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Make volume control more thread safe.

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This change makes a copy of the master volume factor before applying it
so that if another thread changes the volume it won't apply the change
part way through the processing of a period.
This commit is contained in:
David Reid
2020-02-13 17:29:16 +10:00
parent 578496e237
commit c67175c3ea
1 changed files with 13 additions and 12 deletions
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miniaudio.h
+13 -12
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@@ -3007,8 +3007,8 @@ struct ma_device
ma_device_type type;
ma_uint32 sampleRate;
volatile ma_uint32 state; /* The state of the device is variable and can change at any time on any thread, so tell the compiler as such with `volatile`. */
ma_device_callback_proc onData;
ma_stop_proc onStop;
ma_device_callback_proc onData; /* Set once at initialization time and should not be changed after. */
ma_stop_proc onStop; /* Set once at initialization time and should not be changed after. */
void* pUserData; /* Application defined data. */
ma_mutex lock;
ma_event wakeupEvent;
@@ -3022,7 +3022,7 @@ struct ma_device
ma_bool32 isOwnerOfContext : 1; /* When set to true, uninitializing the device will also uninitialize the context. Set to true when NULL is passed into ma_device_init(). */
ma_bool32 noPreZeroedOutputBuffer : 1;
ma_bool32 noClip : 1;
float masterVolumeFactor;
volatile float masterVolumeFactor; /* Volatile so we can use some thread safety when applying volume to periods. */
struct
{
ma_resample_algorithm algorithm;
@@ -7329,16 +7329,17 @@ float ma_gain_db_to_factor(float gain)
static void ma_device__on_data(ma_device* pDevice, void* pFramesOut, const void* pFramesIn, ma_uint32 frameCount)
{
ma_device_callback_proc onData;
float masterVolumeFactor;
masterVolumeFactor = pDevice->masterVolumeFactor;
onData = pDevice->onData;
if (onData) {
if (pDevice->onData) {
if (!pDevice->noPreZeroedOutputBuffer && pFramesOut != NULL) {
ma_zero_pcm_frames(pFramesOut, frameCount, pDevice->playback.format, pDevice->playback.channels);
}
/* Volume control of input makes things a bit awkward because the input buffer is read-only. We'll need to use a temp buffer and loop in this case. */
if (pFramesIn != NULL && pDevice->masterVolumeFactor < 1) {
if (pFramesIn != NULL && masterVolumeFactor < 1) {
ma_uint8 tempFramesIn[MA_DATA_CONVERTER_STACK_BUFFER_SIZE];
ma_uint32 bpfCapture = ma_get_bytes_per_frame(pDevice->capture.format, pDevice->capture.channels);
ma_uint32 bpfPlayback = ma_get_bytes_per_frame(pDevice->playback.format, pDevice->playback.channels);
@@ -7349,21 +7350,21 @@ static void ma_device__on_data(ma_device* pDevice, void* pFramesOut, const void*
framesToProcessThisIteration = sizeof(tempFramesIn)/bpfCapture;
}
ma_copy_and_apply_volume_factor_pcm_frames(tempFramesIn, ma_offset_ptr(pFramesIn, totalFramesProcessed*bpfCapture), framesToProcessThisIteration, pDevice->capture.format, pDevice->capture.channels, pDevice->masterVolumeFactor);
ma_copy_and_apply_volume_factor_pcm_frames(tempFramesIn, ma_offset_ptr(pFramesIn, totalFramesProcessed*bpfCapture), framesToProcessThisIteration, pDevice->capture.format, pDevice->capture.channels, masterVolumeFactor);
onData(pDevice, ma_offset_ptr(pFramesOut, totalFramesProcessed*bpfPlayback), tempFramesIn, framesToProcessThisIteration);
pDevice->onData(pDevice, ma_offset_ptr(pFramesOut, totalFramesProcessed*bpfPlayback), tempFramesIn, framesToProcessThisIteration);
totalFramesProcessed += framesToProcessThisIteration;
}
} else {
onData(pDevice, pFramesOut, pFramesIn, frameCount);
pDevice->onData(pDevice, pFramesOut, pFramesIn, frameCount);
}
/* Volume control and clipping for playback devices. */
if (pFramesOut != NULL) {
if (pDevice->masterVolumeFactor < 1) {
if (masterVolumeFactor < 1) {
if (pFramesIn == NULL) { /* <-- In full-duplex situations, the volume will have been applied to the input samples before the data callback. Applying it again post-callback will incorrectly compound it. */
ma_apply_volume_factor_pcm_frames(pFramesOut, frameCount, pDevice->playback.format, pDevice->playback.channels, pDevice->masterVolumeFactor);
ma_apply_volume_factor_pcm_frames(pFramesOut, frameCount, pDevice->playback.format, pDevice->playback.channels, masterVolumeFactor);
}
}