mov: Evaluate the movie display matrix

Message ID 20161005211826.89815-1-vittorio.giovara@gmail.com
State Superseded
Headers show

Commit Message

Vittorio Giovara Oct. 5, 2016, 9:18 p.m.
This matrix needs to be applied after all others have (currently only
display matrix from trak), but cannot be handled in movie box, since
streams are not allocated yet.

So store it in main context and if not identity, apply it when appropriate,
handling the case when trak display matrix is identity and when it is not.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
---
 libavformat/isom.h |  2 ++
 libavformat/mov.c  | 64 ++++++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 55 insertions(+), 11 deletions(-)

Patch

diff --git a/libavformat/isom.h b/libavformat/isom.h
index 58f0a20..1aa2091 100644
--- a/libavformat/isom.h
+++ b/libavformat/isom.h
@@ -167,6 +167,8 @@  typedef struct MOVContext {
     int export_all;
     int export_xmp;
     int enable_drefs;
+
+    int32_t movie_display_matrix[3][3]; ///< display matrix from mvhd
 } MOVContext;
 
 int ff_mp4_read_descr_len(AVIOContext *pb);
diff --git a/libavformat/mov.c b/libavformat/mov.c
index 00ecdc7..a5609d3 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -950,6 +950,7 @@  static int mov_read_mdhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
 static int mov_read_mvhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
+    int i;
     time_t creation_time;
     int version = avio_r8(pb); /* version */
     avio_rb24(pb); /* flags */
@@ -973,7 +974,12 @@  static int mov_read_mvhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
     avio_skip(pb, 10); /* reserved */
 
-    avio_skip(pb, 36); /* display matrix */
+    /* movie display matrix, store it in main context and use it later on */
+    for (i = 0; i < 3; i++) {
+        c->movie_display_matrix[i][0] = avio_rb32(pb); // 16.16 fixed point
+        c->movie_display_matrix[i][1] = avio_rb32(pb); // 16.16 fixed point
+        c->movie_display_matrix[i][2] = avio_rb32(pb); //  2.30 fixed point
+    }
 
     avio_rb32(pb); /* preview time */
     avio_rb32(pb); /* preview duration */
@@ -2747,9 +2753,24 @@  static int mov_read_meta(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     return 0;
 }
 
+// return 0 when matrix is identity, 1 otherwise
+#define IS_MATRIX_FULL(matrix)       \
+    (matrix[0][0] != (1 << 16) ||    \
+     matrix[1][1] != (1 << 16) ||    \
+     matrix[2][2] != (1 << 30) ||    \
+     matrix[0][1] || matrix[0][2] || \
+     matrix[1][0] || matrix[1][2] || \
+     matrix[2][0] || matrix[2][1])
+
+// fixed point to double
+#define CONV_FP(x, sh) ((double) (x)) / (1 << sh)
+
+// double to fixed point
+#define CONV_DB(x, sh) (int32_t) ((x) * (1 << sh))
+
 static int mov_read_tkhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
-    int i;
+    int i, j, e;
     int width;
     int height;
     int display_matrix[3][3];
@@ -2803,14 +2824,7 @@  static int mov_read_tkhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     sc->height = height >> 16;
 
     // save the matrix when it is not the default identity
-    if (display_matrix[0][0] != (1 << 16) ||
-        display_matrix[1][1] != (1 << 16) ||
-        display_matrix[2][2] != (1 << 30) ||
-        display_matrix[0][1] || display_matrix[0][2] ||
-        display_matrix[1][0] || display_matrix[1][2] ||
-        display_matrix[2][0] || display_matrix[2][1]) {
-        int i, j;
-
+    if (IS_MATRIX_FULL(display_matrix)) {
         av_freep(&sc->display_matrix);
         sc->display_matrix = av_malloc(sizeof(int32_t) * 9);
         if (!sc->display_matrix)
@@ -2821,13 +2835,41 @@  static int mov_read_tkhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
                 sc->display_matrix[i * 3 + j] = display_matrix[i][j];
     }
 
+    // if movie display matrix is not identity, and if this is a video track
+    if (IS_MATRIX_FULL(c->movie_display_matrix) && width && height) {
+        // if trak display matrix was identity, just copy the movie one
+        if (!sc->display_matrix) {
+            sc->display_matrix = av_malloc(sizeof(int32_t) * 9);
+            if (!sc->display_matrix)
+                return AVERROR(ENOMEM);
+
+            for (i = 0; i < 3; i++)
+                for (j = 0; j < 3; j++)
+                    sc->display_matrix[i * 3 + j] = c->movie_display_matrix[i][j];
+        } else { // otherwise multiply the two and store the result
+            double val = 0;
+            for (i = 0; i < 3; i++) {
+                for (j = 0; j < 3; j++) {
+                    int sh = j == 2 ? 30 : 16;
+                    for (e = 0; e < 3; e++) {
+                        val += CONV_FP(display_matrix[i][e], sh) *
+                               CONV_FP(c->movie_display_matrix[e][j], sh);
+                    }
+                    sc->display_matrix[i * 3 + j] = CONV_DB(val, sh);
+                    val = 0;
+                }
+            }
+        }
+    }
+
     // transform the display width/height according to the matrix
     // skip this when the display matrix is the identity one
     if (width && height && sc->display_matrix) {
         double disp_transform[2];
 
         for (i = 0; i < 2; i++)
-            disp_transform[i] = hypot(display_matrix[i][0], display_matrix[i][1]);
+            disp_transform[i] = hypot(sc->display_matrix[i * 3],
+                                      sc->display_matrix[i * 3 + 1]);
 
         // only sane values allowed (no zeros or overflows)
         if (disp_transform[0] > 0 && disp_transform[0] < (1 << 24) &&