def _print_omitted_bits(self, tell):
"""
Display the number of bits omitted since the last displayed value up
until 'tell'.
"""
offset = bitstream.to_bit_offset(*tell)
last_displayed_offset = bitstream.to_bit_offset(*self._last_displayed_tell)
num_bits = offset - last_displayed_offset
print(format_omission_line(last_displayed_offset, num_bits))
def _print_error(self, message):
"""
Print an error message to stderr.
"""
# Avoid interleaving with stdout (and make causality clearer)
sys.stdout.flush()
# The 'trailing bits' print out below might move the read position
# so record it now.
if self._reader is not None:
offset = bitstream.to_bit_offset(*self._reader.tell())
# Display the trailing bits from the bitstream
if self._verbose >= 1:
if self._reader is not None:
self._reader.seek(*self._last_tell)
bits = self._reader.try_read_bitarray(self._num_trailing_bits_on_error)
if len(bits) > 0:
sys.stderr.write(
"{}\n".format(
format_value_line(
bitstream.to_bit_offset(*self._last_tell),
bitarray(bits),
"<next {} bits>".format(len(bits)),
)
)
)
# Display the traceback
if self._verbose >= 2:
if sys.exc_info()[0] is not None:
traceback.print_exc()
# Display offset/target information
prog = os.path.basename(sys.argv[0])
if self._verbose >= 1:
if self._reader is not None:
sys.stderr.write(
"{}: offset: {}\n".format(
prog,
offset,
)
)
if self._serdes is not None:
sys.stderr.write(
"{}: target: {}\n".format(
prog,
format_path_summary(self._serdes.path()),
)
)
# Display the message
message = "{}: error: {}".format(prog, message)
sys.stderr.write("{}\n".format(message))
def monitor(des, target, _value):
# Dirty: Relies on implementation detail of vc2_fixeddicts...
if des.path(target)[4:] in (
["picture_parse", "wavelet_transform", "padding"],
["fragment_parse", "fragment_header", "fragment_slice_count"],
["fragment_parse", "fragment_header", "fragment_y_offset"],
):
slice_start_offset[0] = to_bit_offset(*des.io.tell())
elif target == "qindex":
contained_slices[0] = True
elif target == "parse_code" and slice_start_offset[0] is not None:
if contained_slices[0]:
out.append(to_bit_offset(*des.io.tell()) - slice_start_offset[0])
contained_slices[0] = False
def _update_status_line(self, target):
"""
Update the status line, if a sufficiently long time has ellpased (to
avoid spending too long printing to the console).
"""
now = time.time()
if now - self._status_line_updated >= STATUS_LINE_UPDATE_INTERVAL:
self._status_line_visible = True
self._status_line_updated = now
cur_offset = bitstream.to_bit_offset(*self._reader.tell())
cur_path = format_path_summary(self._serdes.path(target))
terminal_width = get_terminal_size()[0]
line = "{:0{}d}: <{}>".format(
cur_offset,
OFFSET_DIGITS,
ellipsise_lossy(cur_path, terminal_width - OFFSET_DIGITS - 4),
)
# Ensure stdout is fully displayed before printing the status line
sys.stdout.flush()
sys.stderr.write(
(
"\033[2K" # Clear to end of line
"\033[s" # Save cursor position
"{}"
"\033[u" # Restore cursor position
).format(line)
)
sys.stderr.flush()
def _print_conformance_error(self, exception, tb):
"""
Display detailed information from a ConformanceError on stdout.
"""
terminal_width = get_terminal_size()[0]
summary, _, details = wrap_paragraphs(
exception.explain()).partition("\n")
offending_offset = exception.offending_offset()
if offending_offset is None:
offending_offset = to_bit_offset(*tell(self._state))
title = "Conformance error at bit offset {}".format(offending_offset)
bitstream_viewer_hint = (dedent(
exception.bitstream_viewer_hint()).strip().format(
cmd="vc2-bitstream-viewer",
file=quote(self._filename),
offset=offending_offset,
))
out = ""
out += title + "\n"
out += ("=" * len(title)) + "\n"
out += "\n"
out += wrap_paragraphs(summary, terminal_width) + "\n"
out += "\n"
out += "\n"
out += "Details\n"
out += "-------\n"
out += "\n"
out += wrap_paragraphs(details, terminal_width) + "\n"
out += "\n"
out += "\n"
out += "Suggested bitstream viewer commands\n"
out += "-----------------------------------\n"
out += "\n"
out += bitstream_viewer_hint + "\n"
out += "\n"
out += "\n"
out += "Pseudocode traceback\n"
out += "--------------------\n"
out += "\n"
out += "Most recent call last:\n"
out += "\n"
out += format_pseudocode_traceback(tb) + "\n"
print(out)
def test_generate_exp_golomb_numbers_with_ascending_lengths(sign):
for length, number in islice(
generate_exp_golomb_with_ascending_lengths(sign),
128,
):
# Use a known-good implementation of a signed exp-golmb encoder and
# check length is correct.
f = BytesIO()
w = BitstreamWriter(f)
w.write_sint(number)
actual_length = to_bit_offset(*w.tell())
assert actual_length == length
# Check sign of number
if sign < 0:
assert number <= 0
else:
assert number >= 0
def test_to_and_from_bit_offset(bytes, bits, offset):
assert bitstream.to_bit_offset(bytes, bits) == offset
assert bitstream.from_bit_offset(offset) == (bytes, bits)
def __call__(self, serdes, target, value):
"""
Called as the monitoring function of the the
:py:class:`MonitoredDeserialiser`. Responsible for printing values from
the bitstream and terminating once the region of interest has been
parsed.
