`vc2_conformance.pseudocode`: VC-2 pseudocode function implementations¶

The vc2_conformance.pseudocode module contains implementations of many of the VC-2 pseudocode functions and associated data structures. In particular, it includes everything which can be used as-is in the construction of encoders, decoders and so on without any alterations.

The VC-2 pseudocode is augmented by a modest number of additional functions or data structure fields. For instance, additional fields are added to State which are used by conformance checking routines and forward wavelet transform routines.

`vc2_conformance.pseudocode.arrays`¶

VC-2 style 2D array functions (5.5).

new_array(*dimensions)¶: (5.4.2) Makes an N-dimensional array out of nested lists. Dimensions are given in the same order as they are indexed, e.g. new_array(height, width), like array[y][x].

width(a)¶: (5.5.4)

height(a)¶: (5.5.4)

row(a, k)¶: (15.4.1) A 1D-array-like view into a row of a (2D) nested list as returned by new_array().

class column(a, k)¶: (15.4.1) A 1D-array-like view into a column of a (2D) nested list as returned by new_array().

delete_rows_after(a, k)¶: (15.4.5) Delete rows ‘k’ and after in ‘a’.

delete_columns_after(a, k)¶: (15.4.5) Delete columns ‘k’ and after in ‘a’.

`vc2_conformance.pseudocode.offsetting`¶

Picture component offsetting routines (15)

This module collects picture component value offsetting functions from (15) and augments these with complementary de-offsetting functions (inferred from, but not defined by the standard).

offset_picture(state, current_picture)¶

(15.5) Remove picture value offsets (added during encoding).

Parameters

statevc2_conformance.pseudocode.state.State: Where luma_depth and color_diff_depth are defined.
current_picture{comp: [[pixel_value, …], …], …}: Will be mutated in-place.

offset_component(state, comp_data, c)¶: (15.5) Remove picture value offsets from a single component.

remove_offset_picture(state, current_picture)¶: Inverse of offset_picture (15.5). Centers picture values around zero.

remove_offset_component(state, comp_data, c)¶

Inverse of offset_component (15.5). Centers picture values around zero.

Parameters

statevc2_conformance.pseudocode.state.State: Where luma_depth and color_diff_depth are defined.
current_picture{comp: [[pixel_value, …], …], …}: Will be mutated in-place.

`vc2_conformance.pseudocode.parse_code_functions`¶

Parse code classification functions (Table 10.2)

These functions all take a ‘state’ dictionary containing at least parse_code which should be an int or ParseCodes enum value.

is_seq_header(state)¶: (Table 10.2)

is_end_of_sequence(state)¶: (Table 10.2)

is_auxiliary_data(state)¶: (Table 10.2)

is_padding_data(state)¶: (Table 10.2)

is_ld(state)¶: (Table 10.2)

is_hq(state)¶: (Table 10.2)

is_picture(state)¶: (Table 10.2)

is_fragment(state)¶: (Table 10.2)

using_dc_prediction(state)¶: (Table 10.2)

`vc2_conformance.pseudocode.picture_decoding`¶

This module contains the wavelet synthesis filters and associated functions defined in the pseudocode of the VC-2 standard (15).

inverse_wavelet_transform(state)¶: (15.3)

idwt(state, coeff_data)¶

(15.4.1)

Inverse Discrete Wavelet Transform.

Parameters

stateState

A state dictionary containing at least the following:

wavelet_index
wavelet_index_ho
dwt_depth
dwt_depth_ho

coeff_data{level: {orientation: [[coeff, …], …], …}, …}

The complete (power-of-two dimensioned) transform coefficient data.

