版本记录
| 版本号 | 时间 |
|---|---|
| V1.0 | 2017.12.26 |
前言
ios系统中有很多方式可以播放音频文件，这里我们就详细的说明下播放音乐文件的原理和实例。感兴趣的可以看我写的上面几篇。
1. 几种播放音频文件的方式（一） —— 播放本地音乐
2. 几种播放音频文件的方式（二） —— 音效播放
3. 几种播放音频文件的方式（三） —— 网络音乐播放
音频队列作用
它是AudioToolbox中的API，它用来播放网络流媒体文件，可以做到音频的播放和录制。
音频队列的组成
音频队列主要由三部分组成：
- 三个缓冲器
buffer- 每个缓冲器都是一个存储音频数据的临时仓库。
- 一个缓冲队列
Buffer Queue- 一个包含音频缓冲器的有序队列
- 一个回调
callBack- 自定义的队列回调函数。
具体工作流程如下图所示：
在音频播放缓冲队列中，将音频读取到缓冲器中，一旦一个缓冲器填充满之后就放到缓冲队列中，然后继续填充其他缓冲器；当开始播放时，则从第一个缓冲器中读取音频进行播放；一旦播放完之后就会触发回调函数，开始播放下一个缓冲器中的音频，同时填充第一个缓冲器放；填充满之后再次放回到缓冲队列。下面具体说一下工作流程。
- 1.创建
AudioQueue,创建BufferArray数组，用于存放AudioQueueBufferRef。 - 2.通过
AudioQueueAllocateBuffer创建AudioQueueBufferRef一般2-3个，放入到BufferArray数组中。 - 3.有数据时从buffer数组取出一个buffer，memcpy数据后用
AudioQueueEnqueueBuffer方法把buffer插入AudioQueue中。 - 4.
AudioQueue中存在Buffer后，调用AudioQueueStart播放。（具体等到填入多少buffer后再播放可以自己控制，只要能保证播放不间断即可）。 - 5.
AudioQueue播放音乐后消耗了某个buffer，在另一个线程回调并送出该buffer，把buffer放回BufferArray供下一次使用。 - 6.返回步骤3继续循环直到播放结束。
音频队列主要API
1. 创建AudioQueue
/*!
@function AudioQueueNewOutput
@abstract Creates a new audio queue for playing audio data.
@discussion
To create an playback audio queue, you allocate buffers, then queue buffers (using
AudioQueueEnqueueBuffer). The callback receives buffers and typically queues them again.
To schedule a buffer for playback, providing parameter and start time information, call
AudioQueueEnqueueBufferWithParameters.
@param inFormat
A pointer to a structure describing the format of the audio data to be played. For
linear PCM, only interleaved formats are supported. Compressed formats are supported.
@param inCallbackProc
A pointer to a callback function to be called when the audio queue has finished playing
a buffer.
@param inUserData
A value or pointer to data that you specify to be passed to the callback function.
@param inCallbackRunLoop
The event loop on which inCallbackProc is to be called. If you specify NULL, the
callback is called on one of the audio queue's internal threads.
@param inCallbackRunLoopMode
The run loop mode in which to call the callback. Typically, you pass
kCFRunLoopCommonModes. (NULL also specifies kCFRunLoopCommonModes). Other
possibilities are implementation specific. You can choose to create your own thread with
your own run loops. For more information on run loops, see Run Loops or CFRunLoop
Reference.
@param inFlags
Reserved for future use. Pass 0.
@param outAQ
On return, this variable contains a pointer to the newly created playback audio queue
object.
@result An OSStatus result code.
*/
第一个参数表示需要播放的音频数据格式类型，是一个AudioStreamBasicDescription对象，是使用AudioFileStream或者AudioFile解析出来的数据格式信息；
第二个参数AudioQueueOutputCallback是某块Buffer被使用之后的回调；
第三个参数为上下文对象；
第四个参数inCallbackRunLoop为AudioQueueOutputCallback需要在的哪个RunLoop上被回调，如果传入NULL的话就会再AudioQueue的内部RunLoop中被回调，所以一般传NULL就可以了；
第五个参数inCallbackRunLoopMode为RunLoop模式，如果传入NULL就相当于kCFRunLoopCommonModes，也传NULL就可以了；
第六个参数inFlags是保留字段，目前没作用，传0；
第七个参数，返回生成的AudioQueue实例；
return：返回值用来判断是否成功创建（OSStatus == noErr）。
extern OSStatus
AudioQueueNewOutput( const AudioStreamBasicDescription *inFormat,
AudioQueueOutputCallback inCallbackProc,
void * __nullable inUserData,
CFRunLoopRef __nullable inCallbackRunLoop,
CFStringRef __nullable inCallbackRunLoopMode,
UInt32 inFlags,
AudioQueueRef __nullable * __nonnull outAQ)
/*!
