This ensures all defined types are supported, even if only to report
their presence and print their size if a custom implementation is
not added.
Signed-off-by: James Almer <jamrial@gmail.com>
The current code will apply them if the options string does not contain
a 'flags' substring, and will do so by appending the graph-level option
string to the filter option string (with the standard ':' separator).
This is flawed in at least the following ways:
- naive substring matching without actually parsing the options string
may lead to false positives (e.g. flags are specified by shorthand)
and false negatives (e.g. the 'flags' substring is not actually the
option name)
- graph-level sws options are not limited to flags, but may set
arbitrary sws options
This commit simply applies the graph-level options with
av_set_options_string() and lets them be overridden as desired by the
user-specified filter options (if any). This is also shorter and avoids
extra string handling.
This function currently treats AVFilterContext options and
filter-private options differently: the former are immediately applied,
while the latter are stored in a dictionary to be applied later.
There is no good reason for having two branches - storing all options in
the dictionary is simpler and achieves the same effect (since it is
later applied with av_opt_set_dict()).
This will also be useful in future commits.
Current code first sets AVFilterContext-level options, then aplies the
leftover on the filter's private data. This is unnecessary, applying the
options to AVFilterContext with the AV_OPT_SEARCH_CHILDREN flag
accomplishes the same effect.
It appears faster than the iterative method on my machine (1.06x
faster), so I'm guessing compilers improved over time (the iterative
version was slightly faster in the past).
Currently, in case of equality on the first color channel, the order of
the ref colors is defined by the hashing function. This commit makes the
sorting deterministic and improve the hierarchical ordering.
This variable is used only for the running weight (used to reach the
target median). The places where we actually need the box weight are
changed to use box->weight.
The variance computation is simple enough now (since we can use the axis
squared errors) that it doesn't need to have a complex lazy computation
logic.
The equalities in the w{r,g,b} range checks make sure longest is never
0. Even if the alpha ended up being selected in get_next_color() it
would cause underread memory accesses in its caller (colormap_insert).
This reverts commit dea673d0d5.
This change cannot work for several reasons, the most obvious ones are:
- the alpha is being part of the scoring of the color difference, even
though we can not interpret the alpha as part of the perception of the
color (we don't even know if it's premultiplied or postmultiplied)
- the colors are averaged with their alpha value which simply cannot
work
The command proposed in the original thread of the patch actually
produces a completely broken file:
ffmpeg -y -loglevel verbose -i fate-suite/apng/o_sample.png -filter_complex "split[split1][split2];[split1]palettegen=max_colors=254:use_alpha=1[pal1];[split2][pal1]paletteuse=use_alpha=1" -frames:v 1 out.png
We can see that many color pixels are off, but more importantly some
colors have a random alpha value: https://imgur.com/eFQ2UK7
I don't see any easy fix for this unfortunately, the approach appears to
be flawed by design.
Paul B Mahol
James Almer
Anton Khirnov
Clément Bœsch