From: Gerd Hoffmann <kraxel@redhat.com>
To: "Marc-André Lureau" <mlureau@redhat.com>
Cc: Martin Wilck <martin.wilck@ts.fujitsu.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] hda-codec: use smaller dynamic range for input amplifier
Date: Wed, 22 Apr 2015 08:37:24 +0200 [thread overview]
Message-ID: <1429684644.14806.27.camel@nilsson.home.kraxel.org> (raw)
In-Reply-To: <1646928490.3623689.1429636472739.JavaMail.zimbra@redhat.com>
Hi,
> > The "right" solution for this problem would be to implement
> > proper dB scaling in QEMU and the audio backends (such as spice).
Can we try this please?
> > While this clean solution is not available, I suggest to decrease
> > the dynamic range for the the emulated Amps in the QEMU hda codec.
> > Experiments showed that with 32dB dynamic range with a 0.5 dB step,
> > it was possible to set gain values as low as 5 (-29.5dB / 8%).
> > Actual HW seems to use similar ranges for input amplifiers.
> I am afraid guest OS won't like it the card description changes after a migration.
> This will likely need a new VMState field, for the steps, or the amp caps.
Correct. This is a guest-visible change, so we have to make this
runtime-switchable for compatibility with older qemu versions. This
quickly becomes a bit messy, so I'd prefer to avoid this.
cheers,
Gerd
next prev parent reply other threads:[~2015-04-22 6:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-20 14:37 [Qemu-devel] [RFC/PATCH] Bad volume scaling with Win7 guest, spice audio, and Qemu Intel HDA codec Wilck, Martin
2015-04-21 13:06 ` Marc-André Lureau
2015-04-21 16:50 ` [Qemu-devel] [PATCH] hda-codec: use smaller dynamic range for input amplifier Martin Wilck
2015-04-21 17:14 ` Marc-André Lureau
2015-04-22 6:37 ` Gerd Hoffmann [this message]
2015-04-22 8:01 ` Wilck, Martin
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