Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.
In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.
There are multiple important problems with this approach:
- the fields in AVCodecContext are in general one of
* stream parameters
* codec options
* codec state
However, it's not clear which ones are which. It is consequently
unclear which fields are a demuxer allowed to set or a muxer allowed to
read. This leads to erratic behaviour depending on whether decoding or
encoding is being performed or not (and whether it uses the AVStream
embedded codec context).
- various synchronization issues arising from the fact that the same
context is used by several different APIs (muxers/demuxers,
parsers, bitstream filters and encoders/decoders) simultaneously, with
there being no clear rules for who can modify what and the different
processes being typically delayed with respect to each other.
- avformat_find_stream_info() making it necessary to support opening
and closing a single codec context multiple times, thus
complicating the semantics of freeing various allocated objects in the
codec context.
Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
AVFormatParameters are converted into corresponding private options in
av_open_input_file/stream() compat wrappers, so accessing them from
demuxers is redundant.
Show the invalid string in the error message.
While at it also prefer "Could not" over "Couldn't", plain forms are
preferred over contractions (simplify readability, especially for non
English-savvy people).
Signed-off-by: Anton Khirnov <anton@khirnov.net>
The variable is used for containing the parsed value of s1->framerate,
using a lexically consistent name ease readability/understanding.
Signed-off-by: Anton Khirnov <anton@khirnov.net>
Adding _POSIX_C_SOURCE to CPPFLAGS globally produces all sorts of problems
since it causes certain system functions to be hidden on some (BSD) systems.
The solution is to only add the flag on systems that really require it, i.e.
glibc-based ones.
This change makes BSD systems compile out-of-the-box without the need for
adding specific flags manually. It also allows dropping a number of flags
set manually on a file-per-file basis, but were only present to work around
breakage introduced by the presence of _POSIX_C_SOURCE.
Also add _XOPEN_SOURCE to CPPFLAGS for glibc systems. We use XSI extensions
in several places already, so it is preferable to define it globally instead
of littering source files with individual #defines only needed for glibc.
Mark bktr_init function as av_cold.
Tested to work by Michael Kostylev on the NetBSD FATE box.
Originally committed as revision 22487 to svn://svn.ffmpeg.org/ffmpeg/trunk
This make NetBSD compile out of the box at the cost of a hack, but a
locally contained one that is preferable to the one used in the wild.
Currently the NetBSD FATE box adds -D_NETBSD_SOURCE to CPPFLAGS to work
around broken system headers. Since it is unlikely for NetBSD to fix their
headers, it is better to use a standard flag instead of a system-specific one.
As a sideeffect, this allows getting rid of a local _NETBSD_SOURCE definition.
Originally committed as revision 22486 to svn://svn.ffmpeg.org/ffmpeg/trunk
NetBSD is unlikely to fix their headers and the FATE box passes it
as -D_NETBSD_SOURCE on the command line anyway. In this case, it's
better to keep the hack well-contained within this file.
Closes issue 886.
patch by Jorge Acereda, jacereda brainstorm es
Originally committed as revision 22164 to svn://svn.ffmpeg.org/ffmpeg/trunk
patch by Stefano Sabatini, stefano.sabatini-lala poste.it
along with some spelling/consistency fixes for the long names by me
Originally committed as revision 13649 to svn://svn.ffmpeg.org/ffmpeg/trunk
Currently untested; someone with the correct OS and hardware should
test it and report if it works.
Originally committed as revision 11060 to svn://svn.ffmpeg.org/ffmpeg/trunk
Anton Khirnov
Himangi Saraogi
Diego Biurrun
Martin Storsjö
Rémi Denis-Courmont
Stefano Sabatini
Mans Rullgard
Diego Elio Pettenò
Jorge Acereda
Reimar Döffinger
Aurelien Jacobs
Luca Abeni
Ramiro Polla