vc2-bitstream-validator
¶
A command-line utility for validating VC-2 bitstreams’ conformance with the VC-2 specification and providing a reference decoding of the pictures within.
Usage¶
This command should be passed a filename containing a candidate VC-2 bitstream. For example, given a valid stream:
$ vc2-bitstream-validator path/to/bitstream.vc2 --output decoded_picture_%d.raw
No errors found in bitstream. Verify decoded pictures to confirm conformance.
Here the --output
argument specifies the printf-style template for the
decoded picture filenames. The decoded pictures are written as raw files (see
Video file format).
If a conformance error is detected, a detailed explanation of the problem is displayed:
$ vc2-bitstream-validator invalid.vc2
Conformance error at bit offset 104
===================================
Non-zero previous_parse_offset, 5789784, in the parse info at the start of
a sequence (10.5.1).
Details
-------
Was this parse info block copied from another stream without the
previous_parse_offset being updated?
Does this parse info block incorrectly include an offset into an adjacent
sequence?
Suggested bitstream viewer commands
-----------------------------------
To view the offending part of the bitstream:
vc2-bitstream-viewer invalid.vc2 --offset 104
Pseudocode traceback
--------------------
Most recent call last:
* parse_stream (10.3)
* parse_sequence (10.4.1)
* parse_info (10.5.1)
vc2-bitstream-validator: error: non-conformant bitstream (see above)
Errors include an explanation of the conformance problem (along with references to the VC-2 standards documents) along with possible causes of the error. Additionally, a sample invocation of vc2-bitstream-viewer is given which can be used to display the contents of the bitstream at the offending position. Finally, a stack trace for the VC-2 pseudocode functions involved in parsing the stream at the point of failure is also printed.
Arguments¶
The complete set of arguments can be listed using --help
usage: vc2-bitstream-validator [-h] [--version] [--no-status] [--verbose]
[--output OUTPUT]
bitstream
Validate a bitstream's conformance with the VC-2 specifications.
positional arguments:
bitstream The filename of the bitstream to validate.
optional arguments:
-h, --help show this help message and exit
--version show program's version number and exit
--no-status, --quiet, -q
Do not display a status line on stderr while
validating the bitstream.
--verbose, -v Show full Python stack-traces on failure.
--output OUTPUT, -o OUTPUT
The filename pattern for decoded picture data and
metadata. The supplied pattern should a 'printf' style
template with (e.g.) '%d' where an index will be
substituted. The first decoded picture will be
assigned index '0', the second '1' and so on -- i.e.
these indices are unrelated to the picture number. The
file extension supplied will be stripped and two files
will be written for each decoded picture: a '.raw'
planar image file and a '.json' JSON metadata file.
(Default: picture_%d.raw).