Extracting number of bits in a macroblock from VVC VTM reference software

Question

Final:Result after calculating and displaying the differenceI am new to VVC and I am going through the reference software's code trying to understand it. I have encoded and decoded videos using the reference software. I want to extract the bitstream from it, I want to know the number of bits there are in each macroblock. I am not sure which class I should be working with, for now I am looking at, mv.cpp, QuantRDOQ.cpp, and TrQuant.cpp.

I am afraid to mess the code up completely, I don't know where to add what lines of code. Start: Result after calculating and displaying the difference P.S. The linked pictures are after my problem has been solved, I attached these pictures because of my query in the comments.

Answer 1

As the error says, getNumBins() is not supported by the CABAC estimator. So you should make sure you call it "only" during the encoding, and not during the RDO.

This should do the job:

if (isEncoding())
    before = m_BinEncoder.getNumBins()

coding_unit( cu, partitioner, cuCtx );

if (isEncoding())
{
    after = m_BinEncoder.getNumBins();
    diff = after - before;
}

Answer 2

The simpleset solution that I'm aware of is at the encoder side.

The trick is to compute the difference in the number of written bits "before" and "after" encoding a Coding Unit (CU) (aka macroblock). This stuff happens in the CABACWriter.cpp file.

You should go to to coding_tree() function, where coding_unit() function is called, which is responsible for context-coding all syntax elementes in the current CU. There, you may call the function getNumBins() twice: once before and once after coding_unit(). The difference of the two value should do the job for you.