/*
  * DVD subtitle encoding for ffmpeg

  * Copyright (c) 2005 Wolfram Gloger

  *

  * 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

  */
 #include "avcodec.h"

 #include "bytestream.h"

 
 #undef NDEBUG
 #include <assert.h>
 
 // ncnt is the nibble counter
 #define PUTNIBBLE(val)\
 do {\
     if (ncnt++ & 1)\
         *q++ = bitbuf | ((val) & 0x0f);\
     else\
         bitbuf = (val) << 4;\
 } while(0)
 
 static void dvd_encode_rle(uint8_t **pq,
                            const uint8_t *bitmap, int linesize,
                            int w, int h,
                            const int cmap[256])
 {
     uint8_t *q;
     unsigned int bitbuf = 0;
     int ncnt;
     int x, y, len, color;
 
     q = *pq;
 
     for (y = 0; y < h; ++y) {
         ncnt = 0;
         for(x = 0; x < w; x += len) {
             color = bitmap[x];
             for (len=1; x+len < w; ++len)
                 if (bitmap[x+len] != color)
                     break;
             color = cmap[color];
             assert(color < 4);
             if (len < 0x04) {
                 PUTNIBBLE((len << 2)|color);
             } else if (len < 0x10) {
                 PUTNIBBLE(len >> 2);
                 PUTNIBBLE((len << 2)|color);
             } else if (len < 0x40) {
                 PUTNIBBLE(0);
                 PUTNIBBLE(len >> 2);
                 PUTNIBBLE((len << 2)|color);
             } else if (x+len == w) {
                 PUTNIBBLE(0);
                 PUTNIBBLE(0);
                 PUTNIBBLE(0);
                 PUTNIBBLE(color);
             } else {
                 if (len > 0xff)
                     len = 0xff;
                 PUTNIBBLE(0);
                 PUTNIBBLE(len >> 6);
                 PUTNIBBLE(len >> 2);
                 PUTNIBBLE((len << 2)|color);
             }
         }
         /* end of line */
         if (ncnt & 1)
             PUTNIBBLE(0);
         bitmap += linesize;
     }
 
     *pq = q;
 }
 
 static int encode_dvd_subtitles(uint8_t *outbuf, int outbuf_size,
                                 const AVSubtitle *h)
 {
     uint8_t *q, *qq;
     int object_id;
     int offset1[20], offset2[20];
     int i, imax, color, alpha, rects = h->num_rects;
     unsigned long hmax;
     unsigned long hist[256];
     int           cmap[256];
 
     if (rects == 0 || h->rects == NULL)
         return -1;
     if (rects > 20)
         rects = 20;
 
     // analyze bitmaps, compress to 4 colors
     for (i=0; i<256; ++i) {
         hist[i] = 0;
         cmap[i] = 0;
     }
     for (object_id = 0; object_id < rects; object_id++)

         for (i=0; i<h->rects[object_id]->w*h->rects[object_id]->h; ++i) {

             color = h->rects[object_id]->pict.data[0][i];

             // only count non-transparent pixels

             alpha = ((uint32_t*)h->rects[object_id]->pict.data[1])[color] >> 24;

             hist[color] += alpha;
         }
     for (color=3;; --color) {
         hmax = 0;
         imax = 0;
         for (i=0; i<256; ++i)
             if (hist[i] > hmax) {
                 imax = i;
                 hmax = hist[i];
             }
         if (hmax == 0)
             break;
         if (color == 0)
             color = 3;
         av_log(NULL, AV_LOG_DEBUG, "dvd_subtitle hist[%d]=%ld -> col %d\n",
                imax, hist[imax], color);
         cmap[imax] = color;
         hist[imax] = 0;
     }
 
 
     // encode data block
     q = outbuf + 4;
     for (object_id = 0; object_id < rects; object_id++) {
         offset1[object_id] = q - outbuf;
         // worst case memory requirement: 1 nibble per pixel..

         if ((q - outbuf) + h->rects[object_id]->w*h->rects[object_id]->h/2

             + 17*rects + 21 > outbuf_size) {
             av_log(NULL, AV_LOG_ERROR, "dvd_subtitle too big\n");
             return -1;
         }

         dvd_encode_rle(&q, h->rects[object_id]->pict.data[0],

                        h->rects[object_id]->w*2,
                        h->rects[object_id]->w, h->rects[object_id]->h >> 1,

                        cmap);
         offset2[object_id] = q - outbuf;

         dvd_encode_rle(&q, h->rects[object_id]->pict.data[0] + h->rects[object_id]->w,

                        h->rects[object_id]->w*2,
                        h->rects[object_id]->w, h->rects[object_id]->h >> 1,

                        cmap);
     }
 
     // set data packet size
     qq = outbuf + 2;

     bytestream_put_be16(&qq, q - outbuf);

 
     // send start display command

     bytestream_put_be16(&q, (h->start_display_time*90) >> 10);
     bytestream_put_be16(&q, (q - outbuf) /*- 2 */ + 8 + 12*rects + 2);

     *q++ = 0x03; // palette - 4 nibbles
     *q++ = 0x03; *q++ = 0x7f;
     *q++ = 0x04; // alpha - 4 nibbles
     *q++ = 0xf0; *q++ = 0x00;
     //*q++ = 0x0f; *q++ = 0xff;
 
     // XXX not sure if more than one rect can really be encoded..
     // 12 bytes per rect
     for (object_id = 0; object_id < rects; object_id++) {

         int x2 = h->rects[object_id]->x + h->rects[object_id]->w - 1;
         int y2 = h->rects[object_id]->y + h->rects[object_id]->h - 1;

 
         *q++ = 0x05;
         // x1 x2 -> 6 nibbles

         *q++ = h->rects[object_id]->x >> 4;
         *q++ = (h->rects[object_id]->x << 4) | ((x2 >> 8) & 0xf);

         *q++ = x2;
         // y1 y2 -> 6 nibbles

         *q++ = h->rects[object_id]->y >> 4;
         *q++ = (h->rects[object_id]->y << 4) | ((y2 >> 8) & 0xf);

         *q++ = y2;

         *q++ = 0x06;
         // offset1, offset2

         bytestream_put_be16(&q, offset1[object_id]);
         bytestream_put_be16(&q, offset2[object_id]);

     }
     *q++ = 0x01; // start command
     *q++ = 0xff; // terminating command
 
     // send stop display command last

     bytestream_put_be16(&q, (h->end_display_time*90) >> 10);
     bytestream_put_be16(&q, (q - outbuf) - 2 /*+ 4*/);

     *q++ = 0x02; // set end
     *q++ = 0xff; // terminating command
 
     qq = outbuf;

     bytestream_put_be16(&qq, q - outbuf);

     av_log(NULL, AV_LOG_DEBUG, "subtitle_packet size=%td\n", q - outbuf);

     return q - outbuf;
 }
 
 static int dvdsub_encode(AVCodecContext *avctx,
                          unsigned char *buf, int buf_size, void *data)
 {
     //DVDSubtitleContext *s = avctx->priv_data;
     AVSubtitle *sub = data;
     int ret;
 
     ret = encode_dvd_subtitles(buf, buf_size, sub);
     return ret;
 }
 
 AVCodec dvdsub_encoder = {
     "dvdsub",
     CODEC_TYPE_SUBTITLE,
     CODEC_ID_DVD_SUBTITLE,

     0,

     NULL,

     dvdsub_encode,

     .long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),

 };