Fixed some errors when stopping and starting processing again

AVQt/include/AVQt/common/PixelFormat.hpp

AVQt/include/AVQt/decoder/VideoDecoder.hpp

AVQt/include/AVQt/decoder/VideoDecoderFactory.hpp

AVQt/include/AVQt/encoder/IVideoEncoderImpl.hpp

AVQt/include/AVQt/encoder/VideoEncoder.hpp

AVQt/include/AVQt/encoder/VideoEncoderFactory.hpp

AVQt/include/AVQt/input/Demuxer.hpp

AVQt/src/common/PixelFormat.cpp

AVQt/src/decoder/VAAPIDecoderImpl.cpp

AVQt/src/decoder/VAAPIDecoderImpl.hpp

AVQt/src/decoder/VideoDecoder.cpp

AVQt/src/decoder/VideoDecoderFactory.cpp

AVQt/src/encoder/VAAPIEncoderImpl.cpp

AVQt/src/encoder/VAAPIEncoderImpl.hpp

AVQt/src/encoder/VideoEncoder.cpp

AVQt/src/encoder/VideoEncoderFactory.cpp

AVQt/src/encoder/private/VideoEncoder_p.hpp

AVQt/src/input/Demuxer.cpp

AVQt/src/renderers/VAAPIOpenGLRenderMapper.cpp

Player/OpenGlWidgetRenderer.cpp