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/*
* Copyright (c) 2015 Paul B Mahol
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <tesseract/capi.h>
#include "libavutil/opt.h"
#include "avfilter.h"
#include "filters.h"
#include "video.h"
typedef struct OCRContext {
const AVClass *class;
char *datapath;
char *language;
char *whitelist;
char *blacklist;
TessBaseAPI *tess;
} OCRContext;
#define OFFSET(x) offsetof(OCRContext, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption ocr_options[] = {
{ "datapath", "set datapath", OFFSET(datapath), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
{ "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 },
{ NULL }
};
static av_cold int init(AVFilterContext *ctx)
{
OCRContext *s = ctx->priv;
s->tess = TessBaseAPICreate();
if (TessBaseAPIInit3(s->tess, s->datapath, s->language) == -1) {
av_log(ctx, AV_LOG_ERROR, "failed to init tesseract\n");
return AVERROR(EINVAL);
}
if (!TessBaseAPISetVariable(s->tess, "tessedit_char_whitelist", s->whitelist)) {
av_log(ctx, AV_LOG_ERROR, "failed to set whitelist\n");
return AVERROR(EINVAL);
}
if (!TessBaseAPISetVariable(s->tess, "tessedit_char_blacklist", s->blacklist)) {
av_log(ctx, AV_LOG_ERROR, "failed to set blacklist\n");
return AVERROR(EINVAL);
}
av_log(ctx, AV_LOG_DEBUG, "Tesseract version: %s\n", TessVersion());
return 0;
}
static const enum AVPixelFormat pix_fmts[] = {
AV_PIX_FMT_GRAY8,
AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
AV_PIX_FMT_YUVJ411P,
AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
AV_PIX_FMT_NONE
};
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVDictionary **metadata = &in->metadata;
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
OCRContext *s = ctx->priv;
char *result;
int *confs;
result = TessBaseAPIRect(s->tess, in->data[0], 1,
in->linesize[0], 0, 0, in->width, in->height);
confs = TessBaseAPIAllWordConfidences(s->tess);
av_dict_set(metadata, "lavfi.ocr.text", result, 0);
for (int i = 0; confs[i] != -1; i++) {
char number[256];
snprintf(number, sizeof(number), "%d ", confs[i]);
av_dict_set(metadata, "lavfi.ocr.confidence", number, AV_DICT_APPEND);
}
TessDeleteText(result);
TessDeleteIntArray(confs);
return ff_filter_frame(outlink, in);
}
static av_cold void uninit(AVFilterContext *ctx)
{
OCRContext *s = ctx->priv;
TessBaseAPIEnd(s->tess);
TessBaseAPIDelete(s->tess);
}
AVFILTER_DEFINE_CLASS(ocr);
static const AVFilterPad ocr_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.filter_frame = filter_frame,
},
};
const FFFilter ff_vf_ocr = {
.p.name = "ocr",
.p.description = NULL_IF_CONFIG_SMALL("Optical Character Recognition."),
.p.priv_class = &ocr_class,
.p.flags = AVFILTER_FLAG_METADATA_ONLY,
.priv_size = sizeof(OCRContext),
.init = init,
.uninit = uninit,
FILTER_INPUTS(ocr_inputs),
FILTER_OUTPUTS(ff_video_default_filterpad),
FILTER_PIXFMTS_ARRAY(pix_fmts),
};
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