movtextdec: Use default style information from movtext header

As suggested, posting the combined patch with the fate changes.
The patch sets the default style in ASS from the default style
information present in the movtext header.
Signed-off-by: Niklesh <niklesh.lalwani@iitb.ac.in>

libavcodec/movtextdec.c

@@ -37,6 +37,27 @@
 #define HLIT_BOX   (1<<1)
 #define HCLR_BOX   (1<<2)
 
+#define BOTTOM_LEFT     1
+#define BOTTOM_CENTER   2
+#define BOTTOM_RIGHT    3
+#define MIDDLE_LEFT     4
+#define MIDDLE_CENTER   5
+#define MIDDLE_RIGHT    6
+#define TOP_LEFT        7
+#define TOP_CENTER      8
+#define TOP_RIGHT       9
+
+typedef struct {
+    char *font;
+    int fontsize;
+    int color;
+    int back_color;
+    int bold;
+    int italic;
+    int underline;
+    int alignment;
+} MovTextDefault;
+
 typedef struct {
     uint16_t fontID;
     char *font;
@@ -66,6 +87,7 @@ typedef struct {
     HilightcolorBox c;
     FontRecord **ftab;
     FontRecord *ftab_temp;
+    MovTextDefault d;
     uint8_t box_flags;
     uint16_t style_entries, ftab_entries;
     uint64_t tracksize;
@@ -106,6 +128,9 @@ static int mov_text_tx3g(AVCodecContext *avctx, MovTextContext *m)
 {
     char *tx3g_ptr = avctx->extradata;
     int i, box_size, font_length;
+    int8_t v_align, h_align;
+    int style_fontID;
+    StyleBox s_default;
 
     m->count_f = 0;
     m->ftab_entries = 0;
@@ -116,13 +141,52 @@ static int mov_text_tx3g(AVCodecContext *avctx, MovTextContext *m)
     // Display Flags
     tx3g_ptr += 4;
     // Alignment
-    tx3g_ptr += 2;
+    h_align = *tx3g_ptr++;
+    v_align = *tx3g_ptr++;
+    if (h_align == 0) {
+        if (v_align == 0)
+            m->d.alignment = TOP_LEFT;
+        if (v_align == 1)
+            m->d.alignment = MIDDLE_LEFT;
+        if (v_align == -1)
+            m->d.alignment = BOTTOM_LEFT;
+    }
+    if (h_align == 1) {
+        if (v_align == 0)
+            m->d.alignment = TOP_CENTER;
+        if (v_align == 1)
+            m->d.alignment = MIDDLE_CENTER;
+        if (v_align == -1)
+            m->d.alignment = BOTTOM_CENTER;
+    }
+    if (h_align == -1) {
+        if (v_align == 0)
+            m->d.alignment = TOP_RIGHT;
+        if (v_align == 1)
+            m->d.alignment = MIDDLE_RIGHT;
+        if (v_align == -1)
+            m->d.alignment = BOTTOM_RIGHT;
+    }
     // Background Color
+    m->d.back_color = AV_RB24(tx3g_ptr);
     tx3g_ptr += 4;
     // BoxRecord
     tx3g_ptr += 8;
     // StyleRecord
-    tx3g_ptr += 12;
+    tx3g_ptr += 4;
+    // fontID
+    style_fontID = AV_RB16(tx3g_ptr);
+    tx3g_ptr += 2;
+    // face-style-flags
+    s_default.style_flag = *tx3g_ptr++;
+    m->d.bold = s_default.style_flag & STYLE_FLAG_BOLD;
+    m->d.italic = s_default.style_flag & STYLE_FLAG_ITALIC;
+    m->d.underline = s_default.style_flag & STYLE_FLAG_UNDERLINE;
+    // fontsize
+    m->d.fontsize = *tx3g_ptr++;
+    // Primary color
+    m->d.color = AV_RB24(tx3g_ptr);
+    tx3g_ptr += 4;
     // FontRecord
     // FontRecord Size
     tx3g_ptr += 4;
@@ -169,6 +233,10 @@ static int mov_text_tx3g(AVCodecContext *avctx, MovTextContext *m)
         }
         tx3g_ptr = tx3g_ptr + font_length;
     }
+    for (i = 0; i < m->ftab_entries; i++) {
+        if (style_fontID == m->ftab[i]->fontID)
+            m->d.font = m->ftab[i]->font;
+    }
     return 0;
 }
 
@@ -312,9 +380,15 @@ static int mov_text_init(AVCodecContext *avctx) {
      * it's very common to find files where the default style is broken
      * and respecting it results in a worse experience than ignoring it.
      */
+    int ret;
     MovTextContext *m = avctx->priv_data;
-    mov_text_tx3g(avctx, m);
-    return ff_ass_subtitle_header_default(avctx);
+    ret = mov_text_tx3g(avctx, m);
+    if (ret == 0) {
+        return ff_ass_subtitle_header(avctx, m->d.font, m->d.fontsize, m->d.color,
+                                m->d.back_color, m->d.bold, m->d.italic,
+                                m->d.underline, m->d.alignment);
+    } else
+        return ff_ass_subtitle_header_default(avctx);
 }
 
 static int mov_text_decode_frame(AVCodecContext *avctx,

tests/ref/fate/sub-movtext

@@ -6,7 +6,7 @@ PlayResY: 288
 
 [V4+ Styles]
 Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
-Style: Default,Arial,16,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,1,1,0,2,10,10,10,0
+Style: Default,Serif,18,&Hffffff,&Hffffff,&H0,&H0,0,0,0,0,100,100,0,0,1,1,0,2,10,10,10,0
 
 [Events]
 Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text

tests/ref/fate/sub-subripenc

 1
 00:00:00,970 --> 00:00:02,540
-- Test 1.
-- Test 2.
+<font face="Serif" size="18">- Test 1.
+- Test 2.</font>
 
 2
 00:00:03,050 --> 00:00:04,740
-Test 3.
+<font face="Serif" size="18">Test 3.</font>
 
 3
 00:00:05,850 --> 00:00:08,140
-- Test 4.
-- Test 5.
+<font face="Serif" size="18">- Test 4.
+- Test 5.</font>