Mpxgen/MiniRDS no output

[BlackBeard]

Hello folks,

I installed MiniRDS (the RDS encoder from mpxgen) on an Orange Pi Zero 3 (Allwinner H618). OS is Debian 11/Bullseye with the 5.4 kernel. Sadly, I can't output RDS. Tried different OSses as well as a Realtek ALC5686 USB-soundcard. The playback on that sound card stutters, so I stuck to the orange pi zero extension board/it's internal analogue audio output. Sample rate is definetely set to 192kHz - I checked that using pacmd list-sinks.

Does anyone have an idea what I'm doing wrong? The program itself is running, the deps are installed. Maybe the extension board/orange pi's audio output can't sample up to 192kHz?

Thanks for your help!

[tvtv]

Some cards have output filtering. Can’t say if that’s your issue, but try a usb to headphone socket, I got one for less than a tenner and the rate goes above 300, also try turning up your exciter volume till rds lights up on radio, then reset your levels either audio on the pc

[BlackBeard]

Thanks tvtv,

I analyzed the output with my spectrum analyzer so the output of one channel definetely goes til 96kHz. I gave up the OrangePi and switched to an old HP mini-PC. I also have one of the 32bits/384kHz USB-Soundcards but this one only stuttered on my OrangePi. I'm using the OPi now for something else

[BlackBeard]

I got myself a Pi Zero 2 W, a PCM5102 sound card (hifiberry) and thought to give it a try again.

The Pi plays audio without any issues using ffplay.

Mpxgen also generates RDS without any issues.

Just when I try to start mpxgen with an audio file or try to pipe some audio using ffmpeg, I get a weird, noisy, extremely stuttering sound that I normally only know from sound card (e.g. 2 apps using the same card) or sample rate problems (sample rate conversion). I also gave the Orange Pi Zero 3 a try again using Debian Bookworm server with the 6.1 kernel - but no luck. Tried 2 different sound cards that definetely have a sample rate of 192kHz. Interestingly, I faced the exact same issues on the Orange Pi.

This is the command I used (thanks g33ky!):
ffmpeg -i A01.wav -af "lowpass=f=15000" -f wav - | ./mpxgen --audio - --ps PLAYBACK

[teckniqs]

There is a programme called JMPX which works very well on the R-PI

https://github.com/jontio/JMPX

[BlackBeard]

There is a programme called JMPX which works very well on the R-PI

https://github.com/jontio/JMPX

Thanks teckniqs! I know JMPX very well, did my first RDS-experiments with it many years ago. I'd like something for linux that has a CLI/doesn't require a GUI, does dynamic PS and ideally doesn't take up too many system resources. Like this, you could could easily remote control the whole system using SSH, a mobile 4g dongle & dyndns.

Mpxgen would be ideal but simply doesn't work (only RDS) - tried it now on multiple systems with multiple 192kHz sound cards.

I'm experimenting with GnuRadio/gr-rds rn and it works pretty well from the CLI (you can export the flowgraph to a python file)! I just found that my RPi Zero 2 W and my Orange Pi Zero 3 are both too weak for that solution. Luckily, I still have a few HP 260 G2 DMs (mini PCs) laying around that will hopefully do the job. I already prepared a post for Radionecks explaining how to set up everything in detail that I'll upload soon. Will be running a headless debian 12.