Returns

picture[[pixel_value, …], …]: The synthesized picture.

h_synthesis(state, L_data, H_data)¶: (15.4.2) Horizontal-only synthesis.

vh_synthesis(state, LL_data, HL_data, LH_data, HH_data)¶: (15.4.3) Interleaved vertical and horizontal synthesis.

oned_synthesis(A, filter_index)¶: (15.4.4.1) and (15.4.4.3). Acts in-place on ‘A’

filter_bit_shift(state)¶: (15.4.2) Return the bit shift for the current horizontal-only filter.

lift1(A, L, D, taps, S)¶: (15.4.4.1) Update even, add odd.

lift2(A, L, D, taps, S)¶: (15.4.4.1) Update even, subtract odd.

lift3(A, L, D, taps, S)¶: (15.4.4.1) Update odd, add even.

lift4(A, L, D, taps, S)¶: (15.4.4.1) Update odd, subtract even.

idwt_pad_removal(state, pic, c)¶: (15.4.5)

offset_picture(state, current_picture)¶

(15.5) Remove picture value offsets (added during encoding).

Parameters

statevc2_conformance.pseudocode.state.State: Where luma_depth and color_diff_depth are defined.
current_picture{comp: [[pixel_value, …], …], …}: Will be mutated in-place.

offset_component(state, comp_data, c)¶: (15.5) Remove picture value offsets from a single component.

clip_picture(state, current_picture)¶: (15.5)

clip_component(state, comp_data, c)¶: (15.5)

SYNTHESIS_LIFTING_FUNCTION_TYPES = {...}¶: Lookup from lifting function ID to function implementation for implementing wavelet synthesis.

`vc2_conformance.pseudocode.picture_encoding`¶

This module is the inverse of the vc2_conformance.pseudocode.picture_decoding module and contains functions for performing wavelet analysis filtering.

This functionality is not specified by the standard but is used to generate simple bitstreams (and test cases) in this software (and its test suite).

picture_encode(state, current_picture)¶

Inverse of picture_decode (15.2).

Parameters

statevc2_conformance.pseudocode.state.State

A state dictionary containing at least:

luma_width
luma_height
color_diff_width
color_diff_height
luma_depth
color_diff_depth
wavelet_index
wavelet_index_ho
dwt_depth
dwt_depth_ho

The following entries will be added/replaced with the encoded picture.

y_transform
c1_transform
c3_transform

current_picture{component: [[value, …], …], …}

The picture to be encoded.

forward_wavelet_transform(state, current_picture)¶: (15.3)

dwt(state, picture)¶

Discrete Wavelet Transform, inverse of idwt (15.4.1)

Parameters

stateState

A state dictionary containing at least the following:

wavelet_index
wavelet_index_ho
dwt_depth
dwt_depth_ho

picture[[pixel_value, …], …]

The synthesized picture.

Returns

coeff_data{level: {orientation: [[coeff, …], …], …}, …}: The complete (power-of-two dimensioned) transform coefficient data.

h_analysis(state, data)¶

Horizontal-only analysis, inverse of h_synthesis (15.4.2).

Returns a tuple (L_data, H_data)

vh_analysis(state, data)¶

Interleaved vertical and horizontal analysis, inverse of vh_synthesis (15.4.3).

Returns a tuple (LL_data, HL_data, LH_data, HH_data)

oned_analysis(A, filter_index)¶: Inverse of oned_synthesis (15.4.4.1) and (15.4.4.3). Acts in-place on ‘A’

dwt_pad_addition(state, pic, c)¶

Inverse of idwt_pad_removal (15.4.5): pads a picture to a size compatible with wavelet filtering at the level specified by the provided State.

Extra values are obtained by copying the final pixels in the existing rows and columns.

remove_offset_picture(state, current_picture)¶: Inverse of offset_picture (15.5). Centers picture values around zero.

remove_offset_component(state, comp_data, c)¶

Inverse of offset_component (15.5). Centers picture values around zero.

Parameters

statevc2_conformance.pseudocode.state.State: Where luma_depth and color_diff_depth are defined.
current_picture{comp: [[pixel_value, …], …], …}: Will be mutated in-place.

ANALYSIS_LIFTING_FUNCTION_TYPES = {...}¶: Lookup from lifting function ID to function implementation for implementing wavelet analysis.

