[FFmpeg-devel] [PATCH V4] lavf/vf_ocr: add subregion support

[Lingjiang Fang]

On Wed, 21 Jul 2021 09:38:51 +0800
Steven Liu <lq at chinaffmpeg.org> wrote:

> 
> 
> > 2021年7月12日 下午1:14，Lingjiang Fang <vacingfang at foxmail.com>
> > 写道：
> > 
> > follow comments from Steven Liu
> > ---
> > doc/filters.texi     |  8 ++++++++
> > libavfilter/vf_ocr.c | 45
> > +++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 52
> > insertions(+), 1 deletion(-)
> > 
> > diff --git a/doc/filters.texi b/doc/filters.texi
> > index d991c06628..f41ba0ce46 100644
> > --- a/doc/filters.texi
> > +++ b/doc/filters.texi
> > @@ -15457,6 +15457,14 @@ Set character whitelist.
> > 
> > @item blacklist
> > Set character blacklist.
> > +
> > + at item x, y
> > +Set top-left corner of the subregion, in pixels, default is (0,0).
> > +
> > + at item w, h
> > +Set width and height of the subregion, in pixels,
> > +default is the bottom-right part from given top-left corner.
> > +
> > @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..55f04b6592 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, x_in, y_in;
> > +    int w, h, w_in, h_in;
> > 
> >     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 +99,41 @@ 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 config_input(AVFilterLink *inlink)
> > +{
> > +    AVFilterContext *ctx = inlink->dst;
> > +    OCRContext *s = ctx->priv;
> > +
> > +    s->x_in = s->x;
> > +    s->y_in = s->y;
> > +    s->w_in = s->w;
> > +    s->h_in = s->h;
> > +    check_fix(&s->x_in, &s->y_in, &s->w_in, &s->h_in, inlink->w,
> > inlink->h);
> > +    if ( s->x_in != s->x || s->y_in != s->y  ||
> > +        (s->w != 0 && s->w_in != s->w) || (s->h != 0 && s->h_in !=
> > s->h)) {
> > +        av_log(s, AV_LOG_WARNING, "config error, subregion changed
> > to "
> > +                                  "x=%d, y=%d, w=%d, h=%d\n",
> > +                                  s->x_in, s->y_in, s->w_in,
> > s->h_in);
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> > static int filter_frame(AVFilterLink *inlink, AVFrame *in)
> > {
> >     AVDictionary **metadata = &in->metadata;
> > @@ -102,8 +143,9 @@ static int filter_frame(AVFilterLink *inlink,
> > AVFrame *in) char *result;
> >     int *confs;
> > 
> > +    // TODO(vacing): support expression
> What’s vacing? 
"vacing" is my nickname, sorry to make misunderstanding
maybe I should put my email address here, should I?

> >     result = TessBaseAPIRect(s->tess, in->data[0], 1,
> > -                             in->linesize[0], 0, 0, in->width,
> > in->height);
> > +                             in->linesize[0], s->x_in, s->y_in,
> > s->w_in, s->h_in); confs = TessBaseAPIAllWordConfidences(s->tess);
> >     av_dict_set(metadata, "lavfi.ocr.text", result, 0);
> >     for (int i = 0; confs[i] != -1; i++) {
> > @@ -134,6 +176,7 @@ static const AVFilterPad ocr_inputs[] = {
> >         .name         = "default",
> >         .type         = AVMEDIA_TYPE_VIDEO,
> >         .filter_frame = filter_frame,
> > +        .config_props = config_input,
> >     },
> >     { NULL }
> > };
> > -- 
> > 2.29.2
> > 
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> > 
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> > 
> 
> Thanks
> 
> Steven Liu
> 
> 
> 
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Regards,
Lingjiang Fang