I am recording video on iOS using ReplayKit and found that after copying data in the processSampleBuffer:withType: callback using memcpy, the data changes. This occurs particularly frequently when the screen content changes rapidly, making it look like the frames are overlapping. I found that the values starting from byte 672 in the video data on my device often change. Here is the test demo: - (void)processSampleBuffer:(CMSampleBufferRef)sampleBuffer withType:(RPSampleBufferType)sampleBufferType { switch (sampleBufferType) { case RPSampleBufferTypeVideo: { CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); CVPixelBufferLockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly); int ret = 0; uint8_t *oYData = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0); size_t oYSize = CVPixelBufferGetHeightOfPlane(pixelBuffer, 0) * CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 0); uint8_t *oUVData = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1); size_t oUVSize = CVPixelBufferGetHeightOfPlane(pixelBuffer, 1) * CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 1); if (oYSize <= 672) { return; } uint8_t tempValue = oYData[672]; uint8_t *tYData = malloc(oYSize); memcpy(tYData, oYData, oYSize); if (tYData[672] != oYData[672]) { NSLog(@"$$$$$$$$$$$$$$$$------ t:%d o:%d temp:%d", tYData[672], oYData[672], tempValue); } free(tYData); CVPixelBufferUnlockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly); break; } default: { break; } } } Output: $$$$$$$$$$$$$$$$------ t:110 o:124 temp:110 $$$$$$$$$$$$$$$$------ t:111 o:133 temp:111 $$$$$$$$$$$$$$$$------ t:124 o:138 temp:124 $$$$$$$$$$$$$$$$------ t:133 o:144 temp:133 $$$$$$$$$$$$$$$$------ t:138 o:151 temp:138 $$$$$$$$$$$$$$$$------ t:144 o:156 temp:144 $$$$$$$$$$$$$$$$------ t:151 o:135 temp:151 $$$$$$$$$$$$$$$$------ t:156 o:78 temp:156 $$$$$$$$$$$$$$$$------ t:135 o:76 temp:135 $$$$$$$$$$$$$$$$------ t:78 o:77 temp:78 $$$$$$$$$$$$$$$$------ t:76 o:80 temp:76 $$$$$$$$$$$$$$$$------ t:77 o:80 temp:77 $$$$$$$$$$$$$$$$------ t:80 o:79 temp:80 $$$$$$$$$$$$$$$$------ t:79 o:80 temp:79