`vc2_conformance.pseudocode.quantization`¶

Quantization-related VC-2 pseudocode routines (13.3).

inverse_quant(quantized_coeff, quant_index)¶: (13.3.1)

forward_quant(coeff, quant_index)¶: (13.3.1) Based on the informative note 1.

quant_factor(index)¶: (13.3.2)

quant_offset(index)¶: (13.3.2)

`vc2_conformance.pseudocode.slice_sizes`¶

Slice size computation functions (13)

All of the functions below take a ‘state’ argument which should be a dictionary-like object containing the following entries:

"luma_width"
"luma_height"
"color_diff_width"
"color_diff_height"
"dwt_depth"
"dwt_depth_ho"

The slice_bytes(), slice_top(), slice_bottom(), slice_left(), slice_right() and slices_have_same_dimensions() functions all additionally require the following entries:

"slices_x"
"slices_y"

Finally slice_bytes() function requires the following further values:

"slice_bytes_numerator"
"slice_bytes_denominator"

The ‘c’ or ‘comp’ arguments should be set to one of the following strings:

"Y"
"C1"
"C2"

The slices_have_same_dimensions() utility is added beyond the VC-2 pseudocode functions which determines if all slices will contain the same number of samples or not.

subband_width(state, level, comp)¶: (13.2.3)

subband_height(state, level, comp)¶: (13.2.3)

slice_bytes(state, sx, sy)¶: (13.5.3.2) Compute the number of bytes in a low-delay picture slice.

slice_left(state, sx, c, level)¶: (13.5.6.2) Get the x coordinate of the LHS of the given slice.

slice_right(state, sx, c, level)¶: (13.5.6.2) Get the x coordinate of the RHS of the given slice.

slice_top(state, sy, c, level)¶: (13.5.6.2) Get the y coordinate of the top of the given slice.

slice_bottom(state, sy, c, level)¶: (13.5.6.2) Get the y coordinate of the bottom of the given slice.

slices_have_same_dimensions(state)¶: Utility function, not part of the standard. Tests whether all picture slices will have the same dimensions.

`vc2_conformance.pseudocode.state`¶

A fixeddict for the ‘state’ object used by the pseudocode in the VC-2 spec.

fixeddict State¶

The global state variable type.

Entries prefixed with an underscore (_) are not specified by the VC-2 pseudocode but may be used by the conformance software.

