SMPTE ST 2042-1 VC-2 Pseudocode Language Parsing Software

This repository contains software tools for parsing the pseudocode language used in the SMPTE ST 2042-1 (VC-2) professional video codec specification documents.

As well as a parser capable of generating Abstract Syntax Trees (ASTs) for pseudocode listings, tools are also provided for translating the pseudocode language into Python and also pretty-printed, syntax highlighted Word documents for inclusions in specifications.

Installation

To install from PyPI use:

$ pip install vc2_pseudocode_parser

Alternatively, to install directly from a checkout of this repository:

$ python setup.py install --user

This software requires Python 3.6 or later.

To enable support for generating Word documents, python-docx must also be installed (e.g. using pip install python-docx).

Example usage

As an example, consider the following pseudocode listing:

color_spec(state, video_parameters):
    # (11.4.10.1)
    custom_color_spec_flag = read_bool(state)
    if (custom_color_spec_flag):
        index = read_uint(state)
        preset_color_spec(video_parameters, index)
        # NB: index 0 is 'custom'
        if (index == 0):
            color_primaries(state, video_parameters)  # 11.3.9.1
            color_matrix(state, video_parameters)  # 11.3.9.2
            transfer_function(state, video_parameters)  # 11.3.9.3

This may be converted into Python as follows:

$ vc2-pseudocode-to-python listing.pc listing.py
$ cat listing.py
# This file was automatically translated from a pseudocode listing.

def color_spec(state, video_parameters):
    """
    (11.4.10.1)
    """
    custom_color_spec_flag = read_bool(state)
    if custom_color_spec_flag:
        index = read_uint(state)
        preset_color_spec(video_parameters, index)
        # NB: index 0 is 'custom'
        if index == 0:
            color_primaries(state, video_parameters)  # 11.3.9.1
            color_matrix(state, video_parameters)  # 11.3.9.2
            transfer_function(state, video_parameters)  # 11.3.9.3

Or into a Word document with tabular listings as follows:

$ vc2-pseudocode-to-docx listing.pc listing.docx

For a more thorough introduction, see the vc2_pseudocode_parser manual (also available in PDF format).

Development

Testing dependencies may be installed using:

$ pip install -r requirements-test.txt

Tests are then run using:

$ py.test

Though typechecking (using MyPy) is performed as part of the test suite, it may be run manually using:

$ ./run_mypy.sh

Documentation build dependencies can be obtained using:

$ pip install -r requirements-docs.txt

And the documentation built using:

$ make -C docs html latexpdf

Experimental software

The tools in this repository are experimental in nature. They are part of an informal thread of work to see how enhanced machine readability of pseudocode specifications may prove valuable to implementers and specification authors alike. Contact Jonathan Heathcote or John Fletcher for more information.

License

This software is distributed under the GNU General Public License version 3, © BBC 2021.