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.
Some codecs use the codec_tag to signal specific information and
picking the first one would lead to a broken file.
Bug-Id: 883
CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
libc's qsort comparator has a const qualifier on both arguments. This
adds a missing const qualifier to exactly match the comparator API.
Existing usages of av_tree_find, av_tree_insert are appropriately
modified: type signature changes of the comparators, and removal of
unnecessary void * casts of function pointers.
Reviewed-by: Henrik Gramner <henrik@gramner.com>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
This side data does not serve or improve decoding the data, it thus
would semantically be metadata and not side data.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
When the index is not written, several data tables become unneeded,
reducing memory and cpu requirements.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
The broadcast/pipe flags arent stable + 1 they would be 4 or whenever but wouldnt change based
on which is stable
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Add the low overhead pipe mode and the extended broadcast mode.
Export the options as 'syncponts' since it impacts only that.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
This fixes an assertion failure and regression and restores previous behaviour
Fixes Ticket3197
An alternative would be to fail hard in this case and refuse to mux such data.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
While a 25 fps stream can in general store frame durations in 1/25
units, this is not true for the timestamps. For example a 25fps
and a 25000/1001 fps stream when they are stored together might have
a matching 0 timestamp point but when for example a chapter from
this is cut the new start is no longer aligned. The issue gets
MUCH worse when the streams are lower fps, like 1 or 2 fps.
This commit thus makes the muxer choose a multiple of the
framerate as timebase that is at least about 20 micro seconds precise
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
With this, when we use a finer timebase than neccessary to store
durations the demuxer still knows what the original timebase was.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Marton Balint
Anton Khirnov
Michael Niedermayer
Clément Bœsch
Luca Barbato
Ganesh Ajjanagadde
Michael Niedermayer
Martin Storsjö
Timothy Gu
Vittorio Giovara
Diego Biurrun
Derek Buitenhuis
Paul B Mahol
Justin Ruggles