Keys

video_parametersVideoParameters: Set by (10.4.1) parse_sequence
parse_codeParseCodes: Set by (10.5.1) parse_info
next_parse_offsetint: Set by (10.5.1) parse_info
previous_parse_offsetint: Set by (10.5.1) parse_info
picture_coding_modePictureCodingModes: Set by (11.1) sequence_header
major_versionint: Set by (11.2.1) parse_parameters
minor_versionint: Set by (11.2.1) parse_parameters
profileProfiles: Set by (11.2.1) parse_parameters
levelProfiles: Set by (11.2.1) parse_parameters
luma_widthint: Set by (11.6.2) picture_dimensions
luma_heightint: Set by (11.6.2) picture_dimensions
color_diff_widthint: Set by (11.6.2) picture_dimensions
color_diff_heightint: Set by (11.6.2) picture_dimensions
luma_depthint: Set by (11.6.3) video_depth
color_diff_depthint: Set by (11.6.3) video_depth
picture_numberint: Set by (12.2) picture_header and (14.2) fragment_header
wavelet_indexWaveletFilters: Set by (12.4.1) transform_parameters
dwt_depthint: Set by (12.4.1) transform_parameters
wavelet_index_hoWaveletFilters: Set by (12.4.4.1) extended_transform_parameters
dwt_depth_hoint: Set by (12.4.4.1) extended_transform_parameters
slices_xint: Set by (12.4.5.2) slice_parameters
slices_yint: Set by (12.4.5.2) slice_parameters
slice_bytes_numeratorint: Set by (12.4.5.2) slice_parameters
slice_bytes_denominatorint: Set by (12.4.5.2) slice_parameters
slice_prefix_bytesint: Set by (12.4.5.2) slice_parameters
slice_size_scalerint: Set by (12.4.5.2) slice_parameters
quant_matrix{level: {orient: int, …}, …}: Set by (12.4.5.3) quant_matrix
quantizer{level: {orient: int, …}, …}: Set by (13.5.5) slice_quantizers
y_transform{level: {orient: [[int, …], …], …}, …}: Set by (13.5.6.3) slice_band. The dequantised luma transform data read from the bitstream. A 2D array for each subband, indexed as [level][orient][y][x].
c1_transform{level: {orient: [[int, …], …], …}, …}: Set by (13.5.6.3) slice_band and (13.5.6.4) color_diff_slice_band. The dequantised color difference 1 transform data read from the bitstream. A 2D array for each subband, indexed as [level][orient][y][x].
c2_transform{level: {orient: [[int, …], …], …}, …}: Set by (13.5.6.3) slice_band and (13.5.6.4) color_diff_slice_band. The dequantised color difference 2 transform data read from the bitstream. A 2D array for each subband, indexed as [level][orient][y][x].
fragment_data_lengthint: Set by (14.2) fragment_header
fragment_slice_countint: Set by (14.2) fragment_header
fragment_x_offsetint: Set by (14.2) fragment_header
fragment_y_offsetint: Set by (14.2) fragment_header
fragment_slices_receivedint: Set by (14.4) fragment_data
fragmented_picture_doneint: Set by (14.4) fragment_data
current_picture{‘pic_num’: int, ‘Y’: [[int, …], …], ‘C1’: [[int, …], …], ‘C2’: [[int, …], …]}: Set by (15.2) picture_decode, contains the decoded picture.
next_bitint: Set by (A.2.1) read_*
current_byteint: Set by (A.2.1) read_*
bits_leftint: Bits left in the current bounded block (A.4.2)
_generic_sequence_matchervc2_conformance.symbol_re.Matcher: Not in spec, used by vc2_conformance.decoder. A Matcher which checks that the sequence follows the specified general pattern of data units (10.4.1) (e.g. start with a sequence header, end with end of sequence). Other matchers will test for, e.g. level-defined patterns.
_output_picture_callbackfunction({‘pic_num’: int, ‘Y’: [[int, …], …], ‘C1’: [[int, …], …], ‘C2’: [[int, …], …]}, VideoParameters, PictureCodingModes): Not in spec, used by vc2_conformance.decoder. A callback function to call when output_picture (15.2) is called. This callback (if defined) will be passed the picture, video parameters and picture coding mode.
_num_pictures_in_sequenceint: Not in spec, used by vc2_conformance.decoder. (10.4.3) and (12.2) A counter of how many pictures have been encountered in the current sequence. Used to determine if all fields have been received (when pictures are fields) and that the earliest fields have an even picture number. Initialised in parse_sequence (10.4.1) and incremented in vc2_conformance.decoder.assertions.assert_picture_number_incremented_as_expected(), called in picture_header (12.2), and fragment_header (14.2).
_last_parse_info_offsetint: Not in spec, used by vc2_conformance.decoder. (10.5.1) parse_info related state. The byte offset of the previously read parse_info block.
_recorded_bytesbytearray: Not in spec, used by vc2_conformance.decoder. (11.1) sequence_header requires that repeats must be byte-for-byte identical. To facilitate this, the vc2_conformance.decoder.io.record_bitstream_start() and vc2_conformance.decoder.io.record_bitstream_finish() functions are used to make a recording. When this entry is absent, read_byte works as usual. If it is a bytearray, whenever a byte has been completely read, it will be placed into this array.
_last_sequence_header_bytesbytearray: Not in spec, used by vc2_conformance.decoder. (11.1) the bitstream bytes of the data which encoded the previous sequence_header in the sequence. Not present if no previous sequence_header has appeared.
_last_sequence_header_offsetint: Not in spec, used by vc2_conformance.decoder. (11.1) the bitstream offset in bytes of the data which encoded the previous sequence_header in the sequence. Not present if no previous sequence_header has appeared.
_expected_major_versionint: Not in spec, used by vc2_conformance.decoder. Used to record the expected major_version (11.2.1) for this sequence according to the constraints listed in (11.2.2). This field is set by log_version_lower_bound().
_last_picture_number_offset(byte offset, next bit): Not in spec, used by vc2_conformance.decoder. (12.2) picture_header and (14.2) fragment_header: The offset of the last picture number encountered in the sequence (or absent if no pictures have yet been encountered).
_last_picture_numberint: Not in spec, used by vc2_conformance.decoder. (12.2) picture_header and (14.2) fragment_header: The last picture number encountered in the sequence (or absent if no pictures have yet been encountered).
_picture_initial_fragment_offset(byte offset, next bit): Not in spec, used by vc2_conformance.decoder. (14) The offset in the bitstream of the last fragment with fragment_slice_count==0.
_fragment_slices_remainingint: Not in spec, used by vc2_conformance.decoder. (14) The number of fragment slices which remain to be received in the current picture. Initialised to zero by parse_sequence (10.4.1), reset to the number of slices per picture by initialize_fragment_state (14.3) and decremented whenever a slice is received by fragment_data (14.4).
_filefile-like: The Python file-like object from which the bitstream will be read by read_byte (A.2.1) .
_level_sequence_matchervc2_conformance.symbol_re.Matcher: Not in spec, used by vc2_conformance.decoder. A Matcher which checks that the sequence follows the pattern dictated by the current level. Populated after the first (11.2.1) parse_parameters is encountered (and should therefore be ignored until that point).
_level_constrained_values{key: value, …}: Not in spec, used by vc2_conformance.decoder. A dictionary which will be incrementally populated with values read or computed from the bitstream which are constrained by the level constraints table (see vc2_conformance.level_constraints.LEVEL_CONSTRAINTS and vc2_conformance.decoder.assertions.assert_level_constraint()).

