/* * Animated GIF muxer * Copyright (c) 2000 Fabrice Bellard * * first version by Francois Revol * * 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 */ #include "avformat.h" #include "internal.h" #include "mux.h" #include "libavutil/imgutils.h" #include "libavutil/log.h" #include "libavutil/opt.h" #include "libavcodec/bytestream.h" #include "libavcodec/gif.h" typedef struct GIFContext { AVClass *class; int loop; int last_delay; int duration; int64_t last_pos; int have_end; AVPacket *prev_pkt; } GIFContext; static int gif_write_header(AVFormatContext *s) { if (s->nb_streams != 1 || s->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_VIDEO || s->streams[0]->codecpar->codec_id != AV_CODEC_ID_GIF) { av_log(s, AV_LOG_ERROR, "GIF muxer supports only a single video GIF stream.\n"); return AVERROR(EINVAL); } avpriv_set_pts_info(s->streams[0], 64, 1, 100); return 0; } static int gif_parse_packet(AVFormatContext *s, const uint8_t *data, int size) { GetByteContext gb; int x; bytestream2_init(&gb, data, size); while (bytestream2_get_bytes_left(&gb) > 0) { x = bytestream2_get_byte(&gb); if (x != GIF_EXTENSION_INTRODUCER) return 0; x = bytestream2_get_byte(&gb); while (x != GIF_GCE_EXT_LABEL && bytestream2_get_bytes_left(&gb) > 0) { int block_size = bytestream2_get_byte(&gb); if (!block_size) break; bytestream2_skip(&gb, block_size); } if (x == GIF_GCE_EXT_LABEL) return bytestream2_tell(&gb) + 2; } return 0; } static int gif_get_delay(GIFContext *gif, AVPacket *prev, AVPacket *new) { if (new && new->pts != AV_NOPTS_VALUE) gif->duration = av_clip_uint16(new->pts - prev->pts); else if (!new && gif->last_delay >= 0) gif->duration = gif->last_delay; return gif->duration; } static int gif_write_packet(AVFormatContext *s, AVPacket *new_pkt) { GIFContext *gif = s->priv_data; AVIOContext *pb = s->pb; AVPacket *pkt = gif->prev_pkt; if (!gif->prev_pkt) { gif->prev_pkt = av_packet_alloc(); if (!gif->prev_pkt) return AVERROR(ENOMEM); return av_packet_ref(gif->prev_pkt, new_pkt); } gif->last_pos = avio_tell(pb); if (pkt->size > 0) gif->have_end = pkt->data[pkt->size - 1] == GIF_TRAILER; if (!gif->last_pos) { int delay_pos; int off = 13; if (pkt->size < 13) return AVERROR(EINVAL); if (pkt->data[10] & 0x80) off += 3 * (1 << ((pkt->data[10] & 0x07) + 1)); if (pkt->size < off + 2) return AVERROR(EINVAL); avio_write(pb, pkt->data, off); if (pkt->data[off] == GIF_EXTENSION_INTRODUCER && pkt->data[off + 1] == 0xff) off += 19; if (pkt->size <= off) return AVERROR(EINVAL); /* "NETSCAPE EXTENSION" for looped animation GIF */ if (gif->loop >= 0) { avio_w8(pb, GIF_EXTENSION_INTRODUCER); /* GIF Extension code */ avio_w8(pb, GIF_APP_EXT_LABEL); /* Application Extension Label */ avio_w8(pb, 0x0b); /* Length of Application Block */ avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1); avio_w8(pb, 0x03); /* Length of Data Sub-Block */ avio_w8(pb, 0x01); avio_wl16(pb, (uint16_t)gif->loop); avio_w8(pb, 0x00); /* Data Sub-block Terminator */ } delay_pos = gif_parse_packet(s, pkt->data + off, pkt->size - off); if (delay_pos > 0 && delay_pos < pkt->size - off - 2) { avio_write(pb, pkt->data + off, delay_pos); avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt)); avio_write(pb, pkt->data + off + delay_pos + 2, pkt->size - off - delay_pos - 2); } else { avio_write(pb, pkt->data + off, pkt->size - off); } } else { int delay_pos = gif_parse_packet(s, pkt->data, pkt->size); if (delay_pos > 0 && delay_pos < pkt->size - 2) { avio_write(pb, pkt->data, delay_pos); avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt)); avio_write(pb, pkt->data + delay_pos + 2, pkt->size - delay_pos - 2); } else { avio_write(pb, pkt->data, pkt->size); } } av_packet_unref(gif->prev_pkt); if (new_pkt) return av_packet_ref(gif->prev_pkt, new_pkt); return 0; } static int gif_write_trailer(AVFormatContext *s) { GIFContext *gif = s->priv_data; AVIOContext *pb = s->pb; if (!gif->prev_pkt) return AVERROR(EINVAL); gif_write_packet(s, NULL); if (!gif->have_end) avio_w8(pb, GIF_TRAILER); av_packet_free(&gif->prev_pkt); 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: -1 - no loop, 0 - infinite loop", OFFSET(loop), AV_OPT_TYPE_INT, { .i64 = 0 }, -1, 65535, ENC }, { "final_delay", "Force delay (in centiseconds) after the last frame", OFFSET(last_delay), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 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, }; const FFOutputFormat ff_gif_muxer = { .p.name = "gif", .p.long_name = NULL_IF_CONFIG_SMALL("CompuServe Graphics Interchange Format (GIF)"), .p.mime_type = "image/gif", .p.extensions = "gif", .priv_data_size = sizeof(GIFContext), .p.audio_codec = AV_CODEC_ID_NONE, .p.video_codec = AV_CODEC_ID_GIF, .write_header = gif_write_header, .write_packet = gif_write_packet, .write_trailer = gif_write_trailer, .p.priv_class = &gif_muxer_class, .p.flags = AVFMT_VARIABLE_FPS, };