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avcodec/h2645: Fix SEI->display matrix transformation

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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>
This commit is contained in:
Andreas Rheinhardt 2021-12-18 23:46:47 +01:00
parent 04133eb2d5
commit ab6f9d86a9
3 changed files with 31 additions and 3 deletions
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15
libavcodec/h264_metadata_bsf.c
View File

@ -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

9
libavcodec/h264_slice.c
View File

@ -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);

10
libavcodec/hevcdec.c
View File

@ -2769,6 +2769,16 @@ static int set_side_data(HEVCContext *s)
if (!rotation)
return AVERROR(ENOMEM);
/* 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 * !!s->sei.display_orientation.hflip)
* (1 - 2 * !!s->sei.display_orientation.vflip);
av_display_rotation_set((int32_t *)rotation->data, angle);
av_display_matrix_flip((int32_t *)rotation->data,
s->sei.display_orientation.hflip,