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| author | Andreas Rheinhardt <andreas.rheinhardt@outlook.com> | 2021-12-18 23:46:47 +0100 |
|---|---|---|
| committer | Andreas Rheinhardt <andreas.rheinhardt@outlook.com> | 2021-12-23 18:09:46 +0100 |
| commit | ab6f9d86a9db7d0743629ecab422cfb61f2a17e1 (patch) | |
| tree | 8342f2ad956d1693f431f118cc83b8717db77a0f /libavcodec/h264_slice.c | |
| parent | 04133eb2d5c794a077125fbbf9b880060f2123a1 (diff) | |
avcodec/h2645: Fix SEI->display matrix transformation
The earlier code did not account for the fact that
av_display_rotation_set() wants the angle in the anticlockwise
direction (despite what its documentation stated for a long time);
furthermore, the H.2645 spec wants the flips applied first,
whereas our code did it the other way around. This can be fixed
by negating the angle once for every flip.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Diffstat (limited to 'libavcodec/h264_slice.c')
| -rw-r--r-- | libavcodec/h264_slice.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c index 4467882775..c21004df97 100644 --- a/libavcodec/h264_slice.c +++ b/libavcodec/h264_slice.c @@ -1305,6 +1305,15 @@ static int h264_export_frame_props(H264Context *h) AV_FRAME_DATA_DISPLAYMATRIX, sizeof(int32_t) * 9); if (rotation) { + /* av_display_rotation_set() expects the angle in the clockwise + * direction, hence the first minus. + * The below code applies the flips after the rotation, yet + * the H.2645 specs require flipping to be applied first. + * Because of R O(phi) = O(-phi) R (where R is flipping around + * an arbitatry axis and O(phi) is the proper rotation by phi) + * we can create display matrices as desired by negating + * the degree once for every flip applied. */ + angle = -angle * (1 - 2 * !!o->hflip) * (1 - 2 * !!o->vflip); av_display_rotation_set((int32_t *)rotation->data, angle); av_display_matrix_flip((int32_t *)rotation->data, o->hflip, o->vflip); |