pulseaudio: Feed audio data in response to write callbacks.

Instead of waiting until the entire buffer from the SDL callback is ready
to be accepted by PulseAudio, we use pa_stream_set_write_callback and
feed some portion of the buffer as callbacks come in asking for more.

This lets us remove the halving of the buffer size during device open,
and also (hopefully) solves several strange hangs that happen in unusual
circumstances.

Fixes #4387
Fixes #2262
This commit is contained in:
Ryan C. Gordon 2022-04-26 13:14:15 -04:00
parent 01ef98a5d0
commit f6eb4b0759
No known key found for this signature in database
GPG key ID: FA148B892AB48044
2 changed files with 43 additions and 56 deletions

View file

@ -107,8 +107,6 @@ static int (*PULSEAUDIO_pa_stream_connect_record) (pa_stream *, const char *,
static pa_stream_state_t (*PULSEAUDIO_pa_stream_get_state) (const pa_stream *); static pa_stream_state_t (*PULSEAUDIO_pa_stream_get_state) (const pa_stream *);
static size_t (*PULSEAUDIO_pa_stream_writable_size) (const pa_stream *); static size_t (*PULSEAUDIO_pa_stream_writable_size) (const pa_stream *);
static size_t (*PULSEAUDIO_pa_stream_readable_size) (const pa_stream *); static size_t (*PULSEAUDIO_pa_stream_readable_size) (const 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, static int (*PULSEAUDIO_pa_stream_write) (pa_stream *, const void *, size_t,
pa_free_cb_t, int64_t, pa_seek_mode_t); pa_free_cb_t, int64_t, pa_seek_mode_t);
static pa_operation * (*PULSEAUDIO_pa_stream_drain) (pa_stream *, static pa_operation * (*PULSEAUDIO_pa_stream_drain) (pa_stream *,
@ -119,6 +117,7 @@ static pa_operation * (*PULSEAUDIO_pa_stream_flush) (pa_stream *,
pa_stream_success_cb_t, void *); pa_stream_success_cb_t, void *);
static int (*PULSEAUDIO_pa_stream_disconnect) (pa_stream *); static int (*PULSEAUDIO_pa_stream_disconnect) (pa_stream *);
static void (*PULSEAUDIO_pa_stream_unref) (pa_stream *); static void (*PULSEAUDIO_pa_stream_unref) (pa_stream *);
static void (*PULSEAUDIO_pa_stream_set_write_callback)(pa_stream *, pa_stream_request_cb_t, void *);
static int load_pulseaudio_syms(void); static int load_pulseaudio_syms(void);
@ -222,8 +221,6 @@ load_pulseaudio_syms(void)
SDL_PULSEAUDIO_SYM(pa_stream_writable_size); SDL_PULSEAUDIO_SYM(pa_stream_writable_size);
SDL_PULSEAUDIO_SYM(pa_stream_readable_size); SDL_PULSEAUDIO_SYM(pa_stream_readable_size);
SDL_PULSEAUDIO_SYM(pa_stream_write); 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_drain);
SDL_PULSEAUDIO_SYM(pa_stream_disconnect); SDL_PULSEAUDIO_SYM(pa_stream_disconnect);
SDL_PULSEAUDIO_SYM(pa_stream_peek); SDL_PULSEAUDIO_SYM(pa_stream_peek);
@ -232,6 +229,7 @@ load_pulseaudio_syms(void)
SDL_PULSEAUDIO_SYM(pa_stream_unref); SDL_PULSEAUDIO_SYM(pa_stream_unref);
SDL_PULSEAUDIO_SYM(pa_channel_map_init_auto); SDL_PULSEAUDIO_SYM(pa_channel_map_init_auto);
SDL_PULSEAUDIO_SYM(pa_strerror); SDL_PULSEAUDIO_SYM(pa_strerror);
SDL_PULSEAUDIO_SYM(pa_stream_set_write_callback);
return 0; return 0;
} }
@ -359,51 +357,56 @@ ConnectToPulseServer(pa_mainloop **_mainloop, pa_context **_context)
static void static void
PULSEAUDIO_WaitDevice(_THIS) PULSEAUDIO_WaitDevice(_THIS)
{ {
struct SDL_PrivateAudioData *h = this->hidden; /* this is a no-op; we wait in PULSEAUDIO_PlayDevice now. */
}
while (SDL_AtomicGet(&this->enabled)) { static void WriteCallback(pa_stream *p, size_t nbytes, void *userdata)
{
struct SDL_PrivateAudioData *h = (struct SDL_PrivateAudioData *) userdata;
/*printf("PULSEAUDIO WRITE CALLBACK! nbytes=%u\n", (unsigned int) nbytes);*/
h->bytes_requested += nbytes;
}
static void
PULSEAUDIO_PlayDevice(_THIS)
{
struct SDL_PrivateAudioData *h = this->hidden;
int available = h->mixlen;
int written = 0;
int cpy;
/*printf("PULSEAUDIO PLAYDEVICE START! mixlen=%d\n", available);*/
while (SDL_AtomicGet(&this->enabled) && (available > 0)) {
cpy = SDL_min(h->bytes_requested, available);
if (cpy) {
if (PULSEAUDIO_pa_stream_write(h->stream, h->mixbuf + written, cpy, NULL, 0LL, PA_SEEK_RELATIVE) < 0) {
