/*

  * Copyright (c) 2007 Bobby Bingham

  *
  * 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

  * scale video filter
  */
 
 #include "avfilter.h"

 #include "libavutil/avstring.h"
 #include "libavutil/eval.h"

 #include "libavutil/mathematics.h"

 #include "libavutil/pixdesc.h"

 #include "libavutil/avassert.h"

 #include "libswscale/swscale.h"
 

 static const char * const var_names[] = {

     "in_w",   "iw",
     "in_h",   "ih",
     "out_w",  "ow",
     "out_h",  "oh",

     "a",

     "sar",

     "dar",

     "hsub",
     "vsub",
     NULL
 };
 
 enum var_name {
     VAR_IN_W,   VAR_IW,
     VAR_IN_H,   VAR_IH,
     VAR_OUT_W,  VAR_OW,
     VAR_OUT_H,  VAR_OH,

     VAR_A,

     VAR_SAR,

     VAR_DAR,

     VAR_HSUB,
     VAR_VSUB,
     VARS_NB
 };
 

 typedef struct {
     struct SwsContext *sws;     ///< software scaler context

     struct SwsContext *isws[2]; ///< software scaler context for interlaced material

 
     /**
      * New dimensions. Special values are:
      *   0 = original width/height
      *  -1 = keep original aspect
      */
     int w, h;

     unsigned int flags;         ///sws flags

 
     int hsub, vsub;             ///< chroma subsampling
     int slice_y;                ///< top of current output slice
     int input_is_pal;           ///< set to 1 if the input format is paletted

     int interlaced;

     char w_expr[256];           ///< width  expression string
     char h_expr[256];           ///< height expression string

 } ScaleContext;
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     ScaleContext *scale = ctx->priv;

     const char *p;

     av_strlcpy(scale->w_expr, "iw", sizeof(scale->w_expr));
     av_strlcpy(scale->h_expr, "ih", sizeof(scale->h_expr));
 

     scale->flags = SWS_BILINEAR;

     if (args) {

         sscanf(args, "%255[^:]:%255[^:]", scale->w_expr, scale->h_expr);

         p = strstr(args,"flags=");
         if (p) scale->flags = strtoul(p+6, NULL, 0);

         if(strstr(args,"interl=1")){
             scale->interlaced=1;
         }else if(strstr(args,"interl=-1"))
             scale->interlaced=-1;

     }

 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     ScaleContext *scale = ctx->priv;
     sws_freeContext(scale->sws);

     sws_freeContext(scale->isws[0]);
     sws_freeContext(scale->isws[1]);

     scale->sws = NULL;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *formats;

     enum PixelFormat pix_fmt;
     int ret;

 
     if (ctx->inputs[0]) {

         formats = NULL;
         for (pix_fmt = 0; pix_fmt < PIX_FMT_NB; pix_fmt++)
             if (   sws_isSupportedInput(pix_fmt)

                 && (ret = avfilter_add_format(&formats, pix_fmt)) < 0) {

                 avfilter_formats_unref(&formats);
                 return ret;
             }

         avfilter_formats_ref(formats, &ctx->inputs[0]->out_formats);
     }
     if (ctx->outputs[0]) {

         formats = NULL;
         for (pix_fmt = 0; pix_fmt < PIX_FMT_NB; pix_fmt++)

             if (   (sws_isSupportedOutput(pix_fmt) || pix_fmt == PIX_FMT_PAL8)

                 && (ret = avfilter_add_format(&formats, pix_fmt)) < 0) {

                 avfilter_formats_unref(&formats);
                 return ret;
             }

         avfilter_formats_ref(formats, &ctx->outputs[0]->in_formats);
     }
 
     return 0;
 }
 
 static int config_props(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     AVFilterLink *inlink = outlink->src->inputs[0];

     enum PixelFormat outfmt = outlink->format;

     ScaleContext *scale = ctx->priv;
     int64_t w, h;

     double var_values[VARS_NB], res;
     char *expr;
     int ret;
 
     var_values[VAR_IN_W]  = var_values[VAR_IW] = inlink->w;
     var_values[VAR_IN_H]  = var_values[VAR_IH] = inlink->h;
     var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
     var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;

     var_values[VAR_A]     = (double) inlink->w / inlink->h;
 

     var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?

