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![Volker Rümelin](/assets/img/avatar_default.png)
The combined generic buffer management code and buffer run out code in function audio_generic_put_buffer_out has a problematic behaviour. A few hundred milliseconds after playback starts the mixing buffer and the generic buffer are nearly full and the following pattern can be seen. On first call of audio_pcm_hw_run_out the buffer run code in audio_generic_put_buffer_out writes some data to the audio hardware but the generic buffer will fill faster and is full when audio_pcm_hw_run_out returns. This is because emulated audio devices can produce playback data at a higher rate than the audio backend hardware consumes this data. On next call of audio_pcm_hw_run_out the buffer run code in audio_generic_put_buffer_out writes some data to the audio hardware but no audio data is transferred to the generic buffer because the buffer is already full. Then the pattern repeats. For the emulated audio device this looks like the audio timer period has doubled. This patch splits the combined generic buffer management code and buffer run out code and calls the buffer run out code after buffer management code to break this pattern. The bug report is for the wav audio backend. But the problem is not limited to this backend. All audio backends which use the audio_generic_put_buffer_out function show this problem. Buglink: https://bugs.launchpad.net/qemu/+bug/1858488 Signed-off-by: Volker Rümelin <vr_qemu@t-online.de> Message-Id: <20200123074943.6699-5-vr_qemu@t-online.de> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
148 lines
3.8 KiB
C
148 lines
3.8 KiB
C
/*
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* QEMU Timer based audio emulation
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*
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* Copyright (c) 2004-2005 Vassili Karpov (malc)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include "qemu/host-utils.h"
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#include "qemu/module.h"
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#include "audio.h"
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#include "qemu/timer.h"
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#define AUDIO_CAP "noaudio"
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#include "audio_int.h"
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typedef struct NoVoiceOut {
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HWVoiceOut hw;
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RateCtl rate;
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} NoVoiceOut;
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typedef struct NoVoiceIn {
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HWVoiceIn hw;
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RateCtl rate;
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} NoVoiceIn;
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static size_t no_write(HWVoiceOut *hw, void *buf, size_t len)
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{
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NoVoiceOut *no = (NoVoiceOut *) hw;
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return audio_rate_get_bytes(&hw->info, &no->rate, len);
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}
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static int no_init_out(HWVoiceOut *hw, struct audsettings *as, void *drv_opaque)
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{
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NoVoiceOut *no = (NoVoiceOut *) hw;
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audio_pcm_init_info (&hw->info, as);
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hw->samples = 1024;
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audio_rate_start(&no->rate);
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return 0;
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}
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static void no_fini_out (HWVoiceOut *hw)
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{
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(void) hw;
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}
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static void no_enable_out(HWVoiceOut *hw, bool enable)
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{
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NoVoiceOut *no = (NoVoiceOut *) hw;
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if (enable) {
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audio_rate_start(&no->rate);
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}
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}
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static int no_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
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{
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NoVoiceIn *no = (NoVoiceIn *) hw;
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audio_pcm_init_info (&hw->info, as);
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hw->samples = 1024;
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audio_rate_start(&no->rate);
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return 0;
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}
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static void no_fini_in (HWVoiceIn *hw)
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{
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(void) hw;
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}
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static size_t no_read(HWVoiceIn *hw, void *buf, size_t size)
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{
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NoVoiceIn *no = (NoVoiceIn *) hw;
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int64_t bytes = audio_rate_get_bytes(&hw->info, &no->rate, size);
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audio_pcm_info_clear_buf(&hw->info, buf, bytes / hw->info.bytes_per_frame);
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return bytes;
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}
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static void no_enable_in(HWVoiceIn *hw, bool enable)
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{
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NoVoiceIn *no = (NoVoiceIn *) hw;
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if (enable) {
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audio_rate_start(&no->rate);
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}
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}
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static void *no_audio_init(Audiodev *dev)
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{
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return &no_audio_init;
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}
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static void no_audio_fini (void *opaque)
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{
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(void) opaque;
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}
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static struct audio_pcm_ops no_pcm_ops = {
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.init_out = no_init_out,
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.fini_out = no_fini_out,
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.write = no_write,
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.run_buffer_out = audio_generic_run_buffer_out,
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.enable_out = no_enable_out,
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.init_in = no_init_in,
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.fini_in = no_fini_in,
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.read = no_read,
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.enable_in = no_enable_in
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};
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static struct audio_driver no_audio_driver = {
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.name = "none",
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.descr = "Timer based audio emulation",
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.init = no_audio_init,
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.fini = no_audio_fini,
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.pcm_ops = &no_pcm_ops,
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.can_be_default = 1,
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.max_voices_out = INT_MAX,
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.max_voices_in = INT_MAX,
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.voice_size_out = sizeof (NoVoiceOut),
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.voice_size_in = sizeof (NoVoiceIn)
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};
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static void register_audio_none(void)
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{
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audio_driver_register(&no_audio_driver);
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}
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type_init(register_audio_none);
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