[FFmpeg-cvslog] avformat/matroskaenc: use display aspect ratio for DisplayWidth and DisplayHeight when possible

[James Almer]

ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Sat Oct 22 15:56:28 2016 -0300| [5cb57131d3bb2422858467828a5763646f004bbe] | committer: James Almer

avformat/matroskaenc: use display aspect ratio for DisplayWidth and DisplayHeight when possible

This avoids potential rounding errors and guarantees the source aspect
ratio is preserved.
Keep writing pixel values when Stereo 3D Mode is enabled and for WebM,
as the format doesn't support anything else.

This fixes ticket #5743, implementing the suggestion from ticket #5903.

Signed-off-by: James Almer <jamrial at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5cb57131d3bb2422858467828a5763646f004bbe
---

 libavformat/matroskaenc.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 99f61fe..2cfeee9 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -1204,8 +1204,19 @@ static int mkv_write_track(AVFormatContext *s, MatroskaMuxContext *mkv,
                 return AVERROR(EINVAL);
             }
             if (d_width != par->width || display_width_div != 1 || display_height_div != 1) {
-                put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYWIDTH , d_width / display_width_div);
-                put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYHEIGHT, par->height / display_height_div);
+                if (mkv->mode == MODE_WEBM || display_width_div != 1 || display_height_div != 1) {
+                    put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYWIDTH , d_width / display_width_div);
+                    put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYHEIGHT, par->height / display_height_div);
+                } else {
+                    AVRational display_aspect_ratio;
+                    av_reduce(&display_aspect_ratio.num, &display_aspect_ratio.den,
+                              par->width  * (int64_t)st->sample_aspect_ratio.num,
+                              par->height * (int64_t)st->sample_aspect_ratio.den,
+                              1024 * 1024);
+                    put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYWIDTH,  display_aspect_ratio.num);
+                    put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYHEIGHT, display_aspect_ratio.den);
+                    put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYUNIT, MATROSKA_VIDEO_DISPLAYUNIT_DAR);
+                }
             }
         } else if (display_width_div != 1 || display_height_div != 1) {
             put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYWIDTH , par->width / display_width_div);