libavfilter/vf_scale.c

   1 /*
   2  * copyright (c) 2007 Bobby Bingham
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file libavfilter/vf_scale.c
  23  * scale video filter
  24  */
  25
  26 #include "avfilter.h"
  27 #include "libswscale/swscale.h"
  28
  29 typedef struct {
  30     struct SwsContext *sws;     ///< software scaler context
  31
  32     /**
  33      * New dimensions. Special values are:
  34      *   0 = original width/height
  35      *  -1 = keep original aspect
  36      */
  37     int w, h;
  38
  39     int hsub, vsub;             ///< chroma subsampling
  40     int slice_y;                ///< top of current output slice
  41     int slice_dir;              ///< detected slice direction order for the current frame
  42     int input_is_pal;           ///< set to 1 if the input format is paletted
  43 } ScaleContext;
  44
  45 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
  46 {
  47     ScaleContext *scale = ctx->priv;
  48
  49     if (args)
  50         sscanf(args, "%d:%d", &scale->w, &scale->h);
  51
  52     /* sanity check params */
  53     if (scale->w <  -1 || scale->h <  -1) {
  54         av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
  55         return -1;
  56     }
  57     if (scale->w == -1 && scale->h == -1)
  58         scale->w = scale->h = 0;
  59
  60     return 0;
  61 }
  62
  63 static av_cold void uninit(AVFilterContext *ctx)
  64 {
  65     ScaleContext *scale = ctx->priv;
  66     sws_freeContext(scale->sws);
  67     scale->sws = NULL;
  68 }
  69
  70 static int query_formats(AVFilterContext *ctx)
  71 {
  72     AVFilterFormats *formats;
  73
  74     if (ctx->inputs[0]) {
  75         formats = avfilter_all_colorspaces();
  76         avfilter_formats_ref(formats, &ctx->inputs[0]->out_formats);
  77     }
  78     if (ctx->outputs[0]) {
  79         formats = avfilter_all_colorspaces();
  80         avfilter_formats_ref(formats, &ctx->outputs[0]->in_formats);
  81     }
  82
  83     return 0;
  84 }
  85
  86 static int config_props(AVFilterLink *outlink)
  87 {
  88     AVFilterContext *ctx = outlink->src;
  89     AVFilterLink *inlink = outlink->src->inputs[0];
  90     ScaleContext *scale = ctx->priv;
  91     int64_t w, h;
  92
  93     if (!(w = scale->w))
  94         w = inlink->w;
  95     if (!(h = scale->h))
  96         h = inlink->h;
  97     if (w == -1)
  98         w = av_rescale(h, inlink->w, inlink->h);
  99     if (h == -1)
 100         h = av_rescale(w, inlink->h, inlink->w);
 101
 102     if (w > INT_MAX || h > INT_MAX ||
 103         (h * inlink->w) > INT_MAX  ||
 104         (w * inlink->h) > INT_MAX)
 105         av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");
 106
 107     outlink->w = w;
 108     outlink->h = h;
 109
 110     /* TODO: make algorithm configurable */
 111     scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
 112                                 outlink->w, outlink->h, outlink->format,
 113                                 SWS_BILINEAR, NULL, NULL, NULL);
 114
 115     av_log(ctx, AV_LOG_INFO, "w:%d h:%d fmt:%s\n",
 116            outlink->w, outlink->h, avcodec_get_pix_fmt_name(outlink->format));
 117
 118     avcodec_get_chroma_sub_sample(outlink->format, &scale->hsub, &scale->vsub);
 119
 120     scale->input_is_pal = inlink->format == PIX_FMT_PAL8      ||
 121                           inlink->format == PIX_FMT_BGR4_BYTE ||
 122                           inlink->format == PIX_FMT_RGB4_BYTE ||
 123                           inlink->format == PIX_FMT_BGR8      ||
 124                           inlink->format == PIX_FMT_RGB8;
 125
 126     return !scale->sws;
 127 }
 128
 129 static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
 130 {
 131     ScaleContext *scale = link->dst->priv;
 132     AVFilterLink *outlink = link->dst->outputs[0];
 133     AVFilterPicRef *outpicref;
 134
 135     outpicref = avfilter_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
 136     outpicref->pts = picref->pts;
 137     outlink->outpic = outpicref;
 138
 139     av_reduce(&outpicref->pixel_aspect.num, &outpicref->pixel_aspect.den,
 140               (int64_t)picref->pixel_aspect.num * outlink->h * link->w,
 141               (int64_t)picref->pixel_aspect.den * outlink->w * link->h,
 142               INT_MAX);
 143
 144     scale->slice_dir = 0;
 145     avfilter_start_frame(outlink, avfilter_ref_pic(outpicref, ~0));
 146 }
 147
 148 static void draw_slice(AVFilterLink *link, int y, int h)
 149 {
 150     ScaleContext *scale = link->dst->priv;
 151     int out_h;
 152     AVFilterPicRef *cur_pic = link->cur_pic;
 153     uint8_t *data[4];
 154
 155     if (!scale->slice_dir) {
 156         if (y != 0 && y + h != link->h) {
 157             av_log(scale, AV_LOG_ERROR, "Slices start in the middle!\n");
 158             return;
 159         }
 160         scale->slice_dir = y ?                       -1 : 1;
 161         scale->slice_y   = y ? link->dst->outputs[0]->h : y;
 162     }
 163
 164     data[0] = cur_pic->data[0] +  y               * cur_pic->linesize[0];
 165     data[1] = scale->input_is_pal ?
 166               cur_pic->data[1] :
 167               cur_pic->data[1] + (y>>scale->vsub) * cur_pic->linesize[1];
 168     data[2] = cur_pic->data[2] + (y>>scale->vsub) * cur_pic->linesize[2];
 169     data[3] = cur_pic->data[3] +  y               * cur_pic->linesize[3];
 170
 171     out_h = sws_scale(scale->sws, data, cur_pic->linesize, y, h,
 172                       link->dst->outputs[0]->outpic->data,
 173                       link->dst->outputs[0]->outpic->linesize);
 174
 175     if (scale->slice_dir == -1)
 176         scale->slice_y -= out_h;
 177     avfilter_draw_slice(link->dst->outputs[0], scale->slice_y, out_h);
 178     if (scale->slice_dir == 1)
 179         scale->slice_y += out_h;
 180 }
 181
 182 AVFilter avfilter_vf_scale = {
 183     .name      = "scale",
 184     .description = "Scale the input video to width:height size and/or convert the image format.",
 185
 186     .init      = init,
 187     .uninit    = uninit,
 188
 189     .query_formats = query_formats,
 190
 191     .priv_size = sizeof(ScaleContext),
 192
 193     .inputs    = (AVFilterPad[]) {{ .name             = "default",
 194                                     .type             = CODEC_TYPE_VIDEO,
 195                                     .start_frame      = start_frame,
 196                                     .draw_slice       = draw_slice,
 197                                     .min_perms        = AV_PERM_READ, },
 198                                   { .name = NULL}},
 199     .outputs   = (AVFilterPad[]) {{ .name             = "default",
 200                                     .type             = CODEC_TYPE_VIDEO,
 201                                     .config_props     = config_props, },
 202                                   { .name = NULL}},
 203 };