硬編碼錯誤碼OSStatus(VideoToolbox/VTError.h):
　　? kVTPropertyNotSupportedErr = -12900,
　　? kVTPropertyReadOnlyErr = -12901,
　　? kVTParameterErr = -12902,
　　? kVTInvalidSessionErr = -12903,
　　? kVTAllocationFailedErr = -12904,
　　? kVTPixelTransferNotSupportedErr = -12905, // c.f. -8961
　　? kVTCouldNotFindVideoDecoderErr = -12906,
　　? kVTCouldNotCreateInstanceErr = -12907,
　　? kVTCouldNotFindVideoEncoderErr = -12908,
　　? kVTVideoDecoderBadDataErr = -12909, // c.f. -8969
　　? kVTVideoDecoderUnsupportedDataFormatErr = -12910, // c.f. -8970
　　? kVTVideoDecoderMalfunctionErr = -12911, // c.f. -8960
　　? kVTVideoEncoderMalfunctionErr = -12912,//頻繁的啟停編碼器，報錯
　　? kVTVideoDecoderNotAvailableNowErr = -12913,
　　? kVTImageRotationNotSupportedErr = -12914,
　　? kVTVideoEncoderNotAvailableNowErr = -12915,
　　? kVTFormatDescriptionChangeNotSupportedErr = -12916,
　　? kVTCouldNotCreateColorCorrectionDataErr = -12918,
　　? kVTColorSyncTransformConvertFailedErr = -12919,
　　? kVTVideoDecoderAuthorizationErr = -12210,
　　? kVTVideoEncoderAuthorizationErr = -12211,
　　? kVTColorCorrectionPixelTransferFailedErr = -12212,
　　? kVTMultiPassStorageIdentifierMismatchErr = -12213,
　　? kVTMultiPassStorageInvalidErr = -12214,
　　? kVTFrameSiloInvalidTimeStampErr = -12215,
　　? kVTFrameSiloInvalidTimeRangeErr = -12216,
　　? kVTCouldNotFindTemporalFilterErr = -12217,
　　? kVTPixelTransferNotPermittedErr = -12218,
　　? kVTColorCorrectionImageRotationFailedErr = -12219,
　　? kVTVideoDecoderRemovedErr = -17690,

除了上述VTErrors，補充遇到CMFormatDescription，CMBlockBuffer，CMSampleBuffer錯誤。
　　? kCMFormatDescriptionError_InvalidParameter = -12710,
　　? kCMFormatDescriptionError_AllocationFailed = -12711,
　　? kCMFormatDescriptionError_ValueNotAvailable = -12718,
　　? kCMBlockBufferNoErr = 0,
　　? kCMBlockBufferStructureAllocationFailedErr = -12700,
　　? kCMBlockBufferBlockAllocationFailedErr = -12701,
　　? kCMBlockBufferBadCustomBlockSourceErr = -12702,
　　? kCMBlockBufferBadOffsetParameterErr = -12703,
　　? kCMBlockBufferBadLengthParameterErr = -12704,
　　? kCMBlockBufferBadPointerParameterErr = -12705,
　　? kCMBlockBufferEmptyBBufErr = -12706,
　　? kCMBlockBufferUnallocatedBlockErr = -12707,
　　? kCMBlockBufferInsufficientSpaceErr = -12708,
　　? kCMSampleBufferError_AllocationFailed = -12730,
　　? kCMSampleBufferError_RequiredParameterMissing = -12731,
　　? kCMSampleBufferError_AlreadyHasDataBuffer = -12732,
　　? kCMSampleBufferError_BufferNotReady = -12733,
　　? kCMSampleBufferError_SampleIndexOutOfRange = -12734,
　　? kCMSampleBufferError_BufferHasNoSampleSizes = -12735,
　　? kCMSampleBufferError_BufferHasNoSampleTimingInfo = -12736,
　　? kCMSampleBufferError_ArrayTooSmall = -12737,
　　? kCMSampleBufferError_InvalidEntryCount = -12738,
　　? kCMSampleBufferError_CannotSubdivide = -12739,
　　? kCMSampleBufferError_SampleTimingInfoInvalid = -12740,
　　? kCMSampleBufferError_InvalidMediaTypeForOperation = -12741,
　　? kCMSampleBufferError_InvalidSampleData = -12742,
　　? kCMSampleBufferError_InvalidMediaFormat = -12743,
　　? kCMSampleBufferError_Invalidated = -12744,
　　? kCMSampleBufferError_DataFailed = -16750,
　　? kCMSampleBufferError_DataCanceled = -16751,
編碼示例：

VTCompressionSessionRef _encoderSession;
CVPixelBufferPoolRef _pixelBufferPool  = VTCompressionSessionGetPixelBufferPool(_encoderSession);
if(_pixelBufferPool) 
{
    CVPixelBufferPoolRetain(_pixelBufferPool);
} 
else 
{
    printf(this," Failed to create Pixel Buffer in current session.");
}

CVPixelBufferRef pixbuf = NULL;
CVReturn r = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, _pixelBufferPool, &pixbuf);
if (kCVReturnSuccess != r || NULL == pixbuf)
{
   printf(this," create pixel buffer failed! status=%d", r);
   return false;
}
CVPixelBufferLockBaseAddress( pixbuf, 0 );
//copy yuv數據
....
CVPixelBufferUnlockBaseAddress( pixbuf, 0);

CMTime timestamp = CMTimeMake(pts - _timestampBase, 1000);
CMTime duration  = CMTimeMake(1, _frameRate);
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

VTEncodeInfoFlags infoFlags = 0;
status = VTCompressionSessionEncodeFrame(_encoderSession,
                                             pixbuf,
                                             timestamp,
                                             duration,
                                             NULL,
                                             imageBuffer,
                                             &infoFlags);

CVPixelBufferRelease(pixbuf);

....
//獲取sps pps
CFArrayRef array = CMSampleBufferGetSampleAttachmentsArray(sampleBuffer, true);
const void * value = CFArrayGetValueAtIndex(array, 0);
bool keyframe = !CFDictionaryContainsKey(value, kCMSampleAttachmentKey_NotSync);
CMFormatDescriptionRef format = CMSampleBufferGetFormatDescription(sampleBuf);
size_t spsSize = 0, ppsSize = 0;
const uint8_t *sps = 0, *pps = 0;
size_t parmCount = 0;
        
CMVideoFormatDescriptionGetH264ParameterSetAtIndex(format, 0, &sps, &spsSize, &parmCount, NULL);
CMVideoFormatDescriptionGetH264ParameterSetAtIndex(format, 1, &pps, &ppsSize, &parmCount, NULL);
    
memcpy(encoder->_sps, sps, spsSize);
encoder->_spsLen = spsSize;

memcpy(encoder->_pps, pps, ppsSize);
encoder->_ppsLen = ppsSize;
....

if (_encoderSession) 
{
     VTCompressionSessionCompleteFrames(_encoderSession, kCMTimeInvalid);//如果completeUntilPresentationTimeStamp是數字的話,包括當前時間和之前時間的幀都會在方法返回前發出。如果不是數字的話,全部的未處理的幀都會在方法返回前發出。
     VTCompressionSessionInvalidate(_encoderSession);
     CFRelease(_encoderSession);
     _encoderSession = NULL;
        
     CVPixelBufferPoolRelease(_pixelBufferPool);
     _pixelBufferPool = NULL;
}