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 "mux.h"
27 #include "libavutil/imgutils.h"
28 #include "libavutil/log.h"
29 #include "libavutil/opt.h"
30 #include "libavcodec/bytestream.h"
31 #include "libavcodec/gif.h"
32 
33 typedef struct GIFContext {
34  AVClass *class;
35  int loop;
37  int duration;
38  int64_t last_pos;
39  int have_end;
41 } GIFContext;
42 
44 {
45  avpriv_set_pts_info(s->streams[0], 64, 1, 100);
46 
47  return 0;
48 }
49 
50 static int gif_parse_packet(AVFormatContext *s, const uint8_t *data, int size)
51 {
52  GetByteContext gb;
53  int x;
54 
55  bytestream2_init(&gb, data, size);
56 
57  while (bytestream2_get_bytes_left(&gb) > 0) {
58  x = bytestream2_get_byte(&gb);
59  if (x != GIF_EXTENSION_INTRODUCER)
60  return 0;
61 
62  x = bytestream2_get_byte(&gb);
63  while (x != GIF_GCE_EXT_LABEL && bytestream2_get_bytes_left(&gb) > 0) {
64  int block_size = bytestream2_get_byte(&gb);
65  if (!block_size)
66  break;
67  bytestream2_skip(&gb, block_size);
68  }
69 
70  if (x == GIF_GCE_EXT_LABEL)
71  return bytestream2_tell(&gb) + 2;
72  }
73 
74  return 0;
75 }
76 
77 static int gif_get_delay(GIFContext *gif, AVPacket *prev, AVPacket *new)
78 {
79  if (new && new->pts != AV_NOPTS_VALUE)
80  gif->duration = av_clip_uint16(new->pts - prev->pts);
81  else if (!new && gif->last_delay >= 0)
82  gif->duration = gif->last_delay;
83  else if (prev->duration)
84  gif->duration = prev->duration;
85 
86  return gif->duration;
87 }
88 
90 {
91  GIFContext *gif = s->priv_data;
92  AVIOContext *pb = s->pb;
93  AVPacket *pkt = gif->prev_pkt;
94 
95  if (!gif->prev_pkt) {
96  gif->prev_pkt = av_packet_alloc();
97  if (!gif->prev_pkt)
98  return AVERROR(ENOMEM);
99  return av_packet_ref(gif->prev_pkt, new_pkt);
100  }
101 
102  gif->last_pos = avio_tell(pb);
103  if (pkt->size > 0)
104  gif->have_end = pkt->data[pkt->size - 1] == GIF_TRAILER;
105 
106  if (!gif->last_pos) {
107  int delay_pos;
108  int off = 13;
109 
110  if (pkt->size < 13)
111  return AVERROR(EINVAL);
112 
113  if (pkt->data[10] & 0x80)
114  off += 3 * (1 << ((pkt->data[10] & 0x07) + 1));
115 
116  if (pkt->size < off + 2)
117  return AVERROR(EINVAL);
118 
119  avio_write(pb, pkt->data, off);
120 
121  if (pkt->data[off] == GIF_EXTENSION_INTRODUCER && pkt->data[off + 1] == 0xff)
122  off += 19;
123 
124  if (pkt->size <= off)
125  return AVERROR(EINVAL);
126 
127  /* "NETSCAPE EXTENSION" for looped animation GIF */
128  if (gif->loop >= 0) {
129  avio_w8(pb, GIF_EXTENSION_INTRODUCER); /* GIF Extension code */
130  avio_w8(pb, GIF_APP_EXT_LABEL); /* Application Extension Label */
131  avio_w8(pb, 0x0b); /* Length of Application Block */
132  avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);
133  avio_w8(pb, 0x03); /* Length of Data Sub-Block */
134  avio_w8(pb, 0x01);
135  avio_wl16(pb, (uint16_t)gif->loop);
136  avio_w8(pb, 0x00); /* Data Sub-block Terminator */
137  }
138 
139  delay_pos = gif_parse_packet(s, pkt->data + off, pkt->size - off);
140  if (delay_pos > 0 && delay_pos < pkt->size - off - 2) {
141  avio_write(pb, pkt->data + off, delay_pos);
142  avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
143  avio_write(pb, pkt->data + off + delay_pos + 2, pkt->size - off - delay_pos - 2);
144  } else {
145  avio_write(pb, pkt->data + off, pkt->size - off);
146  }
147  } else {
148  int delay_pos = gif_parse_packet(s, pkt->data, pkt->size);
149 
150  if (delay_pos > 0 && delay_pos < pkt->size - 2) {
151  avio_write(pb, pkt->data, delay_pos);
152  avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
153  avio_write(pb, pkt->data + delay_pos + 2, pkt->size - delay_pos - 2);
154  } else {
155  avio_write(pb, pkt->data, pkt->size);
156  }
157  }
158 
160  if (new_pkt)
161  return av_packet_ref(gif->prev_pkt, new_pkt);
162 
163  return 0;
164 }
165 
167 {
168  GIFContext *gif = s->priv_data;
169  AVIOContext *pb = s->pb;
170 
171  if (!gif->prev_pkt)
172  return AVERROR(EINVAL);
173 
175 
176  if (!gif->have_end)
177  avio_w8(pb, GIF_TRAILER);
178  av_packet_free(&gif->prev_pkt);
179 
180  return 0;
181 }
182 
183 #define OFFSET(x) offsetof(GIFContext, x)
184 #define ENC AV_OPT_FLAG_ENCODING_PARAM
185 static const AVOption options[] = {
186  { "loop", "Number of times to loop the output: -1 - no loop, 0 - infinite loop", OFFSET(loop),
187  AV_OPT_TYPE_INT, { .i64 = 0 }, -1, 65535, ENC },
188  { "final_delay", "Force delay (in centiseconds) after the last frame", OFFSET(last_delay),
189  AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 65535, ENC },
190  { NULL },
191 };
192 
193 static const AVClass gif_muxer_class = {
194  .class_name = "GIF muxer",
195  .item_name = av_default_item_name,
