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.
The size variable is (correctly) unsigned, but is passed to several functions
which take signed parameters, such as avio_read, sometimes after having
numbers added to it. So ensure that size remains within the bounds that
these functions can handle.
CC: libav-stable@libav.org
Signed-off-by: Diego Biurrun <diego@biurrun.de>
The following error handling is broken due to signedness.
int file_size;
uint32_t tag_bytes;
int64_t tag_start;
...
tag_start = file_size - tag_bytes - APE_TAG_FOOTER_BYTES;
if (tag_start < 0) { ... }
Note that tag_bytes is unsigned, which makes the right-hand side of
`tag_start = ...' unsigned, too. The 32-bit unsigned value is then
zero-extended to 64 bits. Therefore, tag_start must be non-negative,
and the check (tag_start < 0) is always false, which breaks the error
handling. This patch fixes the check.
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>
In the name of consistency:
get_byte -> avio_r8
get_<type> -> avio_r<type>
get_buffer -> avio_read
get_partial_buffer will be made private later
get_strz is left out becase I want to change it later to return
something useful.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
AVERROR(ENOMEM).
AVERROR_NOMEM is deprecated and will be dropped at the next libavutil
major bump.
Originally committed as revision 22791 to svn://svn.ffmpeg.org/ffmpeg/trunk
arrays of fixed length.
Code from ffmbc with changes to adapt to our metadata API.
Originally committed as revision 20836 to svn://svn.ffmpeg.org/ffmpeg/trunk
It uses the old, deprecated metadata API and prints exactly the same thing
as what ffmpeg/ffplay does.
Originally committed as revision 20280 to svn://svn.ffmpeg.org/ffmpeg/trunk
Based on patch by Matti Hamalainen (mhamalai<mot>students<punkt>oamk<punkt>)
Originally committed as revision 19629 to svn://svn.ffmpeg.org/ffmpeg/trunk
