FFmpeg
gif.c
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1 /*
2  * Animated GIF muxer
3  * Copyright (c) 2000 Fabrice Bellard
4  *
5  * first version by Francois Revol <revol@free.fr>
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 #include "avformat.h"
25 #include "internal.h"
26 #include "libavutil/imgutils.h"
27 #include "libavutil/log.h"
28 #include "libavutil/opt.h"
29 #include "libavcodec/bytestream.h"
30 #include "libavcodec/gif.h"
31 
32 typedef struct GIFContext {
33  AVClass *class;
34  int loop;
36  int duration;
37  int64_t last_pos;
38  int have_end;
40 } GIFContext;
41 
43 {
44  if (s->nb_streams != 1 ||
45  s->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_VIDEO ||
46  s->streams[0]->codecpar->codec_id != AV_CODEC_ID_GIF) {
48  "GIF muxer supports only a single video GIF stream.\n");
49  return AVERROR(EINVAL);
50  }
51 
52  avpriv_set_pts_info(s->streams[0], 64, 1, 100);
53 
54  return 0;
55 }
56 
57 static int gif_parse_packet(AVFormatContext *s, uint8_t *data, int size)
58 {
59  GetByteContext gb;
60  int x;
61 
62  bytestream2_init(&gb, data, size);
63 
64  while (bytestream2_get_bytes_left(&gb) > 0) {
65  x = bytestream2_get_byte(&gb);
66  if (x != GIF_EXTENSION_INTRODUCER)
67  return 0;
68 
69  x = bytestream2_get_byte(&gb);
70  while (x != GIF_GCE_EXT_LABEL && bytestream2_get_bytes_left(&gb) > 0) {
71  int block_size = bytestream2_get_byte(&gb);
72  if (!block_size)
73  break;
74  bytestream2_skip(&gb, block_size);
75  }
76 
77  if (x == GIF_GCE_EXT_LABEL)
78  return bytestream2_tell(&gb) + 2;
79  }
80 
81  return 0;
82 }
83 
84 static int gif_get_delay(GIFContext *gif, AVPacket *prev, AVPacket *new)
85 {
86  if (new && new->pts != AV_NOPTS_VALUE)
87  gif->duration = av_clip_uint16(new->pts - prev->pts);
88  else if (!new && gif->last_delay >= 0)
89  gif->duration = gif->last_delay;
90 
91  return gif->duration;
92 }
93 
95 {
96  GIFContext *gif = s->priv_data;
97  AVIOContext *pb = s->pb;
98  AVPacket *pkt = gif->prev_pkt;
99 
100  if (!gif->prev_pkt) {
101  gif->prev_pkt = av_packet_alloc();
102  if (!gif->prev_pkt)
103  return AVERROR(ENOMEM);
104  return av_packet_ref(gif->prev_pkt, new_pkt);
105  }
106 
107  gif->last_pos = avio_tell(pb);
108  if (pkt->size > 0)
109  gif->have_end = pkt->data[pkt->size - 1] == GIF_TRAILER;
110 
111  if (!gif->last_pos) {
112  int delay_pos;
113  int off = 13;
114 
115  if (pkt->size < 13)
116  return AVERROR(EINVAL);
117 
118  if (pkt->data[10] & 0x80)
119  off += 3 * (1 << ((pkt->data[10] & 0x07) + 1));
120 
121  if (pkt->size < off + 2)
122  return AVERROR(EINVAL);
123 
124  avio_write(pb, pkt->data, off);
125 
126  if (pkt->data[off] == GIF_EXTENSION_INTRODUCER && pkt->data[off + 1] == 0xff)
127  off += 19;
128 
129  if (pkt->size <= off)
130  return AVERROR(EINVAL);
131 
132  /* "NETSCAPE EXTENSION" for looped animation GIF */
133  if (gif->loop >= 0) {
134  avio_w8(pb, GIF_EXTENSION_INTRODUCER); /* GIF Extension code */
135  avio_w8(pb, GIF_APP_EXT_LABEL); /* Application Extension Label */
136  avio_w8(pb, 0x0b); /* Length of Application Block */
