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Re: [fluid-dev] alsa audio driver only accepting huge period size
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From: |
la Fleur |
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Subject: |
Re: [fluid-dev] alsa audio driver only accepting huge period size |
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Date: |
Sat, 08 May 2021 18:03:37 +0200 |
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User-agent: |
Evolution 3.40.1 |
Sounds right - my phone's kernel sources (qcom-msm8916-5.12) have the same features. Is there a way I can workaround this hardware limitation using alsa's dmix ? I would go for JACK if it could help, but the same limitations seem to apply.
I find it quite ironic that everybody present pulseaudio as a non-professional audio system, but it's the only one that achieves low-latency in this case. I really wonder how pulseaudio manages to have a very low latency with the very same hardware. Any clue ?
I just spent hours looking for ways to achieve this using dmix. I tried this in `~/.asoundrc` :
pcm.mixed {
type dmix
ipc_key 1024
slave {
pcm "hw:0"
rate 48000
periods 24
period_size 256
buffer_size 1
}
}
But then `aplay -D plug:mixed /usr/share/sounds/alsa/Front_Center.wav` just plays half of the file. In fact any setting in `pcm.mixed` turns out the same.
Le vendredi 07 mai 2021 à 22:14 +0200, Marcus Weseloh a écrit :
Hi,
my guess is that it's a hardware limitation. It seems like your phone
is using the QTi LPass ASoC driver, which has a fixed number for
period size and periods:
.period_size_min = .period_size_max = LPASS_PLATFORM_BUFFER_SIZE /
LPASS_PLATFORM_PERIODS
So that's 24 * 1024 = 24576. And if you divide that by 4 bytes (max
32bit resolution), you get 6144. Seems to fit.
Cheers
Marcus
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