SDL_OpenedAudioDeviceDisconnected(this);
return;
}
/*printf("PULSEAUDIO FEED! nbytes=%u\n", (unsigned int) cpy);*/
h->bytes_requested -= cpy;
written += cpy;
available -= cpy;
}
/* let WriteCallback fire if necessary. */
/*printf("PULSEAUDIO ITERATE!\n");*/
if (PULSEAUDIO_pa_context_get_state(h->context) != PA_CONTEXT_READY || if (PULSEAUDIO_pa_context_get_state(h->context) != PA_CONTEXT_READY ||
PULSEAUDIO_pa_stream_get_state(h->stream) != PA_STREAM_READY || PULSEAUDIO_pa_stream_get_state(h->stream) != PA_STREAM_READY ||
PULSEAUDIO_pa_mainloop_iterate(h->mainloop, 1, NULL) < 0) { PULSEAUDIO_pa_mainloop_iterate(h->mainloop, 1, NULL) < 0) {
SDL_OpenedAudioDeviceDisconnected(this); SDL_OpenedAudioDeviceDisconnected(this);
return; return;
} }
if (PULSEAUDIO_pa_stream_writable_size(h->stream) >= (h->mixlen/8)) {
return;
}
}
} }
static void /*printf("PULSEAUDIO PLAYDEVICE END! written=%d\n", written);*/
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->pabuf, h->mixlen, NULL, 0LL, PA_SEEK_RELATIVE) < 0) {
SDL_OpenedAudioDeviceDisconnected(this);
}
}
} }
static Uint8 * static Uint8 *
PULSEAUDIO_GetDeviceBuf(_THIS) PULSEAUDIO_GetDeviceBuf(_THIS)
{ {
struct SDL_PrivateAudioData *h = this->hidden; return this->hidden->mixbuf;
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;
} }
@ -604,9 +607,6 @@ PULSEAUDIO_OpenDevice(_THIS, const char *devname)
paspec.format = format; paspec.format = format;
/* Calculate the final parameters for this audio specification */ /* Calculate the final parameters for this audio specification */
#ifdef PA_STREAM_ADJUST_LATENCY
this->spec.samples /= 2; /* Mix in smaller chunck to avoid underruns */
#endif
SDL_CalculateAudioSpec(&this->spec); SDL_CalculateAudioSpec(&this->spec);
/* Allocate mixing buffer */ /* Allocate mixing buffer */
@ -623,22 +623,12 @@ PULSEAUDIO_OpenDevice(_THIS, const char *devname)
paspec.rate = this->spec.freq; paspec.rate = this->spec.freq;
/* Reduced prebuffering compared to the defaults. */ /* Reduced prebuffering compared to the defaults. */
#ifdef PA_STREAM_ADJUST_LATENCY
paattr.fragsize = this->spec.size; paattr.fragsize = this->spec.size;
/* 2x original requested bufsize */ paattr.tlength = h->mixlen;
paattr.tlength = h->mixlen * 4;
paattr.prebuf = -1; paattr.prebuf = -1;
paattr.maxlength = -1; paattr.maxlength = -1;
/* -1 can lead to pa_stream_writable_size() >= mixlen never being true */ paattr.minreq = -1;
paattr.minreq = h->mixlen; flags |= PA_STREAM_ADJUST_LATENCY;
flags = PA_STREAM_ADJUST_LATENCY;
#else
paattr.fragsize = this->spec.size;
paattr.tlength = h->mixlen*2;
paattr.prebuf = h->mixlen*2;
paattr.maxlength = h->mixlen*2;
paattr.minreq = h->mixlen;
#endif
if (ConnectToPulseServer(&h->mainloop, &h->context) < 0) { if (ConnectToPulseServer(&h->mainloop, &h->context) < 0) {
return SDL_SetError("Could not connect to PulseAudio server"); return SDL_SetError("Could not connect to PulseAudio server");
@ -675,6 +665,7 @@ PULSEAUDIO_OpenDevice(_THIS, const char *devname)
if (iscapture) { if (iscapture) {
rc = PULSEAUDIO_pa_stream_connect_record(h->stream, h->device_name, &paattr, flags); rc = PULSEAUDIO_pa_stream_connect_record(h->stream, h->device_name, &paattr, flags);
} else { } else {
PULSEAUDIO_pa_stream_set_write_callback(h->stream, WriteCallback, h);
rc = PULSEAUDIO_pa_stream_connect_playback(h->stream, h->device_name, &paattr, flags, NULL, NULL); rc = PULSEAUDIO_pa_stream_connect_playback(h->stream, h->device_name, &paattr, flags, NULL, NULL);
} }

View file

@ -43,11 +43,7 @@ struct SDL_PrivateAudioData
Uint8 *mixbuf; Uint8 *mixbuf;
int mixlen; int mixlen;
/* Pointer to the actual buffer in use in the current int bytes_requested; /* bytes of data the hardware wants _now_. */
GetDeviceBuf() -> PlayDevice() iteration.
Can be either the pointer returned by pa_stream_begin_write()
or mixbuf */
void *pabuf;
const Uint8 *capturebuf; const Uint8 *capturebuf;
int capturelen; int capturelen;