ass_split: fix handling of streams with no [Events] or Format: line

libavcodec/ass_split.c

@@ -229,7 +229,7 @@ static inline const char *skip_space(const char *buf)
     return buf;
 }
 
-static int *get_default_field_orders(const ASSSection *section)
+static int *get_default_field_orders(const ASSSection *section, int *number)
 {
     int i;
     int *order = av_malloc_array(FF_ARRAY_ELEMS(section->fields), sizeof(*order));
@@ -238,8 +238,9 @@ static int *get_default_field_orders(const ASSSection *section)
         return NULL;
     for (i = 0; section->fields[i].name; i++)
         order[i] = i;
+    *number = i;
     while (i < FF_ARRAY_ELEMS(section->fields))
-        order[i] = -1;
+        order[i++] = -1;
     return order;
 }
 
@@ -255,12 +256,26 @@ static const char *ass_split_section(ASSSplitContext *ctx, const char *buf)
             ctx->current_section = -1;
             break;
         }
-        if (buf[0] == ';' || (buf[0] == '!' && buf[1] == ':')) {
-            /* skip comments */
-        } else if (section->format_header && !order) {
+        if (buf[0] == ';' || (buf[0] == '!' && buf[1] == ':'))
+            goto next_line; // skip comments
+
+        len = strcspn(buf, ":\r\n");
+        if (buf[len] == ':' &&
+            (!section->fields_header || strncmp(buf, section->fields_header, len))) {
+            for (i = 0; i < FF_ARRAY_ELEMS(ass_sections); i++) {
+                if (ass_sections[i].fields_header &&
+                    !strncmp(buf, ass_sections[i].fields_header, len)) {
+                    ctx->current_section = i;
+                    section = &ass_sections[ctx->current_section];
+                    number = &ctx->field_number[ctx->current_section];
+                    order = ctx->field_order[ctx->current_section];
+                    break;
+                }
+            }
+        }
+        if (section->format_header && !order) {
             len = strlen(section->format_header);
-            if (strncmp(buf, section->format_header, len) || buf[len] != ':')
-                goto next_line;
+            if (buf[len] == ':' && !strncmp(buf, section->format_header, len)) {
             buf += len + 1;
             while (!is_eol(*buf)) {
                 buf = skip_space(buf);
@@ -278,7 +293,10 @@ static const char *ass_split_section(ASSSplitContext *ctx, const char *buf)
                 buf = skip_space(buf + len + (buf[len] == ','));
             }
             ctx->field_order[ctx->current_section] = order;
-        } else if (section->fields_header) {
+                goto next_line;
+            }
+        }
+        if (section->fields_header) {
             len = strlen(section->fields_header);
             if (!strncmp(buf, section->fields_header, len) && buf[len] == ':') {
                 uint8_t *ptr, *struct_ptr = realloc_section_array(ctx);
@@ -286,7 +304,7 @@ static const char *ass_split_section(ASSSplitContext *ctx, const char *buf)
 
                 /* No format header line found so far, assume default */
                 if (!order) {
-                    order = get_default_field_orders(section);
+                    order = get_default_field_orders(section, number);
                     if (!order)
                         return NULL;
                     ctx->field_order[ctx->current_section] = order;