avformat/mov: ensure pasp box derived SAR is used if present

It's meant to override any codec specific (but still container level)
information, but its position is not guaranteed, so apply the values after the
entire trak structure has been parsed.
Also, replace the ugly roundabout int -> double -> int method to set SAR from
existing dimensions while at it.

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

libavformat/isom.h

@@ -215,6 +215,8 @@ typedef struct MOVStreamContext {
     int timecode_track;
     int width;            ///< tkhd width
     int height;           ///< tkhd height
+    int h_spacing;        ///< pasp hSpacing
+    int v_spacing;        ///< pasp vSpacing
     int dts_shift;        ///< dts shift when ctts is negative
     uint32_t palette[256];
     int has_palette;

libavformat/mov.c

@@ -1287,14 +1287,18 @@ static int mov_read_pasp(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     const int num = avio_rb32(pb);
     const int den = avio_rb32(pb);
     AVStream *st;
+    MOVStreamContext *sc;
 
     if (c->fc->nb_streams < 1)
         return 0;
     st = c->fc->streams[c->fc->nb_streams-1];
+    sc = st->priv_data;
+
+    av_log(c->fc, AV_LOG_TRACE, "pasp: hSpacing %d, vSpacing %d\n", num, den);
 
     if (den != 0) {
-        av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
-                  num, den, 32767);
+        sc->h_spacing = num;
+        sc->v_spacing = den;
     }
     return 0;
 }
@@ -5031,11 +5035,15 @@ static int mov_read_trak(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     }
 
     if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
+        if (sc->h_spacing && sc->v_spacing)
+            av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
+                      sc->h_spacing, sc->v_spacing, INT_MAX);
         if (!st->sample_aspect_ratio.num && st->codecpar->width && st->codecpar->height &&
             sc->height && sc->width &&
             (st->codecpar->width != sc->width || st->codecpar->height != sc->height)) {
-            st->sample_aspect_ratio = av_d2q(((double)st->codecpar->height * sc->width) /
-                                             ((double)st->codecpar->width * sc->height), INT_MAX);
+            av_reduce(&st->sample_aspect_ratio.num, &st->sample_aspect_ratio.den,
+                      (int64_t)st->codecpar->height * sc->width,
+                      (int64_t)st->codecpar->width  * sc->height, INT_MAX);
         }
 
 #if FF_API_R_FRAME_RATE