[FFmpeg-devel] [PATCH v3] avfilter/vf_subtitles: add wrap_unicode option

[Oneric]

On Mon, May 22, 2023 at 21:26:02 +0800, Zhao Zhili wrote:
> From: Zhao Zhili <zhilizhao at tencent.com>
> 
> So CJK can be wrapped automatically.
> 
> Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
> ---
> v3: Fix build error with older libass
> v2: Don't overwrite wrap automatically for native ASS
>  libavfilter/version.h      |  2 +-
>  libavfilter/vf_subtitles.c | 18 ++++++++++++++++++
>  2 files changed, 19 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..3e5a19e715 100644
> --- a/libavfilter/vf_subtitles.c
> +++ b/libavfilter/vf_subtitles.c
> @@ -45,6 +45,8 @@
>  #include "formats.h"
>  #include "video.h"
>  
> +#define FF_ASS_FEATURE_WRAP_UNICODE     (LIBASS_VERSION >= 0x01600010)
> +
>  typedef struct AssContext {
>      const AVClass *class;
>      ASS_Library  *library;
> @@ -61,6 +63,7 @@ typedef struct AssContext {
>      int original_w, original_h;
>      int shaping;
>      FFDrawContext draw;
> +    int wrap_unicode;
>  } AssContext;
>  
>  #define OFFSET(x) offsetof(AssContext, x)
> @@ -271,6 +274,9 @@ static const AVOption subtitles_options[] = {
>      {"stream_index", "set stream index",             OFFSET(stream_index), AV_OPT_TYPE_INT,    { .i64 = -1 }, -1,       INT_MAX,  FLAGS},
>      {"si",           "set stream index",             OFFSET(stream_index), AV_OPT_TYPE_INT,    { .i64 = -1 }, -1,       INT_MAX,  FLAGS},
>      {"force_style",  "force subtitle style",         OFFSET(force_style),  AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS},
> +#if FF_ASS_FEATURE_WRAP_UNICODE
> +    {"wrap_unicode", "break lines according to the Unicode Line Breaking Algorithm", OFFSET(wrap_unicode), AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1, FLAGS },
> +#endif
>      {NULL},
>  };
>  
> @@ -432,6 +438,18 @@ static av_cold int init_subtitles(AVFilterContext *ctx)
>      if (ret < 0)
>          goto end;
>  
> +#if FF_ASS_FEATURE_WRAP_UNICODE
> +    /* Don't overwrite wrap automatically for native ASS */
> +    if (ass->wrap_unicode == -1)
> +        ass->wrap_unicode = st->codecpar->codec_id != AV_CODEC_ID_ASS;
> +    if (ass->wrap_unicode) {
> +        ret = ass_track_set_feature(ass->track, ASS_FEATURE_WRAP_UNICODE, 1);
> +        if (ret < 0)
> +            av_log(ctx, AV_LOG_WARNING,
> +                   "libass wasn't built with ASS_FEATURE_WRAP_UNICODE support\n");
> +    }
> +#endif
> +
>      if (ass->force_style) {
>          char **list = NULL;
>          char *temp = NULL;
> -- 
> 2.34.1

The new option and its build-time requirement should probably also be
documented in doc/filters.texi. Other than that v3 looks good to me.
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