yading@11: /*
yading@11:  * Animated GIF muxer
yading@11:  * Copyright (c) 2000 Fabrice Bellard
yading@11:  *
yading@11:  * first version by Francois Revol <revol@free.fr>
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "avformat.h"
yading@11: #include "internal.h"
yading@11: #include "libavutil/avassert.h"
yading@11: #include "libavutil/imgutils.h"
yading@11: #include "libavutil/log.h"
yading@11: #include "libavutil/opt.h"
yading@11: 
yading@11: static int gif_image_write_header(AVIOContext *pb, int width, int height,
yading@11:                                   int loop_count, uint32_t *palette)
yading@11: {
yading@11:     int i;
yading@11: 
yading@11:     avio_write(pb, "GIF", 3);
yading@11:     avio_write(pb, "89a", 3);
yading@11:     avio_wl16(pb, width);
yading@11:     avio_wl16(pb, height);
yading@11: 
yading@11:     if (palette) {
yading@11:         avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
yading@11:         avio_w8(pb, 0x1f); /* background color index */
yading@11:         avio_w8(pb, 0);    /* aspect ratio */
yading@11:         for (i = 0; i < 256; i++) {
yading@11:             const uint32_t v = palette[i] & 0xffffff;
yading@11:             avio_wb24(pb, v);
yading@11:         }
yading@11:     } else {
yading@11:         avio_w8(pb, 0); /* flags */
yading@11:         avio_w8(pb, 0); /* background color index */
yading@11:         avio_w8(pb, 0); /* aspect ratio */
yading@11:     }
yading@11: 
yading@11:     /* "NETSCAPE EXTENSION" for looped animation GIF */
yading@11:     avio_w8(pb, 0x21); /* GIF Extension code */
yading@11:     avio_w8(pb, 0xff); /* Application Extension Label */
yading@11:     avio_w8(pb, 0x0b); /* Length of Application Block */
yading@11:     avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);
yading@11:     avio_w8(pb, 0x03); /* Length of Data Sub-Block */
yading@11:     avio_w8(pb, 0x01);
yading@11:     avio_wl16(pb, (uint16_t)loop_count);
yading@11:     avio_w8(pb, 0x00); /* Data Sub-block Terminator */
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: typedef struct {
yading@11:     AVClass *class;         /** Class for private options. */
yading@11:     int loop;
yading@11:     int last_delay;
yading@11:     AVPacket *prev_pkt;
yading@11:     int duration;
yading@11: } GIFContext;
yading@11: 
yading@11: static int gif_write_header(AVFormatContext *s)
yading@11: {
yading@11:     GIFContext *gif = s->priv_data;
yading@11:     AVIOContext *pb = s->pb;
yading@11:     AVCodecContext *video_enc;
yading@11:     int width, height;
yading@11:     uint32_t palette[AVPALETTE_COUNT];
yading@11: 
yading@11:     if (s->nb_streams != 1 ||
yading@11:         s->streams[0]->codec->codec_type != AVMEDIA_TYPE_VIDEO ||
yading@11:         s->streams[0]->codec->codec_id   != AV_CODEC_ID_GIF) {
yading@11:         av_log(s, AV_LOG_ERROR,
yading@11:                "GIF muxer supports only a single video GIF stream.\n");
yading@11:         return AVERROR(EINVAL);
yading@11:     }
yading@11: 
yading@11:     video_enc = s->streams[0]->codec;
yading@11:     width  = video_enc->width;
yading@11:     height = video_enc->height;
yading@11: 
yading@11:     avpriv_set_pts_info(s->streams[0], 64, 1, 100);
yading@11:     if (avpriv_set_systematic_pal2(palette, video_enc->pix_fmt) < 0) {
yading@11:         av_assert0(video_enc->pix_fmt == AV_PIX_FMT_PAL8);
yading@11:         gif_image_write_header(pb, width, height, gif->loop, NULL);
yading@11:     } else {
yading@11:         gif_image_write_header(pb, width, height, gif->loop, palette);
yading@11:     }
yading@11: 
yading@11:     avio_flush(s->pb);
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int flush_packet(AVFormatContext *s, AVPacket *new)
yading@11: {
yading@11:     GIFContext *gif = s->priv_data;
yading@11:     int size;
yading@11:     AVIOContext *pb = s->pb;
yading@11:     uint8_t flags = 0x4, transparent_color_index = 0x1f;
yading@11:     const uint32_t *palette;
yading@11:     AVPacket *pkt = gif->prev_pkt;
yading@11: 
yading@11:     if (!pkt)
yading@11:         return 0;
yading@11: 
