Fix crash due to alpha_blend requiring BGRA (#1165).

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 26b1d4bf8081b7dc1e536c2b0473c919721f9398..2f46f17c649c21b32a97ebcd3936bbec5d612750 100644 (file)
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -595,10 +595,10 @@ FFmpegDecoder::decode_subtitle_packet ()
 void
 FFmpegDecoder::decode_bitmap_subtitle (AVSubtitleRect const * rect, ContentTime from)
 {
-       /* Note RGBA is expressed little-endian, so the first byte in the word is R, second
-          G, third B, fourth A.
+       /* Note BGRA is expressed little-endian, so the first byte in the word is B, second
+          G, third R, fourth A.
        */
-       shared_ptr<Image> image (new Image (AV_PIX_FMT_RGBA, dcp::Size (rect->w, rect->h), true));
+       shared_ptr<Image> image (new Image (AV_PIX_FMT_BGRA, dcp::Size (rect->w, rect->h), true));
 
 #ifdef DCPOMATIC_HAVE_AVSUBTITLERECT_PICT
        /* Start of the first line in the subtitle */
@@ -642,8 +642,8 @@ FFmpegDecoder::decode_bitmap_subtitle (AVSubtitleRect const * rect, ContentTime
                uint32_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 RGBA?) but it looks right on screen */
-                       *out_line_p++ = (p.a << 24) | (p.r << 16) | (p.g << 8) | p.b;
+                       /* 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;
                }
 #ifdef DCPOMATIC_HAVE_AVSUBTITLERECT_PICT
                sub_p += rect->pict.linesize[0];