h.264 bytestream parsing

Question

The input data is a byte array which represents a h.264 frame. The frame consists of a single slice (not multislice frame).

So, as I understood I can cope with this frame as with slice. The slice has header, and slice data - macroblocks, each macroblock with its own header.

So I have to parse that byte array to extract frame number, frame type, quantisation coefficient (as I understood each macroblock has its own coefficient? or I'm wrong?)

Could You advise me, where I can get more detailed information about parsing h.264 frame bytes.

(In fact I've read the standard, but it wasn't very specific, and I'm lost.)

Thanks

Answer 1

The H.264 Standard is a bit hard to read, so here are some tips.

• Read Annex B; make sure your input starts with a start code
• Read section 9.1: you will need it for all of the following
• Slice header is described in section 7.3.3
• "Frame number" is not encoded explicitly in the slice header; frame_num is close to what you probably want.
• "Frame type" probably corresponds to slice_type (the second value in the slice header, so most easy to parse; you should definitely start with this one)
• "Quantization coefficient" - do you mean "quantization parameter"? If yes, be prepared to write a full H.264 parser (or reuse an existing one). Look in section 9.3 to get an idea on a complexity of a H.264 parser.