The VTCompressionOutputCallback is being called only after 2 or more frames have been passed to the encoder. The last sent frame is stored in the encoder buffer and gets emitted only after the next frame comes in. This behavior causes the 1 frame delay on the decoder side and thus there is no real-time streaming. Anyone knows how to reduce the 1 frame delay?

VTCompressionSessionCreate returned 12902 if kVTVideoEncoderSpecification_EnableLowLatencyRateControl was picked. Code: CFMutableDictionaryRef encoderSpecification = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, NULL, NULL);         CFDictionarySetValue(encoderSpecification, kVTVideoEncoderSpecification_EnableLowLatencyRateControl, kCFBooleanTrue);     OSStatus result = VTCompressionSessionCreate(kCFAllocatorDefault, 640, 360, kCMVideoCodecType_H264, encoderSpecification, nullptr, nullptr, cb, outputCallbackRefCon, &m_session);     if(result != noErr){         return result;     }