/* * GIF encoder. * Copyright (c) 2000 Fabrice Bellard * Copyright (c) 2002 Francois Revol * Copyright (c) 2006 Baptiste Coudurier * * 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 "avcodec.h" #include "bytestream.h" #include "internal.h" #include "lzw.h" /* The GIF format uses reversed order for bitstreams... */ /* at least they don't use PDP_ENDIAN :) */ #define BITSTREAM_WRITER_LE #include "put_bits.h" typedef struct { AVFrame picture; LZWState *lzw; uint8_t *buf; } GIFContext; /* GIF header */ static int gif_image_write_header(AVCodecContext *avctx, uint8_t **bytestream, uint32_t *palette) { int i; unsigned int v, smallest_alpha = 0xFF, alpha_component = 0; bytestream_put_buffer(bytestream, "GIF", 3); bytestream_put_buffer(bytestream, "89a", 3); bytestream_put_le16(bytestream, avctx->width); bytestream_put_le16(bytestream, avctx->height); bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */ bytestream_put_byte(bytestream, 0x1f); /* background color index */ bytestream_put_byte(bytestream, 0); /* aspect ratio */ /* the global palette */ for(i=0;i<256;i++) { v = palette[i]; bytestream_put_be24(bytestream, v); if (v >> 24 < smallest_alpha) { smallest_alpha = v >> 24; alpha_component = i; } } if (smallest_alpha < 128) { bytestream_put_byte(bytestream, 0x21); /* Extension Introducer */ bytestream_put_byte(bytestream, 0xf9); /* Graphic Control Label */ bytestream_put_byte(bytestream, 0x04); /* block length */ bytestream_put_byte(bytestream, 0x01); /* Transparent Color Flag */ bytestream_put_le16(bytestream, 0x00); /* no delay */ bytestream_put_byte(bytestream, alpha_component); bytestream_put_byte(bytestream, 0x00); } return 0; } static int gif_image_write_image(AVCodecContext *avctx, uint8_t **bytestream, uint8_t *end, const uint8_t *buf, int linesize) { GIFContext *s = avctx->priv_data; int len = 0, height; const uint8_t *ptr; /* image block */ bytestream_put_byte(bytestream, 0x2c); bytestream_put_le16(bytestream, 0); bytestream_put_le16(bytestream, 0); bytestream_put_le16(bytestream, avctx->width); bytestream_put_le16(bytestream, avctx->height); bytestream_put_byte(bytestream, 0x00); /* flags */ /* no local clut */ bytestream_put_byte(bytestream, 0x08); ff_lzw_encode_init(s->lzw, s->buf, avctx->width*avctx->height, 12, FF_LZW_GIF, put_bits); ptr = buf; for (height = avctx->height; height--;) { len += ff_lzw_encode(s->lzw, ptr, avctx->width); ptr += linesize; } len += ff_lzw_encode_flush(s->lzw, flush_put_bits); ptr = s->buf; while (len > 0) { int size = FFMIN(255, len); bytestream_put_byte(bytestream, size); if (end - *bytestream < size) return -1; bytestream_put_buffer(bytestream, ptr, size); ptr += size; len -= size; } bytestream_put_byte(bytestream, 0x00); /* end of image block */ bytestream_put_byte(bytestream, 0x3b); return 0; } static av_cold int gif_encode_init(AVCodecContext *avctx) { GIFContext *s = avctx->priv_data; avctx->coded_frame = &s->picture; s->lzw = av_mallocz(ff_lzw_encode_state_size); if (!s->lzw) return AVERROR(ENOMEM); s->buf = av_malloc(avctx->width*avctx->height*2); if (!s->buf) return AVERROR(ENOMEM); return 0; } /* better than nothing gif encoder */ static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFrame *pict, int *got_packet) { GIFContext *s = avctx->priv_data; AVFrame *const p = &s->picture; uint8_t *outbuf_ptr, *end; int ret; if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + FF_MIN_BUFFER_SIZE)) < 0) { return ret; } outbuf_ptr = pkt->data; end = pkt->data + pkt->size; *p = *pict; p->pict_type = AV_PICTURE_TYPE_I; p->key_frame = 1; gif_image_write_header(avctx, &outbuf_ptr, (uint32_t *)pict->data[1]); gif_image_write_image(avctx, &outbuf_ptr, end, pict->data[0], pict->linesize[0]); pkt->size = outbuf_ptr - pkt->data; pkt->flags |= AV_PKT_FLAG_KEY; *got_packet = 1; return 0; } static int gif_encode_close(AVCodecContext *avctx) { GIFContext *s = avctx->priv_data; av_freep(&s->lzw); av_freep(&s->buf); return 0; } AVCodec ff_gif_encoder = { .name = "gif", .type = AVMEDIA_TYPE_VIDEO, .id = CODEC_ID_GIF, .priv_data_size = sizeof(GIFContext), .init = gif_encode_init, .encode2 = gif_encode_frame, .close = gif_encode_close, .pix_fmts= (const enum PixelFormat[]){PIX_FMT_RGB8, PIX_FMT_BGR8, PIX_FMT_RGB4_BYTE, PIX_FMT_BGR4_BYTE, PIX_FMT_GRAY8, PIX_FMT_PAL8, PIX_FMT_NONE}, .long_name= NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"), };