2006-11-03 00:13:34 +01:00
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/*
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* GIF encoder.
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2009-01-19 16:46:40 +01:00
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* Copyright (c) 2000 Fabrice Bellard
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* Copyright (c) 2002 Francois Revol
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* Copyright (c) 2006 Baptiste Coudurier
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2006-11-03 00:13:34 +01:00
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/*
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* First version by Francois Revol revol@free.fr
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*
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* Features and limitations:
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* - currently no compression is performed,
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* in fact the size of the data is 9/8 the size of the image in 8bpp
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* - uses only a global standard palette
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* - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS).
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*
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* Reference documents:
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* http://www.goice.co.jp/member/mo/formats/gif.html
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* http://astronomy.swin.edu.au/pbourke/dataformats/gif/
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* http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt
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*
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* this url claims to have an LZW algorithm not covered by Unisys patent:
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* http://www.msg.net/utility/whirlgif/gifencod.html
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* could help reduce the size of the files _a lot_...
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* some sites mentions an RLE type compression also.
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*/
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#include "avcodec.h"
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#include "bytestream.h"
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2012-01-05 16:55:33 +01:00
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#include "internal.h"
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2009-12-03 20:17:39 +01:00
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#include "lzw.h"
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2009-01-14 01:27:43 +01:00
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/* The GIF format uses reversed order for bitstreams... */
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/* at least they don't use PDP_ENDIAN :) */
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#define BITSTREAM_WRITER_LE
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2009-04-12 10:35:26 +02:00
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#include "put_bits.h"
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2006-11-03 00:13:34 +01:00
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2009-12-02 22:01:12 +01:00
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typedef struct {
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AVFrame picture;
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2009-12-03 20:17:39 +01:00
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LZWState *lzw;
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uint8_t *buf;
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2009-12-02 22:01:12 +01:00
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} GIFContext;
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2006-11-03 00:13:34 +01:00
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/* GIF header */
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2009-12-02 22:25:28 +01:00
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static int gif_image_write_header(AVCodecContext *avctx,
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uint8_t **bytestream, uint32_t *palette)
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2006-11-03 00:13:34 +01:00
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{
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int i;
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2011-12-08 02:48:31 +01:00
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unsigned int v, smallest_alpha = 0xFF, alpha_component = 0;
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2006-11-03 00:13:34 +01:00
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bytestream_put_buffer(bytestream, "GIF", 3);
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bytestream_put_buffer(bytestream, "89a", 3);
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2009-12-02 22:25:28 +01:00
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bytestream_put_le16(bytestream, avctx->width);
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bytestream_put_le16(bytestream, avctx->height);
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2006-11-03 00:13:34 +01:00
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bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */
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bytestream_put_byte(bytestream, 0x1f); /* background color index */
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bytestream_put_byte(bytestream, 0); /* aspect ratio */
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/* the global palette */
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2009-02-09 09:14:29 +01:00
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for(i=0;i<256;i++) {
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v = palette[i];
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bytestream_put_be24(bytestream, v);
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2011-12-08 02:48:31 +01:00
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if (v >> 24 < smallest_alpha) {
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smallest_alpha = v >> 24;
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alpha_component = i;
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}
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}
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if (smallest_alpha < 128) {
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bytestream_put_byte(bytestream, 0x21); /* Extension Introducer */
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bytestream_put_byte(bytestream, 0xf9); /* Graphic Control Label */
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bytestream_put_byte(bytestream, 0x04); /* block length */
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bytestream_put_byte(bytestream, 0x01); /* Transparent Color Flag */
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bytestream_put_le16(bytestream, 0x00); /* no delay */
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bytestream_put_byte(bytestream, alpha_component);
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bytestream_put_byte(bytestream, 0x00);
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2006-11-03 00:13:34 +01:00
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}
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return 0;
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}
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2009-12-03 20:17:39 +01:00
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static int gif_image_write_image(AVCodecContext *avctx,
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uint8_t **bytestream, uint8_t *end,
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2009-12-02 22:05:06 +01:00
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const uint8_t *buf, int linesize)
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2006-11-03 00:13:34 +01:00
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{
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2009-12-03 20:17:39 +01:00
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GIFContext *s = avctx->priv_data;
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2011-01-10 22:14:54 +01:00
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int len = 0, height;
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2006-11-03 00:13:34 +01:00
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const uint8_t *ptr;
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/* image block */
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bytestream_put_byte(bytestream, 0x2c);
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2009-12-02 22:04:23 +01:00
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bytestream_put_le16(bytestream, 0);
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bytestream_put_le16(bytestream, 0);
