Due to a quirk of the ASS format some tags depend on the exact storage resolution of the video, so tell libass via ass_set_storage_size.
--- ass_set_storage_size exists since libass 0.10.2; ffmpeg since 5.0 already requires 0.11.0. This resolution dependences of ASS was already recognised when the original_size parameter was added, but it actually goes farther than just the aspect ratio. Conveniently this parameter still has all the required information to retain rendering after resizing :) Sample files to show the difference can be found eg here https://code.videolan.org/videolan/vlc/uploads/b54e0761d0d3f4f79b2947ffb83a3b59/vlc-issue_libass-storage-size.tar.xz ./ffmpeg -i test_1080p.mkv -filter:v ass=./test_1080p.ass tmp_1080.mkv ./ffmpeg -i anamorphic_s720x576_d1024x576.mkv -filter:v ass=./anamorphic_s720x576_d1024x576.ass tmp_anam.mkv --- libavfilter/vf_subtitles.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/libavfilter/vf_subtitles.c b/libavfilter/vf_subtitles.c index 3fc4eeb63d..af6352b315 100644 --- a/libavfilter/vf_subtitles.c +++ b/libavfilter/vf_subtitles.c @@ -146,9 +146,14 @@ static int config_input(AVFilterLink *inlink) ff_draw_init(&ass->draw, inlink->format, ass->alpha ? FF_DRAW_PROCESS_ALPHA : 0); ass_set_frame_size (ass->renderer, inlink->w, inlink->h); - if (ass->original_w && ass->original_h) + if (ass->original_w && ass->original_h) { ass_set_pixel_aspect(ass->renderer, (double)inlink->w / inlink->h / ((double)ass->original_w / ass->original_h)); + ass_set_storage_size(ass->renderer, ass->original_w, ass->original_h); + } else { + ass_set_storage_size(ass->renderer, inlink->w, inlink->h); + } + if (ass->shaping != -1) ass_set_shaper(ass->renderer, ass->shaping); -- 2.30.2 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
