On Wed, 5 Jan 2022, Andreas Rheinhardt wrote:
J. Dekker:
The assembly is written assuming that the width is a multiple of 8.
However the real issue is the functions were errorneously assigned to
the 2, 4, 6 & 12 widths. This behaviour never broke the decoder as
samples which trigger the functions for these widths have not been found
in the wild. This relies on the mappings in ff_hevc_pel_weight[].
Signed-off-by: J. Dekker <j...@itanimul.li>
---
libavcodec/arm/hevcdsp_init_neon.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
This set has already been reviewed by Martin, sending to list for
transparency.
diff --git a/libavcodec/arm/hevcdsp_init_neon.c
b/libavcodec/arm/hevcdsp_init_neon.c
index 201a088dac..112edb5edd 100644
--- a/libavcodec/arm/hevcdsp_init_neon.c
+++ b/libavcodec/arm/hevcdsp_init_neon.c
@@ -270,7 +270,8 @@ av_cold void ff_hevc_dsp_init_neon(HEVCDSPContext *c, const
int bit_depth)
put_hevc_qpel_uw_neon[3][1] = ff_hevc_put_qpel_uw_h1v3_neon_8;
put_hevc_qpel_uw_neon[3][2] = ff_hevc_put_qpel_uw_h2v3_neon_8;
put_hevc_qpel_uw_neon[3][3] = ff_hevc_put_qpel_uw_h3v3_neon_8;
- for (x = 0; x < 10; x++) {
+ for (x = 3; x < 10; x++) {
+ if (x == 4) continue;
c->put_hevc_qpel[x][1][0] = ff_hevc_put_qpel_neon_wrapper;
c->put_hevc_qpel[x][0][1] = ff_hevc_put_qpel_neon_wrapper;
c->put_hevc_qpel[x][1][1] = ff_hevc_put_qpel_neon_wrapper;
This patchset led to regressions; see e.g.
http://fate.ffmpeg.org/report.cgi?time=20220104162724&slot=aarch64-linux-qemu-ubuntu-gcc-4.8
Indeed. I had only ran fate-checkasm while reviewing it, assuming that it
had been fully tested with fate-hevc by the patch author.
Instead of reverting the full 6 patch set, it's enough to revert a couple
patches out of it though (there's some cosmetic cleanup that we can keep
in for now). But I'm afraid we should disable the preexisting
ff_hevc_sao_band_filter_8x8_8_neon function too. It's currently only run
for the [0] case, which I think corresponds to width <= 8. But if that
case also must handle widths that aren't an even multiple of 8, we'd have
a lingering bug that isn't exercised by fate-hevc.
// Martin
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