yading@11:     /* Mark one colour as transparent if the input palette contains at least
yading@11:      * one colour that is more than 50% transparent. */
yading@11:     palette = (uint32_t*)av_packet_get_side_data(pkt, AV_PKT_DATA_PALETTE, &size);
yading@11:     if (palette && size != AVPALETTE_SIZE) {
yading@11:         av_log(s, AV_LOG_ERROR, "Invalid palette extradata\n");
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11:     if (palette) {
yading@11:         unsigned i, smallest_alpha = 0xff;
yading@11: 
yading@11:         for (i = 0; i < AVPALETTE_COUNT; i++) {
yading@11:             const uint32_t v = palette[i];
yading@11:             if (v >> 24 < smallest_alpha) {
yading@11:                 smallest_alpha = v >> 24;
yading@11:                 transparent_color_index = i;
yading@11:             }
yading@11:         }
yading@11:         if (smallest_alpha < 128)
yading@11:             flags |= 0x1; /* Transparent Color Flag */
yading@11:     }
yading@11: 
yading@11:     if (new && new->pts != AV_NOPTS_VALUE)
yading@11:         gif->duration = av_clip_uint16(new->pts - gif->prev_pkt->pts);
yading@11:     else if (!new && gif->last_delay >= 0)
yading@11:         gif->duration = gif->last_delay;
yading@11: 
yading@11:     /* graphic control extension block */
yading@11:     avio_w8(pb, 0x21);
yading@11:     avio_w8(pb, 0xf9);
yading@11:     avio_w8(pb, 0x04); /* block size */
yading@11:     avio_w8(pb, flags);
yading@11:     avio_wl16(pb, gif->duration);
yading@11:     avio_w8(pb, transparent_color_index);
yading@11:     avio_w8(pb, 0x00);
yading@11: 
yading@11:     avio_write(pb, pkt->data, pkt->size);
yading@11: 
yading@11:     av_free_packet(gif->prev_pkt);
yading@11:     if (new)
yading@11:         av_copy_packet(gif->prev_pkt, new);
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
yading@11: {
yading@11:     GIFContext *gif = s->priv_data;
yading@11: 
yading@11:     if (!gif->prev_pkt) {
yading@11:         gif->prev_pkt = av_malloc(sizeof(*gif->prev_pkt));
yading@11:         if (!gif->prev_pkt)
yading@11:             return AVERROR(ENOMEM);
yading@11:         return av_copy_packet(gif->prev_pkt, pkt);
yading@11:     }
yading@11:     return flush_packet(s, pkt);
yading@11: }
yading@11: 
yading@11: static int gif_write_trailer(AVFormatContext *s)
yading@11: {
yading@11:     GIFContext *gif = s->priv_data;
yading@11:     AVIOContext *pb = s->pb;
yading@11: 
yading@11:     flush_packet(s, NULL);
yading@11:     av_freep(&gif->prev_pkt);
yading@11:     avio_w8(pb, 0x3b);
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: #define OFFSET(x) offsetof(GIFContext, x)
yading@11: #define ENC AV_OPT_FLAG_ENCODING_PARAM
yading@11: static const AVOption options[] = {
yading@11:     { "loop", "Number of times to loop the output.", OFFSET(loop),
yading@11:       AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 65535, ENC },
yading@11:     { "final_delay", "Force delay (in ms) after the last frame", OFFSET(last_delay),
yading@11:       AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 65535, ENC },
yading@11:     { NULL },
yading@11: };
yading@11: 
yading@11: static const AVClass gif_muxer_class = {
yading@11:     .class_name = "GIF muxer",
yading@11:     .item_name  = av_default_item_name,
yading@11:     .version    = LIBAVUTIL_VERSION_INT,
yading@11:     .option     = options,
yading@11: };
yading@11: 
yading@11: AVOutputFormat ff_gif_muxer = {
yading@11:     .name           = "gif",
yading@11:     .long_name      = NULL_IF_CONFIG_SMALL("GIF Animation"),
yading@11:     .mime_type      = "image/gif",
yading@11:     .extensions     = "gif",
yading@11:     .priv_data_size = sizeof(GIFContext),
yading@11:     .audio_codec    = AV_CODEC_ID_NONE,
yading@11:     .video_codec    = AV_CODEC_ID_GIF,
yading@11:     .write_header   = gif_write_header,
yading@11:     .write_packet   = gif_write_packet,
yading@11:     .write_trailer  = gif_write_trailer,
yading@11:     .priv_class     = &gif_muxer_class,
yading@11:     .flags          = AVFMT_VARIABLE_FPS,
yading@11: };