Petter Reinholdtsen

Entries from April 2022.

geteltorito make CD firmware upgrades a breeze
20th April 2022

Recently I wanted to upgrade the firmware of my thinkpad, and located the firmware download page from Lenovo (which annoyingly do not allow access via Tor, forcing me to hand them more personal information that I would like). The download from Lenovo is a bootable ISO image, which is a bit of a problem when all I got available is a USB memory stick. I tried booting the ISO as a USB stick, but this did not work. But genisoimage came to the rescue.

The geteltorito program in the genisoimage binary package is able to convert the bootable ISO image to a bootable USB stick using a simple command line recipe, which I then can write to the most recently inserted USB stick:

geteltorito -o usbstick.img lenovo-firmware.iso
sudo dd bs=10M if=usbstick.img of=$(ls -tr /dev/sd?|tail -1)

This USB stick booted the firmware upgrader just fine, and in a few minutes my machine had the latest and greatest BIOS firmware in place.

Tags: debian, english.
Playing and encoding AV1 in Debian Bullseye
16th April 2022

Inspired by the recent news of AV1 hardware encoding support from Intel, I decided to look into the state of AV1 on Linux today. AV1 is a free and open standard as defined by Digistan without any royalty payment requirement, unlike its much used competitor encoding H.264. While looking, I came across an 5 year old question on which in turn inspired me to check out how things are in Debian Stable regarding AV1. The test file listed in the question (askubuntu_test_aom.mp4) did not exist any more, so I tracked down a different set of test files on to test them with the various video tools I had installed on my machine. I was happy to discover that AV1 decoding and playback worked with almost every tool I tested:

mediainfo ok
dragonplayer ok
ffmpeg / ffplay ok
gnome-mplayer fail
mplayer ok
mpv ok
parole ok
vlc ok
firefox ok
chromium ok

AV1 encoding is available in Debian Stable from the aom-tools version 1.0.0.errata1-3 package, using the aomenc tool. The encoding using the package in Debian Stable is quite slow, with the frame rate for my 10 second test video at around 0.25 fps. My 10 second video test took 16 minutes and 11 seconds on my test machine.

I tested by first running ffmpeg and then aomenc using the recipe provided by the askubuntu recipe above. I had to remove the '--row-mt=1' option, as it was not supported in my 1.0.0 version. The encoding only used a single thread, according to top.

ffmpeg -i some-old-video.ogv -t 10 -pix_fmt yuv420p video.y4m
aomenc --fps=24/1 -u 0 --codec=av1 --target-bitrate=1000 \
  --lag-in-frames=25 --auto-alt-ref=1 -t 24 --cpu-used=8 \
  --tile-columns=2 --tile-rows=2 -o output.webm video.y4m

As version 1.0.0 currently have several unsolved security issues in Debian Stable, and to see if the recent backport provided in Debian is any quicker, I ran apt -t bullseye-backports install aom-tools to fetch the backported version and re-encoded the video using the latest version. This time the '--row-mt=1' option worked, and the encoding was done in 46 seconds with a frame rate of around 5.22 fps. This time it seem to be using all my four cores to encode. Encoding speed is still too low for streaming and real time, which would require frame rates above 25 fps, but might be good enough for offline encoding.

I am very happy to see AV1 playback working so well with the default tools in Debian Stable. I hope the encoding situation improve too, allowing even a slow old computer like my 10 year old laptop to be used for encoding.

As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

Tags: english, standard, video.

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