David Rowe writes about open source radio and speech coding projects like Codec 2, plus home engineering projects such as an electric car.
Commenters point to it for Codec 2 as a low-bitrate voice option on devices like the ESP32, and one has followed the blog since 2008.
Can anyone confirm that there are toner cartridges that stop working after a set number of pages? I thought this only applied to inkjets. My (10 year old) laser printer will happily print until the pages become unreadable - and then some more and some more after shaking the toner cartridge.
I think an open source laser printer would be an insanely cool hardware project. Although probably not cost effective due to the complexity, at least you would know exactly why the paper jams occur!
But you never know, the IP0X open source hardware project has had great success with getting chinese manufacturers to produce affordable hardware: http://www.rowetel.com/blog/?page_id=440 some of which can compete with very expensive "mainstream" offerings.
> It would also be great to have this running on ESP32 or similar
ESP32 has its own port of the Codec2 library, which allows intelligible communications using very low bandwidth (a few kb/s). It could make the ideal solution for creating small cheap intercoms scattered around a small area using WiFi, or employing very low bandwidth radio connection such as LoRa for wider coverage. I still didn't see any real application, beside a few simple proof of concept videos on YouTube, though.
More info:
http://www.rowetel.com/?page_id=452
https://www.arduino.cc/reference/en/libraries/esp32_codec2/
I've been waiting for someone to do this* with audio and/or video. Amazing work.
Also worth reading this related link: https://www.rowetel.com/?p=6639
There's some really exciting progress that could be made in this space. The page mentions that they could use it as a post-processing filter for Opus for better decoding to avoid changing the bitstream. It could also be useful as a way to accommodate for packet loss and recover "just enough" to avoid interrupting the conversation.
* encoding audio through a neural network for network transmission
Aside from the seriously impressive WaveNet based results, I think the article doesn't do the codec itself enough justice.
I mean, low-bitrate speech codecs have been around for some time (hey, vocoders are the oldest kind of audio codecs in history!), and I grew skeptical when they started to compare with mp3 and opus.
But looking at this page Codec2 really holds its own when compared to AMBE and especially MELP, two of the most prominent ultra low-bandwidth speech codecs used today:
https://www.rowetel.com/?p=5520
Yeah, with Codec 2 setting the gold standard, I don't find this very impressive. I find this more intelligible at one-third of the Lyra bitrate:
http://www.rowetel.com/downloads/codec2/hts2a_1300.wav
Codec 2 does a better job of isolating the parts of sound which are most necessary to intelligible speech, without necessarily caring too much about preserving the original qualities of the speaker's voice or environment.
Fun fact: Codec 2 can be used to transmit voice over IRC:
https://github.com/asiekierka/voirc
I'm of the opinion that Codec 2 [0][1] should pause on trying to perform better at lower and lower bit rates, and put some work into higher ones.
Getting down to 700 and even 450 b/s is neat and all, but there seems (to me) to be a gap between 4000 and 10000 b/s in the patent-free space.
* [0] http://www.rowetel.com/?page_id=452
* [1] https://en.wikipedia.org/wiki/Codec_2