[x264-devel] commit: Fix aspect ratio writing in the MKV muxer (Mike Matsnev )

[git at videolan.org]

x264 | branch: master | Mike Matsnev <mike at haali.su> | Sun Aug  1 12:08:20 2010 -0700| [7e1e9bc2acca2194bd71ddd02edd884821d19b15] | committer: Jason Garrett-Glaser 

Fix aspect ratio writing in the MKV muxer
The braindead Matroska spec dictates aspect ratio to be measured in pixels instead of, well, an actual aspect ratio.

> http://git.videolan.org/gitweb.cgi/x264.git/?a=commit;h=7e1e9bc2acca2194bd71ddd02edd884821d19b15
---

 output/matroska.c      |   38 ++++++++++++++++++--------------------
 output/matroska_ebml.c |    3 ++-
 output/matroska_ebml.h |    8 +++++++-
 3 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/output/matroska.c b/output/matroska.c
index a1219d0..7b26564 100644
--- a/output/matroska.c
+++ b/output/matroska.c
@@ -27,6 +27,8 @@ typedef struct
 
     int width, height, d_width, d_height;
 
+    int display_size_units;
+
     int64_t frame_duration;
 
     char b_writing_frame;
@@ -74,29 +76,25 @@ static int set_param( hnd_t handle, x264_param_t *p_param )
         p_mkv->frame_duration = 0;
     }
 
-    p_mkv->width = p_param->i_width;
-    p_mkv->height = p_param->i_height;
-
-    if( p_param->vui.i_sar_width && p_param->vui.i_sar_height )
-    {
-        dw = (int64_t)p_param->i_width  * p_param->vui.i_sar_width;
-        dh = (int64_t)p_param->i_height * p_param->vui.i_sar_height;
-    }
-    else
-    {
-        dw = p_param->i_width;
-        dh = p_param->i_height;
-    }
+    p_mkv->width = p_mkv->d_width = p_param->i_width;
+    p_mkv->height = p_mkv->d_height = p_param->i_height;
+    p_mkv->display_size_units = DS_PIXELS;
 
-    if( dw > 0 && dh > 0 )
+    if( p_param->vui.i_sar_width && p_param->vui.i_sar_height
+        && p_param->vui.i_sar_width != p_param->vui.i_sar_height )
     {
-        int64_t x = gcd( dw, dh );
-        dw /= x;
-        dh /= x;
+        if ( p_param->vui.i_sar_width > p_param->vui.i_sar_height ) {
+            dw = (int64_t)p_param->i_width * p_param->vui.i_sar_width / p_param->vui.i_sar_height;
+            dh = p_param->i_height;
+        } else {
+            dw = p_param->i_width;
+            dh = (int64_t)p_param->i_height * p_param->vui.i_sar_height / p_param->vui.i_sar_width;
+        }
+
+        p_mkv->d_width = (int)dw;
+        p_mkv->d_height = (int)dh;
     }
 
-    p_mkv->d_width = (int)dw;
-    p_mkv->d_height = (int)dh;
     p_mkv->i_timebase_num = p_param->i_timebase_num;
     p_mkv->i_timebase_den = p_param->i_timebase_den;
 
@@ -149,7 +147,7 @@ static int write_headers( hnd_t handle, x264_nal_t *p_nal )
     ret = mk_writeHeader( p_mkv->w, "x264" X264_VERSION, "V_MPEG4/ISO/AVC",
                           avcC, avcC_len, p_mkv->frame_duration, 50000,
                           p_mkv->width, p_mkv->height,
-                          p_mkv->d_width, p_mkv->d_height );
+                          p_mkv->d_width, p_mkv->d_height, p_mkv->display_size_units );
     if( ret < 0 )
         return ret;
 
diff --git a/output/matroska_ebml.c b/output/matroska_ebml.c
index adfcaa8..8a50277 100644
--- a/output/matroska_ebml.c
+++ b/output/matroska_ebml.c
@@ -321,7 +321,7 @@ int mk_writeHeader( mk_writer *w, const char *writing_app,
                     int64_t default_frame_duration,
                     int64_t timescale,
                     unsigned width, unsigned height,
-                    unsigned d_width, unsigned d_height )
+                    unsigned d_width, unsigned d_height, int display_size_units )
 {
     mk_context  *c, *ti, *v;
 
@@ -374,6 +374,7 @@ int mk_writeHeader( mk_writer *w, const char *writing_app,
         return -1;
     CHECK( mk_write_uint( v, 0xb0, width ) );
     CHECK( mk_write_uint( v, 0xba, height ) );
+    CHECK( mk_write_uint( v, 0x54b2, display_size_units ) );
     CHECK( mk_write_uint( v, 0x54b0, d_width ) );
     CHECK( mk_write_uint( v, 0x54ba, d_height ) );
     CHECK( mk_close_context( v, 0 ) );
diff --git a/output/matroska_ebml.h b/output/matroska_ebml.h
index 56eb8cc..eb73128 100644
--- a/output/matroska_ebml.h
+++ b/output/matroska_ebml.h
@@ -21,6 +21,12 @@
 #ifndef X264_MATROSKA_EBML_H
 #define X264_MATROSKA_EBML_H
 
+/* Matroska display size units from the spec */
+#define	DS_PIXELS        0
+#define	DS_CM            1
+#define	DS_INCHES        2
+#define	DS_ASPECT_RATIO  3
+
 typedef struct mk_writer mk_writer;
 
 mk_writer *mk_create_writer( const char *filename );
@@ -31,7 +37,7 @@ int mk_writeHeader( mk_writer *w, const char *writing_app,
                     int64_t default_frame_duration,
                     int64_t timescale,
                     unsigned width, unsigned height,
-                    unsigned d_width, unsigned d_height );
+                    unsigned d_width, unsigned d_height, int display_size_units );
 
 int mk_start_frame( mk_writer *w );
 int mk_add_frame_data( mk_writer *w, const void *data, unsigned size );