libavfilter/vf_fieldorder.c
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 /*
  * Copyright (c) 2011 Mark Himsley
  *
  * 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
  * video field order filter, heavily influenced by vf_pad.c
  */
 
 /* #define DEBUG */
 
 #include "libavutil/imgutils.h"
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 
 typedef struct
 {
     unsigned int dst_tff;      ///< output bff/tff
     int          line_size[4]; ///< bytes of pixel data per line for each plane
 } FieldOrderContext;
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     FieldOrderContext *fieldorder = ctx->priv;
 
     const char *tff = "tff";
     const char *bff = "bff";
 
     if (!args) {
         fieldorder->dst_tff = 1;
     } else if (sscanf(args, "%u", &fieldorder->dst_tff) == 1) {
         fieldorder->dst_tff = !!fieldorder->dst_tff;
     } else if (!strcmp(tff, args)) {
         fieldorder->dst_tff = 1;
     } else if (!strcmp(bff, args)) {
         fieldorder->dst_tff = 0;
     } else {
         av_log(ctx, AV_LOG_ERROR, "Invalid argument '%s'.\n", args);
         return AVERROR(EINVAL);
     }
 
     av_log(ctx, AV_LOG_INFO, "output field order: %s\n",
             fieldorder->dst_tff ? tff : bff);
 
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats  *formats;
     enum PixelFormat pix_fmt;
     int              ret;
 
     /** accept any input pixel format that is not hardware accelerated, not
      *  a bitstream format, and does not have vertically sub-sampled chroma */
     if (ctx->inputs[0]) {
         formats = NULL;
         for (pix_fmt = 0; pix_fmt < PIX_FMT_NB; pix_fmt++)
             if (!(  av_pix_fmt_descriptors[pix_fmt].flags & PIX_FMT_HWACCEL
                  || av_pix_fmt_descriptors[pix_fmt].flags & PIX_FMT_BITSTREAM)
                 && av_pix_fmt_descriptors[pix_fmt].nb_components
                 && !av_pix_fmt_descriptors[pix_fmt].log2_chroma_h
                 && (ret = avfilter_add_format(&formats, pix_fmt)) < 0) {
                 avfilter_formats_unref(&formats);
                 return ret;
             }
         avfilter_formats_ref(formats, &ctx->inputs[0]->out_formats);
         avfilter_formats_ref(formats, &ctx->outputs[0]->in_formats);
     }
 
     return 0;
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext   *ctx        = inlink->dst;
     FieldOrderContext *fieldorder = ctx->priv;
     int               plane;
 
     /** full an array with the number of bytes that the video
      *  data occupies per line for each plane of the input video */
     for (plane = 0; plane < 4; plane++) {
         fieldorder->line_size[plane] = av_image_get_linesize(
                 inlink->format,
                 inlink->w,
                 plane);
     }
 
     return 0;
 }
 
 static AVFilterBufferRef *get_video_buffer(AVFilterLink *inlink, int perms, int w, int h)
 {
     AVFilterContext   *ctx        = inlink->dst;
     AVFilterLink      *outlink    = ctx->outputs[0];
 
     return avfilter_get_video_buffer(outlink, perms, w, h);
 }
 
 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
 {
     AVFilterContext   *ctx        = inlink->dst;
     AVFilterLink      *outlink    = ctx->outputs[0];
 
     AVFilterBufferRef *outpicref;
 
     outpicref = avfilter_ref_buffer(inpicref, ~0);
     outlink->out_buf = outpicref;
 
     avfilter_start_frame(outlink, outpicref);
 }
 
 static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
 {
     AVFilterContext   *ctx        = inlink->dst;
     FieldOrderContext *fieldorder = ctx->priv;
     AVFilterLink      *outlink    = ctx->outputs[0];
 
     AVFilterBufferRef *inpicref   = inlink->cur_buf;
 
