/*

  * Animated GIF muxer

  * Copyright (c) 2000 Fabrice Bellard

  *

  * 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

  */
 
 /*
  * First version by Francois Revol revol@free.fr
  *
  * Features and limitations:
  * - currently no compression is performed,
  *   in fact the size of the data is 9/8 the size of the image in 8bpp
  * - uses only a global standard palette
  * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS).
  *
  * Reference documents:
  * http://www.goice.co.jp/member/mo/formats/gif.html
  * http://astronomy.swin.edu.au/pbourke/dataformats/gif/
  * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt
  *
  * this url claims to have an LZW algorithm not covered by Unisys patent:
  * http://www.msg.net/utility/whirlgif/gifencod.html
  * could help reduce the size of the files _a lot_...
  * some sites mentions an RLE type compression also.
  */
 
 #include "avformat.h"

 #include "libavutil/log.h"
 #include "libavutil/opt.h"

 
 /* The GIF format uses reversed order for bitstreams... */
 /* at least they don't use PDP_ENDIAN :) */
 #define BITSTREAM_WRITER_LE
 

 #include "libavcodec/put_bits.h"

 
 /* bitstream minipacket size */
 #define GIF_CHUNKS 100
 

 /* slows down the decoding (and some browsers don't like it) */

 /* update on the 'some browsers don't like it issue from above:
  * this was probably due to missing 'Data Sub-block Terminator'
  * (byte 19) in the app_header */

 #define GIF_ADD_APP_HEADER // required to enable looping of animated gif

 
 typedef struct {
     unsigned char r;
     unsigned char g;
     unsigned char b;
 } rgb_triplet;
 
 /* we use the standard 216 color palette */
 
 /* this script was used to create the palette:

  * for r in 00 33 66 99 cc ff; do
  *     for g in 00 33 66 99 cc ff; do
  *         echo -n "    "
  *         for b in 00 33 66 99 cc ff; do
  *             echo -n "{ 0x$r, 0x$g, 0x$b }, "
  *         done
  *         echo ""
  *     done
  * done

  */
 

 static const rgb_triplet gif_clut[216] = {

     { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
     { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
     { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
     { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
     { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
     { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
     { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
     { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
     { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
     { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
     { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
     { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
     { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
     { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
     { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
     { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
     { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
     { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
     { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
     { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
     { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
     { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
     { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
     { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
     { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
     { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
     { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
     { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
     { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
     { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
     { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
     { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
     { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
     { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
     { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
     { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
 };
 

 /* GIF header */

 static int gif_image_write_header(AVIOContext *pb, int width, int height,
                                   int loop_count, uint32_t *palette)

 {

     int i;

     unsigned int v;

     avio_write(pb, "GIF", 3);
     avio_write(pb, "89a", 3);

     avio_wl16(pb, width);
     avio_wl16(pb, height);

     avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
     avio_w8(pb, 0x1f); /* background color index */
     avio_w8(pb, 0);    /* aspect ratio */

 
     /* the global palette */

     if (!palette) {

         avio_write(pb, (const unsigned char *)gif_clut, 216 * 3);
         for (i = 0; i < ((256 - 216) * 3); i++)

             avio_w8(pb, 0);

     } else {

         for (i = 0; i < 256; i++) {

             v = palette[i];

             avio_w8(pb, (v >> 16) & 0xff);

             avio_w8(pb, (v >>  8) & 0xff);
             avio_w8(pb, (v)       & 0xff);

         }
     }

     /* update: this is the 'NETSCAPE EXTENSION' that allows for looped animated
      * GIF, see http://members.aol.com/royalef/gifabout.htm#net-extension
      *
      * byte   1       : 33 (hex 0x21) GIF Extension code
      * byte   2       : 255 (hex 0xFF) Application Extension Label
      * byte   3       : 11 (hex (0x0B) Length of Application Block
      *                          (eleven bytes of data to follow)
      * bytes  4 to 11 : "NETSCAPE"
      * bytes 12 to 14 : "2.0"
      * byte  15       : 3 (hex 0x03) Length of Data Sub-Block
      *                          (three bytes of data to follow)
      * byte  16       : 1 (hex 0x01)
      * bytes 17 to 18 : 0 to 65535, an unsigned integer in
      *                          lo-hi byte format. This indicate the
      *                          number of iterations the loop should
      *                          be executed.
      * bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
      */

     /* application extension header */
 #ifdef GIF_ADD_APP_HEADER

     if (loop_count >= 0 && loop_count <= 65535) {

         avio_w8(pb, 0x21);
         avio_w8(pb, 0xff);
         avio_w8(pb, 0x0b);
         // bytes 4 to 14
         avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);

         avio_w8(pb, 0x03); // byte 15
         avio_w8(pb, 0x01); // byte 16
         avio_wl16(pb, (uint16_t)loop_count);
         avio_w8(pb, 0x00); // byte 19

     }

 #endif
     return 0;
 }
 
 /* this is maybe slow, but allows for extensions */

 static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)

 {

     return (((r) / 47) % 6) * 6 * 6 + (((g) / 47) % 6) * 6 + (((b) / 47) % 6);

 }
 

 static int gif_image_write_image(AVIOContext *pb,

                                  int x1, int y1, int width, int height,

                                  const uint8_t *buf, int linesize, int pix_fmt)

 {
     PutBitContext p;

     uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */

     int i, left, w, v;

     const uint8_t *ptr;

     /* image block */
 

     avio_w8(pb, 0x2c);
     avio_wl16(pb, x1);
     avio_wl16(pb, y1);
     avio_wl16(pb, width);
     avio_wl16(pb, height);
     avio_w8(pb, 0x00); /* flags */

     /* no local clut */
 

     avio_w8(pb, 0x08);

     left = width * height;

     init_put_bits(&p, buffer, 130);

 
 /*

  * the thing here is the bitstream is written as little packets, with a size
  * byte before but it's still the same bitstream between packets (no flush !)

