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From: Gerd Hoffmann <kraxel@redhat.com>
To: "Volker Rümelin" <vr_qemu@t-online.de>
Cc: "Zoltán Kővágó" <dirty.ice.hu@gmail.com>,
	"Markus Armbruster" <armbru@redhat.com>,
	qemu-devel@nongnu.org
Subject: Re: [PATCH 00/23] next round of audio patches
Date: Thu, 14 Jan 2021 15:36:01 +0100	[thread overview]
Message-ID: <20210114143601.et3x5z3mcpmc467l@sirius.home.kraxel.org> (raw)
In-Reply-To: <9315afe5-5958-c0b4-ea1e-14769511a9d5@t-online.de>

On Sun, Jan 10, 2021 at 11:01:29AM +0100, Volker Rümelin wrote:
> A mix of bug fixes and improvements.
> 
> Patches 01/23 - 11/23 have a few SDL fixes and add audio recording
> functions to the SDL audio backend.
> 
> Patch 12/23 removes unnecessary code from audio/audio.c.
> 
> Patches 13/23 - 16/23 fix a few PulseAudio backend bugs.
> 
> Patch 17/23 shows a PulseAudio backend bug. So far I don't think I
> broke any fine tuned user settings and I don't want to do it here.
> 
> Patches 18/23 - 19/23 are the first steps towards glitch free and
> lower latency PulseAudio playback and recording. Currently qemu
> uses incredibly large buffers in the PulseAudio backend. For
> playback this just increases the playback latency but doesn't
> improve dropout safety, because PulseAudio can't access this buffer
> directly. With these patches it's possible to move the large qemu
> buffer to the PulseAudio server side and just keep a small buffer
> on the qemu side. On the PulseAudio server side PulseAudio tries
> to place a part of these buffers directly on the hardware and
> PulseAudio runs with a higher priority than qemu, so it has a
> better chance to deliver audio data in time.
> 
> Here is an example to show how this works:
> -device intel-hda -device hda-duplex,audiodev=audio0
> -machine pcspk-audiodev=audio0 -audiodev pa,id=audio0,
> out.buffer-length=14000,out.latency=46440,in.latency=46440
> 
> Due to a bug in the PulseAudio backend, these command line options
> actually decrease the playback latency compared to current defaults.
> For playback with defaults (16 bits, stereo, 44100 samples/s)
> we have a 15ms server side buffer + 2 * 46.44ms qemu audio buffer
> + 23.22ms hda codec buffer = 131.1ms latency. With my example it's
> 46.44ms + 2 * 14ms + 23.22ms = 97.66ms latency and I guess you
> won't hear any drop outs. Btw.: 14ms = 10ms timer-period + 4ms
> additional playback data the hda codec can produce in timer-period
> time.
> 
> Patches 20/23 - 23/23 fix small issues with DirectSound.

Nice overall improvements.  Some minor nits (see replies to some
patches).  Can be fixed incrementally though, so I'll do some more
testing and if nothing blows up queue the series for merge.

thanks,
  Gerd



      parent reply	other threads:[~2021-01-14 14:37 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-10 10:01 [PATCH 00/23] next round of audio patches Volker Rümelin
2021-01-10 10:02 ` [PATCH 01/23] sdlaudio: remove leftover SDL1.2 code Volker Rümelin
2021-01-14 15:28   ` Thomas Huth
2021-01-10 10:02 ` [PATCH 02/23] audio: fix bit-rotted code Volker Rümelin
2021-01-14 14:32   ` Gerd Hoffmann
2021-01-31 17:13     ` Volker Rümelin
2021-01-10 10:02 ` [PATCH 03/23] sdlaudio: add -audiodev sdl,out.buffer-count option Volker Rümelin
2021-01-14 14:27   ` [PATCH 03/23] sdlaudio: add -audiodev sdl, out.buffer-count option Gerd Hoffmann
2021-01-31 17:30     ` Volker Rümelin
2021-01-15  8:39   ` Markus Armbruster
2021-01-10 10:02 ` [PATCH 04/23] sdlaudio: don't start playback in init routine Volker Rümelin
2021-01-15  6:28   ` Thomas Huth
2021-01-10 10:02 ` [PATCH 05/23] sdlaudio: always clear the sample buffer Volker Rümelin
2021-01-15  6:31   ` Thomas Huth
2021-01-10 10:02 ` [PATCH 06/23] sdlaudio: fill remaining sample buffer with silence Volker Rümelin
2021-01-14 16:58   ` Thomas Huth
2021-01-17  9:41     ` Volker Rümelin
2021-01-10 10:02 ` [PATCH 07/23] sdlaudio: replace legacy functions with modern ones Volker Rümelin
2021-01-15  7:04   ` Thomas Huth
2021-01-10 10:02 ` [PATCH 08/23] audio: split pcm_ops function get_buffer_in Volker Rümelin
2021-01-10 10:02 ` [PATCH 09/23] sdlaudio: add recording functions Volker Rümelin
2021-01-10 10:02 ` [PATCH 10/23] audio: break generic buffer dependency on mixing-engine Volker Rümelin
2021-01-10 10:02 ` [PATCH 11/23] sdlaudio: enable (in|out).mixing-engine=off Volker Rümelin
2021-01-10 10:02 ` [PATCH 12/23] audio: remove remaining unused plive code Volker Rümelin
2021-01-10 10:02 ` [PATCH 13/23] paaudio: avoid to clip samples multiple times Volker Rümelin
2021-01-10 10:02 ` [PATCH 14/23] paaudio: wait for PA_STREAM_READY in qpa_write() Volker Rümelin
2021-01-10 10:02 ` [PATCH 15/23] paaudio: wait until the playback stream is ready Volker Rümelin
2021-01-10 10:02 ` [PATCH 16/23] paaudio: remove unneeded code Volker Rümelin
2021-01-10 10:02 ` [PATCH 17/23] paaudio: comment bugs in functions qpa_init_* Volker Rümelin
2021-01-10 10:02 ` [PATCH 18/23] paaudio: limit minreq to 75% of audio timer_rate Volker Rümelin
2021-01-10 10:02 ` [PATCH 19/23] paaudio: send recorded data in smaller chunks Volker Rümelin
2021-01-10 10:02 ` [PATCH 20/23] dsoundaudio: replace GetForegroundWindow() Volker Rümelin
2021-01-10 10:02 ` [PATCH 21/23] dsoundaudio: rename dsound_open() Volker Rümelin
2021-01-10 10:02 ` [PATCH 22/23] dsoundaudio: enable f32 audio sample format Volker Rümelin
2021-01-10 10:02 ` [PATCH 23/23] dsoundaudio: fix log message Volker Rümelin
2021-01-10 10:24 ` [PATCH 00/23] next round of audio patches no-reply
2021-01-10 23:09   ` Volker Rümelin
2021-01-14 14:36 ` Gerd Hoffmann [this message]

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