137  avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);
138  avio_w8(pb, 0x03); /* Length of Data Sub-Block */
139  avio_w8(pb, 0x01);
140  avio_wl16(pb, (uint16_t)gif->loop);
141  avio_w8(pb, 0x00); /* Data Sub-block Terminator */
142  }
143 
144  delay_pos = gif_parse_packet(s, pkt->data + off, pkt->size - off);
145  if (delay_pos > 0 && delay_pos < pkt->size - off - 2) {
146  avio_write(pb, pkt->data + off, delay_pos);
147  avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
148  avio_write(pb, pkt->data + off + delay_pos + 2, pkt->size - off - delay_pos - 2);
149  } else {
150  avio_write(pb, pkt->data + off, pkt->size - off);
151  }
152  } else {
153  int delay_pos = gif_parse_packet(s, pkt->data, pkt->size);
154 
155  if (delay_pos > 0 && delay_pos < pkt->size - 2) {
156  avio_write(pb, pkt->data, delay_pos);
157  avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
158  avio_write(pb, pkt->data + delay_pos + 2, pkt->size - delay_pos - 2);
159  } else {
160  avio_write(pb, pkt->data, pkt->size);
161  }
162  }
163 
165  if (new_pkt)
166  return av_packet_ref(gif->prev_pkt, new_pkt);
167 
168  return 0;
169 }
170 
172 {
173  GIFContext *gif = s->priv_data;
174  AVIOContext *pb = s->pb;
175 
176  if (!gif->prev_pkt)
177  return AVERROR(EINVAL);
178 
180 
181  if (!gif->have_end)
182  avio_w8(pb, GIF_TRAILER);
183  av_packet_free(&gif->prev_pkt);
184 
185  return 0;
186 }
187 
188 #define OFFSET(x) offsetof(GIFContext, x)
189 #define ENC AV_OPT_FLAG_ENCODING_PARAM
190 static const AVOption options[] = {
191  { "loop", "Number of times to loop the output: -1 - no loop, 0 - infinite loop", OFFSET(loop),
192  AV_OPT_TYPE_INT, { .i64 = 0 }, -1, 65535, ENC },
193  { "final_delay", "Force delay (in centiseconds) after the last frame", OFFSET(last_delay),
194  AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 65535, ENC },
195  { NULL },
196 };
197 
198 static const AVClass gif_muxer_class = {
199  .class_name = "GIF muxer",
200  .item_name = av_default_item_name,
201  .version = LIBAVUTIL_VERSION_INT,
202  .option = options,
203 };
204 
206  .name = "gif",
207  .long_name = NULL_IF_CONFIG_SMALL("CompuServe Graphics Interchange Format (GIF)"),
208  .mime_type = "image/gif",
209  .extensions = "gif",
210  .priv_data_size = sizeof(GIFContext),
211  .audio_codec = AV_CODEC_ID_NONE,
212  .video_codec = AV_CODEC_ID_GIF,
216  .priv_class = &gif_muxer_class,
218 };
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:417
GIFContext::last_pos
int64_t last_pos
Definition: gif.c:37
AVOutputFormat::name
const char * name
Definition: avformat.h:496
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
gif_write_header
static int gif_write_header(AVFormatContext *s)
Definition: gif.c:42
opt.h
GetByteContext
Definition: bytestream.h:33
AVFMT_VARIABLE_FPS
#define AVFMT_VARIABLE_FPS
Format allows variable fps.
Definition: avformat.h:470
GIF_TRAILER
#define GIF_TRAILER
Definition: gif.h:42
gif_get_delay
static int gif_get_delay(GIFContext *gif, AVPacket *prev, AVPacket *new)
Definition: gif.c:84
AVPacket::data
uint8_t * data
Definition: packet.h:373
AVOption
AVOption.