     /** can only currently do slices if this filter is doing nothing
      *  because this filter is moving picture content, the output
      *  slice will contain different video lines than the input slice
      *  and that complexity will be added later */
     if (  !inpicref->video->interlaced
         || inpicref->video->top_field_first == fieldorder->dst_tff) {
         avfilter_draw_slice(outlink, y, h, slice_dir);
     }
 }
 
 static void end_frame(AVFilterLink *inlink)
 {
     AVFilterContext   *ctx        = inlink->dst;
     FieldOrderContext *fieldorder = ctx->priv;
     AVFilterLink      *outlink    = ctx->outputs[0];
 
     AVFilterBufferRef *inpicref   = inlink->cur_buf;
     AVFilterBufferRef *outpicref  = outlink->out_buf;
 
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     int               h, plane, line_step, line_size, line;
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     uint8_t           *cpy_src, *cpy_dst;
 
     if (    inpicref->video->interlaced
          && inpicref->video->top_field_first != fieldorder->dst_tff) {
         av_dlog(ctx,
                 "picture will move %s one line\n",
                 fieldorder->dst_tff ? "up" : "down");
         h = inpicref->video->h;
         for (plane = 0; plane < 4 && inpicref->data[plane]; plane++) {
             line_step = inpicref->linesize[plane];
             line_size = fieldorder->line_size[plane];
             cpy_src = inpicref->data[plane];
             cpy_dst = outpicref->data[plane];
             if (fieldorder->dst_tff) {
                 /** Move every line up one line, working from
                  *  the top to the bottom of the frame.
                  *  The original top line is lost.
                  *  The new last line is created as a copy of the
                  *  penultimate line from that field. */
                 for (line = 0; line < h; line++) {
                     if (1 + line < outpicref->video->h) {
                         memcpy(cpy_dst, cpy_src + line_step, line_size);
                     } else {
                         memcpy(cpy_dst, cpy_src - line_step - line_step, line_size);
                     }
                     cpy_src += line_step;
                     cpy_dst += line_step;
                 }
             } else {
                 /** Move every line down one line, working from
                  *  the bottom to the top of the frame.
                  *  The original bottom line is lost.
                  *  The new first line is created as a copy of the
                  *  second line from that field. */
                 cpy_src += (h - 1) * line_step;
                 cpy_dst += (h - 1) * line_step;
                 for (line = h - 1; line >= 0 ; line--) {
                     if (line > 0) {
                         memcpy(cpy_dst, cpy_src - line_step, line_size);
                     } else {
                         memcpy(cpy_dst, cpy_src + line_step + line_step, line_size);
                     }
                     cpy_src -= line_step;
                     cpy_dst -= line_step;
                 }
             }
         }
         outpicref->video->top_field_first = fieldorder->dst_tff;
         avfilter_draw_slice(outlink, 0, h, 1);
     } else {
         av_dlog(ctx,
                 "not interlaced or field order already correct\n");
     }
 
     avfilter_end_frame(outlink);
     avfilter_unref_buffer(inpicref);
 }
 
 AVFilter avfilter_vf_fieldorder = {
     .name          = "fieldorder",
     .description   = NULL_IF_CONFIG_SMALL("Set the field order."),
     .init          = init,
     .priv_size     = sizeof(FieldOrderContext),
     .query_formats = query_formats,
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     .inputs        = (const AVFilterPad[]) {{ .name       = "default",
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                                         .type             = AVMEDIA_TYPE_VIDEO,
                                         .config_props     = config_input,
                                         .start_frame      = start_frame,
                                         .get_video_buffer = get_video_buffer,
                                         .draw_slice       = draw_slice,
                                         .end_frame        = end_frame,
                                         .min_perms        = AV_PERM_READ,
                                         .rej_perms        = AV_PERM_REUSE2|AV_PERM_PRESERVE,},
                                       { .name = NULL}},
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     .outputs       = (const AVFilterPad[]) {{ .name       = "default",
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                                         .type             = AVMEDIA_TYPE_VIDEO, },
                                       { .name = NULL}},
 };