sub: reimplement -spugauss as --sub-gauss

Apparently the -spugauss option was popular. The code originally
implementing this is gone (scaler stuff in spudec.c). Reimplement it
using libswscale to scale and blur image subtitles if the --sub-gauss
option is set.

The code does some rather lazy padding to allow the blur to spread
pixels past the original image bounding box. (This problem exists with
normal bilinear scaling too, but is barely noticable.)

Technically, this doesn't just blur subtitles, but anything RGBA (or
indexed) that enters the OSD rendering path. But only image subtitles
produce these OSD formats currently, so no explicit check is done to
prevent blurring in other cases.

1 files changed, 35 insertions, 7 deletions

diff --git a/video/sws_utils.c b/video/sws_utils.c
index 663a0e282a..7a1385cfac 100644
--- a/video/sws_utils.c
+++ b/video/sws_utils.c
@@ -171,12 +171,10 @@ static void to_gbrp(struct mp_image *dst, struct mp_image *src,
     talloc_free(temp);
 }
 
-void mp_image_swscale(struct mp_image *dst, struct mp_image *src,
-                      int my_sws_flags)
-{
-    if (dst->imgfmt == IMGFMT_GBRP)
-        return to_gbrp(dst, src, my_sws_flags);
 
+static void mp_sws_set_conv(struct SwsContext *sws, struct mp_image *dst,
+                            struct mp_image *src, int my_sws_flags)
+{
     enum PixelFormat s_fmt = imgfmt2pixfmt(src->imgfmt);
     if (src->imgfmt == IMGFMT_RGB8 || src->imgfmt == IMGFMT_BGR8)
         s_fmt = PIX_FMT_PAL8;
@@ -195,8 +193,6 @@ void mp_image_swscale(struct mp_image *dst, struct mp_image *src,
     s_range = s_range && s_yuv;
     d_range = d_range && d_yuv;
 
-    struct SwsContext *sws = sws_alloc_context();
-
     av_opt_set_int(sws, "sws_flags", my_sws_flags, 0);
 
     av_opt_set_int(sws, "srcw", src->w, 0);
@@ -210,6 +206,16 @@ void mp_image_swscale(struct mp_image *dst, struct mp_image *src,
     sws_setColorspaceDetails(sws, sws_getCoefficients(s_csp), s_range,
                              sws_getCoefficients(d_csp), d_range,
                              0, 1 << 16, 1 << 16);
+}
+
+void mp_image_swscale(struct mp_image *dst, struct mp_image *src,
+                      int my_sws_flags)
+{
+    if (dst->imgfmt == IMGFMT_GBRP)
+        return to_gbrp(dst, src, my_sws_flags);
+
+    struct SwsContext *sws = sws_alloc_context();
+    mp_sws_set_conv(sws, dst, src, my_sws_flags);
 
     int res = sws_init_context(sws, NULL, NULL);
     assert(res >= 0);
@@ -219,4 +225,26 @@ void mp_image_swscale(struct mp_image *dst, struct mp_image *src,
     sws_freeContext(sws);
 }
 
+void mp_image_sw_blur_scale(struct mp_image *dst, struct mp_image *src,
+                            float gblur)
+{
+    struct SwsContext *sws = sws_alloc_context();
+
+    int flags = SWS_LANCZOS | SWS_FULL_CHR_H_INT | SWS_FULL_CHR_H_INP |
+                SWS_ACCURATE_RND | SWS_BITEXACT;
+
+    mp_sws_set_conv(sws, dst, src, flags);
+
+    SwsFilter *src_filter = sws_getDefaultFilter(gblur, gblur, 0, 0, 0, 0, 0);
+
+    int res = sws_init_context(sws, src_filter, NULL);
+    assert(res >= 0);
+
+    sws_scale(sws, (const uint8_t *const *) src->planes, src->stride,
+              0, src->h, dst->planes, dst->stride);
+    sws_freeContext(sws);
+
+    sws_freeFilter(src_filter);
+}
+
 // vim: ts=4 sw=4 et tw=80