/*
  * PGS subtitle decoder
  * Copyright (c) 2009 Stephen Backway
  *
  * 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

  * PGS subtitle decoder
  */
 
 #include "avcodec.h"
 #include "dsputil.h"
 #include "bytestream.h"

 #include "libavutil/colorspace.h"

 #include "libavutil/imgutils.h"

 
 #define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
 
 enum SegmentType {
     PALETTE_SEGMENT      = 0x14,
     PICTURE_SEGMENT      = 0x15,
     PRESENTATION_SEGMENT = 0x16,
     WINDOW_SEGMENT       = 0x17,
     DISPLAY_SEGMENT      = 0x80,
 };
 
 typedef struct PGSSubPresentation {
     int x;
     int y;
     int id_number;

     int object_number;

 } PGSSubPresentation;
 
 typedef struct PGSSubPicture {
     int          w;
     int          h;
     uint8_t      *rle;
     unsigned int rle_buffer_size, rle_data_len;

     unsigned int rle_remaining_len;

 } PGSSubPicture;
 
 typedef struct PGSSubContext {
     PGSSubPresentation presentation;
     uint32_t           clut[256];
     PGSSubPicture      picture;
 } PGSSubContext;
 
 static av_cold int init_decoder(AVCodecContext *avctx)
 {

     avctx->pix_fmt = PIX_FMT_PAL8;

 
     return 0;
 }
 
 static av_cold int close_decoder(AVCodecContext *avctx)
 {
     PGSSubContext *ctx = avctx->priv_data;
 
     av_freep(&ctx->picture.rle);
     ctx->picture.rle_buffer_size  = 0;
 
     return 0;
 }
 
 /**

  * Decode the RLE data.

  *
  * The subtitle is stored as an Run Length Encoded image.
  *
  * @param avctx contains the current codec context
  * @param sub pointer to the processed subtitle data
  * @param buf pointer to the RLE data to process
  * @param buf_size size of the RLE data to process
  */
 static int decode_rle(AVCodecContext *avctx, AVSubtitle *sub,
                       const uint8_t *buf, unsigned int buf_size)
 {
     const uint8_t *rle_bitmap_end;
     int pixel_count, line_count;
 
     rle_bitmap_end = buf + buf_size;
 
     sub->rects[0]->pict.data[0] = av_malloc(sub->rects[0]->w * sub->rects[0]->h);
 
     if (!sub->rects[0]->pict.data[0])
         return -1;
 
     pixel_count = 0;
     line_count  = 0;
 
     while (buf < rle_bitmap_end && line_count < sub->rects[0]->h) {
         uint8_t flags, color;
         int run;
 
         color = bytestream_get_byte(&buf);
         run   = 1;
 
         if (color == 0x00) {
             flags = bytestream_get_byte(&buf);
             run   = flags & 0x3f;
             if (flags & 0x40)
                 run = (run << 8) + bytestream_get_byte(&buf);
             color = flags & 0x80 ? bytestream_get_byte(&buf) : 0;
         }
 
         if (run > 0 && pixel_count + run <= sub->rects[0]->w * sub->rects[0]->h) {
             memset(sub->rects[0]->pict.data[0] + pixel_count, color, run);
             pixel_count += run;
         } else if (!run) {
             /*
              * New Line. Check if correct pixels decoded, if not display warning
              * and adjust bitmap pointer to correct new line position.
              */
             if (pixel_count % sub->rects[0]->w > 0)
                 av_log(avctx, AV_LOG_ERROR, "Decoded %d pixels, when line should be %d pixels\n",
                        pixel_count % sub->rects[0]->w, sub->rects[0]->w);
             line_count++;
         }
     }
 

     if (pixel_count < sub->rects[0]->w * sub->rects[0]->h) {
         av_log(avctx, AV_LOG_ERROR, "Insufficient RLE data for subtitle\n");
         return -1;
     }
 

     av_dlog(avctx, "Pixel Count = %d, Area = %d\n", pixel_count, sub->rects[0]->w * sub->rects[0]->h);

 
     return 0;
 }
 
 /**

  * Parse the picture segment packet.

  *
  * The picture segment contains details on the sequence id,
  * width, height and Run Length Encoded (RLE) bitmap data.
  *
  * @param avctx contains the current codec context
  * @param buf pointer to the packet to process
  * @param buf_size size of packet to process
  * @todo TODO: Enable support for RLE data over multiple packets
  */
 static int parse_picture_segment(AVCodecContext *avctx,
                                   const uint8_t *buf, int buf_size)
 {
     PGSSubContext *ctx = avctx->priv_data;
 
     uint8_t sequence_desc;
     unsigned int rle_bitmap_len, width, height;
 

     if (buf_size <= 4)
         return -1;
     buf_size -= 4;
 

     /* skip 3 unknown bytes: Object ID (2 bytes), Version Number */
     buf += 3;
 
