libavfilter/vf_detelecine.c
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 /*
  * Copyright (c) 2015 Himangi Saraogi <himangi774@gmail.com>
  *
  * 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
  */
 
 /**
  * @file detelecine filter.
  */
 
 
 #include "libavutil/avstring.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 typedef struct {
     const AVClass *class;
     int first_field;
     char *pattern;
     int start_frame;
     unsigned int pattern_pos;
     unsigned int nskip_fields;
     int64_t start_time;
 
     AVRational pts;
     AVRational ts_unit;
     int occupied;
 
     int nb_planes;
     int planeheight[4];
     int stride[4];
 
     AVFrame *frame;
     AVFrame *temp;
 } DetelecineContext;
 
 #define OFFSET(x) offsetof(DetelecineContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption detelecine_options[] = {
     {"first_field", "select first field", OFFSET(first_field), AV_OPT_TYPE_INT,   {.i64=0}, 0, 1, FLAGS, "field"},
         {"top",    "select top field first",                0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "field"},
         {"t",      "select top field first",                0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "field"},
         {"bottom", "select bottom field first",             0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "field"},
         {"b",      "select bottom field first",             0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "field"},
     {"pattern", "pattern that describe for how many fields a frame is to be displayed", OFFSET(pattern), AV_OPT_TYPE_STRING, {.str="23"}, 0, 0, FLAGS},
     {"start_frame", "position of first frame with respect to the pattern if stream is cut", OFFSET(start_frame), AV_OPT_TYPE_INT, {.i64=0}, 0, 13, FLAGS},
     {NULL}
 };
 
 AVFILTER_DEFINE_CLASS(detelecine);
 
 static av_cold int init(AVFilterContext *ctx)
 {
     DetelecineContext *s = ctx->priv;
     const char *p;
     int max = 0;
 
     if (!strlen(s->pattern)) {
         av_log(ctx, AV_LOG_ERROR, "No pattern provided.\n");
         return AVERROR_INVALIDDATA;
     }
 
     for (p = s->pattern; *p; p++) {
         if (!av_isdigit(*p)) {
             av_log(ctx, AV_LOG_ERROR, "Provided pattern includes non-numeric characters.\n");
             return AVERROR_INVALIDDATA;
         }
 
         max = FFMAX(*p - '0', max);
         s->pts.num += *p - '0';
         s->pts.den += 2;
     }
 
     s->nskip_fields = 0;
     s->pattern_pos = 0;
     s->start_time = AV_NOPTS_VALUE;
 
     if (s->start_frame != 0) {
         int nfields = 0;
         for (p = s->pattern; *p; p++) {
             nfields += *p - '0';
             s->pattern_pos++;
             if (nfields >= 2*s->start_frame) {
                 s->nskip_fields = nfields - 2*s->start_frame;
                 break;
             }
         }
     }
 
     av_log(ctx, AV_LOG_INFO, "Detelecine pattern %s removes up to %d frames per frame, pts advance factor: %d/%d\n",
            s->pattern, (max + 1) / 2, s->pts.num, s->pts.den);
 
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *pix_fmts = NULL;
     int fmt;
 
     for (fmt = 0; av_pix_fmt_desc_get(fmt); fmt++) {
         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL ||
               desc->flags & AV_PIX_FMT_FLAG_PAL     ||
               desc->flags & AV_PIX_FMT_FLAG_BITSTREAM))
             ff_add_format(&pix_fmts, fmt);
     }
 
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     return ff_set_common_formats(ctx, pix_fmts);
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 }
 
 static int config_input(AVFilterLink *inlink)
 {
     DetelecineContext *s = inlink->dst->priv;
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     int ret;
 
     s->temp = ff_get_video_buffer(inlink, inlink->w, inlink->h);
     if (!s->temp)
         return AVERROR(ENOMEM);
 
     s->frame = ff_get_video_buffer(inlink, inlink->w, inlink->h);
     if (!s->frame)
         return AVERROR(ENOMEM);
 
     if ((ret = av_image_fill_linesizes(s->stride, inlink->format, inlink->w)) < 0)
         return ret;
 
     s->planeheight[1] = s->planeheight[2] = FF_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
     s->planeheight[0] = s->planeheight[3] = inlink->h;
 
     s->nb_planes = av_pix_fmt_count_planes(inlink->format);
 
     return 0;
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     DetelecineContext *s = ctx->priv;
     const AVFilterLink *inlink = ctx->inputs[0];
     AVRational fps = inlink->frame_rate;
 
     if (!fps.num || !fps.den) {
         av_log(ctx, AV_LOG_ERROR, "The input needs a constant frame rate; "
                "current rate of %d/%d is invalid\n", fps.num, fps.den);
         return AVERROR(EINVAL);
     }
     fps = av_mul_q(fps, av_inv_q(s->pts));
     av_log(ctx, AV_LOG_VERBOSE, "FPS: %d/%d -> %d/%d\n",
            inlink->frame_rate.num, inlink->frame_rate.den, fps.num, fps.den);
 
     outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
     outlink->frame_rate = fps;
     outlink->time_base = av_mul_q(inlink->time_base, s->pts);
     av_log(ctx, AV_LOG_VERBOSE, "TB: %d/%d -> %d/%d\n",
            inlink->time_base.num, inlink->time_base.den, outlink->time_base.num, outlink->time_base.den);
 
