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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_metadata_bsf.c | |
| parent | 04133eb2d5c794a077125fbbf9b880060f2123a1 (diff) | |
| download | ffmpeg-ab6f9d86a9db7d0743629ecab422cfb61f2a17e1.tar.gz | |
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_metadata_bsf.c')
| -rw-r--r-- | libavcodec/h264_metadata_bsf.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/libavcodec/h264_metadata_bsf.c b/libavcodec/h264_metadata_bsf.c index 452a8ec5dc..8c5d19c5a8 100644 --- a/libavcodec/h264_metadata_bsf.c +++ b/libavcodec/h264_metadata_bsf.c @@ -341,15 +341,24 @@ static int h264_metadata_handle_display_orientation(AVBSFContext *bsf, SEI_TYPE_DISPLAY_ORIENTATION, &message) == 0) { H264RawSEIDisplayOrientation *disp = message->payload; + double angle = disp->anticlockwise_rotation * 180.0 / 65536.0; int32_t *matrix; matrix = av_malloc(9 * sizeof(int32_t)); if (!matrix) return AVERROR(ENOMEM); - av_display_rotation_set(matrix, - disp->anticlockwise_rotation * - 180.0 / 65536.0); + /* 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 * !!disp->hor_flip) * (1 - 2 * !!disp->ver_flip); + + av_display_rotation_set(matrix, angle); av_display_matrix_flip(matrix, disp->hor_flip, disp->ver_flip); // If there are multiple display orientation messages in an |