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Re: [Qemu-devel] [PATCH 16/25] audio: add mixeng option (documentation)
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 16/25] audio: add mixeng option (documentation) |
Date: |
Mon, 26 Aug 2019 08:35:57 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 8/25/19 1:46 PM, Kővágó, Zoltán wrote:
> This will allow us to disable mixeng when we use a decent backend.
>
> Disabling mixeng have a few advantages:
> * we no longer convert the audio output from one format to another, when
> the underlying audio system would just convert it to a third format.
> We no longer convert, only the underlying system, when needed.
> * the underlying system probably has better resampling and sample format
> converting methods anyway...
> * we may support formats that the mixeng currently does not support (S24
> or float samples, more than two channels)
> * when using an audio server (like pulseaudio) different sound card
> outputs will show up as separate streams, even if we use only one
> backend
>
> Disadvantages:
> * audio capturing no longer works (wavcapture, and vnc audio extension)
> * some backends only support a single playback stream or very picky
> about the audio format. In this case we can't disable mixeng.
>
> However mixeng is not removed, only made optional, so this shouldn't be
> a big concern.
>
> Signed-off-by: Kővágó, Zoltán <address@hidden>
> ---
> qapi/audio.json | 5 +++++
> qemu-options.hx | 6 ++++++
> 2 files changed, 11 insertions(+)
>
> diff --git a/qapi/audio.json b/qapi/audio.json
> index 9fefdf5186..dc7f9cb1e2 100644
> --- a/qapi/audio.json
> +++ b/qapi/audio.json
> @@ -11,6 +11,10 @@
> # General audio backend options that are used for both playback and
> # recording.
> #
> +# @mixeng: use QEMU's mixing engine to mix all streams inside QEMU. When set
> to
> +# off, fixed-settings must be also off. Not every backend compatible
> +# with the off setting (default on, since 4.2)
> +#
'mixeng' looks like an accidental typo, when 3 words later is 'mixing'.
Would 'mix-eng' or 'mix-engine' be more obvious?
> ##
> { 'struct': 'AudiodevPerDirectionOptions',
> 'data': {
> + '*mixeng': 'bool',
> '*fixed-settings': 'bool',
And the very next member is an example that QAPI doesn't have to use
abbreviations.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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- [Qemu-devel] [PATCH 02/25] alsaaudio: port to the new audio backend api, (continued)
- [Qemu-devel] [PATCH 02/25] alsaaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 05/25] noaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 04/25] dsoundaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 06/25] ossaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 08/25] sdlaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 10/25] wavaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 07/25] paaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 11/25] audio: remove remains of the old backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 13/25] audio: remove hw->samples, buffer_size_in/out pcm_ops, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 16/25] audio: add mixeng option (documentation), Kővágó, Zoltán, 2019/08/25
- Re: [Qemu-devel] [PATCH 16/25] audio: add mixeng option (documentation),
Eric Blake <=
- [Qemu-devel] [PATCH 17/25] audio: make mixeng optional, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 12/25] audio: unify input and output mixeng buffer management, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 14/25] audio: common rate control code for timer based outputs, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 15/25] audio: split ctl_* functions into enable_* and volume_*, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 19/25] audio: support more than two channels in volume setting, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 21/25] audio: basic support for multichannel audio, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 23/25] usb-audio: do not count on avail bytes actually available, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 20/25] audio: replace shift in audio_pcm_info with bytes_per_frame, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 25/25] usbaudio: change playback counters to 64 bit, Kővágó, Zoltán, 2019/08/25