xcode AVAudioPlayer 不播放 mp3？
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AVAudioPlayer doesn't play mp3?
提问by iWheelBuy
I want my AVAudioPlayerto play some mp3 files. It plays some of them but I have one file that can't be played!
我想AVAudioPlayer播放一些 mp3 文件。它可以播放其中一些，但我有一个文件无法播放！
To play the file I download it on my device into application folder and init it this way:
要播放文件，我将它下载到我的设备上的应用程序文件夹中并以这种方式初始化：
[[AVAudioPlayer alloc] initWithContentsOfURL:soundPath error:nil];
How to play the file? Why it doesn't play?
如何播放文件？为什么不播放？
Link to a file: abc.mp3
链接到文件：abc.mp3
EDIT:
编辑：
(Here is the code that shows the error. There is a README inside the code. Try on the device.)
（这是显示错误的代码。代码里面有一个 README。在设备上试试。）
***.pch
#import <Availability.h>
#ifndef __IPHONE_4_0
#warning "This project uses features only available in iOS SDK 4.0 and later."
#endif
#ifdef __OBJC__
#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#import <SystemConfiguration/SystemConfiguration.h>
#import <MobileCoreServices/MobileCoreServices.h>
#import <AVFoundation/AVFoundation.h>
#import <AudioToolbox/AudioToolbox.h>
#endif
ViewController.h
#import <UIKit/UIKit.h>
#import "AFNetworking.h"
@interface SCRViewController : UIViewController <AVAudioPlayerDelegate>
{
UIButton *button;
__block UIProgressView *view;
NSOperationQueue *queue;
__block BOOL isFile;
UIButton *play;
NSString *path;
AVAudioPlayer *_player;
}
@end
ViewController.m
#import "ViewController.h"
@implementation SCRViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setBackgroundColor:[UIColor yellowColor]];
[button setFrame:CGRectMake(50, 50, 220, 50)];
[button addTarget:self action:@selector(download) forControlEvents:UIControlEventTouchUpInside];
[button setTitle:@"Download" forState:UIControlStateNormal];
[button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[button setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];
[self.view addSubview:button];
play = [UIButton buttonWithType:UIButtonTypeCustom];
[play setBackgroundColor:[UIColor yellowColor]];
[play setFrame:CGRectMake(50, 150, 220, 50)];
[play addTarget:self action:@selector(play) forControlEvents:UIControlEventTouchUpInside];
[play setTitle:@"Play" forState:UIControlStateNormal];
[play setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[play setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];
[self.view addSubview:play];
self->view = [[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleDefault];
self->view.frame = CGRectMake(10, 120, 300, 20);
[self->view setProgress:0];
[self.view addSubview:self->view];
queue = [[NSOperationQueue alloc] init];
isFile = NO;
}
- (void) download
{
[button setBackgroundColor:[UIColor brownColor]];
[button setTitleColor:[UIColor whiteColor] forState:UIControlStateDisabled];
[button setEnabled:NO];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://iwheelbuy.com/abc.mp3"]];
//-------------------------------------------------------
//-------------------------------------------------------
// READ ME
//-------------------------------------------------------
//-------------------------------------------------------
// Test in on device
// I have uploaded another song for you. You can change link to http://iwheelbuy.com/def.mp3 and check the result
// def.mp3 works fine on the device
//-------------------------------------------------------
//-------------------------------------------------------
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
path = [path stringByAppendingPathComponent:@"song"];
if ( [[NSFileManager defaultManager] fileExistsAtPath:path])
[[NSFileManager defaultManager] removeItemAtPath:path error:nil];
operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject)
{
isFile = YES;
} failure:^(AFHTTPRequestOperation *operation, NSError *error)
{
//
}];
[operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead)
{
CGFloat done = (CGFloat)((int)totalBytesRead);
CGFloat expected = (CGFloat)((int)totalBytesExpectedToRead);
CGFloat progress = done / expected;
self->view.progress = progress;
}];
[queue addOperation:operation];
}
- (void) play
{
if (isFile)
{
NSError *error = nil;
NSURL *url = [NSURL fileURLWithPath:path];
_player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
if(error || !_player)
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:[error description] delegate:nil cancelButtonTitle:@"Try def.mp3" otherButtonTitles:nil];
[alert show];
}
else
{
[_player play]; // plays fine
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
[[AVAudioSession sharedInstance] setActive: YES error: nil];
}
}
else
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Warning" message:@"Download the file plz" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles: nil];
[alert show];
}
}
@end
采纳答案by iWheelBuy
http://bugreport.apple.com
Engineering has determined that this issue behaves as intended based on the following information:
工程已根据以下信息确定此问题的行为符合预期：
Could repro with attached sample app, but this is an expected behavior from AudioFile.