reset_state(state)¶: Reset a State dictionary to only include values retained between sequences in a VC-2 stream. Modifies the dictionary in place.

`vc2_conformance.pseudocode.vc2_math`¶

Mathematical functions and operators defined in the spec (5.5.3)

intlog2_float(n)¶

(5.5.3) Implemented as described in the spec, requiring floating point arithmetic.

In practice, the alternative implementation in intlog2() should be used instead since it does not rely on floating point arithmetic (and is therefore faster and has unlimited precision).

intlog2(n)¶: (5.5.3) Implemented via pure integer, arbitrary-precision operations.

sign(a)¶: (5.5.3)

clip(a, b, t)¶: (5.5.3)

mean(*S)¶: (5.5.3)

`vc2_conformance.pseudocode.video_parameters`¶

Video parameter computation functions (11)

The functions in this module make up the purely functional (i.e. non bitstream-reading) logic for computing video parameters. This predominantly consists of preset-loading and component dimension calculation routines.

For functions below which take a ‘state’ argument, this should be a dictionary-like object (e.g. State) with the following entries:

"frame_width"
"frame_height"
"luma_width"
"luma_height"
"color_diff_width"
"color_diff_height"
"luma_depth"
"color_diff_depth"
"picture_coding_mode"

fixeddict VideoParameters¶

(11.4) Video parameters struct.

Keys

frame_widthint: Set by (11.4.3) frame_size
frame_heightint: Set by (11.4.3) frame_size
color_diff_format_indexColorDifferenceSamplingFormats: Set by (11.4.4) color_diff_sampling_format
source_samplingSourceSamplingModes: Set by (11.4.5) scan_format
top_field_firstbool: Set by (11.4.5) set_source_defaults
frame_rate_numerint: Set by (11.4.6) frame_rate
frame_rate_denomint: Set by (11.4.6) frame_rate
pixel_aspect_ratio_numerint: Set by (11.4.7) aspect_ratio
pixel_aspect_ratio_denomint: Set by (11.4.7) aspect_ratio
clean_widthint: Set by (11.4.8) clean_area
clean_heightint: Set by (11.4.8) clean_area
left_offsetint: Set by (11.4.8) clean_area
top_offsetint: Set by (11.4.8) clean_area
luma_offsetint: Set by (11.4.9) signal_range
luma_excursionint: Set by (11.4.9) signal_range
color_diff_offsetint: Set by (11.4.9) signal_range
color_diff_excursionint: Set by (11.4.9) signal_range
color_primaries_indexPresetColorPrimaries: Set by (11.4.10.2) color_primaries
color_matrix_indexPresetColorMatrices: Set by (11.4.10.3) color_matrix
transfer_function_indexPresetTransferFunctions: Set by (11.4.10.4) transfer_function

