[FFmpeg-devel] [PATCH 02/23] lavc/movtextdec: simplify style record walk

[Philip Langdale]

On Mon, 6 Apr 2020 11:51:57 -0600
John Stebbins <jstebbins at jetheaddev.com> wrote:

> It's not necessary to walk the style record list twice per subtitle
> character.  style records are in order and do not overlap.
> ---
>  libavcodec/movtextdec.c | 38 ++++++++++++++++++++------------------
>  1 file changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/libavcodec/movtextdec.c b/libavcodec/movtextdec.c
> index 05becaf64d..47a8401119 100644
> --- a/libavcodec/movtextdec.c
> +++ b/libavcodec/movtextdec.c
> @@ -355,8 +355,9 @@ static int text_to_ass(AVBPrint *buf, const char
> *text, const char *text_end, {
>      MovTextContext *m = avctx->priv_data;
>      int i = 0;
> -    int j = 0;
>      int text_pos = 0;
> +    int style_active = 0;
> +    int entry = 0;
>  
>      if (text < text_end && m->box_flags & TWRP_BOX) {
>          if (m->w.wrap_flag == 1) {
> @@ -369,26 +370,27 @@ static int text_to_ass(AVBPrint *buf, const
> char *text, const char *text_end, while (text < text_end) {
>          int len;
>  
> -        if (m->box_flags & STYL_BOX) {
> -            for (i = 0; i < m->style_entries; i++) {
> -                if (m->s[i]->style_flag && text_pos ==
> m->s[i]->style_end) {
> -                    av_bprintf(buf, "{\\r}");
> +        if ((m->box_flags & STYL_BOX) && entry < m->style_entries) {
> +            if (text_pos == m->s[entry]->style_start) {
> +                style_active = 1;
> +                if (m->s[entry]->style_flag & STYLE_FLAG_BOLD)
> +                    av_bprintf(buf, "{\\b1}");
> +                if (m->s[entry]->style_flag & STYLE_FLAG_ITALIC)
> +                    av_bprintf(buf, "{\\i1}");
> +                if (m->s[entry]->style_flag & STYLE_FLAG_UNDERLINE)
> +                    av_bprintf(buf, "{\\u1}");
> +                av_bprintf(buf, "{\\fs%d}", m->s[entry]->fontsize);
> +                for (i = 0; i < m->ftab_entries; i++) {
> +                    if (m->s[entry]->style_fontID ==
> m->ftab[i]->fontID)
> +                        av_bprintf(buf, "{\\fn%s}",
> m->ftab[i]->font); }
>              }
> -            for (i = 0; i < m->style_entries; i++) {
> -                if (m->s[i]->style_flag && text_pos ==
> m->s[i]->style_start) {
> -                    if (m->s[i]->style_flag & STYLE_FLAG_BOLD)
> -                        av_bprintf(buf, "{\\b1}");
> -                    if (m->s[i]->style_flag & STYLE_FLAG_ITALIC)
> -                        av_bprintf(buf, "{\\i1}");
> -                    if (m->s[i]->style_flag & STYLE_FLAG_UNDERLINE)
> -                        av_bprintf(buf, "{\\u1}");
> -                    av_bprintf(buf, "{\\fs%d}", m->s[i]->fontsize);
> -                    for (j = 0; j < m->ftab_entries; j++) {
> -                        if (m->s[i]->style_fontID ==
> m->ftab[j]->fontID)
> -                            av_bprintf(buf, "{\\fn%s}",
> m->ftab[j]->font);
> -                    }
> +            if (text_pos == m->s[entry]->style_end) {
> +                if (style_active) {
> +                    av_bprintf(buf, "{\\r}");
> +                    style_active = 0;
>                  }
> +                entry++;
>              }
>          }
>          if (m->box_flags & HLIT_BOX) {

OK. I could not convince myself originally that styles could not
overlap, but I could easily have missed that in the spec.

--phil