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Cleanly switch between audio recording, playback, and both, on iOS
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@slouken
slouken committed Apr 15, 2020
1 parent 14661d3 commit a990a34
Showing 1 changed file with 90 additions and 16 deletions.
106 changes: 90 additions & 16 deletions src/audio/coreaudio/SDL_coreaudio.m
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Expand Up @@ -280,11 +280,47 @@
#endif


static int open_playback_devices = 0;
static int open_capture_devices = 0;
static int open_playback_devices;
static int open_capture_devices;
static int num_open_devices;
static SDL_AudioDevice **open_devices;

#if !MACOSX_COREAUDIO

static BOOL session_active = NO;

static void pause_audio_devices()
{
int i;

if (!open_devices) {
return;
}

for (i = 0; i < num_open_devices; ++i) {
SDL_AudioDevice *device = open_devices[i];
if (device->hidden->audioQueue && !device->hidden->interrupted) {
AudioQueuePause(device->hidden->audioQueue);
}
}
}

static void resume_audio_devices()
{
int i;

if (!open_devices) {
return;
}

for (i = 0; i < num_open_devices; ++i) {
SDL_AudioDevice *device = open_devices[i];
if (device->hidden->audioQueue && !device->hidden->interrupted) {
AudioQueueStart(device->hidden->audioQueue, NULL);
}
}
}

static void interruption_begin(_THIS)
{
if (this != NULL && this->hidden->audioQueue != NULL) {
Expand Down Expand Up @@ -379,9 +415,18 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
options |= AVAudioSessionCategoryOptionAllowBluetoothA2DP |
AVAudioSessionCategoryOptionAllowAirPlay;
}
if (category == AVAudioSessionCategoryPlayback ||
category == AVAudioSessionCategoryPlayAndRecord) {
options |= AVAudioSessionCategoryOptionDuckOthers;
}

if ([session respondsToSelector:@selector(setCategory:mode:options:error:)]) {
if (![session.category isEqualToString:category] || session.categoryOptions != options) {
/* Stop the current session so we don't interrupt other application audio */
pause_audio_devices();
[session setActive:NO error:nil];
session_active = NO;

if (![session setCategory:category mode:mode options:options error:&err]) {
NSString *desc = err.description;
SDL_SetError("Could not set Audio Session category: %s", desc.UTF8String);
Expand All @@ -390,6 +435,11 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
}
} else {
if (![session.category isEqualToString:category]) {
/* Stop the current session so we don't interrupt other application audio */
pause_audio_devices();
[session setActive:NO error:nil];
session_active = NO;

if (![session setCategory:category error:&err]) {
NSString *desc = err.description;
SDL_SetError("Could not set Audio Session category: %s", desc.UTF8String);
Expand All @@ -398,7 +448,7 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
}
}

if (open && (open_playback_devices + open_capture_devices) == 1) {
if ((open_playback_devices || open_capture_devices) && !session_active) {
if (![session setActive:YES error:&err]) {
if ([err code] == AVAudioSessionErrorCodeResourceNotAvailable &&
category == AVAudioSessionCategoryPlayAndRecord) {
Expand All @@ -409,8 +459,12 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
SDL_SetError("Could not activate Audio Session: %s", desc.UTF8String);
return NO;
}
} else if (!open_playback_devices && !open_capture_devices) {
session_active = YES;
resume_audio_devices();
} else if (!open_playback_devices && !open_capture_devices && session_active) {
pause_audio_devices();
[session setActive:NO error:nil];
session_active = NO;
}

if (open) {
Expand Down Expand Up @@ -438,14 +492,12 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec

this->hidden->interruption_listener = CFBridgingRetain(listener);
} else {
if (this->hidden->interruption_listener != NULL) {
SDLInterruptionListener *listener = nil;
listener = (SDLInterruptionListener *) CFBridgingRelease(this->hidden->interruption_listener);
[center removeObserver:listener];
@synchronized (listener) {
listener.device = NULL;
}
}
SDLInterruptionListener *listener = nil;
listener = (SDLInterruptionListener *) CFBridgingRelease(this->hidden->interruption_listener);
[center removeObserver:listener];
@synchronized (listener) {
listener.device = NULL;
}
}
}

