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From: "Jörg Krause" <joerg.krause@embedded.rocks>
To: Clemens Ladisch <clemens@ladisch.de>, alsa-devel@alsa-project.org
Subject: Re: [PATCH] pcm: softvol: add support for S24_LE
Date: Tue, 12 Sep 2017 08:13:37 +0200	[thread overview]
Message-ID: <1505196817.26012.4.camel@embedded.rocks> (raw)
In-Reply-To: <720f5f32-9d90-35a5-ec4c-9b0af013f905@ladisch.de>

On Fri, 2017-09-08 at 12:52 +0200, Clemens Ladisch wrote:
> Jörg Krause wrote:
> > Tested with a Wolfson WM8524 DAC on a i.MX6UL board running Linux version
> > 4.13.0-next-20170907.
> > +	case SND_PCM_FORMAT_S24_LE:
> > +		/* 24bit samples, fallthrough */
> >  	case SND_PCM_FORMAT_S32_LE:
> 
> S24_LE cannot be handled with the same algorithm as S32_LE.

That would have been too easy.

> I suspect that the hardware does not actually use S24_LE, and
> that the driver uses the wrong label for this format.

Maybe you are right about that. I will have a look.

> Please describe exactly how the 24-bit sample is aligned into
> the 32-bit memory cell.

According to this old post [1] it is aligned as followed:

00ffff3f 00ffff3f 00ebd96e 00ebd96e 00ffff7f 00ffff7f
Meaning the left-most byte is zeroed, right?

[1] http://mailman.alsa-project.org/pipermail/alsa-devel/2008-July/0090
99.html

Best regards,
Jörg Krause
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  reply	other threads:[~2017-09-12  6:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-08 10:11 [PATCH] pcm: softvol: add support for S24_LE Jörg Krause
2017-09-08 10:52 ` Clemens Ladisch
2017-09-12  6:13   ` Jörg Krause [this message]
2017-09-12  6:19     ` Clemens Ladisch
2017-09-12  6:49       ` Jörg Krause
2017-09-12  7:02         ` Clemens Ladisch
2017-09-12  7:12           ` Takashi Iwai
2017-09-12 14:15             ` Jörg Krause
2017-09-12 14:32               ` Takashi Iwai
2017-09-12 14:53                 ` Takashi Sakamoto

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