Commit 9ed01da70161d3650e6e5bb557a565c7b2ba9f9e
2021-03-02T09:47:47
audio: pipewire: Constify and clarify period size calculations Constify the min/max period variables, use a #define for the base clock rate used in the calculations and note that changing the upper limit can have dire side effects as it's a hard limit in Pipewire.
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diff --git a/src/audio/pipewire/SDL_pipewire.c b/src/audio/pipewire/SDL_pipewire.c
index 9d26650..1f298da 100644
--- a/src/audio/pipewire/SDL_pipewire.c
+++ b/src/audio/pipewire/SDL_pipewire.c
@@ -34,9 +34,13 @@
/*
* These seem to be sane limits as Pipewire
* uses them in several of it's own modules.
+ *
+ * NOTE: 8192 is a hard upper limit in Pipewire and
+ * increasing this value can lead to buffer overflows.
*/
-#define PW_MIN_SAMPLES 32 /* About 0.67ms at 48kHz */
-#define PW_MAX_SAMPLES 8192 /* About 170.6ms at 48kHz */
+#define PW_MIN_SAMPLES 32 /* About 0.67ms at 48kHz */
+#define PW_MAX_SAMPLES 8192 /* About 170.6ms at 48kHz */
+#define PW_BASE_CLOCK_RATE 48000
#define PW_POD_BUFFER_LENGTH 1024
#define PW_THREAD_NAME_BUFFER_LENGTH 128
@@ -1009,10 +1013,13 @@ PIPEWIRE_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
struct pw_properties * props;
const char * stream_name, *stream_role;
const Uint32 node_id = this->handle == NULL ? PW_ID_ANY : PW_HANDLE_TO_ID(this->handle);
- int min_period, adjusted_samples;
enum pw_stream_state state;
int res;
+ /* Clamp the period size to sane values */
+ const int min_period = PW_MIN_SAMPLES * SPA_MAX(this->spec.freq / PW_BASE_CLOCK_RATE, 1);
+ const int adjusted_samples = SPA_CLAMP(this->spec.samples, min_period, PW_MAX_SAMPLES);
+
/* Get the hints for the stream name and role */
stream_name = SDL_GetHint(SDL_HINT_AUDIO_DEVICE_STREAM_NAME);
if (!stream_name || *stream_name == '\0') {
@@ -1035,10 +1042,6 @@ PIPEWIRE_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
return SDL_SetError("Pipewire: Failed to set audio format parameters");
}
- /* Clamp the sample count to sane values */
- min_period = PW_MIN_SAMPLES * SPA_MAX(this->spec.freq / 48000, 1);
- adjusted_samples = SPA_CLAMP(this->spec.samples, min_period, PW_MAX_SAMPLES);
-
if ((this->hidden = priv = SDL_calloc(1, sizeof(struct SDL_PrivateAudioData))) == NULL) {
return SDL_OutOfMemory();
}