         (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;

     var_values[VAR_DAR]   = var_values[VAR_A] * var_values[VAR_SAR];

     var_values[VAR_HSUB]  = 1<<av_pix_fmt_descriptors[inlink->format].log2_chroma_w;
     var_values[VAR_VSUB]  = 1<<av_pix_fmt_descriptors[inlink->format].log2_chroma_h;

 
     /* evaluate width and height */
     av_expr_parse_and_eval(&res, (expr = scale->w_expr),
                            var_names, var_values,
                            NULL, NULL, NULL, NULL, NULL, 0, ctx);

     scale->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;

     if ((ret = av_expr_parse_and_eval(&res, (expr = scale->h_expr),
                                       var_names, var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto fail;

     scale->h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;

     /* evaluate again the width, as it may depend on the output height */
     if ((ret = av_expr_parse_and_eval(&res, (expr = scale->w_expr),
                                       var_names, var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto fail;
     scale->w = res;
 
     w = scale->w;
     h = scale->h;
 
     /* sanity check params */
     if (w <  -1 || h <  -1) {
         av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
         return AVERROR(EINVAL);
     }
     if (w == -1 && h == -1)
         scale->w = scale->h = 0;

 
     if (!(w = scale->w))
         w = inlink->w;
     if (!(h = scale->h))
         h = inlink->h;
     if (w == -1)
         w = av_rescale(h, inlink->w, inlink->h);
     if (h == -1)
         h = av_rescale(w, inlink->h, inlink->w);
 
     if (w > INT_MAX || h > INT_MAX ||
         (h * inlink->w) > INT_MAX  ||
         (w * inlink->h) > INT_MAX)
         av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");
 
     outlink->w = w;
     outlink->h = h;
 
     /* TODO: make algorithm configurable */

     av_log(ctx, AV_LOG_INFO, "w:%d h:%d fmt:%s -> w:%d h:%d fmt:%s flags:0x%0x\n",

            inlink ->w, inlink ->h, av_pix_fmt_descriptors[ inlink->format].name,
            outlink->w, outlink->h, av_pix_fmt_descriptors[outlink->format].name,
            scale->flags);

     scale->input_is_pal = av_pix_fmt_descriptors[inlink->format].flags & PIX_FMT_PAL;

     if (outfmt == PIX_FMT_PAL8) outfmt = PIX_FMT_BGR8;

     if (scale->sws)

         sws_freeContext(scale->sws);

     scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,

                                 outlink->w, outlink->h, outfmt,

                                 scale->flags, NULL, NULL, NULL);

     if (scale->isws[0])
         sws_freeContext(scale->isws[0]);

     scale->isws[0] = sws_getContext(inlink ->w, inlink ->h/2, inlink ->format,

                                     outlink->w, outlink->h/2, outfmt,

                                     scale->flags, NULL, NULL, NULL);

     if (scale->isws[1])
         sws_freeContext(scale->isws[1]);

     scale->isws[1] = sws_getContext(inlink ->w, inlink ->h/2, inlink ->format,

                                     outlink->w, outlink->h/2, outfmt,

                                     scale->flags, NULL, NULL, NULL);

     if (!scale->sws || !scale->isws[0] || !scale->isws[1])

         return AVERROR(EINVAL);

     if (inlink->sample_aspect_ratio.num){
         outlink->sample_aspect_ratio = av_mul_q((AVRational){outlink->h * inlink->w, outlink->w * inlink->h}, inlink->sample_aspect_ratio);
     } else
         outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;
 

     return 0;

 
 fail:
     av_log(NULL, AV_LOG_ERROR,

            "Error when evaluating the expression '%s'.\n"
            "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
            expr, scale->w_expr, scale->h_expr);

     return ret;

