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AVAssetWriterInputPixelBufferAdaptor appendPixelBuffer

I used the code below to record an image in a video

-(void) writeImagesToMovieAtPath:(NSString *) path withSize:(CGSize) size
{
    NSLog(@"Write Started");

    NSError *error = nil;

    AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
                                  [NSURL fileURLWithPath:path] fileType:AVFileTypeMPEG4
                                                              error:&error];
    NSParameterAssert(videoWriter);

    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   AVVideoCodecH264, AVVideoCodecKey,
                                   [NSNumber numberWithInt:size.width], AVVideoWidthKey,
                                   [NSNumber numberWithInt:size.height], AVVideoHeightKey,
                                   nil];

    AVAssetWriterInput* videoWriterInput = [[AVAssetWriterInput
                                             assetWriterInputWithMediaType:AVMediaTypeVideo
                                             outputSettings:videoSettings] retain];


    AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
                                                     assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput
                                                     sourcePixelBufferAttributes:nil];

    NSParameterAssert(videoWriterInput);
    NSParameterAssert([videoWriter canAddInput:videoWriterInput]);
    videoWriterInput.expectsMediaDataInRealTime = YES;
    [videoWriter addInput:videoWriterInput];

    //Start a session:
    [videoWriter startWriting];
    [videoWriter startSessionAtSourceTime:kCMTimeZero];

    CVPixelBufferRef buffer = NULL;

    //convert uiimage to CGImage.

    int frameCount = 16;
    int kRecordingFPS = 30;
    UIImage * im = [UIImage imageNamed:@"IMG_0103.JPG"];

    NSArray * imageArray = [[NSArray alloc]initWithObjects:im,im,im,im,im,im,im,im,im,im,im,im,im,im,im,im, nil];

    for(UIImage * img in imageArray)
    {
        buffer = [self pixelBufferFromCGImage:[img CGImage] andSize:size];

        BOOL append_ok = NO;
        int j = 0;
        while (!append_ok && j < 30)
        {
            if (adaptor.assetWriterInput.readyForMoreMediaData)
            {
                printf("appending %d attemp %d\n", frameCount, j);

                CMTime frameTime = CMTimeMake(frameCount,(int32_t) kRecordingFPS);
                append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];

                if(buffer)
                    CVBufferRelease(buffer);
                [NSThread sleepForTimeInterval:0.05];
            }
            else
            {
                printf("adaptor not ready %d, %d\n", frameCount, j);
                [NSThread sleepForTimeInterval:0.1];
            }
            j++;
        }
        if (!append_ok) {
            printf("error appending image %d times %d\n", frameCount, j);
        }
        frameCount++;
    }


    //Finish the session:
    [videoWriterInput markAsFinished];
    [videoWriter finishWriting];
    NSLog(@"Write Ended");
    [videoWriterInput release];
    [videoWriter release];
    [imageArray release];
}

it works for the first time, but if I ran the code 2.3 times or more, it reported:

！appending 0 0-0 attemp 0
！appending 0 0-0 attemp 1
My App(11385,0xb0103000) malloc: *** error for object 0x9ab4270: double free
*** set a breakpoint in malloc_error_break to debug
！appending 0 0-0 attemp 2
My App(11385,0xb0103000) malloc: *** error for object 0x9ab4270: double free
*** set a breakpoint in malloc_error_break to debug
！appending 0 0-0 attemp 3

Over time, it caused a failure

I'm trying to find a reason, but not a result,

Your comment is welcome.

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2 answers

Instead of using [NSThread sleepForTimeInterval: 0.1]; usage while (! Adapter.assetWriterInput.readyForMoreMediaData) {}

Because many times readyForMoreMediaData strong> never sets YES within 0.1 time interval.

, appendPixelBuffer: withPresentationTime:

+9

CFRelease(), 

if ([assetWriterInput isReadyForMoreMediaData]) {
    CVPixelBufferRef pixelBuffer = [self newPixelBufferFromCGImage:image.CGImage];
    CMTime frameTime = CMTimeMake(frameCount,(int32_t) kRecordingFPS);
    if (![adaptor appendPixelBuffer:pixelBuffer withPresentationTime:frameTime]) {
        NSError *error = [videoWriter error];
        NSLog(@"failed to append sbuf: %@", error);
    }
    CFRelease(pixelBuffer);
}
+1

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