Fix casting of bytes to words, and hence (hopefully) finally fix incorrect bitmapped...

Backported from 74168425c45987b45d4f4e147fb45fab33c3cab9 in v2.15.x.

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index edc0b08d1537a4dfa83bbb60c2013228f834d548..0f39f7727348eadfd124689e5e1e858ab50c0ef6 100644 (file)
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -624,18 +624,18 @@ FFmpegDecoder::decode_bitmap_subtitle (AVSubtitleRect const * rect, ContentTime
 #else
        /* Start of the first line in the subtitle */
        uint8_t* sub_p = rect->data[0];
-       /* sub_p looks up into a BGRA palette which is here
-          (i.e. first byte B, second G, third R, fourth A)
+       /* sub_p looks up into a BGRA palette which is at rect->data[1].
+          (first byte B, second G, third R, fourth A)
        */
-       uint32_t const * palette = (uint32_t *) rect->data[1];
 #endif
        /* And the stream has a map of those palette colours to colours
           chosen by the user; created a `mapped' palette from those settings.
        */
        map<RGBA, RGBA> colour_map = ffmpeg_content()->subtitle_stream()->colours ();
        vector<RGBA> mapped_palette (rect->nb_colors);
+       uint8_t const * palette = rect->data[1];
        for (int i = 0; i < rect->nb_colors; ++i) {
-               RGBA c ((palette[i] & 0xff0000) >> 16, (palette[i] & 0xff00) >> 8, palette[i] & 0xff, (palette[i] & 0xff000000) >> 24);
+               RGBA c (palette[2], palette[1], palette[0], palette[3]);
                map<RGBA, RGBA>::const_iterator j = colour_map.find (c);
                if (j != colour_map.end ()) {
                        mapped_palette[i] = j->second;
@@ -646,25 +646,28 @@ FFmpegDecoder::decode_bitmap_subtitle (AVSubtitleRect const * rect, ContentTime
                        */
                        mapped_palette[i] = c;
                }
+               palette += 4;
        }
 
        /* Start of the output data */
-       uint32_t* out_p = (uint32_t *) image->data()[0];
+       uint8_t* out_p = image->data()[0];
 
        for (int y = 0; y < rect->h; ++y) {
                uint8_t* sub_line_p = sub_p;
-               uint32_t* out_line_p = out_p;
+               uint8_t* out_line_p = out_p;
                for (int x = 0; x < rect->w; ++x) {
                        RGBA const p = mapped_palette[*sub_line_p++];
-                       /* XXX: this seems to be wrong to me (isn't the output image BGRA?) but it looks right on screen */
-                       *out_line_p++ = (p.a << 24) | (p.b << 16) | (p.g << 8) | p.r;
+                       *out_line_p++ = p.b;
+                       *out_line_p++ = p.g;
+                       *out_line_p++ = p.r;
+                       *out_line_p++ = p.a;
                }
 #ifdef DCPOMATIC_HAVE_AVSUBTITLERECT_PICT
                sub_p += rect->pict.linesize[0];
 #else
                sub_p += rect->linesize[0];
 #endif
-               out_p += image->stride()[0] / sizeof (uint32_t);
+               out_p += image->stride()[0];
        }
 
        int target_width = subtitle_codec_context()->width;