     /* Read the Sequence Description to determine if start of RLE data or appended to previous RLE */
     sequence_desc = bytestream_get_byte(&buf);
 
     if (!(sequence_desc & 0x80)) {

         /* Additional RLE data */
         if (buf_size > ctx->picture.rle_remaining_len)
             return -1;

         memcpy(ctx->picture.rle + ctx->picture.rle_data_len, buf, buf_size);
         ctx->picture.rle_data_len += buf_size;

         ctx->picture.rle_remaining_len -= buf_size;

         return 0;

     }
 

     if (buf_size <= 7)
         return -1;
     buf_size -= 7;
 
     /* Decode rle bitmap length, stored size includes width/height data */
     rle_bitmap_len = bytestream_get_be24(&buf) - 2*2;

 
     /* Get bitmap dimensions from data */
     width  = bytestream_get_be16(&buf);
     height = bytestream_get_be16(&buf);
 
     /* Make sure the bitmap is not too large */

     if (avctx->width < width || avctx->height < height) {

         av_log(avctx, AV_LOG_ERROR, "Bitmap dimensions larger than video.\n");

         return -1;
     }
 
     ctx->picture.w = width;
     ctx->picture.h = height;
 
     av_fast_malloc(&ctx->picture.rle, &ctx->picture.rle_buffer_size, rle_bitmap_len);
 
     if (!ctx->picture.rle)
         return -1;
 

     memcpy(ctx->picture.rle, buf, buf_size);
     ctx->picture.rle_data_len = buf_size;
     ctx->picture.rle_remaining_len = rle_bitmap_len - buf_size;

 
     return 0;
 }
 
 /**

  * Parse the palette segment packet.

  *
  * The palette segment contains details of the palette,
  * a maximum of 256 colors can be defined.
  *
  * @param avctx contains the current codec context
  * @param buf pointer to the packet to process
  * @param buf_size size of packet to process
  */
 static void parse_palette_segment(AVCodecContext *avctx,
                                   const uint8_t *buf, int buf_size)
 {
     PGSSubContext *ctx = avctx->priv_data;
 
     const uint8_t *buf_end = buf + buf_size;
     const uint8_t *cm      = ff_cropTbl + MAX_NEG_CROP;
     int color_id;
     int y, cb, cr, alpha;
     int r, g, b, r_add, g_add, b_add;
 
     /* Skip two null bytes */
     buf += 2;
 
     while (buf < buf_end) {
         color_id  = bytestream_get_byte(&buf);
         y         = bytestream_get_byte(&buf);
         cr        = bytestream_get_byte(&buf);

         cb        = bytestream_get_byte(&buf);

         alpha     = bytestream_get_byte(&buf);
 
         YUV_TO_RGB1(cb, cr);
         YUV_TO_RGB2(r, g, b, y);
 

         av_dlog(avctx, "Color %d := (%d,%d,%d,%d)\n", color_id, r, g, b, alpha);

 
         /* Store color in palette */
         ctx->clut[color_id] = RGBA(r,g,b,alpha);
     }
 }
 
 /**

  * Parse the presentation segment packet.

  *
  * The presentation segment contains details on the video
  * width, video height, x & y subtitle position.
  *
  * @param avctx contains the current codec context
  * @param buf pointer to the packet to process
  * @param buf_size size of packet to process
  * @todo TODO: Implement cropping
  * @todo TODO: Implement forcing of subtitles
  */
 static void parse_presentation_segment(AVCodecContext *avctx,
                                        const uint8_t *buf, int buf_size)
 {
     PGSSubContext *ctx = avctx->priv_data;
 
     int x, y;
 

     int w = bytestream_get_be16(&buf);
     int h = bytestream_get_be16(&buf);

     av_dlog(avctx, "Video Dimensions %dx%d\n",

             w, h);

     if (av_image_check_size(w, h, 0, avctx) >= 0)

         avcodec_set_dimensions(avctx, w, h);

 
     /* Skip 1 bytes of unknown, frame rate? */
     buf++;
 
     ctx->presentation.id_number = bytestream_get_be16(&buf);
 

     /*
      * Skip 3 bytes of unknown:
      *     state
      *     palette_update_flag (0x80),
      *     palette_id_to_use,
      */
     buf += 3;
 
     ctx->presentation.object_number = bytestream_get_byte(&buf);
     if (!ctx->presentation.object_number)
         return;
 
     /*
      * Skip 4 bytes of unknown:
      *     object_id_ref (2 bytes),
      *     window_id_ref,
      *     composition_flag (0x80 - object cropped, 0x40 - object forced)
      */
     buf += 4;
 
     x = bytestream_get_be16(&buf);
     y = bytestream_get_be16(&buf);
 
     /* TODO If cropping, cropping_x, cropping_y, cropping_width, cropping_height (all 2 bytes).*/
 

     av_dlog(avctx, "Subtitle Placement x=%d, y=%d\n", x, y);

 
     if (x > avctx->width || y > avctx->height) {
         av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",
                x, y, avctx->width, avctx->height);
         x = 0; y = 0;
     }

     /* Fill in dimensions */
     ctx->presentation.x = x;
     ctx->presentation.y = y;

 }
 
 /**

  * Parse the display segment packet.

