If the alignment is less than 16, certain libswscale code paths will
silently corrupt memory outside of the target buffer. This actually
affected the libmpv software rendering API (that was fun to debug).
Rather than passing this problem to the next API user, try to avoid it
within libmpv.
It's unclear which alignment libswscale requires for safe operation. I'm
picking 32 (one more than the observed safe value in the case I
experienced), because libavfilter mostly uses this value.
The way to work this around is slow: just make a full copy of the entire
input or output image. Possibly this could be optimized by using the
slice API, but that would be more effort, and would likely expose
further libswscale bugs. Hope that this is a rarely needed path.
The next commit will update the alignment requirement documentation
bits.
Used to be used by vo_x11, and some other situations where software
conversion was employed. Haven't seen anyone complain about how software
brightness controls went away (originating from mplayer), so whatever,
it won't be needed again.
This sucks, but is helpful for testing.
Obviously, it would be much nicer if there were a way to specify _all_
scaler options per filter (if the user wanted), instead of always using
the global options. But this is "too hard" for now. For testing, it is
extremely convenient to select the scaler backend, so add this option,
but make clear that it could go away. We'd delete it once there is a
better mechanism for this.
Raise swscale and zimg default parameters. This restores screenshot
quality settings (maybe) unset in the commit before. Also expose some
more libswscale and zimg options.
Since these options are also used for VOs like x11 and drm, this will
make x11/drm/etc. much slower. For compensation, provide a profile that
sets the old option values: sw-fast. I'm also enabling zimg here, just
as an experiment.
The core problem is that we have a single set of command line options
which control the settings used for most swscale/zimg uses. This was
done in the previous commit. It cannot differentiate between the VOs,
which need to be realtime and may accept/require lower quality options,
and things like screenshots or vo_image, which can be slower, but should
not sacrifice quality by default.
Should this have two sets of options or something similar to do the
right thing depending on the code which calls libswscale? Maybe. Or
should I just ignore the problem, make it someone else's problem (users
who want to use software conversion VOs), provide a sub-optimal
solution, and call it a day? Definitely, sounds good, pushing to master,
goodbye.
Purpose uncertain. I guess it's slightly better, maybe.
The move of the sws/zimg options from VO opts (vo_opt_list) to the
top-level option list is tricky. VO opts have some helper code in vo.c,
that sends VOCTRL_SET_PANSCAN to the VO on every VO opts change. That's
because updating certain VO options used to be this way (and not just
the panscan option). This isn't needed anymore for sws/zimg options, so
explicitly move them away.
Normally, input and output are orthogonal. But zimg may gain image
formats not supported by FFmpeg, which means the conversion will only
work if zimg is used at all. This on the other hand, depends on whether
the other format is also supported by zimg. (For example, a later commit
adds RGB30 output to zimg. libswscale does not support this format. But
if you have P010 as input, which the zimg wrapper does not support at
all, the conversion won't work.)
This makes such a function needed; so add it.
Awful shit. I probably wouldn't accept this code from someone else, just
so you know.
The idea is that a sws_utils user can automatically use zimg without
large code changes. Basically, laziness. Since zimg support is still
very new, and I don't want that anything breaks just because zimg was
enabled at build time, an option needs to be set to enable it. (I have
especially especially obscure stuff in mind, which is all what
libswscale is used in mpv.)
This _still_ doesn't cause zimg to be used anywhere, because the
sws_utils user has to opt-in by setting allow_zimg. This is because some
users depend on certain libswscale features.
Generally, using x86 SIMD efficiently (or crash-free) requires aligning
all data on boundaries of 16, 32, or 64 (depending on instruction set
used). 64 bytes is needed or AVX-512, 32 for old AVX, 16 for SSE. Both
FFmpeg and zimg usually require aligned data for this reason.
FFmpeg is very unclear about alignment. Yes, it requires you to align
data pointers and strides. No, it doesn't tell you how much, except
sometimes (libavcodec has a legacy-looking avcodec_align_dimensions2()
API function, that requires a heavy-weight AVCodecContext as argument).
Sometimes, FFmpeg will take a shit on YOUR and ITS OWN alignment. For
example, vf_crop will randomly reduce alignment of data pointers,
depending on the crop parameters. On the other hand, some libavfilter
filters or libavcodec encoders may randomly crash if they get the wrong
alignment. I have no idea how this thing works at all.
FFmpeg usually doesn't seem to signal alignment internal anywhere, and
usually leaves it to av_malloc() etc. to allocate with proper alignment.
libavutil/mem.c currently has a ALIGN define, which is set to 64 if
FFmpeg is built with AVX-512 support, or as low as 16 if built without
any AVX support. The really funny thing is that a normal FFmpeg build
will e.g. align tiny string allocations to 64 bytes, even if the machine
does not support AVX at all.
For zimg use (in a later commit), we also want guaranteed alignment.
