded scripts, but device names did not match up, and I moved on. After all, 720p at 30FPS would not be enough for todays content creation for YouTube & co.

I left some comments on the thread and browsed another reddit thread (a video recording success story), and downloaded a fairly recent script², which records video in 720p, adjusts rotation and compresses it afterwards by reencoding it to VP9 and opus in a .webm container. Being made for Manjaro, it (as I had expected) did not work right out of the box after installing the necessary packages:

sudo apk add ffmpeg v4l-utils

I gave up then, and tried again this morning.

Adjusting the script

The first adjustments I had to make were to line 8 and 9. I figured this out by using the well known and simple command ls :

ls /sys/bus/iio/devices

listed three devices: iio:device0, iio:device1, and iio:device3.

I then used ls to show the content of these "device folders" and figured out that it had to be iio:device1 on postmarketOS and changed the script accordingly.

Now, the script failed differently, something could not be linked. I did not even know where, so I added some echo statements before line 30 (echo "media-ctl does its magic now") and line 32 (echo "ffmpeg takes over").

And... it was media-ctl, sadly - I had hoped for ffmpeg, since I have used it a lot more.

I ended up reading through media-ctl --help to understand the error better. Apparently, device names or IDs were different here, too. To solve this, I went a way that did not require much thinking, working around my utter lack of knowledge and my not wanting to get out of bed: Just compiling Megapixels with meson and ninja right on the device. I had to install a lot of packages³ for that, but after successfully running

meson build && cd build
ninja

I could now run megapixels-list-devices which told me what I needed to do: Adjusting lines 30 and 31 was necessary: 3-003c and 3-004c had to be changed to 4-003c and 4-004c respectively.

Now, I could run the script with a simple ./record.sh test, but had forgot the way to skip recording to move on to ffmpeg (it's pressing q, as documented on the corresponding post on the Manjaro forums). I looked that up, and did again. After pressing q, ffmpeg did it's job, which took multiple minutes. I plugged my PinePhone into its power supply and went to take a shower.⁴

Results

While I won't share my 21 second long video (privacy, you know), here are some metrics:

-rw-r--r--    1 user     user      380.6M Sep 11 12:44 test.mkv
-rw-r--r--    1 user     user        7.2M Sep 11 13:15 test.webm

As you can see, video recording at 720p leads to quite large files quickly, and encoding, to free up storage, takes a lot of time. I think this could be improved by trying different encodings - x264 may be an option, as that has at least hardware support for accelerated decoding.

The result is quite okay. I think that adding a desktop file and maybe a minimal GUI (e.g. using yad) could bring this to a more user-friendly state rather quickly. But that's more than a simple sunday morning thing.

Other projects

There are more options to record video that may be better starting points (this is not a complete list, just the projects that I know of):

• Martijn Braam's original python-pinecamera script (a precursor to Megapixels),
• Adam Plumbs pinecam.

Conclusions

While the hardware is obviously limiting the use of video recording on the PinePhone, it's doable. Maybe this post inspires someone to take it on as a seperate project, or to integrate it into Megapixels. Maybe, you, dear reader, are the one to make it happen!

Update, 2023-10-03: A video recorded on PinePhone

While I have not looked into this since publishing this blog post, YouTube user Flax published a video which was actually recorded on PinePhone: Pinephone video recording - YouTube

Here's the script they came up with/used: record.sh - Pastebin.com

Update, 2023-10-09: A GUI for video recording

alaraajavamma has put together recent video recording scripts and asimple GUI for using them which you can find on GitLab. Great job!