Core Audio. MSDOSX : Lecture 20

Transcription

1 Core Audio MSDOSX : Lecture 20

2 Overview What is Core Audio? Core Audio Programming Interfaces Common Tasks With Core Audio Core Audio Frameworks What s Been Shipping Since 10.4? Supported Audio and Data Formats Resources

3 What is Core Audio?

4 What is Core Audio? Plug-in interfaces for audio synthesis and audio digital signal processing (DSP)

5 What is Core Audio? Built in support for reading and writing a wide variety of audio file and data formats

6 What is Core Audio? Plug-in interfaces for handling custom file and data formats

7 What is Core Audio? A modular approach for constructing signal chains

8 What is Core Audio? Scalable multichannel input and output

9 What is Core Audio? Easy synchronization of audio and MIDI data during recording or

10 What is Core Audio? A standardized interface to all built-in and external hardware devices, regardless of connection type (USB, Firewire, PCI, and so on)

11 A standardized interface to all built-in and external hardware devices, regardless of connection type (USB, Firewire, PCI, and so on)

12 A standardized interface to all built-in and external hardware devices, regardless of connection type (USB, Firewire, PCI, and so on)

13 A standardized interface to all built-in and external hardware devices, regardless of connection type (USB, Firewire, PCI, and so on)

14 Interfaces Audio Unit Services Audio Processing Graph API Audio File and Converter Services Hardware Abstraction Layer (HAL) Services Music Player API Core MIDI Services and MIDI Server Services Core Audio Clock API OpenAL (Open Audio Library) System Sound API

15 Audio Unit Services Allows you to create and manipulate audio units.

16 Audio Processing Graph API

17 Audio Processing Graph API

18 Audio File and Converter Services Audio Converters and Codecs File Format Information Audio Metadata Core Audio File Format

19 Hardware Abstraction Layer (HAL) Services Core Audio uses a hardware abstraction layer (HAL) to provide a consistent and predictable interface for applications to deal with hardware.

20 Hardware Abstraction Layer (HAL) Services

21 Music Player API The Music Player API allows you to arrange and play a collection of music tracks. MIDI

22 Core MIDI Services and MIDI Server Services Core MIDI Services defines an interface that applications and audio units can use to communicate with MIDI devices. It uses a number of abstractions that allow an application to interact with a MIDI network.

23 Core MIDI Services and MIDI Server Services

24 Core MIDI Services and MIDI Server Services

25 Core Audio Clock API The Core Audio Clock API provides: A reference clock that you can use to synchronize applications or devices. A standalone timing source, or... A synchronized timer with an external trigger, such as a MIDI beat clock or MIDI time code. You can start and stop the clock yourself, or... You can set the clock to activate or deactivate in response to certain events.

26 Core Audio Clock API

27 OpenAL (Open Audio Library) OpenAL is a crossplatform API used to position and manipulate sounds in a simulated three-dimensional space.

28 System Sound API The System Sound API provides a simple way to play standard system sounds in your application.

29 Common Tasks in Core Audio Reading and Writing Audio Data Interfacing with Hardware Devices The AUHAL Using Aggregate Devices Creating Audio Units & Hosting Audio Units Handling MIDI Data

30 Reading and Writing Audio Data

31 Interfacing with Hardware Devices Operations must go through the hardware abstraction layer (HAL).

32 The AUHAL If you need to connect to an input device, or a hardware device other than the default output device, you need to use the AUHAL.

33 The AUHAL If you need to connect to an input device, or a hardware device other than the default output device, you need to use the AUHAL.

34 Using Aggregate Devices When interfacing with hardware audio devices, Core Audio allows you to add an additional level of abstraction, creating aggregate devices which combine the inputs and outputs of multiple devices to appear as a single device.

35 Creating Audio Units & Hosting Audio Units...probably read the documentation. :-)

36 Handling MIDI Data MIDI File Read

37 Handling MIDI Data MIDI Sequence Playback

38 Handling MIDI Data MIDI Device Play-through

39 Handling MIDI Data MIDI File Recording

40 Handling MIDI Data Mixing Audio Sources

41 Handling MIDI Data Big Picture

42 Core Audio Frameworks AudioToolbox.framework AudioUnit.framework CoreAudioKit.framework CoreAudio.framework CoreMIDI.framework CoreMIDIServer.framework OpenAL.framework

43 System Supplied Audio Units System-supplied effect units (kaudiounittype_effect) AUHiPass kaudiounitsubtype_highpassfilter A high-pass filter with an adjustable resonance peak.

44 System Supplied Audio Units System-supplied instrument unit DLSMusicDevice kaudiounitsubtype_dlssynth A virtual instrument unit that lets you play MIDI data using sound banks

45 System Supplied Audio Units System-supplied mixer units (kaudiounittype_mixer) AUMixer3D kaudiounitsubtype_3dmixer...can take several different signals and mix them so they appear to be positioned in a three-dimensional space.

46 System Supplied Audio Units System-supplied converter units (kaudiounittype_formatconverter) AUTimePitch kaudiounitsubtype_timepitch A unit that lets you change the speed of playback without altering the pitch, or vice versa.

47 System Supplied Audio Units System-supplied output units (kaudiounittype_output) AudioDeviceOutput kaudiounitsubtype_haloutput A unit that interfaces with an audio device using the hardware abstraction layer. Also called the AUHAL.

48 System Supplied Audio Units System-supplied generator units (kaudiounittype_generator) AUNetReceive kaudiounitsubtype_netreceive A unit that receives streamed audio data from a network.

49 Supported Audio and Data File Formats AAC (.aac,.adts) AC3 (.ac3) AIFC (.aif,.aiff,.aifc) AIFF (.aiff) Apple Core Audio Format (.caf) MPEG Layer 3 (.mp3) MPEG 4 Audio (.mp4) MPEG 4 Audio (.m4a) NeXT/Sun Audio (.snd,.au) Sound Designer II (.sd2) WAVE (.wav) Audio File Formats

50 Supported Audio and Data File Formats MPEG Layer 3 ('.mp3') MACE 3:1 ('MAC3') MACE 6:1 ('MAC6') QDesign Music 2 ('QDM2') QDesign ('QDMC') Qualcomm PureVoice ('Qclp') Qualcomm QCELP ('qclq') AAC ('aac ') Apple Lossless ('alac') Apple GSM 10:1 ('agsm') Apple DRM Audio Decoder ('drms') AC-3 DVI 4:1 ('dvi ') Apple IMA 4:1 ('ima4') LPC 23:1 ('lpc ') Microsoft ADPCM DVI ADPCM GSM610 AMR Narrowband ('samr') µlaw 2:1 ('ulaw') ALaw 2:1 'alaw') Data File Formats

51 Resources Overview Conceptual/CoreAudioOverview/Introduction/Introduction.html Core Audio Frameworks Conceptual/CoreAudioOverview/CoreAudioFrameworks/ CoreAudioFrameworks.html System Supplied Audio Units Conceptual/CoreAudioOverview/SystemAudioUnits/ SystemAudioUnits.html "iphone Core Audio Brain Dump"