Core audio clock api

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Streams may be half duplex input or output or full duplex simultaneous input and output. PortAudio usually tries to translate error conditions into portable PaError error codes. To use Audio Queue Services, you first create an audio queue object—of which there are two flavors, although both have the data type AudioQueueRef. There are many such identifiers available in Audio File Services that let you obtain metadata that may be in a file, such as region markers, copyright information, and playback tempo. The later sections in this chapter introduce you to how Core Audio works with files, streams, recording and playback, and plug-ins. The other way—typically used for property listeners—is by using a dedicated function call, as you will see later in this section. Proper configuration, even by the best audio developers, needs tons of spaghetti code, and you need to handle many events as well. When a VBR file is long—say, a podcast—obtaining the entire packet table can take a significant amount of time. Audio Session Programming Guide provides details and code examples.

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  • objective c How to use Core Audio's Clock API Stack Overflow
  • Core Audio Essentials
  • Superpowered iOS Audio Output without using RemoteIO Audio Unit

  • The answer is that there is almost no documentation, and the only reference I found was an Apple list serv stating that it's not a fully developed.

    Video: Core audio clock api DO YOU NEED A WORDCLOCK IN YOUR STUDIO? - Black Lion Audio MK III XB word clock - review

    I'm trying to use the CoreAudio api to setup sound playback. I'm not using any of the fancy stuff like AudioUnits or AudioQueues.

    Antelope Audio Digital clarity Analog warmth

    I just get a. Provides an overview of Core Audio and its programming interfaces.
    You can start and stop the clock yourself, or you can set the clock to activate or deactivate in response to certain events. The iOS audio units are:. Listing shows one way you might implement a property listener callback function to respond to property changes in a playback audio queue object.

    objective c How to use Core Audio's Clock API Stack Overflow

    It is unique in that it can contain any audio data format supported on a platform. For these formats, the value of the mBitsPerChannel member is 0. You cannot connect a single output to more than one input unless you use an intervening splitter unit, as shown in Figure

    images core audio clock api
    To play multiple sounds simultaneously, create one playback audio queue object for each sound.

    PortAudio supports all the major native audio APIs on each supported platform. In iOS, audio units provide the mechanism for applications to achieve low-latency input and output.

    images core audio clock api

    If you know that you will use a sound only once—for example, in the case of a startup sound—you can destroy the sound ID object immediately after playing the sound, freeing memory.

    In this role, an audio unit has its own user interface, or view. The canonical representation is in seconds, expressed as a double-precision floating point value.

    Video: Core audio clock api Learn Core Audio

    These notifications let you respond to changes in the larger audio environment—such as an interruption due to in an incoming phone call—gracefully.

    These API services in the audio system are presented in frameworks. A Figure illustrates the core audio architecture on Mac OS X and its various. Specifically, an Audio Device represents a single I/O cycle, a clock. Hardware Abstraction Layer (HAL) Services Music Player API Core MIDI Services and MIDI Server Services Core Audio Clock API.

    PortAudio provides a uniform interface to native audio APIs.

    Core Audio Essentials

    Some examples of Host APIs are Core Audio on Mac OS, WMME and DirectSound on Windows and OSS. All times are measured in seconds relative to a Stream-specific clock.
    At the same time, it gives you an array of AudioStreamPacketDescription structures that describes each of those packets.

    Besides letting you work with the basics—unique file ID, file type, and data format—Audio File Services lets you work with regions and markers, looping, playback direction, SMPTE time code, and more.

    In CBR and VBR formats that is, in all commonly used formatsthe number of packets per second is fixed for a given audio file or stream. I'm trying to use the CoreAudio api to setup sound playback. The AVAudioPlayer class provides a simple Objective-C interface for playing and looping audio as well as implementing rewind and fast-forward.

    Superpowered iOS Audio Output without using RemoteIO Audio Unit

    Core Audio insulates you from needing detailed knowledge of audio data formats. A recording application on an iOS-based device can record only if hardware audio input is available.

    images core audio clock api
    In iOS, the system supplies these plug-ins.

    images core audio clock api

    Related Does anyone know of a good example in english or any docs on this API? Please try submitting your feedback later. Audio units also use a parameter mechanism for settings that are adjustable in real time, often by the end user. A splitter unit does this, for example.

    5 thoughts on “Core audio clock api

    1. For now I am just outputing a constant sine wave. What APIs are you using to play the sound?

    2. Does this make sense? Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

    3. When you use an audio converter explicitly in OS X, you call a conversion function with a particular converter instance, specifying where to find the input data and where to write the output. Media times do not have to correspond to real time.

    4. This is an essential aspect of the so-called pull mechanism that audio units use to obtain data. I believe you are correct in that I'm trying to enqueue samples at the same rate as the consuming audio thread dequeues them, but I don't see any way around this for something interactive like a game.