196  .version = LIBAVUTIL_VERSION_INT,
197  .option = options,
198 };
199 
201  .p.name = "gif",
202  .p.long_name = NULL_IF_CONFIG_SMALL("CompuServe Graphics Interchange Format (GIF)"),
203  .p.mime_type = "image/gif",
204  .p.extensions = "gif",
205  .priv_data_size = sizeof(GIFContext),
206  .p.audio_codec = AV_CODEC_ID_NONE,
207  .p.video_codec = AV_CODEC_ID_GIF,
208  .p.subtitle_codec = AV_CODEC_ID_NONE,
209  .flags_internal = FF_OFMT_FLAG_MAX_ONE_OF_EACH |
211  .init = gif_init,
212  .write_packet = gif_write_packet,
213  .write_trailer = gif_write_trailer,
214  .p.priv_class = &gif_muxer_class,
215  .p.flags = AVFMT_VARIABLE_FPS,
216 };
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: packet.c:427
GIFContext::last_pos
int64_t last_pos
Definition: gif.c:38
gif_init
static av_cold int gif_init(AVFormatContext *s)
Definition: gif.c:43
AVOutputFormat::name
const char * name
Definition: avformat.h:510
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
opt.h
GetByteContext
Definition: bytestream.h:33
AVFMT_VARIABLE_FPS
#define AVFMT_VARIABLE_FPS
Format allows variable fps.
Definition: avformat.h:482
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:77
AVPacket::data
uint8_t * data
Definition: packet.h:520
AVOption
AVOption.
Definition: opt.h:357
data
const char data[16]
Definition: mxf.c:148
AVPacket::duration
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:538
FF_OFMT_FLAG_ONLY_DEFAULT_CODECS
#define FF_OFMT_FLAG_ONLY_DEFAULT_CODECS
If this flag is set, then the only permitted audio/video/subtitle codec ids are AVOutputFormat....
Definition: mux.h:59
GIF_GCE_EXT_LABEL
#define GIF_GCE_EXT_LABEL
Definition: gif.h:45
ENC
#define ENC
Definition: gif.c:184
av_packet_free
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
Definition: packet.c:74
GIFContext::loop
int loop
Definition: gif.c:35
FFOutputFormat::p
AVOutputFormat p
The public AVOutputFormat.
Definition: mux.h:65
avio_wl16
void avio_wl16(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:437
bytestream2_skip
static av_always_inline void bytestream2_skip(GetByteContext *g, unsigned int size)
Definition: bytestream.h:168
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: avformat.c:853
ff_gif_muxer
const FFOutputFormat ff_gif_muxer
Definition: gif.c:200
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:494
loop
static int loop
Definition: ffplay.c:335
GIFContext::prev_pkt
AVPacket * prev_pkt
Definition: gif.c:40
GIFContext::have_end
int have_end
Definition: gif.c:39
GIFContext::last_delay
int last_delay
Definition: gif.c:36
gif_muxer_class
static const AVClass gif_muxer_class
Definition: gif.c:193
pkt
AVPacket * pkt
Definition: movenc.c:60
av_cold
#define av_cold
Definition: attributes.h:90
GIFContext::duration
int duration
Definition: gif.c:37
s
#define s(width, name)
Definition: cbs_vp9.c:198
AVFormatContext
Format I/O context.
Definition: avformat.h:1255
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
av_default_item_name
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:237
FFOutputFormat
Definition: mux.h:61
avio_w8
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:179
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: packet.c:435
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:160
AVPacket::size
int size
Definition: packet.h:521
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:94
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:45
gif_write_trailer
static int gif_write_trailer(AVFormatContext *s)
Definition: gif.c:166
avio_write
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:201
av_packet_alloc
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
Definition: packet.c:63
AV_CODEC_ID_GIF
@ AV_CODEC_ID_GIF
Definition: codec_id.h:149
gif_parse_packet
static int gif_parse_packet(AVFormatContext *s, const uint8_t *data, int size)
Definition: gif.c:50
log.h
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:50
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:513
GIF_EXTENSION_INTRODUCER
#define GIF_EXTENSION_INTRODUCER
Definition: gif.h:43
FF_OFMT_FLAG_MAX_ONE_OF_EACH
#define FF_OFMT_FLAG_MAX_ONE_OF_EACH
If this flag is set, it indicates that for each codec type whose corresponding default codec (i....
Definition: mux.h:50
options
static const AVOption options[]
Definition: gif.c:185
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:245
av_clip_uint16
#define av_clip_uint16
Definition: common.h:112
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:89
AVPacket
This structure stores compressed data.
Definition: packet.h:497
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
OFFSET
#define OFFSET(x)
Definition: gif.c:183
mux.h