@function AudioQueueNewOutputWithDispatchQueue
@abstract Creates a new audio queue for playing audio data.
@discussion
To create an playback audio queue, you allocate buffers, then queue buffers (using
AudioQueueEnqueueBuffer). The callback receives buffers and typically queues them again.
To schedule a buffer for playback, providing parameter and start time information, call
AudioQueueEnqueueBufferWithParameters.
@param outAQ
On return, this variable contains a pointer to the newly created playback audio queue
object.
@param inFormat
A pointer to a structure describing the format of the audio data to be played. For
linear PCM, only interleaved formats are supported. Compressed formats are supported.
@param inFlags
Reserved for future use. Pass 0.
@param inCallbackDispatchQueue
The dispatch queue from which inCallbackBlock is to be called.
@param inCallbackBlock
A pointer to a callback block to be called when the audio queue has finished playing
a buffer.
@result An OSStatus result code.
*/
参数和上面基本相同，只是把RunLoop换成了dispatch queue
AudioQueueNewOutputWithDispatchQueue(AudioQueueRef __nullable * __nonnull outAQ,
const AudioStreamBasicDescription *inFormat,
UInt32 inFlags,
dispatch_queue_t inCallbackDispatchQueue,
AudioQueueOutputCallbackBlock inCallbackBlock)
2. 创建Buffer
/*!
@function AudioQueueAllocateBuffer
@abstract Asks an audio queue to allocate a buffer.
@discussion
Once allocated, the pointer to the buffer and the buffer's size are fixed and cannot be
changed. The mAudioDataByteSize field in the audio queue buffer structure,
AudioQueueBuffer, is initially set to 0.
@param inAQ
The audio queue you want to allocate a buffer.
@param inBufferByteSize
The desired size of the new buffer, in bytes. An appropriate buffer size depends on the
processing you will perform on the data as well as on the audio data format.
@param outBuffer
On return, points to the newly created audio buffer. The mAudioDataByteSize field in the
audio queue buffer structure, AudioQueueBuffer, is initially set to 0.
@result An OSStatus result code.
*/
第一个参数方法传入AudioQueue实例
第二个参数Buffer大小
第三个传出的BufferArray实例；
extern OSStatus
AudioQueueAllocateBuffer(AudioQueueRef inAQ,
UInt32 inBufferByteSize,
AudioQueueBufferRef __nullable * __nonnull outBuffer)
/*!
@function AudioQueueAllocateBufferWithPacketDescriptions
@abstract Asks an audio queue to allocate a buffer with space for packet descriptions.
@discussion
Once allocated, the pointer to the buffer and the buffer's size are fixed and cannot be
changed. The mAudioDataByteSize field in the audio queue buffer structure,
AudioQueueBuffer, is initially set to 0.
@param inAQ
The audio queue you want to allocate a buffer.
@param inBufferByteSize
The desired size of the new buffer, in bytes. An appropriate buffer size depends on the
processing you will perform on the data as well as on the audio data format.
@param inNumberPacketDescriptions
The desired capacity of the packet description array in the new buffer.
@param outBuffer
On return, points to the newly created audio buffer. The mAudioDataByteSize field in the
audio queue buffer structure, AudioQueueBuffer, is initially set to 0.
@result An OSStatus result code.
*/
比上面的方法多了一个inNumberPacketDescriptions，这个参数可以指定生成的Buffer中PacketDescriptions的个数
extern OSStatus
AudioQueueAllocateBufferWithPacketDescriptions(
AudioQueueRef inAQ,
UInt32 inBufferByteSize,
UInt32 inNumberPacketDescriptions,
AudioQueueBufferRef __nullable * __nonnull outBuffer)
3. 释放buffer
/*!
