Tidy up a bit.

[dcpomatic.git] / src / lib / ffmpeg_decoder.cc

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index 8feb366239cbb0b19e04a63552aff60ec989af50..8dbec87fd364bd50f96acd612f8753157ddedbd4 100644 (file)
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -233,13 +233,10 @@ FFmpegDecoder::do_pass ()
                int frame_finished;
                if (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
                        
-                       cout << "decoded some video.\n";
                        if (_have_subtitle) {
-                               cout << "have a subtitle; " << _subtitle.num_rects << "\n";
                                for (unsigned int i = 0; i < _subtitle.num_rects; ++i) {
                                        AVSubtitleRect* rect = _subtitle.rects[i];
                                        if (rect->type != SUBTITLE_BITMAP) {
-                                               cout << "not a bitmap\n";
                                                throw DecodeError ("non-bitmap subtitles not yet supported");
                                        }
 
@@ -255,25 +252,24 @@ FFmpegDecoder::do_pass ()
                                        
                                        /* Start of the first line in the subtitle */
                                        uint8_t* sub_p = rect->pict.data[0];
-
-                                       cout << "frame ls 0 is " << _frame->linesize[0] << "\n";
-                                       cout << "frame ls 1 is " << _frame->linesize[1] << "\n";
-                                       cout << "frame ls 2 is " << _frame->linesize[2] << "\n";
-
-                                       uint32_t* palette = (uint32_t *) rect->pict.data[1];
+                                       /* sub_p looks up into a RGB palette which is here */
+                                       uint32_t const * palette = (uint32_t *) rect->pict.data[1];
                                        
                                        for (int sub_y = 0; sub_y < rect->h; ++sub_y) {
+                                               /* Pointers to the start of this line */
                                                uint8_t* sub_line_p = sub_p;
                                                uint8_t* frame_line_y_p = frame_y_p + rect->x;
                                                uint8_t* frame_line_u_p = frame_u_p + (rect->x / 2);
                                                uint8_t* frame_line_v_p = frame_v_p + (rect->x / 2);
 
+                                               /* U and V are subsampled */
                                                uint8_t current_u = 0;
                                                uint8_t current_v = 0;
                                                int subsample_step = 0;
                                                
                                                for (int sub_x = 0; sub_x < rect->w; ++sub_x) {
 
+                                                       /* RGB value for this subtitle pixel */
                                                        uint32_t const val = palette[*sub_line_p++];
                                                        
                                                        int const     red =  (val &       0xff);
@@ -281,14 +277,16 @@ FFmpegDecoder::do_pass ()
                                                        int const    blue =  (val &   0xff0000) >> 16;
                                                        float const alpha = ((val & 0xff000000) >> 24) / 255.0;
 
+                                                       /* Alpha-blend Y */
                                                        int const cy = *frame_line_y_p;
-
                                                        *frame_line_y_p++ = int (cy * (1 - alpha)) + int (RGB_TO_Y_CCIR (red, green, blue) * alpha);
-                                                       
+
+                                                       /* Store up U and V */
                                                        current_u |= ((RGB_TO_U_CCIR (red, green, blue, 0) & 0xf0) >> 4) << (4 * subsample_step);
                                                        current_v |= ((RGB_TO_V_CCIR (red, green, blue, 0) & 0xf0) >> 4) << (4 * subsample_step);
 
                                                        if (subsample_step == 1 && (sub_y % 2) == 0) {
+                                                               /* We have complete U and V bytes, so alpha-blend them into the frame */
                                                                int const cu = *frame_line_u_p;
                                                                int const cv = *frame_line_v_p;
                                                                *frame_line_u_p++ = int (cu * (1 - alpha)) + int (current_u * alpha);
@@ -335,7 +333,6 @@ FFmpegDecoder::do_pass ()
 
                int got_subtitle;
                if (avcodec_decode_subtitle2 (_subtitle_codec_context, &_subtitle, &got_subtitle, &_packet) && got_subtitle) {
-                       cout << "got a subtitle.\n";
                        _have_subtitle = true;
                }
        }