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.
New option can be used to avoid creating very short segments with inputs
whose GOP size is variable or unharmonic with segment_time.
Only effective with segment_time.
Similar to how the encoder looks at frame color information to write the frame
header bitstream.
Should workaround ticket #10091, where container level color parameters passed
to the decoder context were being overwritten.
Signed-off-by: James Almer <jamrial@gmail.com>
Some encoders, like flac, can send side data only packets at the end.
Eventually, said extradata update should ideally be used to update the header
when writting to seekable output, but for now, ignore them.
Should fix the undefined behavior of passing NULL to memcpy().
Signed-off-by: James Almer <jamrial@gmail.com>
PFM (aka Portable FloatMap) encodes its scanlines from bottom-to-top,
not from top-to-bottom, unlike other NetPBM formats. Without this
patch, FFmpeg ignores this exception and decodes/encodes PFM images
mirrored vertically from their proper orientation.
For reference, see the NetPBM tool pfmtopam, which encodes a .pam
from a .pfm, using the correct orientation (and which FFmpeg reads
correctly). Also compare ffplay to magick display, which shows the
correct orientation as well.
See: http://www.pauldebevec.com/Research/HDR/PFM/ and see:
https://netpbm.sourceforge.net/doc/pfm.html for descriptions of this
image format.
Signed-off-by: Leo Izen <leo.izen@gmail.com>
Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: James Almer <jamrial@gmail.com>
EAGAIN is not correct in this scenario. FFCodec.cb.decode() callback decoders
always return the amount of bytes consumed from the input packet (if any), and
report if a frame was generated by setting got_frame.
Signed-off-by: James Almer <jamrial@gmail.com>
Add encoding of 32 bit-per-sample PCM to FLAC files to libavcodec.
Coding to this format is at this point considered experimental and
-strict experimental is needed to get ffmpeg to encode such files.