可以使用附加的示例应用程序重现，但这是 AudioFile 的预期行为。
The issue is that AVAudioPlayeris being initialized with a url without a file extension and the corresponding file does not have a valid ID3tag.Without a file extension or valid data, we cannot determine the right file format and hence such files will fail to open.This is an expected behavior.
问题是AVAudioPlayer正在使用没有文件扩展名的 url 进行初始化，并且相应的文件没有有效的ID3标签。没有文件扩展名或有效数据，我们无法确定正确的文件格式，因此此类文件将无法打开。此是预期的行为。
In the sample code attached:
在所附的示例代码中：
path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
path = [path stringByAppendingPathComponent:@"song"];
--> path will be something like:
--> 路径类似于：
/var/mobile/Applications/2FFD0147-E56B-47D4-B143-A9F19BE92818/Documents/song
/var/mobile/Applications/2FFD0147-E56B-47D4-B143-A9F19BE92818/Documents/song
--> NOTE: no file extension at the end.
--> 注意：最后没有文件扩展名。
abc.mp3 has an invalid ID3tag size (0x2EE) unlike def.mp3 which has a valid tag size (0x927). Hence when these are specified as "…./song" without any extension, AudioFile just looks at the data and finds a valid sync word for def.mp3 but not for abc.mp3.
abc.mp3 有一个无效的ID3标签大小 (0x2EE)，不像 def.mp3 有一个有效的标签大小 (0x927)。因此，当这些被指定为没有任何扩展名的“..../song”时，AudioFile 只是查看数据并找到 def.mp3 的有效同步字，而不是 abc.mp3。
However, replacing stringByAppendingPathComponent:@"song"with stringByAppendingPathComponent:@"song.mp3"succeeds for abc.mp3, and could help for other mp3 files in general.
但是，更换stringByAppendingPathComponent:@"song"有stringByAppendingPathComponent:@"song.mp3"成功的abc.mp3，并能帮助其他一般的MP3文件。
We consider this issue closed. If you have any questions or concern regarding this issue, please update your report directly (http://bugreport.apple.com).
我们认为这个问题已经结束。如果您对此问题有任何疑问或疑虑，请直接更新您的报告 ( http://bugreport.apple.com)。
Thank you for taking the time to notify us of this issue.
感谢您抽出宝贵时间通知我们此问题。
回答by HKTonyLee
Non-ARC
非ARC
You have to retain it during playback because it does not retain itself. It will stop playing instantly once it is dealloc-ed.
您必须在播放期间保留它，因为它不会保留自身。一旦解除分配，它将立即停止播放。
ARC
弧
You need to hold the AVAudioPlayerinstance in the class. And release it after it stops playing. For example,
您需要AVAudioPlayer在类中保存实例。并在停止播放后释放它。例如，
#import <AVFoundation/AVFoundation.h>
@interface TAViewController () <AVAudioPlayerDelegate> {
AVAudioPlayer *_somePlayer; // strong reference
}
@end
@implementation TAViewController
- (IBAction)playAudio:(id)sender
{
NSURL *url = [[NSBundle mainBundle] URLForResource:@"kogmawjoke" withExtension:@"mp3"];
_somePlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:NULL];
_somePlayer.delegate = self;
[_somePlayer play];
}
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
if (player == _somePlayer) {
_somePlayer = nil;
}
}
@end
