paaudio: limit minreq to 75% of audio timer_rate

Currently with the playback buffer attribute minreq = -1 and flag
PA_STREAM_EARLY_REQUESTS PulseAudio uses minreq = tlength / 4.
To improve audio playback with larger PulseAudio server side
buffers, limit minreq to a maximum of 75% of audio timer_rate.
That way there is a good chance qemu receives a stream buffer
size update before it tries to write data to the playback stream.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 9315afe5-5958-c0b4-ea1e-14769511a9d5@t-online.de
Message-Id: <20210110100239.27588-18-vr_qemu@t-online.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/audio/paaudio.c b/audio/paaudio.c
index ff3dd01c96ddd3a49555ab63ad860d9a18f38658..3186868294282307eb89738039e45b392438240b 100644 (file)
--- a/audio/paaudio.c
+++ b/audio/paaudio.c
@@ -517,7 +517,8 @@ static int qpa_init_out(HWVoiceOut *hw, struct audsettings *as,
     ss.rate = as->freq;
 
     ba.tlength = pa_usec_to_bytes(ppdo->latency, &ss);
-    ba.minreq = -1;
+    ba.minreq = pa_usec_to_bytes(MIN(ppdo->latency >> 2,
+                                     (g->dev->timer_period >> 2) * 3), &ss);
     ba.maxlength = -1;
     ba.prebuf = -1;