     s->ts_unit = av_inv_q(av_mul_q(fps, outlink->time_base));
 
     return 0;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     DetelecineContext *s = ctx->priv;
     int i, len = 0, ret = 0, out = 0;
 
     if (s->start_time == AV_NOPTS_VALUE)
         s->start_time = inpicref->pts;
 
     if (s->nskip_fields >= 2) {
         s->nskip_fields -= 2;
         return 0;
     } else if (s->nskip_fields >= 1) {
         if (s->occupied) {
             s->occupied = 0;
             s->nskip_fields--;
         }
         else {
             for (i = 0; i < s->nb_planes; i++) {
                 av_image_copy_plane(s->temp->data[i], s->temp->linesize[i],
                                     inpicref->data[i], inpicref->linesize[i],
                                     s->stride[i],
                                     s->planeheight[i]);
             }
             s->occupied = 1;
             s->nskip_fields--;
             return 0;
         }
     }
 
     if (s->nskip_fields == 0) {
         while(!len && s->pattern[s->pattern_pos]) {
             len = s->pattern[s->pattern_pos] - '0';
             s->pattern_pos++;
         }
 
         if (!s->pattern[s->pattern_pos])
             s->pattern_pos = 0;
 
         if(!len) { // do not output any field as the entire pattern is zero
             av_frame_free(&inpicref);
             return 0;
         }
 
         if (s->occupied) {
             for (i = 0; i < s->nb_planes; i++) {
                 // fill in the EARLIER field from the new pic
                 av_image_copy_plane(s->frame->data[i] + s->frame->linesize[i] * s->first_field,
                                     s->frame->linesize[i] * 2,
                                     inpicref->data[i] + inpicref->linesize[i] * s->first_field,
                                     inpicref->linesize[i] * 2,
                                     s->stride[i],
                                     (s->planeheight[i] - s->first_field + 1) / 2);
                 // fill in the LATER field from the buffered pic
                 av_image_copy_plane(s->frame->data[i] + s->frame->linesize[i] * !s->first_field,
                                     s->frame->linesize[i] * 2,
                                     s->temp->data[i] + s->temp->linesize[i] * !s->first_field,
                                     s->temp->linesize[i] * 2,
                                     s->stride[i],
                                     (s->planeheight[i] - !s->first_field + 1) / 2);
             }
             len -= 2;
             for (i = 0; i < s->nb_planes; i++) {
                 av_image_copy_plane(s->temp->data[i], s->temp->linesize[i],
                                     inpicref->data[i], inpicref->linesize[i],
                                     s->stride[i],
                                     s->planeheight[i]);
             }
             s->occupied = 1;
             out = 1;
         } else {
             if (len >= 2) {
                 // output THIS image as-is
                 for (i = 0; i < s->nb_planes; i++)
                     av_image_copy_plane(s->frame->data[i], s->frame->linesize[i],
                                         inpicref->data[i], inpicref->linesize[i],
                                         s->stride[i],
                                         s->planeheight[i]);
                 len -= 2;
                 out = 1;
             } else if (len == 1) {
                 // fill in the EARLIER field from the new pic
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                 for (i = 0; i < s->nb_planes; i++) {
                     av_image_copy_plane(s->frame->data[i] +
                                         s->frame->linesize[i] * s->first_field,
                                         s->frame->linesize[i] * 2,
                                         inpicref->data[i] +
                                         inpicref->linesize[i] * s->first_field,
                                         inpicref->linesize[i] * 2, s->stride[i],
                                         (s->planeheight[i] - s->first_field + 1) / 2);
                  }
 
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                 // TODO: not sure about the other field
 
                 len--;
                 out = 1;
             }
         }
 
         if (len == 1 && s->occupied)
         {
             len--;
             s->occupied = 0;
         }
     }
     s->nskip_fields = len;
 
     if (out) {
         AVFrame *frame = av_frame_clone(s->frame);
 
         if (!frame) {
             av_frame_free(&inpicref);
             return AVERROR(ENOMEM);
         }
 
         av_frame_copy_props(frame, inpicref);
         frame->pts = ((s->start_time == AV_NOPTS_VALUE) ? 0 : s->start_time) +
                      av_rescale(outlink->frame_count, s->ts_unit.num,
                                 s->ts_unit.den);
         ret = ff_filter_frame(outlink, frame);
     }
 
     av_frame_free(&inpicref);
 
     return ret;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     DetelecineContext *s = ctx->priv;
 
     av_frame_free(&s->temp);
     av_frame_free(&s->frame);
 }
 
 static const AVFilterPad detelecine_inputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .filter_frame  = filter_frame,
         .config_props  = config_input,
     },
     { NULL }
 };
 
 static const AVFilterPad detelecine_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
     },
     { NULL }
 };
 
 AVFilter ff_vf_detelecine = {
     .name          = "detelecine",
     .description   = NULL_IF_CONFIG_SMALL("Apply an inverse telecine pattern."),
     .priv_size     = sizeof(DetelecineContext),
     .priv_class    = &detelecine_class,
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
     .inputs        = detelecine_inputs,
     .outputs       = detelecine_outputs,
 };