PeerStreamer

/*

 * 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"

/* 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(ByteIOContext *pb,

                                  int width, int height, int loop_count,

                                  uint32_t *palette)

{

    int i;

    unsigned int v;

    put_tag(pb, "GIF");

    put_tag(pb, "89a");

    put_le16(pb, width);

    put_le16(pb, height);

    put_byte(pb, 0xf7); /* flags: global clut, 256 entries */

    put_byte(pb, 0x1f); /* background color index */

    put_byte(pb, 0); /* aspect ratio */

    /* the global palette */

    if (!palette) {

        put_buffer(pb, (const unsigned char *)gif_clut, 216*3);

        for(i=0;i<((256-216)*3);i++)

            put_byte(pb, 0);

    } else {

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

            v = palette[i];

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

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

            put_byte(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) {

    put_byte(pb, 0x21);

    put_byte(pb, 0xff);

    put_byte(pb, 0x0b);

        put_tag(pb, "NETSCAPE2.0");  // bytes 4 to 14

        put_byte(pb, 0x03); // byte 15

        put_byte(pb, 0x01); // byte 16

        put_le16(pb, (uint16_t)loop_count);

        put_byte(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(ByteIOContext *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 */

    put_byte(pb, 0x2c);

    put_le16(pb, x1);

    put_le16(pb, y1);

    put_le16(pb, width);

    put_le16(pb, height);

    put_byte(pb, 0x00); /* flags */

    /* no local clut */

    put_byte(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 == 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(pbBufPtr(&p) - p.buf > 0) {

            put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */

            put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */

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

        }

        left-=GIF_CHUNKS;

    }

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

    return 0;

}

typedef struct {

    int64_t time, file_time;

    uint8_t buffer[100]; /* data chunks */

} GIFContext;

static int gif_write_header(AVFormatContext *s)

{

    GIFContext *gif = s->priv_data;

    ByteIOContext *pb = s->pb;

    AVCodecContext *enc, *video_enc;

    int i, width, height, loop_count /*, 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 != CODEC_TYPE_AUDIO)

            video_enc = enc;

    }

    if (!video_enc) {

        av_free(gif);

        return -1;

    } else {

        width = video_enc->width;

        height = video_enc->height;

        loop_count = s->loop_output;

//        rate = video_enc->time_base.den;

    }

    if (video_enc->pix_fmt != 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, loop_count, NULL);

    put_flush_packet(s->pb);

    return 0;

}

static int gif_write_video(AVFormatContext *s,

                           AVCodecContext *enc, const uint8_t *buf, int size)

{

    ByteIOContext *pb = s->pb;

    GIFContext *gif = s->priv_data;

    int jiffies;

    int64_t delay;

    /* graphic control extension block */

    put_byte(pb, 0x21);

    put_byte(pb, 0xf9);

    put_byte(pb, 0x04); /* block size */

    put_byte(pb, 0x04); /* flags */

    /* 1 jiffy is 1/70 s */

    /* the delay_time field indicates the number of jiffies - 1 */

    delay = gif->file_time - gif->time;

    /* 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;

    put_le16(pb, jiffies);

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

    put_byte(pb, 0x00);

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

                          buf, enc->width * 3, PIX_FMT_RGB24);

    put_flush_packet(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 == CODEC_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)

{

    ByteIOContext *pb = s->pb;

    put_byte(pb, 0x3b);

    put_flush_packet(s->pb);

    return 0;

}

AVOutputFormat gif_muxer = {

    "gif",

    NULL_IF_CONFIG_SMALL("GIF Animation"),

    "image/gif",

    "gif",

    sizeof(GIFContext),

    CODEC_ID_NONE,

    CODEC_ID_RAWVIDEO,

    gif_write_header,

    gif_write_packet,

    gif_write_trailer,

};