 }
 

 static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)

 {
     ScaleContext *scale = link->dst->priv;
     AVFilterLink *outlink = link->dst->outputs[0];

     AVFilterBufferRef *outpicref;

     scale->hsub = av_pix_fmt_descriptors[link->format].log2_chroma_w;
     scale->vsub = av_pix_fmt_descriptors[link->format].log2_chroma_h;

     outpicref = avfilter_get_video_buffer(outlink, AV_PERM_WRITE|AV_PERM_ALIGN, outlink->w, outlink->h);

     avfilter_copy_buffer_ref_props(outpicref, picref);

     outpicref->video->w = outlink->w;
     outpicref->video->h = outlink->h;

     outlink->out_buf = outpicref;

     av_reduce(&outpicref->video->sample_aspect_ratio.num, &outpicref->video->sample_aspect_ratio.den,
               (int64_t)picref->video->sample_aspect_ratio.num * outlink->h * link->w,
               (int64_t)picref->video->sample_aspect_ratio.den * outlink->w * link->h,

               INT_MAX);
 

     scale->slice_y = 0;

     avfilter_start_frame(outlink, avfilter_ref_buffer(outpicref, ~0));

 }
 

 static int scale_slice(AVFilterLink *link, struct SwsContext *sws, int y, int h, int mul, int field)
 {
     ScaleContext *scale = link->dst->priv;
     AVFilterBufferRef *cur_pic = link->cur_buf;
     AVFilterBufferRef *out_buf = link->dst->outputs[0]->out_buf;

     const uint8_t *in[4];
     uint8_t *out[4];

     int in_stride[4],out_stride[4];
     int i;
 
     for(i=0; i<4; i++){
         int vsub= ((i+1)&2) ? scale->vsub : 0;
          in_stride[i] = cur_pic->linesize[i] * mul;
         out_stride[i] = out_buf->linesize[i] * mul;
          in[i] = cur_pic->data[i] + ((y>>vsub)+field) * cur_pic->linesize[i];
         out[i] = out_buf->data[i] +            field  * out_buf->linesize[i];
     }
     if(scale->input_is_pal){
          in[1] = cur_pic->data[1];
         out[1] = out_buf->data[1];
     }
 
     return sws_scale(sws, in, in_stride, y/mul, h,
                          out,out_stride);
 }
 

 static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)

 {
     ScaleContext *scale = link->dst->priv;
     int out_h;
 

     if (scale->slice_y == 0 && slice_dir == -1)
         scale->slice_y = link->dst->outputs[0]->h;

     if(scale->interlaced>0 || (scale->interlaced<0 && link->cur_buf->video->interlaced)){

         av_assert0(y%(2<<scale->vsub) == 0);

         out_h = scale_slice(link, scale->isws[0], y, (h+1)/2, 2, 0);
         out_h+= scale_slice(link, scale->isws[1], y,  h   /2, 2, 1);
     }else{
         out_h = scale_slice(link, scale->sws, y, h, 1, 0);
     }

     if (slice_dir == -1)

         scale->slice_y -= out_h;

     avfilter_draw_slice(link->dst->outputs[0], scale->slice_y, out_h, slice_dir);
     if (slice_dir == 1)

         scale->slice_y += out_h;
 }
 
 AVFilter avfilter_vf_scale = {
     .name      = "scale",

     .description = NULL_IF_CONFIG_SMALL("Scale the input video to width:height size and/or convert the image format."),

 
     .init      = init,
     .uninit    = uninit,
 
     .query_formats = query_formats,
 
     .priv_size = sizeof(ScaleContext),
 

     .inputs    = (const AVFilterPad[]) {{ .name       = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO,

                                     .start_frame      = start_frame,
                                     .draw_slice       = draw_slice,
                                     .min_perms        = AV_PERM_READ, },
                                   { .name = NULL}},

     .outputs   = (const AVFilterPad[]) {{ .name       = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO,

                                     .config_props     = config_props, },
                                   { .name = NULL}},
 };