set_source_defaults(base_video_format)¶: (11.4.2) Create a VideoParameters object with the parameters specified in a base video format.

set_coding_parameters(state, video_parameters)¶: (11.6.1) Set picture coding mode parameter.

picture_dimensions(state, video_parameters)¶: (11.6.2) Compute the picture component dimensions in global state.

video_depth(state, video_parameters)¶: (11.6.3) Compute the bits-per-sample for the decoded video.

preset_frame_rate(video_parameters, index)¶: (11.4.6) Set frame rate from preset.

preset_pixel_aspect_ratio(video_parameters, index)¶: (11.4.7) Set pixel aspect ratio from preset.

preset_signal_range(video_parameters, index)¶: (11.4.7) Set signal range from preset.

preset_color_primaries(video_parameters, index)¶: (11.4.10.2) Set the color primaries parameter from a preset.

preset_color_matrix(video_parameters, index)¶: (11.4.10.3) Set the color matrix parameter from a preset.

preset_transfer_function(video_parameters, index)¶: (11.4.10.4) Set the transfer function parameter from a preset.

preset_color_spec(video_parameters, index)¶: (11.4.10.1) Load a preset color specification.

`vc2_conformance.pseudocode.metadata`¶

The vc2_conformance.pseudocode.metadata module is used to record the relationship between the functions in the vc2_conformance software and the pseudocode functions in the VC-2 specification documents. This information has two main uses:

To produce more helpful error messages which include cross-references to published specifications.
To enable automatic verification that the behaviour of this software exactly matches the published specifications (see verification).

Implementing pseudocode functions¶

Functions in the codebase which implement a pseudocode function in the specification must be labelled as such using the ref_pseudocode() decorator:

>>> from vc2_conformance.pseudocode.metadata import ref_pseudocode

>>> @ref_pseudocode
... def parse_info(state):
...     '''(10.5.1) Read a parse_info header.'''
...     byte_align()
...     read_uint_lit(state, 4)
...     state["parse_code"] = read_uint_lit(state, 1)
...     state["next_parse_offset"] = read_uint_lit(state, 4)
...     state["previous_parse_offset"] = read_uint_lit(state, 4)

The ref_pseudocode() decorator will log the existence of the decorated function, along with the reference to the spec at the start of its docstring.

By default, it is implied that a decorated function does not deviate from the pseudocode – a fact which is verified by the verification module in the test suite. When a function does deviate (for example for use in serialisation/deserialisation) or is not defined in the spec, the deviation argument should be provided. This is used by the verification logic to determine how the function will be verified. See Pseudocode deviations for the allowed values. For example:

>>> @ref_pseudocode(deviation="serdes")
... def parse_parameters(serdes, state):
...     '''(11.2.1)'''
...     state["major_version"] = serdes.uint("major_version")
...     state["minor_version"] = serdes.uint("minor_version")
...     state["profile"] = serdes.uint("profile")
...     state["level"] = serdes.uint("level")

ref_pseudocode(*args, **kwargs)¶

Decorator for marking functions which are derived from the VC-2 pseudocode.

Example usage:

@ref_pseudocode
def parse_info(state):
    ''''(10.5.1) Read a parse_info header.'''
    # ...

@ref_pseudocode("10.5.1", deviation="alternative_implementation")
def parse_info(state):
    '''Some alternative implementation of parse info.'''

