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 next frame time could slip, causing the frame rate to drop until
frames were dropped. Now will capture at the next correct moment instead.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Incidentally `-y` also collides with avconv global options.
Update x11grab to match and document the option.
CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
The paint_mouse_pointer() code uses XFixes to retrieve the cursor
coordinates, but XFixes gives no information about which screen the
pointer is on; this results in always drawing the cursor on the
captured screen even if the mouse pointer was on another screen.
For example, when capturing from screen 1 (i.e. -f x11grab -i ":0.1")
the cursor was being drawn in the captured image even when the mouse
pointer was actually on screen 0, which is wrong and visually confusing.
CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
The code uses XFixes to retrieve the cursor coordinates, but XFixes
gives no information of what screen the pointer is on; this results in
always drawing the cursor on the captured screen even if the mouse
pointer was on another screen.
For example, when capturing from screen 1 (i.e. -f x11grab -i ":0.1")
the cursor was being drawn in the captured image even when the mouse
pointer was actually on screen 0, which is wrong and visually confusing.
Use XQueryPointer to check that the pointer is actually on the screen
which is being captured.
Signed-off-by: Antonio Ospite <ao2@ao2.it>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This specifies better the meaning of the variable, and is also in
preparation of a subsequent change which will introduce a temporary
Window variable for which "w" is an good name.
Signed-off-by: Antonio Ospite <ao2@ao2.it>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
The X11 servers by VNC, at 32-bits depths, has the following masks:
R:0x000007ff G:0x003ff800 B:0xffc00000
This is not compatible with AV_PIX_FMT_0RGB32, and the result
is success with completely wrong colors.
In particular, do not upcase first word, do not use final dot, use a verb
to specify what the option does, sort entries by name, apply random
vertical align.
When using "-f x11grab -i :0.0" valgrind reports a definitely lost
memory block with this message:
==31544== 5 bytes in 1 blocks are definitely lost in loss record 1 of 2
==31544== at 0x4026E68: memalign (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31544== by 0x4026F17: posix_memalign (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31544== by 0x60D399A: av_malloc (in /usr/lib/x86_64-linux-gnu/libavutil.so.51.22.1)
==31544== by 0x60D3A70: av_strdup (in /usr/lib/x86_64-linux-gnu/libavutil.so.51.22.1)
==31544== by 0x4A2BE58: ??? (in /usr/lib/x86_64-linux-gnu/libavdevice.so.53.2.0)
==31544== by 0x506D29E: avformat_open_input (in /usr/lib/x86_64-linux-gnu/libavformat.so.53.21.0)
==31544== by 0x400A80: main (in /home/ao2/WIP/am7xxx-play/tests/a.out)
The 5 bytes lost are the ones from param = av_strdup(":0.0"), so let's
free param in the exit path.
Also check the av_strdup() return value.
Note: calling av_free(param) even when av_strdup() fails and param is
NULL is OK and keeps the code simpler without adding another label to
skip av_free().
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
Michael Niedermayer
Vittorio Giovara
Anton Khirnov
Trevor \\\\ Higgins
Clément Bœsch
Diego Biurrun
Christian Hujer
Luca Barbato
Antonio Ospite
Michael Niedermayer
Nicolas George
Lukasz Marek
Carl Eugen Hoyos
Paul B Mahol
Isaac Dooley
Martin Storsjö
Stefano Sabatini
Clément Bœsch
Nicolas George
Antonio Ospite