| Message ID | 20240202011051.46786-1-connorbworley@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel,v2,1/2] lavc/texturedsp: fix premult2straight inversion | expand |
| Context | Check | Description |
|---|---|---|
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
On Thu, 01 Feb 2024 17:10:50 -0800 Connor Worley <connorbworley@gmail.com> wrote: > + src[0] = (uint8_t) FFMIN(r * 255 / a, 255); > + src[1] = (uint8_t) FFMIN(g * 255 / a, 255); > + src[2] = (uint8_t) FFMIN(b * 255 / a, 255); av_clip_uint8?
Niklas Haas: > On Thu, 01 Feb 2024 17:10:50 -0800 Connor Worley <connorbworley@gmail.com> wrote: >> + src[0] = (uint8_t) FFMIN(r * 255 / a, 255); >> + src[1] = (uint8_t) FFMIN(g * 255 / a, 255); >> + src[2] = (uint8_t) FFMIN(b * 255 / a, 255); > > av_clip_uint8? That is for int values and therefore has to take care of negative values as well. At least the C version is more complicated (i.e. the compiler will have to work harder to optimize it to something like the above). - Andreas
Linked are some demo files. I converted a sample to DDS with texconv.exe -f DXT4 -pmalpha sample.png I converted it back to PNG against master with ffmpeg -i sample.dds master.png I converted it back to PNG against this patch with ffmpeg -i sample.dds patch.png The color in master.png is dark due to being premultiplied twice. The color in patch.png is true to sample.png. https://connorworley.com/sample.png https://connorworley.com/sample.dds https://connorworley.com/master.png https://connorworley.com/patch.png
diff --git a/libavcodec/texturedsp.c b/libavcodec/texturedsp.c index 5fb79937da..721bfc17f5 100644 --- a/libavcodec/texturedsp.c +++ b/libavcodec/texturedsp.c @@ -175,9 +175,12 @@ static av_always_inline void premult2straight(uint8_t *src) int b = src[2]; int a = src[3]; /* unchanged */ - src[0] = (uint8_t) r * a / 255; - src[1] = (uint8_t) g * a / 255; - src[2] = (uint8_t) b * a / 255; + if (a == 0) + return; + + src[0] = (uint8_t) FFMIN(r * 255 / a, 255); + src[1] = (uint8_t) FFMIN(g * 255 / a, 255); + src[2] = (uint8_t) FFMIN(b * 255 / a, 255); } /** diff --git a/tests/ref/fate/dds-dxt2 b/tests/ref/fate/dds-dxt2 index b5bdfbadc3..1744ef41f6 100644 --- a/tests/ref/fate/dds-dxt2 +++ b/tests/ref/fate/dds-dxt2 @@ -3,4 +3,4 @@ #codec_id 0: rawvideo #dimensions 0: 64x64 #sar 0: 0/1 -0, 0, 0, 1, 16384, 0x11cebeb0 +0, 0, 0, 1, 16384, 0xd7f7241b diff --git a/tests/ref/fate/dds-dxt4 b/tests/ref/fate/dds-dxt4 index 136dfd8006..f22878da56 100644 --- a/tests/ref/fate/dds-dxt4 +++ b/tests/ref/fate/dds-dxt4 @@ -3,4 +3,4 @@ #codec_id 0: rawvideo #dimensions 0: 64x64 #sar 0: 0/1 -0, 0, 0, 1, 16384, 0x31aaacd6 +0, 0, 0, 1, 16384, 0xf18d4216
This function should convert premultiplied alpha to straight, but does the opposite. Signed-off-by: Connor Worley <connorbworley@gmail.com> --- libavcodec/texturedsp.c | 9 ++++++--- tests/ref/fate/dds-dxt2 | 2 +- tests/ref/fate/dds-dxt4 | 2 +- 3 files changed, 8 insertions(+), 5 deletions(-)