@function AudioQueueFreeBuffer
@abstract Disposes of an audio queue buffer.
@discussion
This function disposes of the buffer allocated by AudioQueueAllocateBuffer. Disposing of
an audio queue also automatically disposes of any associated buffers and timeline
objects. Call this function only if you want to dispose of a particular buffer while
continuing to use an audio queue. You can dispose of buffers only when the associated
queue is stopped (that is, not processing audio data).
@param inAQ
The queue from which the buffer was allocated.
@param inBuffer
The buffer to be disposed.
@result An OSStatus result code.
*/
第一个参数AudioQueue实例
第二个参数指定的buffer
extern OSStatus
AudioQueueFreeBuffer( AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer)
4. 插入buffer
/*!
@function AudioQueueEnqueueBuffer
@abstract Assigns a buffer to an audio queue for recording or playback.
@discussion
If the buffer was allocated with AudioQueueAllocateBufferWithPacketDescriptions,
the client should provide packet descriptions in the buffer's mPacketDescriptions
and mPacketDescriptionCount fields rather than in inPacketDescs and
inNumPacketDescs, which should be NULL and 0, respectively, in this case.
For an input queue, pass 0 and NULL for inNumPacketDescs and inPacketDescs,
respectively. Your callback will receive packet descriptions owned by the audio queue.
@param inAQ
The audio queue you are assigning the buffer to.
@param inBuffer
The buffer to queue (that is, to be recorded into or played from).
@param inNumPacketDescs
The number of packet descriptions pointed to by the inPacketDescs pointer. Applicable
only for output queues and required only for variable-bit-rate (VBR) audio formats. Pass
0 for input queues (no packet descriptions are required).
@param inPacketDescs
An array of packet descriptions. Applicable only for output queues and required only for
variable-bit-rate (VBR) audio formats. Pass NULL for input queues (no packet
descriptions are required).
@result An OSStatus result code.
*/
第一个参数AudioQueue实例
第二个参数指定的Buffer
第三个参数数据包的个数
第四个参数数据包描述
extern OSStatus
AudioQueueEnqueueBuffer( AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer,
UInt32 inNumPacketDescs,
const AudioStreamPacketDescription * __nullable inPacketDescs)
/*!
@function AudioQueueEnqueueBufferWithParameters
@abstract Assigns a buffer to an audio queue for playback, providing parameters
and start time information.
@discussion
You can exert some control of the buffer queue by using this function. You can assign
audio queue settings that are in effect carried by an audio queue buffer as you enqueue
it. Hence, these changes only take effect when an audio queue buffer begins playing.
This function queues a buffer for playback only, not for recording. Audio queues for
recording have no parameters, do not support variable-bit-rate (VBR) formats (which
might require trimming), and have a different way to handle timing. When queued for
playback, the buffer must contain the audio data to be played back. See
AudioQueueEnqueueBuffer for details on queuing a buffer for recording.
If the buffer was allocated with AudioQueueAllocateBufferWithPacketDescriptions,
the client should provide packet descriptions in the buffer's mPacketDescriptions
and mPacketDescriptionCount fields rather than in inPacketDescs and
inNumPacketDescs, which should be NULL and 0, respectively, in this case.
@param inAQ
The audio queue associated with the buffer.
@param inBuffer
The buffer to be played from.
@param inNumPacketDescs
The number of packet descriptions pointed to by the inPacketDescs parameter. Required
only for variable-bit-rate (VBR) audio formats. Pass 0 if no packet descriptions are
required.
@param inPacketDescs
A pointer to an array of audio stream packet descriptions. Required only for VBR audio
formats. Pass NULL if no packet descriptions are required.
@param inTrimFramesAtStart
The number of priming frames to skip at the start of the buffer.
@param inTrimFramesAtEnd
The number of frames to skip at the end of the buffer.
@param inNumParamValues
The number of parameter values pointed to by the inParamValues parameter.
@param inParamValues
An array of parameter values. (In Mac OS X v10.5, there is only one parameter,
kAudioQueueParam_Volume.) These values are set before buffer playback and cannot be
changed while the buffer is playing. How accurately changes in parameters can be
scheduled depends on the size of the buffer. If there are no parameters to set
(inNumParamValues = 0), pass NULL.