Definition: opt.h:247
data
const char data[16]
Definition: mxf.c:143
GIF_GCE_EXT_LABEL
#define GIF_GCE_EXT_LABEL
Definition: gif.h:45
ENC
#define ENC
Definition: gif.c:189
av_packet_free
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
Definition: avpacket.c:75
GIFContext::loop
int loop
Definition: gif.c:34
avio_wl16
void avio_wl16(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:451
bytestream2_skip
static av_always_inline void bytestream2_skip(GetByteContext *g, unsigned int size)
Definition: bytestream.h:168
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:486
loop
static int loop
Definition: ffplay.c:339
GIFContext::prev_pkt
AVPacket * prev_pkt
Definition: gif.c:39
GIFContext::have_end
int have_end
Definition: gif.c:38
GIFContext::last_delay
int last_delay
Definition: gif.c:35
gif_muxer_class
static const AVClass gif_muxer_class
Definition: gif.c:198
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
GIFContext::duration
int duration
Definition: gif.c:36
s
#define s(width, name)
Definition: cbs_vp9.c:257
AVFormatContext
Format I/O context.
Definition: avformat.h:1097
internal.h
LIBAVUTIL_VERSION_INT
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
NULL
#define NULL
Definition: coverity.c:32
write_trailer
static int write_trailer(AVFormatContext *s1)
Definition: v4l2enc.c:98
av_default_item_name
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
avio_w8
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:196
av_packet_ref
int av_packet_ref(AVPacket *dst, const AVPacket *src)
Setup a new reference to the data described by a given packet.
Definition: avpacket.c:425
bytestream2_get_bytes_left
static av_always_inline int bytestream2_get_bytes_left(GetByteContext *g)
Definition: bytestream.h:158
bytestream2_tell
static av_always_inline int bytestream2_tell(GetByteContext *g)
Definition: bytestream.h:192
AVIOContext
Bytestream IO Context.
Definition: avio.h:161
AVPacket::size
int size
Definition: packet.h:374
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
gif.h
size
int size
Definition: twinvq_data.h:10344
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
GIFContext
Definition: gif.c:47
gif_write_trailer
static int gif_write_trailer(AVFormatContext *s)
Definition: gif.c:171
avio_write
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:218
av_packet_alloc
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
Definition: avpacket.c:64
write_packet
static void write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost, int unqueue)
Definition: ffmpeg.c:731
AV_CODEC_ID_GIF
@ AV_CODEC_ID_GIF
Definition: codec_id.h:147
log.h
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:48
AVOutputFormat
Definition: avformat.h:495
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:366
GIF_EXTENSION_INTRODUCER
#define GIF_EXTENSION_INTRODUCER
Definition: gif.h:43
options
static const AVOption options[]
Definition: gif.c:190
AVClass::class_name
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:71
avformat.h
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:224
avpriv_set_pts_info
void avpriv_set_pts_info(AVStream *st, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:1146
av_clip_uint16
#define av_clip_uint16
Definition: common.h:108
ff_gif_muxer
const AVOutputFormat ff_gif_muxer
Definition: gif.c:205
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
GIF_APP_EXT_LABEL
#define GIF_APP_EXT_LABEL
Definition: gif.h:47
gif_write_packet
static int gif_write_packet(AVFormatContext *s, AVPacket *new_pkt)
Definition: gif.c:94
AVPacket
This structure stores compressed data.
Definition: packet.h:350
gif_parse_packet
static int gif_parse_packet(AVFormatContext *s, uint8_t *data, int size)
Definition: gif.c:57
bytestream.h
imgutils.h
bytestream2_init
static av_always_inline void bytestream2_init(GetByteContext *g, const uint8_t *buf, int buf_size)
Definition: bytestream.h:137
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
OFFSET
#define OFFSET(x)
Definition: gif.c:188
write_header
static void write_header(FFV1Context *f)
Definition: ffv1enc.c:347