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[patch] Improve WASAPI audio backend latency

WASAPI_PERIOD.patch (text/plain), 2.26 KB, created by Anthony Pesch on 2019-04-12 04:48:50 UTC

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Creator: Anthony Pesch

Created: 2019-04-12 04:48:50 UTC

Size: 2.26 KB

patch

obsolete

>diff --git a/src/audio/wasapi/SDL_wasapi.c b/src/audio/wasapi/SDL_wasapi.c
>index b7c8dda5..b47abd37 100644
>--- a/src/audio/wasapi/SDL_wasapi.c
>+++ b/src/audio/wasapi/SDL_wasapi.c
>@@ -523,7 +523,7 @@ WASAPI_PrepDevice(_THIS, const SDL_bool updatestream)
>     const SDL_AudioSpec oldspec = this->spec;
>     const AUDCLNT_SHAREMODE sharemode = AUDCLNT_SHAREMODE_SHARED;
>     UINT32 bufsize = 0;  /* this is in sample frames, not samples, not bytes. */
>-    REFERENCE_TIME duration = 0;
>+    REFERENCE_TIME default_period = 0;
>     IAudioClient *client = this->hidden->client;
>     IAudioRenderClient *render = NULL;
>     IAudioCaptureClient *capture = NULL;
>@@ -587,7 +587,7 @@ WASAPI_PrepDevice(_THIS, const SDL_bool updatestream)
>         return SDL_SetError("WASAPI: Unsupported audio format");
>     }
> 
>-    ret = IAudioClient_GetDevicePeriod(client, NULL, &duration);
>+    ret = IAudioClient_GetDevicePeriod(client, &default_period, NULL);
>     if (FAILED(ret)) {
>         return WIN_SetErrorFromHRESULT("WASAPI can't determine minimum device period", ret);
>     }
>@@ -606,7 +606,7 @@ WASAPI_PrepDevice(_THIS, const SDL_bool updatestream)
>     }
> 
>     streamflags |= AUDCLNT_STREAMFLAGS_EVENTCALLBACK;
>-    ret = IAudioClient_Initialize(client, sharemode, streamflags, duration, sharemode == AUDCLNT_SHAREMODE_SHARED ? 0 : duration, waveformat, NULL);
>+    ret = IAudioClient_Initialize(client, sharemode, streamflags, 0, 0, waveformat, NULL);
>     if (FAILED(ret)) {
>         return WIN_SetErrorFromHRESULT("WASAPI can't initialize audio client", ret);
>     }
>@@ -621,10 +621,11 @@ WASAPI_PrepDevice(_THIS, const SDL_bool updatestream)
>         return WIN_SetErrorFromHRESULT("WASAPI can't determine buffer size", ret);
>     }
> 
>-    this->spec.samples = (Uint16) bufsize;
>-    if (!this->iscapture) {
>-        this->spec.samples /= 2;  /* fill half of the DMA buffer on each run. */
>-    }
>+    /* Match the callback size to the period size to cut down on the number of
>+       interrupts waited for in each call to WaitDevice */
>+    float period_millis = default_period / 10000.0f;
>+    float period_frames = period_millis * this->spec.freq / 1000.0f;
>+    this->spec.samples = (Uint16)ceil(period_frames);
> 
>     /* Update the fragment size as size in bytes */
>     SDL_CalculateAudioSpec(&this->spec);

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We are currently migrating Bugzilla to GitHub issues.Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.

We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.