問題描述

我有這段用于從 AVAssetReaderOutput 讀取數據的代碼片段，該方法在 iOS 4.0 中運行良好，但在 5.0 中它會因訪問錯誤而崩潰，不知道為什么，任何人都有有什么意見嗎?

I have this snippet of code used to read data from an AVAssetReaderOutput, the method works fine in iOS 4.0, however in 5.0 it crashes towards the end with bad access, not sure why, anyone have any input?

AVAssetReaderOutput *output=[myOutputs objectAtIndex:0];
 int totalBuff=0;
while(TRUE)
{
     CMSampleBufferRef ref=[output copyNextSampleBuffer];
    if(ref==NULL)
        break;
    //copy data to file
    //read next one
    AudioBufferList audioBufferList;
    NSMutableData *data=[[NSMutableData alloc] init];
    CMBlockBufferRef blockBuffer;
    CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(ref, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, 0, &blockBuffer);

for( int y=0; y<audioBufferList.mNumberBuffers; y++ )
{
    AudioBuffer audioBuffer = audioBufferList.mBuffers[y];
    Float32 *frame = audioBuffer.mData;


    NSLog(@"Gonna write %d", audioBuffer.mDataByteSize);
    //crashes here
    [data appendBytes:frame length:audioBuffer.mDataByteSize];



}

totalBuff++;
CFRelease(blockBuffer);
CFRelease(ref);


   [fileHandle writeData:data];
    [data release];
}

謝謝

丹尼爾

推薦答案

我實際上是通過檢查 blockBuffer 是否為 null 來解決這個問題，如果是則繼續，問題是 ref 不是 null 但 blockBuffer 是所以這段代碼修復了我的問題

I actually fixed this by checking that blockBuffer was null and continuing if it was, the problem was that ref was not null but the blockBuffer was so this code fixed my issue

-(void)doExportSong:(NSURL*)url toFileUrl:(NSString*)fileURL 
{
    AVURLAsset *asset=[[[AVURLAsset alloc] initWithURL:url options:nil] autorelease];
    AVAssetReader *reader=[[[AVAssetReader alloc] initWithAsset:asset error:nil] autorelease];
    [reader setTimeRange:CMTimeRangeMake(kCMTimeZero, kCMTimePositiveInfinity)];
    NSMutableArray *myOutputs =[[NSMutableArray alloc] init];
    for(id track in [asset tracks])
    {
        AVAssetReaderTrackOutput *ot=[AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:track outputSettings:nil];

        [myOutputs addObject:ot]; 
        [reader addOutput:ot];
    }
    [reader startReading];
    NSFileHandle *fileHandle ;
    NSFileManager *fm=[NSFileManager defaultManager];
    if(![fm fileExistsAtPath:fileURL])
    {
        [fm createFileAtPath:fileURL contents:[[[NSData alloc] init] autorelease] attributes:nil];
    }
    fileHandle=[NSFileHandle fileHandleForUpdatingAtPath:fileURL];    
    [fileHandle seekToEndOfFile];

    AVAssetReaderOutput *output=[myOutputs objectAtIndex:0];

    int totalBuff=0;
    BOOL one=TRUE;
    while(TRUE)
    {
        CMSampleBufferRef ref=[output copyNextSampleBuffer];
        // NSLog(@"%@",ref);
        if(ref==NULL)
            break;
        //copy data to file
        //read next one
        AudioBufferList audioBufferList;
        NSMutableData *data=[[NSMutableData alloc] init];
        CMBlockBufferRef blockBuffer;
        CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(ref, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, 0, &blockBuffer);
        // NSLog(@"%@",blockBuffer);

        if(blockBuffer==NULL)
        {

                [data release];
                continue;

        }
        if(&audioBufferList==NULL)
        {
            [data release];
            continue;
        }

        for( int y=0; y<audioBufferList.mNumberBuffers; y++ )
        {
            AudioBuffer audioBuffer = audioBufferList.mBuffers[y];
            Float32 *frame = (Float32*)audioBuffer.mData;


            [data appendBytes:frame length:audioBuffer.mDataByteSize];



        }

        totalBuff++;

        CFRelease(blockBuffer);
        CFRelease(ref);
        ref=NULL;
        blockBuffer=NULL;
        [fileHandle writeData:data];
        [data release];
    }

    [fileHandle closeFile];
    [myOutputs release];  
}

這篇關于從 AVAssetReaderOutput 讀取數據時，iOS 5.0 崩潰的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！