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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `SDL_DequeueAudio` fn in crate `sdl2_sys`."><meta name="keywords" content="rust, rustlang, rust-lang, SDL_DequeueAudio"><title>sdl2_sys::SDL_DequeueAudio - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../dark.css"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script src="../storage.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="shortcut icon" href="../favicon.ico"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></head><body class="rustdoc fn"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../sdl2_sys/index.html'><div class='logo-container'><img src='../rust-logo.png' alt='logo'></div></a><div class="sidebar-elems"><p class='location'><a href='index.html'>sdl2_sys</a></p><script>window.sidebarCurrent = {name: 'SDL_DequeueAudio', ty: 'fn', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" disabled autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../src/sdl2_sys/Users/travis/build/Rust-SDL2/rust-sdl2/target/debug/build/sdl2-sys-f32779682524d647/out/sdl_bindings.rs.html#3446-3447' title='goto source code'>[src]</a></span><span class='in-band'>Function <a href='index.html'>sdl2_sys</a>::<wbr><a class="fn" href=''>SDL_DequeueAudio</a></span></h1><pre class='rust fn'>pub unsafe extern "C" fn SDL_DequeueAudio(<br> dev: <a class="type" href="../sdl2_sys/type.SDL_AudioDeviceID.html" title="type sdl2_sys::SDL_AudioDeviceID">SDL_AudioDeviceID</a>, <br> data: *mut <a class="enum" href="https://doc.rust-lang.org/nightly/core/ffi/enum.c_void.html" title="enum core::ffi::c_void">c_void</a>, <br> len: <a class="type" href="../sdl2_sys/type.Uint32.html" title="type sdl2_sys::Uint32">Uint32</a><br>) -> <a class="type" href="../sdl2_sys/type.Uint32.html" title="type sdl2_sys::Uint32">Uint32</a></pre><div class='docblock'><p>Dequeue more audio on non-callback devices.</p>
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<p>(If you are looking to queue audio for output on a non-callback playback
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device, you want SDL_QueueAudio() instead. This will always return 0
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if you use it with playback devices.)</p>
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<p>SDL offers two ways to retrieve audio from a capture device: you can
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either supply a callback that SDL triggers with some frequency as the
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device records more audio data, (push method), or you can supply no
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callback, and then SDL will expect you to retrieve data at regular
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intervals (pull method) with this function.</p>
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<p>There are no limits on the amount of data you can queue, short of
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exhaustion of address space. Data from the device will keep queuing as
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necessary without further intervention from you. This means you will
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eventually run out of memory if you aren't routinely dequeueing data.</p>
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<p>Capture devices will not queue data when paused; if you are expecting
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to not need captured audio for some length of time, use
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SDL_PauseAudioDevice() to stop the capture device from queueing more
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data. This can be useful during, say, level loading times. When
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unpaused, capture devices will start queueing data from that point,
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having flushed any capturable data available while paused.</p>
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<p>This function is thread-safe, but dequeueing from the same device from
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two threads at once does not promise which thread will dequeued data
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first.</p>
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<p>You may not dequeue audio from a device that is using an
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application-supplied callback; doing so returns an error. You have to use
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the audio callback, or dequeue audio with this function, but not both.</p>
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<p>You should not call SDL_LockAudio() on the device before queueing; SDL
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handles locking internally for this function.</p>
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<p>\param dev The device ID from which we will dequeue audio.
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\param data A pointer into where audio data should be copied.
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\param len The number of bytes (not samples!) to which (data) points.
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\return number of bytes dequeued, which could be less than requested.</p>
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<p>\sa SDL_GetQueuedAudioSize
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\sa SDL_ClearQueuedAudio</p>
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