libavfilter/vf_interlace.c

   1 /*
   2  * This file is part of Libav.
   3  *
   4  * Libav is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * Libav is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with Libav; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 /**
  20  * @file
  21  * progressive to interlaced content filter, inspired by heavy debugging of tinterlace filter
  22  */
  23
  24 #include "libavutil/common.h"
  25 #include "libavutil/opt.h"
  26 #include "libavutil/imgutils.h"
  27 #include "libavutil/avassert.h"
  28
  29 #include "formats.h"
  30 #include "avfilter.h"
  31 #include "internal.h"
  32 #include "video.h"
  33
  34 enum ScanMode {
  35     MODE_TFF = 0,
  36     MODE_BFF = 1,
  37 };
  38
  39 enum FieldType {
  40     FIELD_UPPER = 0,
  41     FIELD_LOWER = 1,
  42 };
  43
  44 typedef struct {
  45     const AVClass *class;
  46     enum ScanMode scan;    // top or bottom field first scanning
  47     int lowpass;           // enable or disable low pass filterning
  48     AVFrame *cur, *next;   // the two frames from which the new one is obtained
  49     int got_output;        // signal an output frame is reday to request_frame()
  50 } InterlaceContext;
  51
  52 #define OFFSET(x) offsetof(InterlaceContext, x)
  53 #define V AV_OPT_FLAG_VIDEO_PARAM
  54 static const AVOption options[] = {
  55     { "scan", "scanning mode", OFFSET(scan),
  56         AV_OPT_TYPE_INT,   {.i64 = MODE_TFF }, 0, 1, .flags = V, .unit = "scan" },
  57     { "tff", "top field first", 0,
  58         AV_OPT_TYPE_CONST, {.i64 = MODE_TFF }, INT_MIN, INT_MAX, .flags = V, .unit = "scan" },
  59     { "bff", "bottom field first", 0,
  60         AV_OPT_TYPE_CONST, {.i64 = MODE_BFF }, INT_MIN, INT_MAX, .flags = V, .unit = "scan" },
  61     { "lowpass", "enable vertical low-pass filter", OFFSET(lowpass),
  62         AV_OPT_TYPE_INT,   {.i64 = 1 },        0, 1, .flags = V },
  63     { NULL }
  64 };
  65
  66 static const AVClass class = {
  67     .class_name = "interlace filter",
  68     .item_name  = av_default_item_name,
  69     .option     = options,
  70     .version    = LIBAVUTIL_VERSION_INT,
  71 };
  72
  73
  74 static const enum AVPixelFormat formats_supported[] = {
  75     AV_PIX_FMT_YUV420P,  AV_PIX_FMT_YUV422P,  AV_PIX_FMT_YUV444P,
  76     AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUV410P,  AV_PIX_FMT_YUVA420P,
  77     AV_PIX_FMT_GRAY8,    AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
  78     AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_NONE
  79 };
  80
  81 static int query_formats(AVFilterContext *ctx)
  82 {
  83     ff_set_common_formats(ctx, ff_make_format_list(formats_supported));
  84     return 0;
  85 }
  86
  87 static av_cold void uninit(AVFilterContext *ctx)
  88 {
  89     InterlaceContext *s = ctx->priv;
  90
  91     av_frame_free(&s->cur);
  92     av_frame_free(&s->next);
  93
  94     av_opt_free(s);
  95 }
  96
  97 static int config_out_props(AVFilterLink *outlink)
  98 {
  99     AVFilterContext *ctx = outlink->src;
 100     AVFilterLink *inlink = outlink->src->inputs[0];
 101     InterlaceContext *s = ctx->priv;
 102
 103     if (inlink->h < 2) {
 104         av_log(ctx, AV_LOG_ERROR, "input video height is too small\n");
 105         return AVERROR_INVALIDDATA;
 106     }
 107     // same input size
 108     outlink->w = inlink->w;
 109     outlink->h = inlink->h;
 110     outlink->time_base = inlink->time_base;
 111     // half framerate
 112     outlink->time_base.num *= 2;
 113
 114     av_log(ctx, AV_LOG_VERBOSE, "%s interlacing %s lowpass filter\n",
 115            s->scan == MODE_TFF ? "tff" : "bff", (s->lowpass) ? "with" : "without");
 116
 117     return 0;
 118 }
 119
 120 static void copy_picture_field(AVFrame *src_frame, AVFrame *dst_frame,
 121                                AVFilterLink *inlink, enum FieldType field_type,
 122                                int lowpass)
 123 {
 124     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
 125     int vsub = desc->log2_chroma_h;
 126     int plane, i, j;
 127
 128     for (plane = 0; plane < desc->nb_components; plane++) {
 129         int lines = (plane == 1 || plane == 2) ? inlink->h >> vsub : inlink->h;
 130         int linesize = av_image_get_linesize(inlink->format, inlink->w, plane);
 131         uint8_t *dstp = dst_frame->data[plane];
 132         const uint8_t *srcp = src_frame->data[plane];
 133
 134         av_assert0(linesize >= 0);
 135
 136         lines /= 2;
 137         if (field_type == FIELD_LOWER)
 138             srcp += src_frame->linesize[plane];
 139         if (field_type == FIELD_LOWER)
 140             dstp += dst_frame->linesize[plane];
 141         if (lowpass) {
 142             int srcp_linesize = src_frame->linesize[plane] * 2;
 143             int dstp_linesize = dst_frame->linesize[plane] * 2;
 144             for (j = lines; j > 0; j--) {
 145                 const uint8_t *srcp_above = srcp - src_frame->linesize[plane];
 146                 const uint8_t *srcp_below = srcp + src_frame->linesize[plane];
 147                 if (j == lines)
 148                     srcp_above = srcp; // there is no line above
 149                 if (j == 1)
 150                     srcp_below = srcp; // there is no line below
 151                 for (i = 0; i < linesize; i++) {
 152                     // this calculation is an integer representation of
 153                     // '0.5 * current + 0.25 * above + 0.25 + below'
 154                     // '1 +' is for rounding.
