[FFmpeg-devel] [PATCH] lavf/vf_ocr: add subregion support

[Gyan Doshi]

On 2021-06-17 11:31, Lingjiang Fang wrote:
> ---
>   doc/filters.texi     |  7 +++++++
>   libavfilter/vf_ocr.c | 30 +++++++++++++++++++++++++++++-
>   2 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index da8f7d7726..9c650a2a5a 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -15451,6 +15451,13 @@ Set character whitelist.
>   
>   @item blacklist
>   Set character blacklist.
> +
> + at item x, y
> +Set top point position of subregion, not support expression now

--> Set position of top-left corner, in pixels.

> +
> + at item w, h
> +Set Width and height of subregion

s/Width/width


> +
>   @end table
>   
>   The filter exports recognized text as the frame metadata @code{lavfi.ocr.text}.
> diff --git a/libavfilter/vf_ocr.c b/libavfilter/vf_ocr.c
> index 6de474025a..7beb101679 100644
> --- a/libavfilter/vf_ocr.c
> +++ b/libavfilter/vf_ocr.c
> @@ -33,6 +33,8 @@ typedef struct OCRContext {
>       char *language;
>       char *whitelist;
>       char *blacklist;
> +    int x, y;
> +    int w, h;
>   
>       TessBaseAPI *tess;
>   } OCRContext;
> @@ -45,6 +47,10 @@ static const AVOption ocr_options[] = {
>       { "language",  "set language",            OFFSET(language),  AV_OPT_TYPE_STRING, {.str="eng"}, 0, 0, FLAGS },
>       { "whitelist", "set character whitelist", OFFSET(whitelist), AV_OPT_TYPE_STRING, {.str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.:;,-+_!?\"'[]{}()<>|/\\=*&%$#@!~ "}, 0, 0, FLAGS },
>       { "blacklist", "set character blacklist", OFFSET(blacklist), AV_OPT_TYPE_STRING, {.str=""},    0, 0, FLAGS },
> +    { "x",         "top x of sub region",     OFFSET(x),         AV_OPT_TYPE_INT,    {.i64=0},     0, INT_MAX, FLAGS },
> +    { "y",         "top y of sub region",     OFFSET(y),         AV_OPT_TYPE_INT,    {.i64=0},     0, INT_MAX, FLAGS },
> +    { "w",         "width of sub region",     OFFSET(w),         AV_OPT_TYPE_INT,    {.i64=0},     0, INT_MAX, FLAGS },
> +    { "h",         "height of sub region",    OFFSET(h),         AV_OPT_TYPE_INT,    {.i64=0},     0, INT_MAX, FLAGS },
>       { NULL }
>   };
>   
> @@ -73,6 +79,19 @@ static av_cold int init(AVFilterContext *ctx)
>       return 0;
>   }
>   
> +static int config_input(AVFilterLink *inlink)
> +{
> +    OCRContext  *s = inlink->dst->priv;
> +
> +    // may call many times, we don't check w/h here
> +    if (s->x < 0 || s->y < 0) {
> +        s->x = 0;
> +        s->y = 0;

These are AV_OPT_TYPE_INT with range set as 0 to INT_MAX, so the opt 
parser should disallow negative values.

Regards,
Gyan

> +    }
> +
> +    return 0;
> +}
> +
>   static int query_formats(AVFilterContext *ctx)
>   {
>       static const enum AVPixelFormat pix_fmts[] = {
> @@ -101,9 +120,17 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
>       OCRContext *s = ctx->priv;
>       char *result;
>       int *confs;
> +    int w = s->w;
> +    int h = s->h;
> +
> +    if (w <= 0 || h <= 0) {
> +        w = in->width;
> +        h = in->height;
> +    }
>   
> +    av_log(s, AV_LOG_ERROR, "x=%d, y=%d, w=%d, h=%d\n", s->x, s->y, w, h);
>       result = TessBaseAPIRect(s->tess, in->data[0], 1,
> -                             in->linesize[0], 0, 0, in->width, in->height);
> +                             in->linesize[0], s->x, s->y, w, h);
>       confs = TessBaseAPIAllWordConfidences(s->tess);
>       av_dict_set(metadata, "lavfi.ocr.text", result, 0);
>       for (int i = 0; confs[i] != -1; i++) {
> @@ -134,6 +161,7 @@ static const AVFilterPad ocr_inputs[] = {
>           .name         = "default",
>           .type         = AVMEDIA_TYPE_VIDEO,
>           .filter_frame = filter_frame,
> +        .config_props = config_input,
>       },
>       { NULL }
>   };