From 08547adb52080e6eddbdd7a0e9f6847859631d8a Mon Sep 17 00:00:00 2001
From: Oschowa <[EMAIL REDACTED]>
Date: Sat, 20 Feb 2021 09:28:03 +0100
Subject: [PATCH] pulseaudio: Add "zerocopy" playback path
---
src/audio/pulseaudio/SDL_pulseaudio.c | 22 ++++++++++++++++++++--
src/audio/pulseaudio/SDL_pulseaudio.h | 6 ++++++
2 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/src/audio/pulseaudio/SDL_pulseaudio.c b/src/audio/pulseaudio/SDL_pulseaudio.c
index eded4b6d1..25dba67d3 100644
--- a/src/audio/pulseaudio/SDL_pulseaudio.c
+++ b/src/audio/pulseaudio/SDL_pulseaudio.c
@@ -103,6 +103,8 @@ static int (*PULSEAUDIO_pa_stream_connect_record) (pa_stream *, const char *,
static pa_stream_state_t (*PULSEAUDIO_pa_stream_get_state) (pa_stream *);
static size_t (*PULSEAUDIO_pa_stream_writable_size) (pa_stream *);
static size_t (*PULSEAUDIO_pa_stream_readable_size) (pa_stream *);
+static int (*PULSEAUDIO_pa_stream_begin_write) (pa_stream *, void **, size_t*);
+static int (*PULSEAUDIO_pa_stream_cancel_write) (pa_stream *);
static int (*PULSEAUDIO_pa_stream_write) (pa_stream *, const void *, size_t,
pa_free_cb_t, int64_t, pa_seek_mode_t);
static pa_operation * (*PULSEAUDIO_pa_stream_drain) (pa_stream *,
@@ -216,6 +218,8 @@ load_pulseaudio_syms(void)
SDL_PULSEAUDIO_SYM(pa_stream_writable_size);
SDL_PULSEAUDIO_SYM(pa_stream_readable_size);
SDL_PULSEAUDIO_SYM(pa_stream_write);
+ SDL_PULSEAUDIO_SYM(pa_stream_begin_write);
+ SDL_PULSEAUDIO_SYM(pa_stream_cancel_write);
SDL_PULSEAUDIO_SYM(pa_stream_drain);
SDL_PULSEAUDIO_SYM(pa_stream_disconnect);
SDL_PULSEAUDIO_SYM(pa_stream_peek);
@@ -366,7 +370,7 @@ PULSEAUDIO_PlayDevice(_THIS)
/* Write the audio data */
struct SDL_PrivateAudioData *h = this->hidden;
if (SDL_AtomicGet(&this->enabled)) {
- if (PULSEAUDIO_pa_stream_write(h->stream, h->mixbuf, h->mixlen, NULL, 0LL, PA_SEEK_RELATIVE) < 0) {
+ if (PULSEAUDIO_pa_stream_write(h->stream, h->pabuf, h->mixlen, NULL, 0LL, PA_SEEK_RELATIVE) < 0) {
SDL_OpenedAudioDeviceDisconnected(this);
}
}
@@ -375,7 +379,21 @@ PULSEAUDIO_PlayDevice(_THIS)
static Uint8 *
PULSEAUDIO_GetDeviceBuf(_THIS)
{
- return (this->hidden->mixbuf);
+ struct SDL_PrivateAudioData *h = this->hidden;
+ size_t nbytes = h->mixlen;
+ int ret;
+
+ ret = PULSEAUDIO_pa_stream_begin_write(h->stream, &h->pabuf, &nbytes);
+
+ if (ret != 0) {
+ /* fall back it intermediate buffer */
+ h->pabuf = h->mixbuf;
+ } else if (nbytes < h->mixlen) {
+ PULSEAUDIO_pa_stream_cancel_write(h->stream);
+ h->pabuf = h->mixbuf;
+ }
+
+ return (Uint8 *)h->pabuf;
}
diff --git a/src/audio/pulseaudio/SDL_pulseaudio.h b/src/audio/pulseaudio/SDL_pulseaudio.h
index d06e62085..4b8755cfd 100644
--- a/src/audio/pulseaudio/SDL_pulseaudio.h
+++ b/src/audio/pulseaudio/SDL_pulseaudio.h
@@ -43,6 +43,12 @@ struct SDL_PrivateAudioData
Uint8 *mixbuf;
int mixlen;
+ /* Pointer to the actual buffer in use in the current
+ GetDeviceBuf() -> PlayDevice() iteration.
+ Can be either the pointer returned by pa_stream_begin_write()
+ or mixbuf */
+ void *pabuf;
+
const Uint8 *capturebuf;
int capturelen;
};