使用AVSampleBufferDisplayLayer解码帧和显示的IOS App失败

Question

我正在编写一个IOS应用程序，它将解码H.264帧并使用AVSampleBufferDisplayLayer进行渲染。我已经修改了帧以不具有NAL起始码但具有4字节NAL大小。这已得到验证。

但我所看到的只是我的IOS模拟器中的白框，没有错误;是否有可能转储解码后的帧并验证？任何其他调试点都会有所帮助。

@implementation DecodeClass

- (void) viewDidLoad {
}

/* method to decode and render a frame */
- (void)decodeFrame{
NSLog(@"Decode Start");

/* local variable declaration */

//OSStatus status;
size_t spsSize, ppsSize,dataLen;
//_frameSize = 320*240*1.5;

uint8_t sps[] = {0x67, 0x42, 0xC0, 0x0D, 0x96, 0x64, 0x0A, 0x0F, 0xDF, 0xF8, 0x00, 0x20, 0x00, 0x18, 0x80, 0x00,
                 0x00, 0x7D, 0x00, 0x00, 0x0B, 0xB5, 0x47, 0x8A, 0x15, 0x50};

uint8_t pps[] = {0x68, 0xCE, 0x32, 0xC8};

const uint8_t* props[] = {sps, pps};
spsSize = (sizeof(sps)/sizeof(uint8_t));
ppsSize = (sizeof(pps)/sizeof(uint8_t));
const size_t sizes[] = {spsSize,ppsSize};

FILE* pFile;
int result;
pFile = fopen("/Documents/input_mod1.264","r");
fseeko(pFile, 0, SEEK_END);
unsigned long fileSize = ftello(pFile);
fseek(pFile, 0, SEEK_SET);
_dataBuf = (uint8_t*)malloc(sizeof(uint8_t) * (fileSize));
memset(_dataBuf,0,sizeof(uint8_t) * (fileSize));

if (pFile ){
        result = fread(_dataBuf,sizeof(uint8_t),fileSize,pFile);
        fclose(pFile);
}
else
    NSLog(@"Can't open file");

[self MUX_Modify_AVC_Start_Code:_dataBuf size:&fileSize Header:false];
dataLen = fileSize;

//construct h.264 parameter set
CMVideoFormatDescriptionRef formatDesc;
OSStatus formatCreateResult =  CMVideoFormatDescriptionCreateFromH264ParameterSets(kCFAllocatorDefault, 2, props, sizes, 4, &formatDesc);
if (formatCreateResult)
{
    NSLog(@"construct CMVideoFormatDescriptionCreateFromH264ParameterSets Failed :%ld",(long)formatCreateResult);
}

//construct cmBlockbuffer .
CMBlockBufferRef blockBufferOut = nil;
CMBlockBufferCreateEmpty (0,0,kCMBlockBufferAlwaysCopyDataFlag, &blockBufferOut);

CMBlockBufferAppendMemoryBlock(blockBufferOut,
                               _dataBuf,
                               dataLen,
                               NULL,
                               NULL,
                               0,
                               dataLen,
                               kCMBlockBufferAlwaysCopyDataFlag);

//construct cmsamplebuffer ok
size_t sampleSizeArray[1] = {0};
sampleSizeArray[0] = CMBlockBufferGetDataLength(blockBufferOut);    
CMSampleTimingInfo tmInfos[1] = {
    {CMTimeMake(5,1), CMTimeMake(5,1), CMTimeMake(5,1)}
};
CMSampleBufferRef sampBuf = nil;
formatCreateResult = CMSampleBufferCreate(kCFAllocatorDefault,
                                          blockBufferOut,
                                          YES,
                                          NULL,
                                          NULL,
                                          formatDesc,
                                          1,
                                          1,
                                          tmInfos,
                                          1,
                                          sampleSizeArray,
                                          &sampBuf);
NSLog(@"Decode End :: Construct CMSampleBufferRef value of formatCreateResult is %d", formatCreateResult);

if(!_dspLayer)
{
    _dspLayer = [[AVSampleBufferDisplayLayer alloc]init];
    [_dspLayer setFrame:CGRectMake(0,0,320,240)];
    _dspLayer.bounds = CGRectMake(0, 0, 300, 300);
    _dspLayer.videoGravity = AVLayerVideoGravityResizeAspect;
    _dspLayer.position = CGPointMake(500, 500);
    _dspLayer.backgroundColor = [UIColor blueColor].CGColor;

    CMTimebaseRef tmBase = nil;
     CMTimebaseCreateWithMasterClock(NULL,CMClockGetHostTimeClock(),&tmBase);
    _dspLayer.controlTimebase = tmBase;
    CMTimebaseSetTime(_dspLayer.controlTimebase, kCMTimeZero);
    CMTimebaseSetRate(_dspLayer.controlTimebase, 1.0);

    [self.layerView.layer addSublayer:_dspLayer];
}

//put to AVSampleBufferdisplayLayer,just one frame.
if([self.dspLayer isReadyForMoreMediaData])
{
    [self.dspLayer enqueueSampleBuffer:sampBuf];
}
[self.dspLayer setNeedsDisplay];
}

-(void)MUX_Modify_AVC_Start_Code:(uint8_t*)pData size:(uint32_t *)nSize Header:(bool)bHeader{
....
}

-(uint32_t)MUX_FindNextPattern:(uint8_t*)streamBuf buffSize:(uint32_t)bufSize startCode:(uint32_t)startcode{
....
}

- (void)dealloc{
//free(_dataBuf);
}

@end


int main(int argc, char * argv[]) {

//[decodeClass release];
@autoreleasepool {
    DecodeClass *decodeClass = [[DecodeClass alloc]init];
    [decodeClass decodeFrame];
    decodeClass = nil;
    return UIApplicationMain(argc, argv, nil,   NSStringFromClass([AppDelegate class]));
}
}