/*
  * Copyright (c) 2010 Brandon Mintern
  * 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
  * video fade filter
  * based heavily on vf_negate.c by Bobby Bingham
  */
 
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 
 typedef struct {
     int factor, fade_per_frame;
     unsigned int frame_index, start_frame, stop_frame;
     int hsub, vsub, bpp;
 } FadeContext;
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     FadeContext *fade = ctx->priv;
     unsigned int nb_frames;
     char in_out[4];
 
     if (!args ||
         sscanf(args, " %3[^:]:%u:%u", in_out, &fade->start_frame, &nb_frames) != 3) {
         av_log(ctx, AV_LOG_ERROR,
                "Expected 3 arguments '(in|out):#:#':'%s'\n", args);
         return AVERROR(EINVAL);
     }
 
     nb_frames = nb_frames ? nb_frames : 1;
     fade->fade_per_frame = (1 << 16) / nb_frames;
     if (!strcmp(in_out, "in"))
         fade->factor = 0;
     else if (!strcmp(in_out, "out")) {
         fade->fade_per_frame = -fade->fade_per_frame;
         fade->factor = (1 << 16);
     } else {
         av_log(ctx, AV_LOG_ERROR,
                "first argument must be 'in' or 'out':'%s'\n", in_out);
         return AVERROR(EINVAL);
     }
     fade->stop_frame = fade->start_frame + nb_frames;
 
     av_log(ctx, AV_LOG_INFO,
            "type:%s start_frame:%d nb_frames:%d\n",
            in_out, fade->start_frame, nb_frames);
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     const static enum PixelFormat pix_fmts[] = {
         PIX_FMT_YUV444P,  PIX_FMT_YUV422P,  PIX_FMT_YUV420P,
         PIX_FMT_YUV411P,  PIX_FMT_YUV410P,
         PIX_FMT_YUVJ444P, PIX_FMT_YUVJ422P, PIX_FMT_YUVJ420P,
         PIX_FMT_YUV440P,  PIX_FMT_YUVJ440P,
         PIX_FMT_RGB24,    PIX_FMT_BGR24,
         PIX_FMT_NONE
     };
 

     avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));

     return 0;
 }
 
 static int config_props(AVFilterLink *inlink)
 {
     FadeContext *fade = inlink->dst->priv;
     const AVPixFmtDescriptor *pixdesc = &av_pix_fmt_descriptors[inlink->format];
 
     fade->hsub = pixdesc->log2_chroma_w;
     fade->vsub = pixdesc->log2_chroma_h;
 
     fade->bpp = av_get_bits_per_pixel(pixdesc) >> 3;
     return 0;
 }
 
 static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
 {
     FadeContext *fade = inlink->dst->priv;
     AVFilterBufferRef *outpic = inlink->cur_buf;
     uint8_t *p;
     int i, j, plane;
 

     if (fade->factor < UINT16_MAX) {

         /* luma or rgb plane */
         for (i = 0; i < h; i++) {
             p = outpic->data[0] + (y+i) * outpic->linesize[0];
             for (j = 0; j < inlink->w * fade->bpp; j++) {
                 /* fade->factor is using 16 lower-order bits for decimal
                  * places. 32768 = 1 << 15, it is an integer representation
                  * of 0.5 and is for rounding. */
                 *p = (*p * fade->factor + 32768) >> 16;
                 p++;
             }
         }
 

         if (outpic->data[1] && outpic->data[2]) {

             /* chroma planes */
             for (plane = 1; plane < 3; plane++) {
                 for (i = 0; i < h; i++) {
                     p = outpic->data[plane] + ((y+i) >> fade->vsub) * outpic->linesize[plane];
                     for (j = 0; j < inlink->w >> fade->hsub; j++) {
                         /* 8421367 = ((128 << 1) + 1) << 15. It is an integer
                          * representation of 128.5. The .5 is for rounding
                          * purposes. */
                         *p = ((*p - 128) * fade->factor + 8421367) >> 16;
                         p++;
                     }
                 }
             }
         }
     }
 
     avfilter_draw_slice(inlink->dst->outputs[0], y, h, slice_dir);
 }
 
 static void end_frame(AVFilterLink *inlink)
 {
     FadeContext *fade = inlink->dst->priv;
 
     avfilter_end_frame(inlink->dst->outputs[0]);
 
     if (fade->frame_index >= fade->start_frame &&
         fade->frame_index <= fade->stop_frame)
         fade->factor += fade->fade_per_frame;
     fade->factor = av_clip_uint16(fade->factor);
     fade->frame_index++;
 }
 
 AVFilter avfilter_vf_fade = {
     .name          = "fade",
     .description   = NULL_IF_CONFIG_SMALL("Fade in/out input video"),
     .init          = init,
     .priv_size     = sizeof(FadeContext),
     .query_formats = query_formats,
 
     .inputs    = (AVFilterPad[]) {{ .name            = "default",
                                     .type            = AVMEDIA_TYPE_VIDEO,
                                     .config_props    = config_props,
                                     .get_video_buffer = avfilter_null_get_video_buffer,
                                     .start_frame      = avfilter_null_start_frame,
                                     .draw_slice      = draw_slice,
                                     .end_frame       = end_frame,
                                     .min_perms       = AV_PERM_READ | AV_PERM_WRITE,
                                     .rej_perms       = AV_PERM_PRESERVE, },
                                   { .name = NULL}},
     .outputs   = (AVFilterPad[]) {{ .name            = "default",
                                     .type            = AVMEDIA_TYPE_VIDEO, },
                                   { .name = NULL}},
 };