[FFmpeg-devel] [PATCH] avfilter/vf_subtitles: add wrap_unicode option

[Lance Wang]

On Fri, May 19, 2023 at 3:59 PM Zhao Zhili <quinkblack at foxmail.com> wrote:

> From: Zhao Zhili <zhilizhao at tencent.com>
>
> So CJK can be wrapped automatically.
>
> Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
> ---
>  libavfilter/version.h      |  2 +-
>  libavfilter/vf_subtitles.c | 13 +++++++++++++
>  2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/libavfilter/version.h b/libavfilter/version.h
> index ba8a6fdab2..08779130f5 100644
> --- a/libavfilter/version.h
> +++ b/libavfilter/version.h
> @@ -32,7 +32,7 @@
>  #include "version_major.h"
>
>  #define LIBAVFILTER_VERSION_MINOR   8
> -#define LIBAVFILTER_VERSION_MICRO 100
> +#define LIBAVFILTER_VERSION_MICRO 101
>
>
>  #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR,
> \
> diff --git a/libavfilter/vf_subtitles.c b/libavfilter/vf_subtitles.c
> index 82e140e986..d6a68e5cdd 100644
> --- a/libavfilter/vf_subtitles.c
> +++ b/libavfilter/vf_subtitles.c
> @@ -61,6 +61,7 @@ typedef struct AssContext {
>      int original_w, original_h;
>      int shaping;
>      FFDrawContext draw;
> +    int wrap_unicode;
>  } AssContext;
>
>  #define OFFSET(x) offsetof(AssContext, x)
> @@ -72,6 +73,7 @@ typedef struct AssContext {
>      {"original_size",  "set the size of the original video (used to scale
> fonts)", OFFSET(original_w), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL},  0, 0,
> FLAGS }, \
>      {"fontsdir",       "set the directory containing the fonts to read",
>          OFFSET(fontsdir),   AV_OPT_TYPE_STRING,     {.str = NULL},  0, 0,
> FLAGS }, \
>      {"alpha",          "enable processing of alpha channel",
>          OFFSET(alpha),      AV_OPT_TYPE_BOOL,       {.i64 = 0   },
>  0,        1, FLAGS }, \
> +    {"wrap_unicode",   "break lines according to the Unicode Line
> Breaking Algorithm", OFFSET(wrap_unicode), AV_OPT_TYPE_BOOL, {.i64 = 1
>  },         0,        1, FLAGS }, \
>
>  /* libass supports a log level ranging from 0 to 7 */
>  static const int ass_libavfilter_log_level_map[] = {
> @@ -329,6 +331,17 @@ static av_cold int init_subtitles(AVFilterContext
> *ctx)
>          return AVERROR(EINVAL);
>      }
>
> +    if (ass->wrap_unicode) {
> +#if (LIBASS_VERSION >= 0x01600010)
> +        ret = ass_track_set_feature(ass->track, ASS_FEATURE_WRAP_UNICODE,
> 1);
> +        if (ret < 0)
> +            av_log(ctx, AV_LOG_WARNING, "libass doesn't build with
> ASS_FEATURE_WRAP_UNICODE support\n");
> +#else
> +        av_log(ctx, AV_LOG_INFO, "libass version %#x doesn't support
> ASS_FEATURE_WRAP_UNICODE\n",
> +               LIBASS_VERSION);
> +#endif
> +    }
> +
>

I prefer to enable the feature default(if libass library support) instead
of adding a new option to turn off it(default is on).
Also, if the version is right, then why to check the return?
+#if (LIBASS_VERSION >= 0x01600010)
+        ass_track_set_feature(ass->track, ASS_FEATURE_WRAP_UNICODE, 1);
+#endif
+


>      /* Open subtitles file */
>      ret = avformat_open_input(&fmt, ass->filename, NULL, NULL);
>      if (ret < 0) {
> --
> 2.25.1
>
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