@param inStartTime
A pointer to a structure containing the desired start time for playing the buffer. If
you specify the time using the mSampleTime field of the AudioTimeStamp structure, the
sample time is relative to the time the queue started. If you pass NULL for the start
time, the buffer starts immediately after the previously queued buffer, or as soon as
possible if no buffers are queued ahead of it. Buffers are played in the order they are
queued. If multiple buffers are queued, their times must be in ascending order or NULL;
otherwise, an error occurs. The start time indicates when the actual audio data in the
buffer is to be played (that is, the trim frames are not counted).
Note: When specifying a start time for a buffer, if the buffer is not the first enqueued
since AudioQueueStop or AudioQueueReset, it is normally necessary to call AudioQueueFlush
before AudioQueueEnqueueBufferWithParameters.
@param outActualStartTime
On return, points to an AudioTimeStamp structure indicating when the buffer will
actually play.
@result An OSStatus result code.
*/
上面的方法基本满足要求，这个方法对插入的buffer进行额外的更多的操作
extern OSStatus
AudioQueueEnqueueBufferWithParameters(
AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer,
UInt32 inNumPacketDescs,
const AudioStreamPacketDescription * __nullable inPacketDescs,
UInt32 inTrimFramesAtStart,
UInt32 inTrimFramesAtEnd,
UInt32 inNumParamValues,
const AudioQueueParameterEvent * __nullable inParamValues,
const AudioTimeStamp * __nullable inStartTime,
AudioTimeStamp * __nullable outActualStartTime) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
5. 开始播放
/*!
@function AudioQueueStart
@abstract Begins playing or recording audio.
@discussion
If the audio hardware is not already running, this function starts it.
@param inAQ
The audio queue to start.
@param inStartTime
A pointer to the time at which the audio queue should start. If you specify the time
using the mSampleTime field of the AudioTimeStamp structure, the sample time is
referenced to the sample frame timeline of the associated audio device. May be NULL.
@result An OSStatus result code.
*/
第一个参数AudioQueue实例
第二个参数播放时间，如果直接开始播放 传NULL
extern OSStatus
AudioQueueStart( AudioQueueRef inAQ,
const AudioTimeStamp * __nullable inStartTime)
6. 解码数据，不常用，调用开始播放会自动解码
/*!
@function AudioQueuePrime
@abstract Begins decoding buffers in preparation for playback.
@discussion
This function begins decoding buffers in preparation for playback. It returns when at
least the number of audio sample frames are decoded and ready to play or when all
enqueued buffers have been completely decoded. To ensure that a buffer has been decoded
and is completely ready for playback, before playback:
1. Call AudioQueueEnqueueBuffer.
2. Call AudioQueuePrime, which waits if you pass 0 to have a default number of
frames decoded.
3. Call AudioQueueStart.
Calls to AudioQueuePrime following AudioQueueStart/AudioQueuePrime, and before
AudioQueueReset/AudioQueueStop, will have no useful effect. In this situation,
outNumberOfFramesPrepared will not have a useful return value.
@param inAQ
The audio queue to be primed.
@param inNumberOfFramesToPrepare
The number of frames to decode before returning. Pass 0 to decode all enqueued buffers.
@param outNumberOfFramesPrepared
If not NULL, on return, a pointer to the number of frames actually decoded and prepared
for playback.
@result An OSStatus result code.
*/
extern OSStatus
AudioQueuePrime( AudioQueueRef inAQ,
UInt32 inNumberOfFramesToPrepare,
UInt32 * __nullable outNumberOfFramesPrepared)
7. 停止播放
/*!
@function AudioQueueStop
@abstract Stops playing or recording audio.
@discussion
This function resets the audio queue and stops the audio hardware associated with the
queue if it is not in use by other audio services. Synchronous stops occur immediately,
regardless of previously buffered audio data. Asynchronous stops occur after all queued
buffers have been played or recorded.
@param inAQ
The audio queue to stop.
@param inImmediate
If you pass true, the stop request occurs immediately (that is, synchronously), and the
function returns when the audio queue has stopped. Buffer callbacks are invoked during
the stopping. If you pass false, the function returns immediately, but the queue does
not stop until all its queued buffers are played or filled (that is, the stop occurs
asynchronously). Buffer callbacks are invoked as necessary until the queue actually
stops. Also, a playback audio queue callback calls this function when there is no more
audio to play.
