This extends the syntax for specifying input streams in -map and complex
filtergraph labels, to allow selecting a view by view ID, index, or
position. The corresponding decoder is then set up to decode the
appropriate view and send frames for that view to the correct
filtergraph input(s).
This approach has the major advantage that only parsing can fail (due to
a malformed specifier or memory allocation failure). Since parsing is
done generically, while matching is per-option, this will allow to
remove substantial amounts of error checking code in following commits.
The new code also explicitly allows stream specifiers to be followed by
additional characters, which should allow cleaner handling of optional
maps, i.e. -map <stream_specifier>?, which is currently implemented in a
hacky way that breaks when the stream specifier itself contains the '?'
character (this can happen when matching metadata). It will also allow
further extending the syntax, which will be useful in following commits.
This introduces some minor behaviour changes:
* Matching metadata tags now requires the ':' character in keys or
values to be escaped. Previously it could not be present in keys, and
would be used verbatim in values. The change is required in order to
know where the value terminates.
* Multiple stream types in a single specifier are now rejected - such a
specifier makes no sense.
* Non-existent stream group ID or index is now ignored with a warning
rather than causing a failure. This is consistent with program
handling and is required to make matching fail-free.
Stream specifiers were originally designed exclusively for CLI use and
were not intended to be public API. Handling them in avformat places
major restrictions on how they are used. E.g. if ffmpeg CLI wishes to
override some stream parameters, it has to change the demuxer fields
(since avformat_match_stream_specifier() does not have access to
anything else). However, such fields are supposed to be read-only for
the caller.
Furthermore having this code in avformat restricts extending the
specifier syntax. An example of such an extension will be added in
following commits.
This has multiple advantages:
* The macro has multiple parameters that often have similar or identical
values, yet very different meanings (one is the name of the
OptionsContext member where the parsed options are stored, the other
the name of the variable into which the result is written); this
change makes each of these explicit.
* The macro returns on failure, which may cause leaks - this was the
reason for adding MATCH_PER_STREAM_OPT_CLEAN(), also ost_add()
currently leaks encoder_opts. The new function returns failure to its
caller, which decides how to deal with it. While that adds a lot of
error checks/forwards for now, those will be reduced in following
commits.
* new code is type- and const- correct
Invocations of MATCH_PER_STREAM_OPT() with other types will be converted
in following commits.
Share the code between encoding and decoding. Instead of checking every
stream's options dictionary (which is also used for other purposes),
track all used options in a dedicated dictionary.
issue found while reviewing CID1452612 Free of array-typed value
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
There are lots of files that don't need it: The number of object
files that actually need it went down from 2011 to 884 here.
Keep it for external users in order to not cause breakages.
Also improve the other headers a bit while just at it.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
There is only a single caller of filter_codec_opts() that passes
a NULL codec to it, which is streamcopy in ffmpeg CLI. In that case we
only want generic AVCodecContext options, not private options of any
specific encoder.
It is only used by ffprobe (once) and ffplay (twice);
inlining it avoids including it unnecessarily into ffmpeg.
Reviewed-by: Stefano Sabatini <stefasab@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Currently it requires every single OPT_SPEC option to be accompanied by
an array of alternate names for this option. The vast majority of
options have no alternate names, resulting in a large numbers of
unnecessary single-element arrays that merely contain the option name.
Extend the option parsing API to allow marking options as having
alternate names, or as being the canonical name for some existing
alternatives. Use this new information to avoid the need for
abovementioned unnecessary single-element arrays.
This option flag only carries nontrivial information for options that
call a function, in all other cases its presence can be inferred from
the option type (bool options do not have arguments, all other types do)
and is thus nothing but useless clutter.
Change the option parsing code to infer its value when it can, and drop
the flag from options where it's not needed.
av_err2str which is a wrapper for av_strerror already calls
strerror_r if available and if not has a fallback for the other
error codes that would be handled by that, so manually calling
strerror again if it fails is not necessary.
Signed-off-by: Anton Khirnov <anton@khirnov.net>
Anton Khirnov
Marvin Scholz
Michael Niedermayer
Marton Balint
Zhao Zhili
Andreas Rheinhardt