[FFmpeg-devel] [PATCH 6/7] avcodec/ass_split: assume default order when "Format:" line is not found

[wm4]

On Sat, 11 Oct 2014 19:59:11 +0200
Clément Bœsch <u at pkh.me> wrote:

> Fixes the decoding of the ASS stream in a mkv from a fansub release from
> Coalgirls.
> ---
>  libavcodec/ass_split.c | 26 +++++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/libavcodec/ass_split.c b/libavcodec/ass_split.c
> index fea38e7..bd7db93 100644
> --- a/libavcodec/ass_split.c
> +++ b/libavcodec/ass_split.c
> @@ -229,6 +229,20 @@ static inline const char *skip_space(const char *buf)
>      return buf;
>  }
>  
> +static int *get_default_field_orders(const ASSSection *section)
> +{
> +    int i;
> +    int *order = av_malloc(FF_ARRAY_ELEMS(section->fields) * sizeof(*order));
> +
> +    if (!order)
> +        return NULL;
> +    for (i = 0; section->fields[i].name; i++)
> +        order[i] = i;
> +    while (i < FF_ARRAY_ELEMS(section->fields))
> +        order[i] = -1;
> +    return order;
> +}
> +
>  static const char *ass_split_section(ASSSplitContext *ctx, const char *buf)
>  {
>      const ASSSection *section = &ass_sections[ctx->current_section];
> @@ -246,7 +260,7 @@ static const char *ass_split_section(ASSSplitContext *ctx, const char *buf)
>          } else if (section->format_header && !order) {
>              len = strlen(section->format_header);
>              if (strncmp(buf, section->format_header, len) || buf[len] != ':')
> -                return NULL;
> +                goto next_line;
>              buf += len + 1;
>              while (!is_eol(*buf)) {
>                  buf = skip_space(buf);
> @@ -269,6 +283,15 @@ static const char *ass_split_section(ASSSplitContext *ctx, const char *buf)
>              if (!strncmp(buf, section->fields_header, len) && buf[len] == ':') {
>                  uint8_t *ptr, *struct_ptr = realloc_section_array(ctx);
>                  if (!struct_ptr)  return NULL;
> +
> +                /* No format header line found so far, assume default */
> +                if (!order) {
> +                    order = get_default_field_orders(section);
> +                    if (!order)
> +                        return NULL;
> +                    ctx->field_order[ctx->current_section] = order;
> +                }
> +
>                  buf += len + 1;
>                  for (i=0; !is_eol(*buf) && i < *number; i++) {
>                      int last = i == *number - 1;
> @@ -298,6 +321,7 @@ static const char *ass_split_section(ASSSplitContext *ctx, const char *buf)
>                      }
>              }
>          }
> +next_line:
>          buf += strcspn(buf, "\n");
>          buf += !!*buf;
>      }

I think you must distinguish between ASS and SSA when doing this.