USB Audio w GeneralPlus chip

[yavuzg]

I'm experimenting on a CM4 (Raspberry Pi 4 Compute Module) setup with the standard IO module, using the VGA666 along with a VGA-to-SCART adapter (sync combiner) to get the new 8.0 Beta connected to a CRT.

So far, I successfully get 240p on the CRT. The ES menus, the sample games etc displaying fine.

I'm using a USB audio adapter to get sound out of the pi, since the CM4 and the IO module do not have a barrel jack analog audio out option to be connected to SCART.

However, I cannot get sound out of my USB audio adapter (which apperantly show as GeneralPlus tech on lsusb).

I've configured the order in asound.conf as follows;

pcm.!default { type hw card 2 } ctl.!default { type hw card 2 }

0 and 1 are vc4-hdmi-0 and vc4-hdmi-1 (the two HDMI ports on the IO module). The "2" is the snd_usb_audio (our guy).

This brings up the USB audio adapter as default (according to alsamixer).

The HDMI sound/music is fine (before the CRT configuration) but I can only get static from the USB audio device (no audio on TV via SCART or on headphone attached via barrel jack on the device)

The USB audio device however works on regular Windows PC...

I've spent the whole day to get this thing going but I gave up, after trying all the scenarios and rebooting the pi may be 50 times.

Conclusion; This USB audio adapter (with GeneralPlus chip) does not work on recalbox beta 8 (yet?)

Anybody has a suggestion? or Anybody knows any usb audio adapter which works?

Thx

[Zing]

@yavuzg

Anybody has a suggestion?

1st Check the wiki and confirm that you haven't forgotten to configure anything:
https://wiki.recalbox.com/en/tutorials/video/crt

8.0 Beta

2nd If it doesn't work, post your problem in the specific topic of BETA 8 to make it easier for developers to see:
https://forum.recalbox.com/topic/25351/recalbox-8-0-beta

[yavuzg]

8.0 Beta seems taking care of the CRT part smootly. Most of the CRT configuration is already in place which the wiki suggests. Some info in the wiki is irrelevant though (I guess they'll be udated with the official release of 8.0)

Anyway, the CRT & 240p are working fine...

Before posting this as an issue I've checked the Alsaproject site which mainly related with my problem. There they have listed the USB sound adapters they support.

https://www.alsa-project.org/wiki/Matrix:Main

Apperantly my USB audio adapter chip/manufacturer (GeneralPlus) is not listed there. (I should have guessed, it was no-name and the price was little over a dollar )

I decided to buy another one, a waveshare (c-media) branded one (hopefully the chip inside turns out to be officially supported by alsa) and update this topic...

Thanks...

[yavuzg]

Update:

Purchased a Waveshare USB to Audio device...

It worked without any issues

Additionally, just letting you know, Waveshare device fits perfectly to my cabinet setup since it can drive the speakers directly and the audio quality is clean and loud.

Reminder, do not connect the output of that device directly to SCART or head-phone jacks since its amplifier chip is, by default, configured in "bridge-tied load" mode. Which mean its output level is too high for devices accepting line-in level audio.

So anyone looking for an "line-out" level USB audio, that device is not the right thing for you (unless you open it up and hack the PCB to change the operation mode of the APA2068KAI-TRG chip to SE (single-end) and accomodate a line-out jack.

Cheers...