From 4e21fff19d1df0ce75d0a19e44865be152197418 Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Sat, 18 Dec 2021 21:40:26 +0100 Subject: [PATCH] fftools/ffmpeg_filter: Fix autorotation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In case of an orthogonal transformation av_display_rotation_get() returns the (anticlockwise) degree that the unit vector in x-direction gets rotated by; get_rotation in cmdutils.c makes a clockwise degree out of this. So if one inserts a transpose filter corresponding to this degree, then the x-vector gets mapped correctly and there are two possibilities for image of the y-vector, namely the two unit vectors orthogonal to the image of the x-vector. E.g. if the x-vector gets rotated by 90° clockwise, then the two possibilities for the y-vector are the unit vector in x direction or its opposite. The latter case is a simple 90° rotation for both vectors* whereas the former is a simple 90° clockwise rotation followed by a horizontal flip. These two cases can be distinguished by looking at the x-coordinate of the image of the y-vector, i.e. by looking at displaymatrix[3]. Similarly for the case of a 270° clockwise rotation. These two cases were previously wrong (they were made to match wrongly parsed exif rotation tag values). *: For display matrices, the y-axis points downward. Signed-off-by: Andreas Rheinhardt --- fftools/ffmpeg_filter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c index 501a0acd61e23..8c929ab9fa0c2 100644 --- a/fftools/ffmpeg_filter.c +++ b/fftools/ffmpeg_filter.c @@ -761,12 +761,12 @@ static int configure_input_video_filter(FilterGraph *fg, InputFilter *ifilter, theta = get_rotation(displaymatrix); if (fabs(theta - 90) < 1.0) { + ret = insert_filter(&last_filter, &pad_idx, "transpose", "clock"); if (displaymatrix[3] > 0) { ret = insert_filter(&last_filter, &pad_idx, "hflip", NULL); if (ret < 0) return ret; } - ret = insert_filter(&last_filter, &pad_idx, "transpose", "clock"); } else if (fabs(theta - 180) < 1.0) { if (displaymatrix[0] < 0) { ret = insert_filter(&last_filter, &pad_idx, "hflip", NULL); @@ -777,12 +777,12 @@ static int configure_input_video_filter(FilterGraph *fg, InputFilter *ifilter, ret = insert_filter(&last_filter, &pad_idx, "vflip", NULL); } } else if (fabs(theta - 270) < 1.0) { + ret = insert_filter(&last_filter, &pad_idx, "transpose", "cclock"); if (displaymatrix[3] < 0) { ret = insert_filter(&last_filter, &pad_idx, "hflip", NULL); if (ret < 0) return ret; } - ret = insert_filter(&last_filter, &pad_idx, "transpose", "cclock"); } else if (fabs(theta) > 1.0) { char rotate_buf[64]; snprintf(rotate_buf, sizeof(rotate_buf), "%f*PI/180", theta);