Parameters

deviationstr or None

If this function deviates from the pseudocode in any way, indicates the nature of this deviation. None indicates that this function exactly matches the pseudocode.

Automatic checks for pseudocode equivalence in the test suite (see verification) will use this value to determine how exactly this function must match the pseudocode for tests to pass. See Pseudocode deviations for details of values this field may hold.

document, sectionstr or None

The name of the document and section defining this function. If None, will be extracted from the function docstring. Defaults to the main VC-2 specification. If not provided, and not found in the docstring, a TypeError will be thrown.

When extracted from a docstring, a reference of one of the following forms must be used at the start of the docstring:

(1.2.3): Reference a section in the main VC-2 spec
(SMPTE ST 20402-2:2017: 1.2.3): Reference a section in another spec

namestr or None

The name of the pseudocode function this function implements. If None, the provided function’s name will be used.

Accessing the metadata¶

After all submodules of vc2_conformance have been loaded, the pseudocode_derived_functions list will be populated with PseudocodeDerivedFunction instances for every pseudocode derived function annotated with ref_pseudocode().

class PseudocodeDerivedFunction(function, deviation=None, document=None, section=None, name=None)¶

A record of a pseudocode-derived function within this codebase.

Parameters

functionfunction

The Python function which was derived from a pseudocode function.

deviationstr or None

If this function deviates from the pseudocode in any way, indicates the nature of this deviation. None indicates that this function exactly matches the pseudocode.

Automatic checks for pseudocode equivalence in the test suite (see verification) will use this value to determine how exactly this function must match the pseudocode for tests to pass. See Pseudocode deviations for details of values this field may hold.

document, sectionstr or None

The name of the document and section defining this function. If None, will be extracted from the function docstring. Defaults to the main VC-2 specification. If not provided, and not found in the docstring, a TypeError will be thrown.

When extracted from a docstring, a reference of one of the following forms must be used at the start of the docstring:

(1.2.3): Reference a section in the main VC-2 spec
(SMPTE ST 20402-2:2017: 1.2.3): Reference a section in another spec

namestr or None

The name of the pseudocode function this function implements. If None, the provided function’s name will be used.

property citation¶: A human-readable citation string for this pseudocode function.

pseudocode_derived_functions = [PseudocodeDerivedFunction, ...]¶: The complete set of PseudocodeDerivedFunctions in this code base, in no particular order.

Warning

This array is only completely populated once every module of vc2_conformance has been loaded.

Pseudocode tracebacks¶

The make_pseudocode_traceback() function may be used to convert a Python traceback into a pseudocode function traceback.

make_pseudocode_traceback(tb)¶: Given a traceback.extract_tb() generated traceback description, return a list of PseudocodeDerivedFunction objects for the stack trace, most recently called last. Entries in the traceback which don’t have a corresponding pseudocode-derived function are omitted.

`vc2_conformance.pseudocode`: VC-2 pseudocode function implementations¶

`vc2_conformance.pseudocode.arrays`¶

`vc2_conformance.pseudocode.offsetting`¶

`vc2_conformance.pseudocode.parse_code_functions`¶

`vc2_conformance.pseudocode.picture_decoding`¶

`vc2_conformance.pseudocode.picture_encoding`¶

`vc2_conformance.pseudocode.quantization`¶

`vc2_conformance.pseudocode.slice_sizes`¶

`vc2_conformance.pseudocode.state`¶

`vc2_conformance.pseudocode.vc2_math`¶

`vc2_conformance.pseudocode.video_parameters`¶

`vc2_conformance.pseudocode.metadata`¶

Implementing pseudocode functions¶

Accessing the metadata¶

Pseudocode tracebacks¶

Table of Contents

Previous topic

Next topic

This Page

vc2_conformance.pseudocode: VC-2 pseudocode function implementations¶

Implementing pseudocode functions¶

Accessing the metadata¶

Pseudocode tracebacks¶

`vc2_conformance.pseudocode`: VC-2 pseudocode function implementations¶