Note that when stopping immediately, all pending buffer callbacks are normally invoked
during the process of stopping. But if the calling thread is responding to a buffer
callback, then it is possible for additional buffer callbacks to occur after
AudioQueueStop returns.
@result An OSStatus result code.
*/
第二个参数Bool值，控制是否立即停止，如果传false，会把Enqueue的所有buffer播放完成再停止
extern OSStatus
AudioQueueStop( AudioQueueRef inAQ,
Boolean inImmediate) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
8. 暂停播放
/*!
@function AudioQueuePause
@abstract Pauses audio playback or recording.
@discussion
Pausing the queue does not affect buffers or reset the audio queue. To resume playback
or recording using the audio queue, call AudioQueueStart.
@param inAQ
The queue to be paused.
@result An OSStatus result code.
*/
extern OSStatus
AudioQueuePause( AudioQueueRef inAQ) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
9. 重置解码器
/*!
@function AudioQueueFlush
@abstract Resets the audio queue's decoder state.
@discussion
After all queued buffers have been played, the function cleans up all decoder state
information. You must call this function following a sequence of buffers of encoded
audio; otherwise, some of the audio might not play in the next set of queued buffers.
The only time it is not necessary to call AudioQueueFlush is following AudioQueueStop
with inImmediate=false. (This action internally calls AudioQueueFlush.)
Also, you might wish to call this function before calling AudioQueueStop depending on
whether you want to stop immediately regardless of what has played or whether you want
to ensure that all buffered data and all data that is in the middle of processing gets
recorded or played before stopping.
@param inAQ
The audio queue to be flushed.
@result An OSStatus result code.
*/
这个方法会播放完队列中的buffer后重置解码器，防止当前的解码器影响下一段音频，比如切换歌曲的时候，如果和AudioQueueStop(AQ,false)
一起使用并不会起效，因为Stop方法的false参数也会做同样的事情。
extern OSStatus
AudioQueueFlush( AudioQueueRef inAQ) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
10. 重置AudioQueue
/*!
@function AudioQueueReset
@abstract Resets an audio queue.
@discussion
This function immediately resets an audio queue, flushes any queued buffer, removes all
buffers from previously scheduled use, and resets any decoder and digital signal
processing (DSP) state information. It also invokes callbacks for any flushed buffers.
If you queue any buffers after calling this function, processing does not occur until
the decoder and DSP state information is reset. Hence, a discontinuity (that is, a
"glitch") might occur.
Note that when resetting, all pending buffer callbacks are normally invoked
during the process of resetting. But if the calling thread is responding to a buffer
callback, then it is possible for additional buffer callbacks to occur after
AudioQueueReset returns.
@param inAQ
The audio queue to reset.
@result An OSStatus result code.
*/
重置AudioQueue会清除所有已经Enqueue的buffer，并触发AudioQueueOutputCallback,调用AudioQueueStop方法时同样会触发该方法。这个方法的直接调用一般在seek时使用，用来清除残留的buffer（seek时还有一种做法是先AudioQueueStop
，等seek完成后重新start）。
extern OSStatus
AudioQueueReset( AudioQueueRef inAQ) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
11. 获取播放时间
/*!
@function AudioQueueGetCurrentTime
@abstract Obtains the current audio queue time.
@discussion
You must specify a timeline object if you want to be notified about any timeline
discontinuities in the outTimelineDiscontinuity parameter. If you don't care about
discontinuities, pass NULL in the inTimeLine and outTimelineDiscontinuity parameters.
@param inAQ
The audio queue whose current time you want to obtain.
@param inTimeline
The audio queue timeline object to which any timeline discontinuities are reported. May
be NULL.
@param outTimeStamp
On return, points to an audio timestamp structure containing the current audio queue
time. The mSampleTime field is in terms of the audio queue's sample rate, and relative
to the time at which the queue has started or will start.
@param outTimelineDiscontinuity
Can be NULL. On return, only set to true or false if the inTimeLine parameter is not
NULL. Set to true if a discontinuity has occurred in the sample timeline of the audio
queue. For instance, the device's sample rate changed and a gap occurred in playback or
recording, or the audio queue was unable to prepare and playback in time because it was
late.
