在我的程序中，我希望用户能够：
- 录下他的声音，
- 暂停录制过程，
- 听听他录的
- 然后继续录制。
我已经成功地达到了可以使用 AVAudioRecorder 和 AVAudioPlayer 录制和播放录音的地步。但是每当我尝试录制、暂停录制然后播放时，播放部分都会失败且没有错误。
我可以猜测它没有播放的原因是因为音频文件尚未保存并且仍在内存中或其他东西。
有没有办法可以播放暂停的录音？如果有请告诉我如何
我正在使用 xcode 4.3.2
问问题
3648 次
3 回答
10
如果要播放录音，那么是的，您必须先停止录音，然后才能将文件加载到 AVAudioPlayer 实例中。
如果您希望能够播放某些录音，然后在听完录音后添加更多录音，或者在中间说录音..那么您就有麻烦了。
您必须创建一个新的音频文件，然后将它们组合在一起。
这是我的解决方案：
// Generate a composition of the two audio assets that will be combined into
// a single track
AVMutableComposition* composition = [AVMutableComposition composition];
AVMutableCompositionTrack* audioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
// grab the two audio assets as AVURLAssets according to the file paths
AVURLAsset* masterAsset = [[AVURLAsset alloc] initWithURL:[NSURL fileURLWithPath:self.masterFile] options:nil];
AVURLAsset* activeAsset = [[AVURLAsset alloc] initWithURL:[NSURL fileURLWithPath:self.newRecording] options:nil];
NSError* error = nil;
// grab the portion of interest from the master asset
[audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, masterAsset.duration)
ofTrack:[[masterAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]
atTime:kCMTimeZero
error:&error];
if (error)
{
// report the error
return;
}
// append the entirety of the active recording
[audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, activeAsset.duration)
ofTrack:[[activeAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]
atTime:masterAsset.duration
error:&error];
if (error)
{
// report the error
return;
}
// now export the two files
// create the export session
// no need for a retain here, the session will be retained by the
// completion handler since it is referenced there
AVAssetExportSession* exportSession = [AVAssetExportSession
exportSessionWithAsset:composition
presetName:AVAssetExportPresetAppleM4A];
if (nil == exportSession)
{
// report the error
return;
}
NSString* combined = @"combined file path";// create a new file for the combined file
// configure export session output with all our parameters
exportSession.outputURL = [NSURL fileURLWithPath:combined]; // output path
exportSession.outputFileType = AVFileTypeAppleM4A; // output file type
[exportSession exportAsynchronouslyWithCompletionHandler:^{
// export status changed, check to see if it's done, errored, waiting, etc
switch (exportSession.status)
{
case AVAssetExportSessionStatusFailed:
break;
case AVAssetExportSessionStatusCompleted:
break;
case AVAssetExportSessionStatusWaiting:
break;
default:
break;
}
NSError* error = nil;
// your code for dealing with the now combined file
}];
我不能完全归功于这项工作，但它是根据其他几个人的意见拼凑而成的：
AVAudioRecorder / AVAudioPlayer - 将录音附加到文件
（我暂时找不到其他链接）
于 2012-11-18T07:50:10.143 回答
3
我们对我们的应用程序有与 OP 描述的相同的要求，并且遇到了相同的问题（即，如果用户想听她到目前为止录制的内容，则必须停止录制，而不是暂停）。我们的应用程序（项目的 Github存储库）AVQueuePlayer用于播放和类似于kermitology 的回答的方法来连接部分录音，但有一些显着差异：
- 在Swift中实现
- 将多个录音连接成一个
- 不弄乱曲目
最后一项背后的基本原理是，简单的录音AVAudioRecorder只有一个轨道，整个解决方法的主要原因是连接资产中的这些单一轨道（参见附录 3）。那么为什么不使用AVMutableComposition'insertTimeRange方法来AVAsset代替AVAssetTrack呢？
相关部分：（完整代码）
import UIKit
import AVFoundation
class RecordViewController: UIViewController {
/* App allows volunteers to record newspaper articles for the
blind and print-impaired, hence the name.
*/
var articleChunks = [AVURLAsset]()
func concatChunks() {
let composition = AVMutableComposition()
/* `CMTimeRange` to store total duration and know when to
insert subsequent assets.
*/
var insertAt = CMTimeRange(start: kCMTimeZero, end: kCMTimeZero)
repeat {
let asset = self.articleChunks.removeFirst()
let assetTimeRange =
CMTimeRange(start: kCMTimeZero, end: asset.duration)
do {
try composition.insertTimeRange(assetTimeRange,
of: asset,
at: insertAt.end)
} catch {
NSLog("Unable to compose asset track.")