Modern x86 should actually not be much slower at unaligned accesses, but
that doesn't help. zimg's dumb intrinsic code apparently randomly
chooses between aligned or unaligned accesses (depending on compiler, I
guess), and on some CPUs these can even cause crashes. So just treat the
requirement to align as a fact of life.
All this means that we should probably make sure our own allocations are
64 bit aligned. This still doesn't guarantee alignment in all cases, but
it's slightly better than before.
This also makes me wonder whether we should always override libavcodec's
buffer pool, just so we have a guaranteed alignment. Currently, we only
do that if --vd-lavc-dr is used (and if that actually works). On the
other hand, it always uses DR on my machine, so who cares.
mp_sws_set_from_cmdline() has the only purpose to respect the --sws-
command line options. Instead of forcing callers to get the option
struct containing these, let callers pass mpv_global, and get it from
the option core code directly. This avoids minor annoyances later on.
I really wouldn't care much about this, but some parts of the core code
are under HAVE_GPL, so there's some need to get rid of it. Simply turn
the video equalizer from its current fine-grained handling with vf/vo
fallbacks into global options. This makes updating them much simpler.
This removes any possibility of applying video equalizers in filters,
which affects vf_scale, and the previously removed vf_eq. Not a big
loss, since the preferred VOs have this builtin.
Remove video equalizer handling from vo_direct3d, vo_sdl, vo_vaapi, and
vo_xv. I'm not going to waste my time on these legacy VOs.
vo.eq_opts_cache exists _only_ to send a VOCTRL_SET_EQUALIZER, which
exists _only_ to trigger a redraw. This seems silly, but for now I feel
like this is less of a pain. The rest of the equalizer using code is
self-updating.
See commit 96b906a51d for how some video equalizer code was GPL only.
Some command line option names and ranges can probably be traced back to
a GPL only committer, but we don't consider these copyrightable.
This time (there are a lot of times), libswscale randomly ignores
brightness/saturation/contrast settings.
Looking at MPlayer code, it appears the return value of
sws_setColorspaceDetails() signals if changing these settings is
supported at all.
(Nevermind that supporting this feature has almost 0 value, and
obviously eats maintenance time.)
The intention is that we can test vo_opengl with high bit depth PNGs
better. This throws libswscale completely out of the loop, which before
was needed in order to convert from big endian to little endian.
Also apply a minimal cleanup to fmt-conversion.c (unrelated).
Additionally to removing the global variables, this makes the options
more uniform. --ssf-... becomes --sws-..., and --sws becomes --sws-
scaler. For --sws-scaler, use choices instead of magic integer values.
This requires the caller to provide a mp_log in order to see error
messages. Unfortunately we don't do this in most places, but I guess we
have to live with it.
This splits the monolithic mp_image_swscale() function into a bunch of
functions and a context struct. This means it's possible to set
arbitrary parameters (e.g. even obscure ones without getting in the
way), and you don't have to create the context on every call.
This code is preparation for removing duplicated libswscale API usage
from other parts of the code.
Apparently the -spugauss option was popular. The code originally
implementing this is gone (scaler stuff in spudec.c). Reimplement it
using libswscale to scale and blur image subtitles if the --sub-gauss
option is set.
The code does some rather lazy padding to allow the blur to spread
pixels past the original image bounding box. (This problem exists with
normal bilinear scaling too, but is barely noticable.)
Technically, this doesn't just blur subtitles, but anything RGBA (or
indexed) that enters the OSD rendering path. But only image subtitles
produce these OSD formats currently, so no explicit check is done to
prevent blurring in other cases.
sws_getContextFromCmdLine_hq() was used by the screenshot code, which
now uses mp_image_swscale().
Also move the mp_sws_set_colorspace() declaration from sws_utils.h to
vf_scale.c.
Tis drops the silly lib prefixes, and attempts to organize the tree in
a more logical way. Make the top-level directory less cluttered as
well.
Renames the following directories:
libaf -> audio/filter
libao2 -> audio/out
libvo -> video/out
libmpdemux -> demux
Split libmpcodecs:
vf* -> video/filter
vd*, dec_video.* -> video/decode
mp_image*, img_format*, ... -> video/
ad*, dec_audio.* -> audio/decode
libaf/format.* is moved to audio/ - this is similar to how mp_image.*
is located in video/.
Move most top-level .c/.h files to core. (talloc.c/.h is left on top-
level, because it's external.) Park some of the more annoying files
in compat/. Some of these are relicts from the time mplayer used
ffmpeg internals.
sub/ is not split, because it's too much of a mess (subtitle code is
mixed with OSD display and rendering).
Maybe the organization of core is not ideal: it mixes playback core
(like mplayer.c) and utility helpers (like bstr.c/h). Should the need
arise, the playback core will be moved somewhere else, while core
contains all helper and common code.
wm4