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Bug 2835

Summary: Audio Latency - Artificial buffer limit of 1/4 second.
Product: SDL Reporter: Jon Olick <zelexi>
Component: audioAssignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 Keywords: triage-2.0.4
Version: 2.0.3   
Hardware: x86_64   
OS: Windows 8   

Description Jon Olick 2015-01-07 01:05:50 UTC 
Turns out in the code there is an artificial mimimum audio buffer size of a quarter second. This is a pretty significant amount of latency, especially in VR. Removing the minimum was an easy fix for this.

--- a/deps/sdl2-2.0.3/src/audio/winmm/SDL_winmm.c
+++ b/deps/sdl2-2.0.3/src/audio/winmm/SDL_winmm.c
@@ -280,8 +280,8 @@ WINMM_OpenDevice(_THIS, const char *devname, int iscapture)
         this->spec.channels = 2;        /* !!! FIXME: is this right? */

     /* Check the buffer size -- minimum of 1/4 second (word aligned) */
-    if (this->spec.samples < (this->spec.freq / 4))
-        this->spec.samples = ((this->spec.freq / 4) + 3) & ~3;
+    //if (this->spec.samples < (this->spec.freq / 4))
+    //    this->spec.samples = ((this->spec.freq / 4) + 3) & ~3;

     while ((!valid_datatype) && (test_format)) {
         switch (test_format) {
Comment 1 Ryan C. Gordon 2015-02-19 06:32:14 UTC 
Marking a large number of bugs with the "triage-2.0.4" keyword at once. Sorry
if you got a lot of email from this. This is to help me sort through some bugs
in regards to a 2.0.4 release. We may or may not fix this bug for 2.0.4,
though!
Comment 2 Ryan C. Gordon 2015-03-24 06:13:41 UTC 
This patch is now https://hg.libsdl.org/SDL/rev/eb1bde345c4b, thanks!

--ryan.