[FFmpeg-devel] [PATCH] 3GPP TS 26.245 Timed Text decoder: decode rich formatting in sample modifier boxes

Wes root670 at gmail.com
Wed Mar 18 05:12:43 CET 2015


My cover letter was sent in a separate email, apologies!

Wesley

On Tue, Mar 17, 2015 at 9:09 PM, Wesley Castro <root670 at gmail.com> wrote:

> Bold, italic, and underlined type will be converted to their equivilent
> ASS styles when encountered in a text style sample modifier box.
>
> Signed-off-by: Wesley Castro <root670 at gmail.com>
> ---
>  libavcodec/movtextdec.c | 72
> ++++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 69 insertions(+), 3 deletions(-)
>
> diff --git a/libavcodec/movtextdec.c b/libavcodec/movtextdec.c
> index 1c7ffea..4dba1e4 100644
> --- a/libavcodec/movtextdec.c
> +++ b/libavcodec/movtextdec.c
> @@ -26,9 +26,25 @@
>  #include "libavutil/bprint.h"
>  #include "libavutil/intreadwrite.h"
>
> -static int text_to_ass(AVBPrint *buf, const char *text, const char
> *text_end)
> +#define STYLE_FLAG_BOLD         1
> +#define STYLE_FLAG_ITALIC       2
> +#define STYLE_FLAG_UNDERLINE    4
> +
> +static int text_to_ass(AVBPrint *buf, const char *text, const char
> *text_end,
> +                       const char *style_start, const char *style_end,
> +                       const int style_flags)
>  {
>      while (text < text_end) {
> +        if (style_flags && text == style_start)
> +        {
> +            if (style_flags & STYLE_FLAG_BOLD)
> +                av_bprintf(buf, "{\\b1}");
> +            if (style_flags & STYLE_FLAG_ITALIC)
> +                av_bprintf(buf, "{\\i1}");
> +            if (style_flags & STYLE_FLAG_UNDERLINE)
> +                av_bprintf(buf, "{\\u1}");
> +        }
> +
>          switch (*text) {
>          case '\r':
>              break;
> @@ -36,9 +52,22 @@ static int text_to_ass(AVBPrint *buf, const char *text,
> const char *text_end)
>              av_bprintf(buf, "\\N");
>              break;
>          default:
> +
>              av_bprint_chars(buf, *text, 1);
> +
>              break;
>          }
> +
> +        if (style_flags && text == style_end)
> +        {
> +            if (style_flags & STYLE_FLAG_BOLD)
> +                av_bprintf(buf, "{\\b1}");
> +            if (style_flags & STYLE_FLAG_ITALIC)
> +                av_bprintf(buf, "{\\i1}");
> +            if (style_flags & STYLE_FLAG_UNDERLINE)
> +                av_bprintf(buf, "{\\u1}");
> +        }
> +
>          text++;
>      }
>
> @@ -63,6 +92,9 @@ static int mov_text_decode_frame(AVCodecContext *avctx,
>      AVBPrint buf;
>      const char *ptr = avpkt->data;
>      const char *end;
> +    int text_length, tsmb_type, style_entries, style_flags;
> +    const char *style_start, *style_end;
> +    const uint8_t *tsmb;
>
>      if (!ptr || avpkt->size < 2)
>          return AVERROR_INVALIDDATA;
> @@ -82,7 +114,9 @@ static int mov_text_decode_frame(AVCodecContext *avctx,
>       * In complex cases, there are style descriptors appended to the
> string
>       * so we can't just assume the packet size is the string size.
>       */
> -    end = ptr + FFMIN(2 + AV_RB16(ptr), avpkt->size);
> +    text_length = AV_RB16(ptr);
> +
> +    end = ptr + FFMIN(2 + text_length, avpkt->size);
>      ptr += 2;
>
>      ts_start = av_rescale_q(avpkt->pts,
> @@ -94,7 +128,39 @@ static int mov_text_decode_frame(AVCodecContext *avctx,
>
>      // Note that the spec recommends lines be no longer than 2048
> characters.
>      av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
> -    text_to_ass(&buf, ptr, end);
> +
> +    if (text_length + 2 != avpkt->size)
> +    {
> +        tsmb = ptr + text_length;
> +
> +        //tsmb_size = AV_RB32(tsmb);
> +        tsmb += 4;
> +        tsmb_type = AV_RB32(tsmb);
> +        tsmb += 4;
> +
> +        if (tsmb_type == MKTAG('s','t','y','l'))
> +        {
> +            style_entries = AV_RB16(tsmb);
> +            tsmb += 2;
> +
> +            for(int i = 0; i < style_entries;i++)
> +            {
> +                style_start = ptr + AV_RB16(tsmb);
> +                tsmb += 2;
> +                style_end = ptr + AV_RB16(tsmb);
> +                tsmb += 2;
> +                // fontID = AV_RB16(tsmb);
> +                tsmb += 2;
> +                style_flags = AV_RB8(tsmb++);
> +
> +
> +                text_to_ass(&buf, ptr, end, style_start, style_end,
> style_flags);
> +            }
> +        }
> +    }
> +    else
> +        text_to_ass(&buf, ptr, end, NULL, NULL, 0);
> +
>      ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_end-ts_start);
>      av_bprint_finalize(&buf, NULL);
>      if (ret < 0)
> --
> 1.9.1
>
>


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