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path: root/libavformat/webpenc.c (plain)
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1/*
2 * webp muxer
3 * Copyright (c) 2014 Michael Niedermayer
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include "libavutil/intreadwrite.h"
23#include "libavutil/opt.h"
24#include "avformat.h"
25#include "internal.h"
26
27typedef struct WebpContext{
28 AVClass *class;
29 int frame_count;
30 AVPacket last_pkt;
31 int loop;
32 int wrote_webp_header;
33 int using_webp_anim_encoder;
34} WebpContext;
35
36static int webp_write_header(AVFormatContext *s)
37{
38 AVStream *st;
39
40 if (s->nb_streams != 1) {
41 av_log(s, AV_LOG_ERROR, "Only exactly 1 stream is supported\n");
42 return AVERROR(EINVAL);
43 }
44 st = s->streams[0];
45 if (st->codecpar->codec_id != AV_CODEC_ID_WEBP) {
46 av_log(s, AV_LOG_ERROR, "Only WebP is supported\n");
47 return AVERROR(EINVAL);
48 }
49 avpriv_set_pts_info(st, 24, 1, 1000);
50
51 return 0;
52}
53
54static int is_animated_webp_packet(AVPacket *pkt)
55{
56 if (pkt->size) {
57 int skip = 0;
58 unsigned flags = 0;
59
60 if (pkt->size < 4)
61 return 0;
62 if (AV_RL32(pkt->data) == AV_RL32("RIFF"))
63 skip = 12;
64
65 if (pkt->size < skip + 4)
66 return 0;
67 if (AV_RL32(pkt->data + skip) == AV_RL32("VP8X")) {
68 flags |= pkt->data[skip + 4 + 4];
69 }
70
71 if (flags & 2) // ANIMATION_FLAG is on
72 return 1;
73 }
74 return 0;
75}
76
77static int flush(AVFormatContext *s, int trailer, int64_t pts)
78{
79 WebpContext *w = s->priv_data;
80 AVStream *st = s->streams[0];
81
82 if (w->last_pkt.size) {
83 int skip = 0;
84 unsigned flags = 0;
85 int vp8x = 0;
86
87 if (w->last_pkt.size < 4)
88 return 0;
89 if (AV_RL32(w->last_pkt.data) == AV_RL32("RIFF"))
90 skip = 12;
91
92 if (w->last_pkt.size < skip + 4)
93 return 0; // Safe to do this as a valid WebP bitstream is >=30 bytes.
94 if (AV_RL32(w->last_pkt.data + skip) == AV_RL32("VP8X")) {
95 flags |= w->last_pkt.data[skip + 4 + 4];
96 vp8x = 1;
97 skip += AV_RL32(w->last_pkt.data + skip + 4) + 8;
98 }
99
100 if (!w->wrote_webp_header) {
101 avio_write(s->pb, "RIFF\0\0\0\0WEBP", 12);
102 w->wrote_webp_header = 1;
103 if (w->frame_count > 1) // first non-empty packet
104 w->frame_count = 1; // so we don't count previous empty packets.
105 }
106
107 if (w->frame_count == 1) {
108 if (!trailer) {
109 vp8x = 1;
110 flags |= 2 + 16;
111 }
112
113 if (vp8x) {
114 avio_write(s->pb, "VP8X", 4);
115 avio_wl32(s->pb, 10);
116 avio_w8(s->pb, flags);
117 avio_wl24(s->pb, 0);
118 avio_wl24(s->pb, st->codecpar->width - 1);
119 avio_wl24(s->pb, st->codecpar->height - 1);
120 }
121 if (!trailer) {
122 avio_write(s->pb, "ANIM", 4);
123 avio_wl32(s->pb, 6);
124 avio_wl32(s->pb, 0xFFFFFFFF);
125 avio_wl16(s->pb, w->loop);
126 }
127 }
128
129 if (w->frame_count > trailer) {
130 avio_write(s->pb, "ANMF", 4);
131 avio_wl32(s->pb, 16 + w->last_pkt.size - skip);
132 avio_wl24(s->pb, 0);
133 avio_wl24(s->pb, 0);
134 avio_wl24(s->pb, st->codecpar->width - 1);
135 avio_wl24(s->pb, st->codecpar->height - 1);
136 if (w->last_pkt.pts != AV_NOPTS_VALUE && pts != AV_NOPTS_VALUE) {
137 avio_wl24(s->pb, pts - w->last_pkt.pts);
138 } else
139 avio_wl24(s->pb, w->last_pkt.duration);
140 avio_w8(s->pb, 0);
141 }
142 avio_write(s->pb, w->last_pkt.data + skip, w->last_pkt.size - skip);
143 av_packet_unref(&w->last_pkt);
144 }
145
146 return 0;
147}
148
149static int webp_write_packet(AVFormatContext *s, AVPacket *pkt)
150{
151 WebpContext *w = s->priv_data;
152 w->using_webp_anim_encoder |= is_animated_webp_packet(pkt);
153
154 if (w->using_webp_anim_encoder) {
155 avio_write(s->pb, pkt->data, pkt->size);
156 w->wrote_webp_header = 1; // for good measure
157 } else {
158 int ret;
159 if ((ret = flush(s, 0, pkt->pts)) < 0)
160 return ret;
161 av_copy_packet(&w->last_pkt, pkt);
162 }
163 ++w->frame_count;
164
165 return 0;
166}
167
168static int webp_write_trailer(AVFormatContext *s)
169{
170 unsigned filesize;
171 WebpContext *w = s->priv_data;
172
173 if (w->using_webp_anim_encoder) {
174 if ((w->frame_count > 1) && w->loop) { // Write loop count.
175 avio_seek(s->pb, 42, SEEK_SET);
176 avio_wl16(s->pb, w->loop);
177 }
178 } else {
179 int ret;
180 if ((ret = flush(s, 1, AV_NOPTS_VALUE)) < 0)
181 return ret;
182
183 filesize = avio_tell(s->pb);
184 avio_seek(s->pb, 4, SEEK_SET);
185 avio_wl32(s->pb, filesize - 8);
186 // Note: without the following, avio only writes 8 bytes to the file.
187 avio_seek(s->pb, filesize, SEEK_SET);
188 }
189
190 return 0;
191}
192
193#define OFFSET(x) offsetof(WebpContext, x)
194#define ENC AV_OPT_FLAG_ENCODING_PARAM
195static const AVOption options[] = {
196 { "loop", "Number of times to loop the output: 0 - infinite loop", OFFSET(loop),
197 AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 65535, ENC },
198 { NULL },
199};
200
201static const AVClass webp_muxer_class = {
202 .class_name = "WebP muxer",
203 .item_name = av_default_item_name,
204 .version = LIBAVUTIL_VERSION_INT,
205 .option = options,
206};
207AVOutputFormat ff_webp_muxer = {
208 .name = "webp",
209 .long_name = NULL_IF_CONFIG_SMALL("WebP"),
210 .extensions = "webp",
211 .priv_data_size = sizeof(WebpContext),
212 .video_codec = AV_CODEC_ID_WEBP,
213 .write_header = webp_write_header,
214 .write_packet = webp_write_packet,
215 .write_trailer = webp_write_trailer,
216 .priv_class = &webp_muxer_class,
217 .flags = AVFMT_VARIABLE_FPS,
218};
219
generated by cgit at 2024-05-17 02:05:25 (GMT)