"""
last_tell = self._last_tell
this_tell = self._reader.tell()
self._last_tell = this_tell
if self._show_internal_state:
# Only show at start of new data unit (NB: strictly speaking this
# will display the state was it was after parsing the first field
# of each data unit. Since this is a padding field, the state
# should still be correct.
num_data_units = sum(
len(sequence["data_units"])
for sequence in self._serdes.context["sequences"]
)
if self._last_num_data_units != num_data_units:
self._last_num_data_units = num_data_units
self._hide_status_line()
self._print_internal_state()
this_offset = bitstream.to_bit_offset(*this_tell)
enable_display = False
enable_display = (
# Within the specified region (NB: we terminate once past it)
(self._from_offset == 0 or this_offset > self._from_offset)
and
# Is the current context selected to be shown
(
self._hidden_types is None
or self._serdes.cur_context.__class__ not in self._hidden_types
)
and (
self._shown_types is None
or self._serdes.cur_context.__class__ in self._shown_types
)
)
if enable_display:
self._hide_status_line()
last_offset = bitstream.to_bit_offset(*last_tell)
# Print message if we've skipped some bits
if self._last_displayed_tell != last_tell:
self._print_omitted_bits(last_tell)
self._last_displayed_tell = this_tell
# Re-read the bits within the value just read and display it
self._reader.seek(*last_tell)
raw_bits = self._reader.read_bitarray(this_offset - last_offset)
self._print_value(last_offset, raw_bits, target, value)
else:
if self._show_status:
self._update_status_line(target)
# Stop if we've encountered an invalid parse_info prefix code
if self._check_parse_info_prefix:
# The test below relies on the only use of the target name
# 'parse_info_prefix' being for the parse info prefix. (This should
# be the case).
if target == "parse_info_prefix" and value != PARSE_INFO_PREFIX:
raise BitstreamViewer._TerminateError(
"invalid parse_info prefix ({})".format(Hex(8)(value))
)
# Stop when we've reached/passed the end of the region of interest
if self._to_offset != 0 and this_offset >= self._to_offset:
raise BitstreamViewer._TerminateSuccess()
# Save memory by discarding previously deserialised data units
current_data_unit = True
for sequence in reversed(self._serdes.context["sequences"]):
for i in reversed(range(len(sequence["data_units"]))):
if not current_data_unit:
sequence["data_units"][i] = None
current_data_unit = False
def test_happy_cases(self, block_bits, num_values, magnitude):
value_sets = {
dangle_type: generate_dangling_transform_values(
block_bits,
num_values,
dangle_type,
magnitude,
)
for dangle_type in DanglingTransformValueType
}
values_and_bits_beyond_ends = {}
for description, values in value_sets.items():
# Should all have required number of values
assert len(values) == num_values
# Should correctly encode into bounded block
f = BytesIO()
w = BitstreamWriter(f)
w.bounded_block_begin(block_bits)
for value in values:
w.write_sint(value)
# Should completely fill the block
length_used = to_bit_offset(*w.tell())
assert length_used == block_bits
# Check we actually wrote 'beyond' the end of the block
assert w.bits_remaining < 0
# Work out which value and which bits actually first crossed the
# end-of-block boundary (we'll later check that these actually
# match our expectations later)
w.flush()
f.seek(0)
r = BitstreamReader(f)
r.bounded_block_begin(block_bits)
value_beyond_end = None
bits_beyond_end = None
while r.bits_remaining >= 0:
value_beyond_end = r.read_sint()
bits_beyond_end = -r.bits_remaining
values_and_bits_beyond_ends[description] = (
value_beyond_end,
bits_beyond_end,
)
# Check that the dangling value dangles in the expected way
v, b = values_and_bits_beyond_ends[
DanglingTransformValueType.zero_dangling]
assert v == 0
assert b == 1
v, b = values_and_bits_beyond_ends[
DanglingTransformValueType.sign_dangling]
assert v != 0
assert (-v).bit_length() == magnitude
assert b == 1
v, b = values_and_bits_beyond_ends[
DanglingTransformValueType.stop_and_sign_dangling]
assert v != 0
assert (-v).bit_length() == magnitude
assert b == 2
v, b = values_and_bits_beyond_ends[
DanglingTransformValueType.lsb_stop_and_sign_dangling]
assert v != 0
# NB: Larger due to exp-golmb code needing to end in 1
assert (-v).bit_length() == magnitude + 1
assert b == 3
