[FFmpeg-devel] [PATCH 1/2] movtextdec.c: Improve upon dynarrays and text_to_ass

[Niklesh Lalwani]

From: Niklesh <niklesh.lalwani at iitb.ac.in>

This Patch uses a single dynarray instead of 3 dynarrays used before. Changes are also done in text_to_ass() which previously failed to produce correct results for a few specific cases.
Signed-off-by: Niklesh <niklesh.lalwani at iitb.ac.in>
---
 libavcodec/movtextdec.c | 83 ++++++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 42 deletions(-)

diff --git a/libavcodec/movtextdec.c b/libavcodec/movtextdec.c
index 8dda5ce..d1e2d61 100644
--- a/libavcodec/movtextdec.c
+++ b/libavcodec/movtextdec.c
@@ -31,19 +31,36 @@
 #define STYLE_FLAG_ITALIC       2
 #define STYLE_FLAG_UNDERLINE    4
 
+typedef struct {
+    uint16_t style_start;
+    uint16_t style_end;
+    uint8_t style_flag;
+} StyleBox;
+
 static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end,
-                        char **style_start, char **style_end,
-                        uint8_t **style_flags, int style_entries)
+                        StyleBox **s, int style_entries)
 {
     int i = 0;
+    int text_pos = 0;
     while (text < text_end) {
         for (i = 0; i < style_entries; i++) {
-            if (*style_flags[i] && text == style_start[i]) {
-                if (*style_flags[i] & STYLE_FLAG_BOLD)
+            if (s[i]->style_flag && text_pos == s[i]->style_end) {
+                if (s[i]->style_flag & STYLE_FLAG_BOLD)
+                    av_bprintf(buf, "{\\b0}");
+                if (s[i]->style_flag & STYLE_FLAG_ITALIC)
+                    av_bprintf(buf, "{\\i0}");
+                if (s[i]->style_flag & STYLE_FLAG_UNDERLINE)
+                    av_bprintf(buf, "{\\u0}");
+            }
+        }
+
+        for (i = 0; i < style_entries; i++) {
+            if (s[i]->style_flag && text_pos == s[i]->style_start) {
+                if (s[i]->style_flag & STYLE_FLAG_BOLD)
                     av_bprintf(buf, "{\\b1}");
-                if (*style_flags[i] & STYLE_FLAG_ITALIC)
+                if (s[i]->style_flag & STYLE_FLAG_ITALIC)
                     av_bprintf(buf, "{\\i1}");
-                if (*style_flags[i] & STYLE_FLAG_UNDERLINE)
+                if (s[i]->style_flag & STYLE_FLAG_UNDERLINE)
                     av_bprintf(buf, "{\\u1}");
             }
         }
@@ -58,18 +75,8 @@ static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end,
             av_bprint_chars(buf, *text, 1);
             break;
         }
-
-        for (i = 0; i < style_entries; i++) {
-            if (*style_flags[i] && text == style_end[i]) {
-                if (*style_flags[i] & STYLE_FLAG_BOLD)
-                    av_bprintf(buf, "{\\b0}");
-                if (*style_flags[i] & STYLE_FLAG_ITALIC)
-                    av_bprintf(buf, "{\\i0}");
-                if (*style_flags[i] & STYLE_FLAG_UNDERLINE)
-                    av_bprintf(buf, "{\\u0}");
-            }
-        }
         text++;
+        text_pos++;
     }
 
     return 0;
@@ -96,13 +103,10 @@ static int mov_text_decode_frame(AVCodecContext *avctx,
     //char *ptr_temp;
     int text_length, tsmb_type, style_entries;
     uint64_t tsmb_size, tracksize;
-    char **style_start = { 0, };
-    char **style_end = { 0, };
-    uint8_t **style_flags = { 0, };
+    StyleBox **s = {0, };
+    StyleBox *s_temp;
     const uint8_t *tsmb;
-    int index, i, size_var;
-    uint8_t *flag;
-    char *style_pos;
+    int count, i, size_var;
 
     if (!ptr || avpkt->size < 2)
         return AVERROR_INVALIDDATA;
@@ -170,40 +174,35 @@ static int mov_text_decode_frame(AVCodecContext *avctx,
                     break;
 
                 for(i = 0; i < style_entries; i++) {
-                    style_pos = ptr + AV_RB16(tsmb);
-                    index = i;
-                    av_dynarray_add(&style_start, &index, style_pos);
+                    s_temp = av_malloc(sizeof(StyleBox));
+                    if (!s_temp)
+                        return AVERROR(ENOMEM);
+
+                    s_temp->style_start = AV_RB16(tsmb);
                     tsmb += 2;
-                    style_pos = ptr + AV_RB16(tsmb);
-                    index = i;
-                    av_dynarray_add(&style_end, &index, style_pos);
+                    s_temp->style_end = AV_RB16(tsmb);
                     tsmb += 2;
                     // fontID = AV_RB16(tsmb);
                     tsmb += 2;
-                    flag = av_malloc(1);
-                    if (!flag)
-                        return AVERROR(ENOMEM);
-                    *flag = AV_RB8(tsmb);
-                    index = i;
-                    av_dynarray_add(&style_flags, &index, flag);
+                    s_temp->style_flag = AV_RB8(tsmb);
+                    count = i;
+                    av_dynarray_add(&s, &count, s_temp);
                     //fontsize=AV_RB8(tsmb);
                     tsmb += 2;
                     // text-color-rgba
                     tsmb += 4;
                 }
-                text_to_ass(&buf, ptr, end, style_start, style_end, style_flags, style_entries);
+                text_to_ass(&buf, ptr, end, s, style_entries);
 
-                for(i = 0; i < style_entries; i++) {
-                    av_freep(&style_flags[i]);
+                for(i = 0; i < count; i++) {
+                    av_freep(&s[i]);
                 }
-                av_freep(&style_start);
-                av_freep(&style_end);
-                av_freep(&style_flags);
+                av_freep(&s);
             }
             tracksize = tracksize + tsmb_size;
         }
     } else
-        text_to_ass(&buf, ptr, end, NULL, NULL, 0, 0);
+        text_to_ass(&buf, ptr, end, NULL, 0);
 
     ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_end - ts_start);
     av_bprint_finalize(&buf, NULL);
-- 
1.9.1