  */

     ptr = buf;

     w   = width;
     while (left > 0) {

         put_bits(&p, 9, 0x0100); /* clear code */

         for (i = (left < GIF_CHUNKS) ? left : GIF_CHUNKS; i; i--) {

             if (pix_fmt == AV_PIX_FMT_RGB24) {

                 v    = gif_clut_index(ptr[0], ptr[1], ptr[2]);
                 ptr += 3;

             } else {
                 v = *ptr++;
             }

             put_bits(&p, 9, v);

             if (--w == 0) {

                 w    = width;

                 buf += linesize;

                 ptr  = buf;

             }

         }
 

         if (left <= GIF_CHUNKS) {

             put_bits(&p, 9, 0x101); /* end of stream */
             flush_put_bits(&p);

         }

         if (put_bits_ptr(&p) - p.buf > 0) {

             avio_w8(pb, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
             avio_write(pb, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */

             p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
         }

         left -= GIF_CHUNKS;

     }

     avio_w8(pb, 0x00); /* end of image block */

     return 0;
 }
 
 typedef struct {

     AVClass *class;         /** Class for private options. */

     int64_t time, file_time;
     uint8_t buffer[100]; /* data chunks */

     int loop;

 } GIFContext;
 
 static int gif_write_header(AVFormatContext *s)
 {
     GIFContext *gif = s->priv_data;

     AVIOContext *pb = s->pb;

     AVCodecContext *enc, *video_enc;

     int i, width, height /*, rate*/;

 
 /* XXX: do we reject audio streams or just ignore them ?

  *  if (s->nb_streams > 1)
  *      return -1;
  */
     gif->time      = 0;

     gif->file_time = 0;
 
     video_enc = NULL;

     for (i = 0; i < s->nb_streams; i++) {

         enc = s->streams[i]->codec;

         if (enc->codec_type != AVMEDIA_TYPE_AUDIO)

             video_enc = enc;
     }
 
     if (!video_enc) {
         av_free(gif);
         return -1;
     } else {

         width  = video_enc->width;

         height = video_enc->height;

 //        rate = video_enc->time_base.den;

     }
 

     if (video_enc->pix_fmt != AV_PIX_FMT_RGB24) {

         av_log(s, AV_LOG_ERROR,
                "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n");

         return AVERROR(EIO);

     }

     gif_image_write_header(pb, width, height, gif->loop, NULL);

     avio_flush(s->pb);

     return 0;
 }
 

 static int gif_write_video(AVFormatContext *s, AVCodecContext *enc,
                            const uint8_t *buf, int size)

 {

     AVIOContext *pb = s->pb;

     int jiffies;
 
     /* graphic control extension block */

     avio_w8(pb, 0x21);
     avio_w8(pb, 0xf9);
     avio_w8(pb, 0x04); /* block size */
     avio_w8(pb, 0x04); /* flags */

     /* 1 jiffy is 1/70 s */
     /* the delay_time field indicates the number of jiffies - 1 */
     /* XXX: should use delay, in order to be more accurate */
     /* instead of using the same rounded value each time */
     /* XXX: don't even remember if I really use it for now */

     jiffies = (70 * enc->time_base.num / enc->time_base.den) - 1;

     avio_wl16(pb, jiffies);

     avio_w8(pb, 0x1f); /* transparent color index */
     avio_w8(pb, 0x00);

 
     gif_image_write_image(pb, 0, 0, enc->width, enc->height,

                           buf, enc->width * 3, AV_PIX_FMT_RGB24);

     avio_flush(s->pb);

     return 0;
 }
 

 static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)

 {

     AVCodecContext *codec = s->streams[pkt->stream_index]->codec;

     if (codec->codec_type == AVMEDIA_TYPE_AUDIO)

         return 0; /* just ignore audio */
     else

         return gif_write_video(s, codec, pkt->data, pkt->size);

 }
 
 static int gif_write_trailer(AVFormatContext *s)
 {

     AVIOContext *pb = s->pb;

     avio_w8(pb, 0x3b);

     return 0;
 }
 

 #define OFFSET(x) offsetof(GIFContext, x)
 #define ENC AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {

     { "loop", "Number of times to loop the output.", OFFSET(loop),

       AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 65535, ENC },

     { NULL },
 };
 
 static const AVClass gif_muxer_class = {
     .class_name = "GIF muxer",
     .item_name  = av_default_item_name,
     .version    = LIBAVUTIL_VERSION_INT,
     .option     = options,
 };
 

 AVOutputFormat ff_gif_muxer = {

     .name           = "gif",
     .long_name      = NULL_IF_CONFIG_SMALL("GIF Animation"),
     .mime_type      = "image/gif",
     .extensions     = "gif",
     .priv_data_size = sizeof(GIFContext),

     .audio_codec    = AV_CODEC_ID_NONE,
     .video_codec    = AV_CODEC_ID_RAWVIDEO,

     .write_header   = gif_write_header,
     .write_packet   = gif_write_packet,
     .write_trailer  = gif_write_trailer,
     .priv_class     = &gif_muxer_class,

 };