@result
An OSStatus result code.
*/
调用时传入AudioTimeStamp，从这个结构体当中获取播放时间
extern OSStatus
AudioQueueGetCurrentTime( AudioQueueRef inAQ,
AudioQueueTimelineRef __nullable inTimeline,
AudioTimeStamp * __nullable outTimeStamp,
Boolean * __nullable outTimelineDiscontinuity) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
12. 销毁AudioQueue
/*!
@function AudioQueueDispose
@abstract Disposes an existing audio queue.
@discussion
Disposing of the audio queue also disposes of all its resources, including its buffers.
@param inAQ
The audio queue you want to dispose of
@param inImmediate
If you pass true, the audio queue is disposed of immediately (that is, synchronously).
If you pass false, disposal does not take place until all enqueued buffers are
processed. Whether you call AudioQueueDispose synchronously or asynchronously, you can
no longer interact with the queue, and the queue no longer invokes any callbacks to your
application after the function returns.
Note that if AudioQueueDispose is called from a buffer completion callback or property
listener, you may receive further callbacks afterwards.
@result An OSStatus result code.
*/
参数的意义基本和AudioQueueStop一样
extern OSStatus
AudioQueueDispose( AudioQueueRef inAQ,
Boolean inImmediate) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
13. AudioQueue参数
AudioQueueGetParameter
/*!
@function AudioQueueGetParameter
@abstract Obtains an audio queue parameter value.
@discussion
You can access the current parameter values for an audio queue at any time with this
function.
@param inAQ
The audio queue whose parameter value you want to obtain.
@param inParamID
The ID of the parameter you want to obtain. In Mac OS X v10.5, audio queues have one
parameter available: kAudioQueueParam_Volume, which controls the queue's playback
volume.
@param outValue
On return, points to the current value of the specified parameter.
@result
An OSStatus result code.
*/
extern OSStatus
AudioQueueGetParameter( AudioQueueRef inAQ,
AudioQueueParameterID inParamID,
AudioQueueParameterValue * outValue) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
AudioQueueSetParameter
/*!
@function AudioQueueSetParameter
@abstract Sets an audio queue parameter value.
@discussion
@param inAQ
The audio queue whose parameter value you want to set.
@param inParamID
The ID of the parameter you want to set.
@param inValue
The parameter value to set.
@result
An OSStatus result code.
*/
extern OSStatus
AudioQueueSetParameter( AudioQueueRef inAQ,
AudioQueueParameterID inParamID,
AudioQueueParameterValue inValue) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
参数列表
CF_ENUM(AudioQueueParameterID)
{
kAudioQueueParam_Volume = 1,
kAudioQueueParam_PlayRate = 2,
kAudioQueueParam_Pitch = 3,
kAudioQueueParam_VolumeRampTime = 4,
kAudioQueueParam_Pan = 13
};
14. AudioQueue属性
AudioQueueGetPropertySize
/*!
@function AudioQueueGetPropertySize
@abstract Obtains the size of an audio queue property.
@discussion
@param inAQ
The audio queue containing the property value whose size you want to obtain.
@param inID
The ID of the property value whose size you want to obtain. See "Audio Queue Property
IDs" for possible values.
@param outDataSize
On return, points to the size of the specified property value.
@result
An OSStatus result code.
*/
extern OSStatus
AudioQueueGetPropertySize( AudioQueueRef inAQ,
AudioQueuePropertyID inID,
UInt32 * outDataSize) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
AudioQueueGetProperty
/*!
@function AudioQueueGetProperty
@abstract Obtains an audio queue property value.
@discussion
@param inAQ
The audio queue whose property value you want to obtain.
@param inID
The ID of the property you want to obtain. See "Audio Queue Property IDs."
@param outData
On return, points to the desired property value.
@param ioDataSize
A pointer to the size of the property data. On input, points to the maximum bytes of
space the caller expects to receive. On return, points to the actual data size.
@result
An OSStatus result code.
*/
extern OSStatus
AudioQueueGetProperty( AudioQueueRef inAQ,
AudioQueuePropertyID inID,
void * outData,
UInt32 * ioDataSize) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
AudioQueueSetProperty
/*!
