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From: "Volker Rümelin" <vr_qemu@t-online.de>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: QEMU <qemu-devel@nongnu.org>, "Zoltán Kővágó" <dirty.ice.hu@gmail.com>
Subject: [PATCH 13/23] paaudio: avoid to clip samples multiple times
Date: Sun, 10 Jan 2021 11:02:29 +0100
Message-ID: <20210110100239.27588-13-vr_qemu@t-online.de> (raw)
In-Reply-To: <9315afe5-5958-c0b4-ea1e-14769511a9d5@t-online.de>

The pulseaudio backend currently converts, clips and copies audio
playback samples in the mixing-engine sample buffer multiple
times.

In qpa_get_buffer_out() the function pa_stream_begin_write()
returns a rather large buffer and this allows audio_pcm_hw_run_out()
in audio/audio.c to copy all samples in the mixing-engine buffer
to the pulse audio buffer. Immediately after copying, qpa_write()
notices with a call to pa_stream_writable_size() that pulse audio
only needs a smaller part of the copied samples and ignores the
rest. This copy and ignore process happens several times for each
audio sample.

To fix this behaviour, call pa_stream_writable_size() in
qpa_get_buffer_out() to limit the number of samples
audio_pcm_hw_run_out() will convert. With this change the
pulseaudio pcm_ops functions put_buffer_out and write are no
longer identical and a separate qpa_put_buffer_out is needed.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
---
 audio/paaudio.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/audio/paaudio.c b/audio/paaudio.c
index b052084698..229bcfcae8 100644
--- a/audio/paaudio.c
+++ b/audio/paaudio.c
@@ -207,6 +207,7 @@ static void *qpa_get_buffer_out(HWVoiceOut *hw, size_t *size)
     PAVoiceOut *p = (PAVoiceOut *) hw;
     PAConnection *c = p->g->conn;
     void *ret;
+    size_t l;
     int r;
 
     pa_threaded_mainloop_lock(c->mainloop);
@@ -214,12 +215,19 @@ static void *qpa_get_buffer_out(HWVoiceOut *hw, size_t *size)
     CHECK_DEAD_GOTO(c, p->stream, unlock_and_fail,
                     "pa_threaded_mainloop_lock failed\n");
 
+    l = pa_stream_writable_size(p->stream);
+    CHECK_SUCCESS_GOTO(c, l != (size_t) -1, unlock_and_fail,
+                       "pa_stream_writable_size failed\n");
+
     *size = -1;
     r = pa_stream_begin_write(p->stream, &ret, size);
     CHECK_SUCCESS_GOTO(c, r >= 0, unlock_and_fail,
                        "pa_stream_begin_write failed\n");
 
     pa_threaded_mainloop_unlock(c->mainloop);
+    if (*size > l) {
+        *size = l;
+    }
     return ret;
 
 unlock_and_fail:
@@ -228,6 +236,28 @@ unlock_and_fail:
     return NULL;
 }
 
+static size_t qpa_put_buffer_out(HWVoiceOut *hw, void *data, size_t length)
+{
+    PAVoiceOut *p = (PAVoiceOut *)hw;
+    PAConnection *c = p->g->conn;
+    int r;
+
+    pa_threaded_mainloop_lock(c->mainloop);
+
+    CHECK_DEAD_GOTO(c, p->stream, unlock_and_fail,
+                    "pa_threaded_mainloop_lock failed\n");
+
+    r = pa_stream_write(p->stream, data, length, NULL, 0LL, PA_SEEK_RELATIVE);
+    CHECK_SUCCESS_GOTO(c, r >= 0, unlock_and_fail, "pa_stream_write failed\n");
+
+    pa_threaded_mainloop_unlock(c->mainloop);
+    return length;
+
+unlock_and_fail:
+    pa_threaded_mainloop_unlock(c->mainloop);
+    return 0;
+}
+
 static size_t qpa_write(HWVoiceOut *hw, void *data, size_t length)
 {
     PAVoiceOut *p = (PAVoiceOut *) hw;
@@ -861,7 +891,7 @@ static struct audio_pcm_ops qpa_pcm_ops = {
     .fini_out = qpa_fini_out,
     .write    = qpa_write,
     .get_buffer_out = qpa_get_buffer_out,
-    .put_buffer_out = qpa_write, /* pa handles it */
+    .put_buffer_out = qpa_put_buffer_out,
     .volume_out = qpa_volume_out,
 
     .init_in  = qpa_init_in,
-- 
2.26.2



  parent reply index

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 ` Volker Rümelin [this message]
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

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