Expand All @@ -471,7 +523,7 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
Uint8 *ptr = (Uint8 *) inBuffer->mAudioData;

while (remaining > 0) {
if ( SDL_AudioStreamAvailable(this->stream) == 0 ) {
if (SDL_AudioStreamAvailable(this->stream) == 0) {
/* Generate the data */
SDL_LockMutex(this->mixer_lock);
(*this->callbackspec.callback)(this->callbackspec.userdata,
Expand All @@ -480,10 +532,10 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
this->hidden->bufferOffset = 0;
SDL_AudioStreamPut(this->stream, this->hidden->buffer, this->hidden->bufferSize);
}
if ( SDL_AudioStreamAvailable(this->stream) > 0 ) {
if (SDL_AudioStreamAvailable(this->stream) > 0) {
int got;
UInt32 len = SDL_AudioStreamAvailable(this->stream);
if ( len > remaining )
if (len > remaining)
len = remaining;
got = SDL_AudioStreamGet(this->stream, ptr, len);
SDL_assert((got < 0) || (got == len));
Expand Down Expand Up @@ -529,7 +581,7 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
static void
inputCallback(void *inUserData, AudioQueueRef inAQ, AudioQueueBufferRef inBuffer,
const AudioTimeStamp *inStartTime, UInt32 inNumberPacketDescriptions,
const AudioStreamPacketDescription *inPacketDescs )
const AudioStreamPacketDescription *inPacketDescs)
{
SDL_AudioDevice *this = (SDL_AudioDevice *) inUserData;

Expand Down Expand Up @@ -619,6 +671,7 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
COREAUDIO_CloseDevice(_THIS)
{
const SDL_bool iscapture = this->iscapture;
int i;

/* !!! FIXME: what does iOS do when a bluetooth audio device vanishes? Headphones unplugged? */
/* !!! FIXME: (we only do a "default" device on iOS right now...can we do more?) */
Expand All @@ -638,6 +691,20 @@ static BOOL update_audio_session(_THIS, SDL_bool open, SDL_bool allow_playandrec
update_audio_session(this, SDL_FALSE, SDL_TRUE);
#endif

for (i = 0; i < num_open_devices; ++i) {
if (open_devices[i] == this) {
--num_open_devices;
if (i < num_open_devices) {
SDL_memmove(&open_devices[i], &open_devices[i+1], sizeof(open_devices[i])*(num_open_devices - i));
}
break;
}
}
if (num_open_devices == 0) {
SDL_free(open_devices);
open_devices = NULL;
}

/* if callback fires again, feed silence; don't call into the app. */
SDL_AtomicSet(&this->paused, 1);

Expand Down Expand Up @@ -942,6 +1009,7 @@ output device (in which case we'll try again). */
AudioStreamBasicDescription *strdesc;
SDL_AudioFormat test_format = SDL_FirstAudioFormat(this->spec.format);
int valid_datatype = 0;
SDL_AudioDevice **new_open_devices;

/* Initialize all variables that we clean on shutdown */
this->hidden = (struct SDL_PrivateAudioData *)
Expand All @@ -959,6 +1027,12 @@ output device (in which case we'll try again). */
open_playback_devices++;
}

new_open_devices = (SDL_AudioDevice **)SDL_realloc(open_devices, sizeof(open_devices[0]) * (num_open_devices + 1));
if (new_open_devices) {
open_devices = new_open_devices;
open_devices[num_open_devices++] = this;
}

#if !MACOSX_COREAUDIO
if (!update_audio_session(this, SDL_TRUE, SDL_TRUE)) {
return -1;
Expand Down

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