  *
  * The display segment controls the updating of the display.
  *
  * @param avctx contains the current codec context
  * @param data pointer to the data pertaining the subtitle to display
  * @param buf pointer to the packet to process
  * @param buf_size size of packet to process
  * @todo TODO: Fix start time, relies on correct PTS, currently too late
  *
  * @todo TODO: Fix end time, normally cleared by a second display
  * @todo       segment, which is currently ignored as it clears
  * @todo       the subtitle too early.
  */
 static int display_end_segment(AVCodecContext *avctx, void *data,
                                const uint8_t *buf, int buf_size)
 {
     AVSubtitle    *sub = data;
     PGSSubContext *ctx = avctx->priv_data;
 
     /*
      *      The end display time is a timeout value and is only reached
      *      if the next subtitle is later then timeout or subtitle has
      *      not been cleared by a subsequent empty display command.
      */
 

     // Blank if last object_number was 0.
     // Note that this may be wrong for more complex subtitles.
     if (!ctx->presentation.object_number)
         return 1;

     sub->start_display_time = 0;
     sub->end_display_time   = 20000;
     sub->format             = 0;
 

     sub->rects     = av_mallocz(sizeof(*sub->rects));
     sub->rects[0]  = av_mallocz(sizeof(*sub->rects[0]));
     sub->num_rects = 1;

 
     sub->rects[0]->x    = ctx->presentation.x;
     sub->rects[0]->y    = ctx->presentation.y;
     sub->rects[0]->w    = ctx->picture.w;
     sub->rects[0]->h    = ctx->picture.h;
     sub->rects[0]->type = SUBTITLE_BITMAP;
 
     /* Process bitmap */
     sub->rects[0]->pict.linesize[0] = ctx->picture.w;
 

     if (ctx->picture.rle) {
         if (ctx->picture.rle_remaining_len)
             av_log(avctx, AV_LOG_ERROR, "RLE data length %u is %u bytes shorter than expected\n",
                    ctx->picture.rle_data_len, ctx->picture.rle_remaining_len);

         if(decode_rle(avctx, sub, ctx->picture.rle, ctx->picture.rle_data_len) < 0)
             return 0;

     }

     /* Allocate memory for colors */
     sub->rects[0]->nb_colors    = 256;

     sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);

 
     memcpy(sub->rects[0]->pict.data[1], ctx->clut, sub->rects[0]->nb_colors * sizeof(uint32_t));
 
     return 1;
 }
 
 static int decode(AVCodecContext *avctx, void *data, int *data_size,
                   AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
 
     const uint8_t *buf_end;
     uint8_t       segment_type;
     int           segment_length;
     int i;
 

     av_dlog(avctx, "PGS sub packet:\n");

 
     for (i = 0; i < buf_size; i++) {

         av_dlog(avctx, "%02x ", buf[i]);

         if (i % 16 == 15)

             av_dlog(avctx, "\n");

     }
 
     if (i & 15)

         av_dlog(avctx, "\n");

 
     *data_size = 0;
 
     /* Ensure that we have received at a least a segment code and segment length */
     if (buf_size < 3)
         return -1;
 
     buf_end = buf + buf_size;
 
     /* Step through buffer to identify segments */
     while (buf < buf_end) {
         segment_type   = bytestream_get_byte(&buf);
         segment_length = bytestream_get_be16(&buf);
 

         av_dlog(avctx, "Segment Length %d, Segment Type %x\n", segment_length, segment_type);

 
         if (segment_type != DISPLAY_SEGMENT && segment_length > buf_end - buf)
             break;
 
         switch (segment_type) {
         case PALETTE_SEGMENT:
             parse_palette_segment(avctx, buf, segment_length);
             break;
         case PICTURE_SEGMENT:
             parse_picture_segment(avctx, buf, segment_length);
             break;
         case PRESENTATION_SEGMENT:
             parse_presentation_segment(avctx, buf, segment_length);
             break;
         case WINDOW_SEGMENT:
             /*
              * Window Segment Structure (No new information provided):
              *     2 bytes: Unkown,
              *     2 bytes: X position of subtitle,
              *     2 bytes: Y position of subtitle,
              *     2 bytes: Width of subtitle,
              *     2 bytes: Height of subtitle.
              */
             break;
         case DISPLAY_SEGMENT:
             *data_size = display_end_segment(avctx, data, buf, segment_length);
             break;
         default:
             av_log(avctx, AV_LOG_ERROR, "Unknown subtitle segment type 0x%x, length %d\n",
                    segment_type, segment_length);
             break;
         }
 
         buf += segment_length;
     }
 
     return buf_size;
 }
 

 AVCodec ff_pgssub_decoder = {

     .name           = "pgssub",
     .type           = AVMEDIA_TYPE_SUBTITLE,
     .id             = CODEC_ID_HDMV_PGS_SUBTITLE,
     .priv_data_size = sizeof(PGSSubContext),
     .init           = init_decoder,
     .close          = close_decoder,
     .decode         = decode,

     .long_name = NULL_IF_CONFIG_SMALL("HDMV Presentation Graphic Stream subtitles"),
 };