硬件解码器
本课演示如何使用VideoToolbox进行iOS硬件解码
硬件解码器步骤
// 1. Get SPS,PPS form stream data, and create CMFormatDescription, VTDecompressionSession
// 2. create CMFormatDescription
// 3. create VTDecompressionSession
// 4. get NALUnit payload into a CMBlockBuffer
// 5. making sure to replace the separator code with a 4 byte length code (the length of the NalUnit including the unit code)
// 6. create a CMSam
