[FFmpeg-devel] [PATCH V2] lavf/vf_ocr: add subregion support

[Lingjiang Fang]

On Thu, 17 Jun 2021 22:08:52 +0530
Gyan Doshi <ffmpeg at gyani.pro> wrote:

> On 2021-06-17 20:28, Lingjiang Fang wrote:
> > fix bugs of previous patch, ping for review
> > ---
> >   doc/filters.texi     |  7 +++++++
> >   libavfilter/vf_ocr.c | 35 ++++++++++++++++++++++++++++++++++-
> >   2 files changed, 41 insertions(+), 1 deletion(-)
> >
> > diff --git a/doc/filters.texi b/doc/filters.texi
> > index da8f7d7726..a955cf46e0 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  
> 
> This isn't idiomatic. And the docs should state what the option
> accepts, not what it doesn't.
> 
> Change to
> 
>      Set position of top-left corner, in pixels.
> 
thank you for your correction

If no more comments I will send v3 later

> 
> > +
> > + at item w, h
> > +Set width and height of subregion
> > +
> >   @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..e96dce2d87 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 }
> >   };
> >   
> > @@ -93,6 +99,21 @@ static int query_formats(AVFilterContext *ctx)
> >       return ff_set_common_formats(ctx, fmts_list);
> >   }
> >   
> > +static void check_fix(int *x, int *y, int *w, int *h, int pic_w,
> > int pic_h) +{
> > +    // 0 <= x < pic_w
> > +    if (*x >= pic_w)
> > +        *x = 0;
> > +    // 0 <= y < pic_h
> > +    if (*y >= pic_h)
> > +        *y = 0;
> > +
> > +    if (*w == 0 || *w + *x > pic_w)
> > +        *w = pic_w - *x;
> > +    if (*h == 0 || *h + *y > pic_h)
> > +        *h = pic_h - *y;
> > +}
> > +
> >   static int filter_frame(AVFilterLink *inlink, AVFrame *in)
> >   {
> >       AVDictionary **metadata = &in->metadata;
> > @@ -102,8 +123,20 @@ static int filter_frame(AVFilterLink *inlink,
> > AVFrame *in) char *result;
> >       int *confs;
> >   
> > +    // TODO: support expression
> > +    int x = s->x;
> > +    int y = s->y;
> > +    int w = s->w;
> > +    int h = s->h;
> > +    check_fix(&x, &y, &w, &h, in->width, in->height);
> > +    if ( x != s->x || y != s->y  ||
> > +        (s->w != 0 && w != s->w) || (s->h != 0 && h != s->h)) {
> > +        av_log(s, AV_LOG_WARNING, "config error, subregion changed
> > to x=%d, y=%d, w=%d, h=%d\n",
> > +
> >  x, y, w, h);
> > +    }
> > +
> >       result = TessBaseAPIRect(s->tess, in->data[0], 1,
> > -                             in->linesize[0], 0, 0, in->width,
> > in->height);
> > +                             in->linesize[0], x, y, w, h);
> >       confs = TessBaseAPIAllWordConfidences(s->tess);
> >       av_dict_set(metadata, "lavfi.ocr.text", result, 0);
> >       for (int i = 0; confs[i] != -1; i++) {  
> 
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Regards,
Lingjiang Fang