[a52] Strange behavior with 5.1 surround on ALC1220

GitHub issues - edited github at alsa-project.org
Wed May 5 09:01:07 CEST 2021


alsa-project/alsa-plugins issue #21 was edited from davidebeatrici:

I originally encountered the issue ~1 year ago, when I started using a motherboard with an ALC1120 on it.

The out-of-box experience was flawless: I simply connected the optical SPDIF cable to my amplifier/receiver and stereo sound immediately worked.

Once I switched to 5.1 surround, audio output became extremely fast; even videos were affected by it, to the point that they were being reproduced in seconds instead of minutes.

After a few days of research and experiments I managed to workaround the issue by replacing the content of `60-a52-encoder.conf` with:
```
pcm.a52 {
	@args [CARD]
	@args.CARD {
		type string
        }
	type rate
	slave {
		pcm {   
			type a52
			card $CARD
		}
		rate 48000
	}
}
pcm.pulse {
	type pulse
}
ctl.pulse {
	type pulse
}
pcm.!default {
	type pulse
}
ctl.!default {
	type pulse
}
```

Based on https://help.ubuntu.com/community/DigitalAC-3Pulseaudio#Configuring_asound.conf.

After that, I wanted to investigate the cause and report my findings to either ALSA or PulseAudio (depending on the results).

Unfortunately that never happened and I kinda forgot about it, as [libasound2-plugins](https://packages.debian.org/bullseye/libasound2-plugins) was updated a single time in the past year and thus I only had to replace the file's content once more.

Fast-forward to today: I switch from PulseAudio to PipeWire and while troubleshooting https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/1143 I decided to try to restore the original file.

Interestingly, the behavior is different compared to PulseAudio: audio, instead of being fast, is crackling. It's basically as if a frame every two is being skipped.

Unfortunately PipeWire reports no errors whatsoever.

Issue URL     : https://github.com/alsa-project/alsa-plugins/issues/21
Repository URL: https://github.com/alsa-project/alsa-plugins


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