Simple Directmedia Layer
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Sam Lantinga 723d014336 Fixed bug 4171 - SDL_GetQueuedAudioSize is broken with WASAPI
Cameron Gutman

I was trying to use SDL_GetQueuedAudioSize() to ensure my audio latency didn't get too high while streaming data in from the network. If I get more than N frames of audio queued, I know that the network is giving me more data than I can play and I need to drop some to keep latency low.

This doesn't work well on WASAPI out of the box, due to the addition of GetPendingBytes() to the amount of queued data. As a terrible hack, I loop 100 times calling SDL_Delay(10) and SDL_GetQueuedAudioSize() before I ever call SDL_QueueAudio() to get a "baseline" amount that I then subtract from SDL_GetQueuedAudioSize() later. However, because this value isn't actually a constant, this hack can cause SDL_GetQueuedAudioSize() - baselineSize to be < 0. This means I have no accurate way of determining how much data is actually queued in SDL's audio buffer queue.

The SDL_GetQueuedAudioSize() documentation says: "This is the number of bytes that have been queued for playback with SDL_QueueAudio(), but have not yet been sent to the hardware." Yet, SDL_GetQueuedAudioSize() returns > 0 value when SDL_QueueAudio() has never been called.

Based on that documentation, I believe the current behavior contradicts the documented behavior of this function and should be changed in line with Boris's patch.

I understand that exposing the IAudioClient::GetCurrentPadding() value is useful, but a solution there needs to take into account what of that data is silence inserted by SDL and what is actual data queued by the user with SDL_QueueAudio(). Until that happens, I think the best approach is to remove the GetPendingBytes() call until SDL is able to keep track of queued data to make sense of it. This would make SDL_GetQueuedAudioSize() possible to use accurately with WASAPI.
2019-06-04 17:32:15 -07:00
acinclude Added missing PKG_CONFIG macros 2019-03-16 17:39:15 -07:00
android-project Fixed hiding the Android virtual keyboard when the return key is pressed 2019-05-23 11:05:43 -07:00
android-project-ant Added the old ant Android build project structure 2017-10-28 12:11:25 -07:00
build-scripts Updated minimum supported Android version to API 16, to match latest NDK toolchain 2019-01-12 12:11:06 -08:00
cmake mir: Removed mir client support. 2018-11-02 21:34:17 -04:00
debian Updated copyright for 2019 2019-01-04 22:01:14 -08:00
docs Android: add hint SDL_HINT_ANDROID_BLOCK_ON_PAUSE 2019-04-05 09:16:30 +02:00
include test: unify all the command line usage logging. 2019-05-28 17:39:13 -04:00
src Fixed bug 4171 - SDL_GetQueuedAudioSize is broken with WASAPI 2019-06-04 17:32:15 -07:00
test test: unify all the command line usage logging. 2019-05-28 17:39:13 -04:00
VisualC Fixed Visual Studio build 2019-03-16 19:46:37 -07:00
VisualC-WinRT Added display event files to the Visual Studio projects 2018-08-23 02:48:47 -07:00
visualtest test: unify all the command line usage logging. 2019-05-28 17:39:13 -04:00
wayland-protocols wayland: ask xdg-decoration protocol extension to use server-side decorations if possible. 2018-11-04 21:08:40 +01:00
Xcode Added support for building SDL as a dynamic library on iOS 2019-03-19 07:53:33 -07:00
Xcode-iOS Created Xcode schemes for building on iOS and tvOS 2019-04-23 14:08:09 -07:00
.hgignore First pass on the new SDL sensor API 2018-08-21 12:11:34 -07:00
Android.mk Initial Android OpenSL ES implementation, contributed by ANTA 2019-01-12 12:18:44 -08:00
autogen.sh Don't use pushd/popd in autogen.sh; Ubuntu's /bin/sh doesn't support it. 2016-12-26 22:58:58 -05:00
BUGS.txt BUGS.txt: Changed mailing list link to discourse.libsdl.org. 2017-04-01 00:05:25 -04:00
cmake_uninstall.cmake.in Fixed bug 3867 - Can't find install_manifest.txt when running 'uninstall' target 2017-10-12 08:44:45 -07:00
CMakeLists.txt Fixed bug 4639 - CMake build does not generate libhidapi.so for Android 2019-05-21 17:33:31 -07:00
configure Use _Exit() when available 2019-04-23 07:59:31 -07:00
configure.ac Use _Exit() when available 2019-04-23 07:59:31 -07:00
COPYING.txt Updated copyright for 2019 2019-01-04 22:01:14 -08:00
CREDITS.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
INSTALL.txt More HTTPS doc tweaks. 2017-02-16 16:59:07 -05:00
Makefile.in Add a configure option allowing users to choose whether to install sdl2-config 2019-04-07 23:01:07 +10:00
Makefile.minimal Added a dummy sensor driver 2018-08-21 13:29:21 -07:00
Makefile.os2 minor update to Makefile.os2, added a test/Makefile.os2. 2018-11-20 10:55:00 +03:00
Makefile.pandora Added a dummy sensor driver 2018-08-21 13:29:21 -07:00
Makefile.psp Added a dummy sensor driver 2018-08-21 13:29:21 -07:00
Makefile.wiz Added a dummy sensor driver 2018-08-21 13:29:21 -07:00
README-SDL.txt More HTTPS changes in the documentation. 2017-02-16 16:52:03 -05:00
README.txt readme: correct webpage URL to use HTTPS. 2017-02-16 13:30:34 -05:00
sdl2-config.cmake.in Applied Ubuntu patch bug_822210_fix_sdl2-config.cmake_whitespace.patch 2016-10-07 15:08:37 -07:00
sdl2-config.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
sdl2.m4 Fixed bug 4544 - SDL2.m4 SDL2.framework patch made it impossible to fail detection 2019-03-16 18:45:10 -07:00
sdl2.pc.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
SDL2.spec.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
SDL2Config.cmake Fixed bug 3651 - CMake build does not install CMake package configuration 2017-08-09 19:03:10 -07:00
TODO.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
VisualC.html Fixed two typos in documentation. 2016-01-12 22:23:53 +01:00
WhatsNew.txt Android: add hint SDL_HINT_ANDROID_BLOCK_ON_PAUSE 2019-04-05 09:16:30 +02:00

                         Simple DirectMedia Layer

                                  (SDL)

                                Version 2.0

---
https://www.libsdl.org/

Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.

More extensive documentation is available in the docs directory, starting
with README.md

Enjoy!
	Sam Lantinga				(slouken@libsdl.org)