@function AudioQueueSetProperty
@abstract Sets an audio queue property value.
@discussion
@param inAQ
The audio queue whose property value you want to set.
@param inID
The ID of the property you want to set. See "Audio Queue Property IDs" for the various
audio queue properties.
@param inData
A pointer to the property value to set.
@param inDataSize
The size of the property data.
@result
An OSStatus result code.
*/
extern OSStatus
AudioQueueSetProperty( AudioQueueRef inAQ,
AudioQueuePropertyID inID,
const void * inData,
UInt32 inDataSize) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
属性列表
CF_ENUM(AudioQueuePropertyID) {
kAudioQueueProperty_IsRunning = 'aqrn', // value is UInt32
kAudioQueueDeviceProperty_SampleRate = 'aqsr', // value is Float64
kAudioQueueDeviceProperty_NumberChannels = 'aqdc', // value is UInt32
kAudioQueueProperty_CurrentDevice = 'aqcd', // value is CFStringRef
kAudioQueueProperty_MagicCookie = 'aqmc', // value is void*
kAudioQueueProperty_MaximumOutputPacketSize = 'xops', // value is UInt32
kAudioQueueProperty_StreamDescription = 'aqft', // value is AudioStreamBasicDescription
kAudioQueueProperty_ChannelLayout = 'aqcl', // value is AudioChannelLayout
kAudioQueueProperty_EnableLevelMetering = 'aqme', // value is UInt32
kAudioQueueProperty_CurrentLevelMeter = 'aqmv', // value is array of AudioQueueLevelMeterState, 1 per channel
kAudioQueueProperty_CurrentLevelMeterDB = 'aqmd', // value is array of AudioQueueLevelMeterState, 1 per channel
kAudioQueueProperty_DecodeBufferSizeFrames = 'dcbf', // value is UInt32
kAudioQueueProperty_ConverterError = 'qcve', // value is UInt32
kAudioQueueProperty_EnableTimePitch = 'q_tp', // value is UInt32, 0/1
kAudioQueueProperty_TimePitchAlgorithm = 'qtpa', // value is UInt32. See values below.
kAudioQueueProperty_TimePitchBypass = 'qtpb', // value is UInt32, 1=bypassed
};
15. 添加监听属性
AudioQueueAddPropertyListener
/*!
@function AudioQueueAddPropertyListener
@abstract Adds a listener callback for a property.
@discussion
This callback is used to act upon a change in an audio queue property such as
kAudioQueueProperty_IsRunning. For instance, if your application has a user interface
with a Play/Stop button, and kAudioQueueProperty_IsRunning changes, you need to update
your button.
@param inAQ
The audio queue that owns the property you want to assign the listener callback to.
@param inID
The ID of the property to which you want to assign a listener callback. See "Audio Queue Property IDs".
@param inProc
The listener callback to be called when the property value changes.
@param inUserData
A value to be passed to the listener callback when it is called.
@result
An OSStatus result code.
*/
extern OSStatus
AudioQueueAddPropertyListener( AudioQueueRef inAQ,
AudioQueuePropertyID inID,
AudioQueuePropertyListenerProc inProc,
void * __nullable inUserData) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
16. 移除监听属性
AudioQueueRemovePropertyListener
/*!
@function AudioQueueRemovePropertyListener
@abstract Removes a listener callback for a property.
@discussion
@param inAQ
The audio queue that owns the property from which you want to remove a listener.
@param inID
The ID of the property from which you want to remove a listener.
@param inProc
The listener being removed.
@param inUserData
The same inUserData value that was previously passed to AudioQueueAddPropertyListener.
@result
An OSStatus result code.
*/
extern OSStatus
AudioQueueRemovePropertyListener( AudioQueueRef inAQ,
AudioQueuePropertyID inID,
AudioQueuePropertyListenerProc inProc,
void * __nullable inUserData) __OSX_AVAILABLE_STARTING(__MAC_10_5,__IPHONE_2_0);
大家如果对AudioQueue感兴趣，有大牛给大家推荐两个github地址，一个是AudioStreamer，一个是FreeStreamer，这里的两个播放都是使用AudioQueue实现的。更多请详见技术文档。
参考文章
后记
未完，待续~~~
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