}
let nextDuration = insertAt.duration + assetTimeRange.duration
insertAt = CMTimeRange(start: kCMTimeZero, duration: nextDuration)
} while self.articleChunks.count != 0
let exportSession =
AVAssetExportSession(
asset: composition,
presetName: AVAssetExportPresetAppleM4A)
exportSession?.outputFileType = AVFileType.m4a
exportSession?.outputURL = /* create URL for output */
// exportSession?.metadata = ...
exportSession?.exportAsynchronously {
switch exportSession?.status {
case .unknown?: break
case .waiting?: break
case .exporting?: break
case .completed?: break
case .failed?: break
case .cancelled?: break
case .none: break
}
}
/* Clean up (delete partial recordings, etc.) */
}
该图帮助我了解了期望什么以及从哪里继承的问题。（NSObject在没有继承箭头的情况下隐含为超类。）
附录 1：我对此switch部分持保留意见，而不是在 上使用 KVO AVAssetExportSessionStatus，但文档很清楚exportAsynchronously' 的回调块“在写入完成或写入失败时调用”。
附录 2：以防万一有人遇到以下问题AVQueuePlayer：“一个 AVPlayerItem 不能与多个 AVPlayer 实例关联”
附录 3：除非您以立体声录制，但据我所知，移动设备只有一个输入。此外，使用精美的音频混合还需要使用AVCompositionTrack. 一个好的 SO 线程：Proper AVAudioRecorder Settings for Recording Voice？
于 2018-04-23T05:20:33.590 回答
1
RecordAudioViewController.h
#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
#import <CoreAudio/CoreAudioTypes.h>
@interface record_audio_testViewController : UIViewController <AVAudioRecorderDelegate> {
IBOutlet UIButton * btnStart;
IBOutlet UIButton * btnPlay;
IBOutlet UIActivityIndicatorView * actSpinner;
BOOL toggle;
//Variables setup for access in the class:
NSURL * recordedTmpFile;
AVAudioRecorder * recorder;
NSError * error;
}
@property (nonatomic,retain)IBOutlet UIActivityIndicatorView * actSpinner;
@property (nonatomic,retain)IBOutlet UIButton * btnStart;
@property (nonatomic,retain)IBOutlet UIButton * btnPlay;
- (IBAction) start_button_pressed;
- (IBAction) play_button_pressed;
@end
RecordAudioViewController.m
@synthesize actSpinner, btnStart, btnPlay;
- (void)viewDidLoad {
[super viewDidLoad];
//Start the toggle in true mode.
toggle = YES;
btnPlay.hidden = YES;
//Instanciate an instance of the AVAudioSession object.
AVAudioSession * audioSession = [AVAudioSession sharedInstance];
//Setup the audioSession for playback and record.
//We could just use record and then switch it to playback leter, but
//since we are going to do both lets set it up once.
[audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error: &error];
//Activate the session
[audioSession setActive:YES error: &error];
}
- (IBAction) start_button_pressed{
if(toggle)
{
toggle = NO;
[actSpinner startAnimating];
[btnStart setTitle:@"Stop Recording" forState: UIControlStateNormal ];
btnPlay.enabled = toggle;
btnPlay.hidden = !toggle;
//Begin the recording session.
//Error handling removed. Please add to your own code.
//Setup the dictionary object with all the recording settings that this
//Recording sessoin will use
//Its not clear to me which of these are required and which are the bare minimum.
//This is a good resource: http://www.totodotnet.net/tag/avaudiorecorder/
NSMutableDictionary* recordSetting = [[NSMutableDictionary alloc] init];
[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatAppleIMA4] forKey:AVFormatIDKey];
[recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
[recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];
//Now that we have our settings we are going to instanciate an instance of our recorder instance.
//Generate a temp file for use by the recording.
//This sample was one I found online and seems to be a good choice for making a tmp file that
//will not overwrite an existing one.
//I know this is a mess of collapsed things into 1 call. I can break it out if need be.
recordedTmpFile = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent: [NSString stringWithFormat: @"%.0f.%@", [NSDate timeIntervalSinceReferenceDate] * 1000.0, @"caf"]]];
NSLog(@"Using File called: %@",recordedTmpFile);
//Setup the recorder to use this file and record to it.
recorder = [[ AVAudioRecorder alloc] initWithURL:recordedTmpFile settings:recordSetting error:&error];
//Use the recorder to start the recording.
//Im not sure why we set the delegate to self yet.
//Found this in antother example, but Im fuzzy on this still.
[recorder setDelegate:self];
//We call this to start the recording process and initialize
//the subsstems so that when we actually say "record" it starts right away.
[recorder prepareToRecord];
//Start the actual Recording
[recorder record];
//There is an optional method for doing the recording for a limited time see
//[recorder recordForDuration:(NSTimeInterval) 10]
}
else
{
toggle = YES;
[actSpinner stopAnimating];
[btnStart setTitle:@"Start Recording" forState:UIControlStateNormal ];
btnPlay.enabled = toggle;
btnPlay.hidden = !toggle;
NSLog(@"Using File called: %@",recordedTmpFile);
//Stop the recorder.
[recorder stop];
}
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
-(IBAction) play_button_pressed{
//The play button was pressed...
//Setup the AVAudioPlayer to play the file that we just recorded.
AVAudioPlayer * avPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:recordedTmpFile error:&error];
[avPlayer prepareToPlay];
[avPlayer play];
}
- (void)viewDidUnload {
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
//Clean up the temp file.
NSFileManager * fm = [NSFileManager defaultManager];
[fm removeItemAtPath:[recordedTmpFile path] error:&error];
//Call the dealloc on the remaining objects.
[recorder dealloc];
recorder = nil;
recordedTmpFile = nil;
}
- (void)dealloc {
[super dealloc];
}
@end
RecordAudioViewController.xib
拿 2 个按钮。1个用于开始录制，另一个用于播放录制
于 2012-06-13T10:16:28.087 回答