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[Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes |
Date: |
Tue, 06 May 2008 19:59:03 +0200 |
User-agent: |
Thunderbird 2.0.0.12 (X11/20080226) |
malc wrote:
> On Mon, 5 May 2008, Jan Kiszka wrote:
>
>> malc wrote:
>>> On Sun, 4 May 2008, Jan Kiszka wrote:
>>>
>>>> Jan Kiszka wrote:
>>>>> malc wrote:
>>>>>> On Sun, 4 May 2008, Jan Kiszka wrote:
>>>>>>
>>>
>>> [..snip..]
>>>
>>>>>
>>>>> Yeah, great, that was the key! Find below the version that works
>>>>> for me
>>>>> (on 64 bit 8) ). It even obsoletes my buffer size patch. Please merge!
>>>>
>>>> Declaring the buffer size tweak obsolete was too quick. I still need
>>>> more under certain guest load, but now I'm already fine with
>>>> DEFAULT_BUFFER_SIZE=4096. Or all in one:
>>>
>>> I wonder if everyone will be happy with quadrupled latency, apart from
>>
>> Hmm, I wonder about the scenario where this latency may actually hurt.
>> QEMU is not /that/ fast anyway. ;)
>
> You would be surprised.
Tell me more! :->
>
>>
>>> you and this other user on some (kvm was it) mailing list there are no
>>> huge outcries of dissatisfaction, then again i'm not sure how many
>>> people
>>> use ALSA+QEMU or QEMUs+AUDIO in general.
>>
>> I don't think many users are actually running QEMU (or KVM) against
>> ALSA. You have to
>> - manually enable it during configure
>> - pass QEMU_AUDIO_DRV=alsa (OSS remains default even if ALSA is on - I
>> ran into this trap first.)
>
> I don't see how it's a trap. You can also enable esd or fmod drivers
> in configure along with alsa, which one should be the default?
For sure, you need this mechanism with >1 audio backends being enabled
in parallel. It's just the question how one is supposed to find out
about this additional requirement:
$ grep -r QEMU_AUDIO_DRV qemu
qemu/audio/audio.c: " set QEMU_AUDIO_DRV=wav\n"
qemu/audio/audio.c: " export QEMU_AUDIO_DRV=wav\n"
qemu/audio/audio.c: drvname = audio_get_conf_str ("QEMU_AUDIO_DRV",
NULL, &def);
Am I missing some reference? Then sorry in advance.
>
>> - possibly have to fix up your configuration with FIXED_FREQ and
>> BUFFER_SIZE (as reported by >1 kvm users) until
>>
>> As OSS does not give us shared sound device access and, in the end, is a
>> deprecated API under Linux, my goal is to overcome remaining issues of
>> the ALSA support and then make /this/ the default one (under Linux).
>>
>
> Huh? Even OSS/lite that is/was shipping with default Linux gave me
> "shared" sound, though i had a decent sound card with possibility to
> open the same /dev/dsp 16 times (it actually had 16 sigmatel chips on
> board). And the real OSS has vmix. And fwiw to have this wonderful
> "shared" sound you have to configure "dmix" (or whatever its called)
> too.
Well, probably configurable as well with compat-OSS (real OSS is dead on
Linux). The fact is that - not only for me - this sharing does not work
out-of-the-box with OSS, while it does with ALSA. Don't ask me why, I'm
not an expert on this, I'm rather looking at it from a "normal" user
perspective.
Jan
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- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, (continued)
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, malc, 2008/05/02
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, Jan Kiszka, 2008/05/02
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, malc, 2008/05/03
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, Jan Kiszka, 2008/05/04
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, malc, 2008/05/04
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, Jan Kiszka, 2008/05/04
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, Jan Kiszka, 2008/05/04
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, malc, 2008/05/05
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, Jan Kiszka, 2008/05/05
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, malc, 2008/05/06
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes,
Jan Kiszka <=
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, malc, 2008/05/07
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, Jan Kiszka, 2008/05/07
- [Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes, malc, 2008/05/08