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2009-12-02 22:25:28 +01:00
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bytestream_put_le16(bytestream, avctx->width);
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bytestream_put_le16(bytestream, avctx->height);
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2006-11-03 00:13:34 +01:00
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bytestream_put_byte(bytestream, 0x00); /* flags */
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/* no local clut */
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bytestream_put_byte(bytestream, 0x08);
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2009-12-03 20:17:39 +01:00
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ff_lzw_encode_init(s->lzw, s->buf, avctx->width*avctx->height,
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12, FF_LZW_GIF, put_bits);
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2006-11-03 00:13:34 +01:00
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ptr = buf;
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2009-12-03 20:17:39 +01:00
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for (height = avctx->height; height--;) {
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len += ff_lzw_encode(s->lzw, ptr, avctx->width);
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ptr += linesize;
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}
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len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
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ptr = s->buf;
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while (len > 0) {
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int size = FFMIN(255, len);
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bytestream_put_byte(bytestream, size);
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if (end - *bytestream < size)
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return -1;
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bytestream_put_buffer(bytestream, ptr, size);
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ptr += size;
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len -= size;
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2006-11-03 00:13:34 +01:00
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}
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bytestream_put_byte(bytestream, 0x00); /* end of image block */
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bytestream_put_byte(bytestream, 0x3b);
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return 0;
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}
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2008-03-21 04:11:20 +01:00
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static av_cold int gif_encode_init(AVCodecContext *avctx)
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2006-11-03 00:13:34 +01:00
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{
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GIFContext *s = avctx->priv_data;
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avctx->coded_frame = &s->picture;
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2009-12-03 20:17:39 +01:00
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s->lzw = av_mallocz(ff_lzw_encode_state_size);
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if (!s->lzw)
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2010-04-03 16:15:00 +02:00
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return AVERROR(ENOMEM);
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2009-12-03 20:17:39 +01:00
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s->buf = av_malloc(avctx->width*avctx->height*2);
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if (!s->buf)
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2010-04-03 16:15:00 +02:00
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return AVERROR(ENOMEM);
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2006-11-03 00:13:34 +01:00
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return 0;
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}
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/* better than nothing gif encoder */
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2012-01-05 16:55:33 +01:00
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static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
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const AVFrame *pict, int *got_packet)
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2006-11-03 00:13:34 +01:00
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{
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GIFContext *s = avctx->priv_data;
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AVFrame *const p = (AVFrame *)&s->picture;
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2012-01-05 16:55:33 +01:00
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uint8_t *outbuf_ptr, *end;
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int ret;
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if ((ret = ff_alloc_packet(pkt, avctx->width*avctx->height*7/5 + FF_MIN_BUFFER_SIZE)) < 0) {
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av_log(avctx, AV_LOG_ERROR, "Error getting output packet.\n");
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return ret;
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}
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outbuf_ptr = pkt->data;
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end = pkt->data + pkt->size;
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2006-11-03 00:13:34 +01:00
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*p = *pict;
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2011-04-28 01:40:44 +02:00
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p->pict_type = AV_PICTURE_TYPE_I;
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2006-11-03 00:13:34 +01:00
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p->key_frame = 1;
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2009-12-02 22:25:28 +01:00
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gif_image_write_header(avctx, &outbuf_ptr, (uint32_t *)pict->data[1]);
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2009-12-03 20:17:39 +01:00
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gif_image_write_image(avctx, &outbuf_ptr, end, pict->data[0], pict->linesize[0]);
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2012-01-05 16:55:33 +01:00
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pkt->size = outbuf_ptr - pkt->data;
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pkt->flags |= AV_PKT_FLAG_KEY;
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*got_packet = 1;
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return 0;
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2006-11-03 00:13:34 +01:00
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}
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2009-12-03 20:17:39 +01:00
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static int gif_encode_close(AVCodecContext *avctx)
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{
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GIFContext *s = avctx->priv_data;
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av_freep(&s->lzw);
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av_freep(&s->buf);
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return 0;
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}
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2011-01-25 22:40:11 +01:00
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AVCodec ff_gif_encoder = {
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2011-07-17 12:54:31 +02:00
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.name = "gif",
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.type = AVMEDIA_TYPE_VIDEO,
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.id = CODEC_ID_GIF,
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.priv_data_size = sizeof(GIFContext),
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.init = gif_encode_init,
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2012-01-05 16:55:33 +01:00
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.encode2 = gif_encode_frame,
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2011-07-17 12:54:31 +02:00
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.close = gif_encode_close,
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2009-09-06 18:09:21 +02:00
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.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},
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2008-06-12 23:50:13 +02:00
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.long_name= NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
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2006-11-03 00:13:34 +01:00
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};
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