 155                     dstp[i] = (1 + srcp[i] + srcp[i] + srcp_above[i] + srcp_below[i]) >> 2;
 156                 }
 157                 dstp += dstp_linesize;
 158                 srcp += srcp_linesize;
 159             }
 160         } else {
 161             av_image_copy_plane(dstp, dst_frame->linesize[plane] * 2,
 162                                 srcp, src_frame->linesize[plane] * 2,
 163                                 linesize, lines);
 164         }
 165     }
 166 }
 167
 168 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
 169 {
 170     AVFilterContext *ctx = inlink->dst;
 171     AVFilterLink *outlink = ctx->outputs[0];
 172     InterlaceContext *s = ctx->priv;
 173     AVFrame *out;
 174     int tff, ret;
 175
 176     av_frame_free(&s->cur);
 177     s->cur  = s->next;
 178     s->next = buf;
 179
 180     /* we need at least two frames */
 181     if (!s->cur || !s->next)
 182         return 0;
 183
 184     tff = (s->scan == MODE_TFF);
 185     out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
 186     if (!out)
 187         return AVERROR(ENOMEM);
 188
 189     av_frame_copy_props(out, s->cur);
 190     out->interlaced_frame = 1;
 191     out->top_field_first  = tff;
 192     out->pts             /= 2;  // adjust pts to new framerate
 193
 194     /* copy upper/lower field from cur */
 195     copy_picture_field(s->cur, out, inlink, tff ? FIELD_UPPER : FIELD_LOWER, s->lowpass);
 196     av_frame_free(&s->cur);
 197
 198     /* copy lower/upper field from next */
 199     copy_picture_field(s->next, out, inlink, tff ? FIELD_LOWER : FIELD_UPPER, s->lowpass);
 200     av_frame_free(&s->next);
 201
 202     ret = ff_filter_frame(outlink, out);
 203     s->got_output = 1;
 204
 205     return ret;
 206 }
 207
 208 static int request_frame(AVFilterLink *outlink)
 209 {
 210     AVFilterContext *ctx = outlink->src;
 211     InterlaceContext *s  = ctx->priv;
 212     int ret = 0;
 213
 214     s->got_output = 0;
 215     while (ret >= 0 && !s->got_output)
 216         ret = ff_request_frame(ctx->inputs[0]);
 217
 218     return ret;
 219 }
 220
 221 static const AVFilterPad inputs[] = {
 222     {
 223         .name         = "default",
 224         .type         = AVMEDIA_TYPE_VIDEO,
 225         .filter_frame = filter_frame,
 226     },
 227     { NULL }
 228 };
 229
 230 static const AVFilterPad outputs[] = {
 231     {
 232         .name          = "default",
 233         .type          = AVMEDIA_TYPE_VIDEO,
 234         .config_props  = config_out_props,
 235         .request_frame = request_frame,
 236     },
 237     { NULL }
 238 };
 239
 240 AVFilter avfilter_vf_interlace = {
 241     .name          = "interlace",
 242     .description   = NULL_IF_CONFIG_SMALL("Convert progressive video into interlaced."),
 243     .uninit        = uninit,
 244
 245     .priv_class    = &class,
 246     .priv_size     = sizeof(InterlaceContext),
 247     .query_formats = query_formats,
 248
 249     .inputs        = inputs,
 250     .outputs       = outputs,
 251 };
 252