FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavformat/webm_chunk.c
Date: 2025-10-10 03:51:19
Exec Total Coverage
Lines: 0 147 0.0%
Functions: 0 8 0.0%
Branches: 0 72 0.0%

Line Branch Exec Source
1 /*
2 * Copyright (c) 2015, Vignesh Venkatasubramanian
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file WebM Chunk Muxer
23 * The chunk muxer enables writing WebM Live chunks where there is a header
24 * chunk, followed by data chunks where each Cluster is written out as a Chunk.
25 */
26
27 #include "avformat.h"
28 #include "avio.h"
29 #include "avio_internal.h"
30 #include "internal.h"
31 #include "mux.h"
32
33 #include "libavutil/bprint.h"
34 #include "libavutil/log.h"
35 #include "libavutil/mem.h"
36 #include "libavutil/opt.h"
37 #include "libavutil/mathematics.h"
38
39 typedef struct WebMChunkContext {
40 const AVClass *class;
41 char *header_filename;
42 int chunk_duration;
43 int chunk_index;
44 char *http_method;
45 uint64_t duration_written;
46 int64_t prev_pts;
47 AVFormatContext *avf;
48 int header_written;
49 } WebMChunkContext;
50
51 static int webm_chunk_init(AVFormatContext *s)
52 {
53 WebMChunkContext *wc = s->priv_data;
54 const AVOutputFormat *oformat;
55 AVFormatContext *oc;
56 AVStream *st, *ost = s->streams[0];
57 AVDictionary *dict = NULL;
58 int ret;
59
60 // DASH Streams can only have one track per file.
61 if (s->nb_streams != 1)
62 return AVERROR(EINVAL);
63
64 if (!wc->header_filename) {
65 av_log(s, AV_LOG_ERROR, "No header filename provided\n");
66 return AVERROR(EINVAL);
67 }
68
69 wc->prev_pts = AV_NOPTS_VALUE;
70
71 oformat = av_guess_format("webm", s->url, "video/webm");
72 if (!oformat)
73 return AVERROR_MUXER_NOT_FOUND;
74
75 ret = avformat_alloc_output_context2(&wc->avf, oformat, NULL, NULL);
76 if (ret < 0)
77 return ret;
78 oc = wc->avf;
79
80 ff_format_set_url(oc, wc->header_filename);
81 wc->header_filename = NULL;
82
83 oc->interrupt_callback = s->interrupt_callback;
84 oc->max_delay = s->max_delay;
85 oc->flags = s->flags & ~AVFMT_FLAG_FLUSH_PACKETS;
86 oc->strict_std_compliance = s->strict_std_compliance;
87 oc->avoid_negative_ts = s->avoid_negative_ts;
88
89 oc->flush_packets = 0;
90
91 if ((ret = av_dict_copy(&oc->metadata, s->metadata, 0)) < 0)
92 return ret;
93
94 st = ff_stream_clone(oc, ost);
95 if (!st)
96 return AVERROR(ENOMEM);
97
98 if (wc->http_method)
99 if ((ret = av_dict_set(&dict, "method", wc->http_method, 0)) < 0)
100 return ret;
101 ret = s->io_open(s, &oc->pb, oc->url, AVIO_FLAG_WRITE, &dict);
102 av_dict_free(&dict);
103 if (ret < 0)
104 return ret;
105 oc->pb->seekable = 0;
106
107 if ((ret = av_dict_set_int(&dict, "dash", 1, 0)) < 0 ||
108 (ret = av_dict_set_int(&dict, "cluster_time_limit",
109 wc->chunk_duration, 0)) < 0 ||
110 (ret = av_dict_set_int(&dict, "live", 1, 0)) < 0)
111 goto fail;
112
113 ret = avformat_init_output(oc, &dict);
114 fail:
115 av_dict_free(&dict);
116 if (ret < 0)
117 return ret;
118
119 // Copy the timing info back to the original stream
120 // so that the timestamps of the packets are directly usable
121 avpriv_set_pts_info(ost, st->pts_wrap_bits, st->time_base.num,
122 st->time_base.den);
123
124 // This ensures that the timestamps will already be properly shifted
125 // when the packets arrive here, so we don't need to shift again.
126 s->avoid_negative_ts = oc->avoid_negative_ts;
127 ffformatcontext(s)->avoid_negative_ts_use_pts =
128 ffformatcontext(oc)->avoid_negative_ts_use_pts;
129 oc->avoid_negative_ts = AVFMT_AVOID_NEG_TS_DISABLED;
130 ffformatcontext(oc)->avoid_negative_ts_status = AVOID_NEGATIVE_TS_DISABLED;
131
132 return 0;
133 }
134
135 static int get_chunk_filename(AVFormatContext *s, AVBPrint *filename)
136 {
137 WebMChunkContext *wc = s->priv_data;
138 int ret = ff_bprint_get_frame_filename(filename, s->url, wc->chunk_index - 1, 0);
139 if (ret < 0) {
140 av_log(s, AV_LOG_ERROR, "Invalid chunk filename template '%s'\n", s->url);
141 return ret;
142 }
143 return 0;
144 }
145
146 static int webm_chunk_write_header(AVFormatContext *s)
147 {
148 WebMChunkContext *wc = s->priv_data;
149 AVFormatContext *oc = wc->avf;
150 AVStream *st = s->streams[0], *ost = oc->streams[0];
151 int ret;
152
153 ret = avformat_write_header(oc, NULL);
154 ff_format_io_close(s, &oc->pb);
155 ffstream(st)->lowest_ts_allowed = ffstream(ost)->lowest_ts_allowed;
156 ffstream(ost)->lowest_ts_allowed = 0;
157 wc->header_written = 1;
158 if (ret < 0)
159 return ret;
160 return 0;
161 }
162
163 static int chunk_start(AVFormatContext *s)
164 {
165 WebMChunkContext *wc = s->priv_data;
166 AVFormatContext *oc = wc->avf;
167 int ret;
168
169 ret = avio_open_dyn_buf(&oc->pb);
170 if (ret < 0)
171 return ret;
172 wc->chunk_index++;
173 return 0;
174 }
175
176 static int chunk_end(AVFormatContext *s, int flush)
177 {
178 WebMChunkContext *wc = s->priv_data;
179 AVFormatContext *oc = wc->avf;
180 int ret;
181 int buffer_size;
182 uint8_t *buffer;
183 AVIOContext *pb;
184 AVBPrint filename;
185 AVDictionary *options = NULL;
186
187 if (!oc->pb)
188 return 0;
189
190 if (flush)
191 // Flush the cluster in WebM muxer.
192 av_write_frame(oc, NULL);
193 buffer_size = avio_close_dyn_buf(oc->pb, &buffer);
194 oc->pb = NULL;
195 av_bprint_init(&filename, 0, AV_BPRINT_SIZE_UNLIMITED);
196 ret = get_chunk_filename(s, &filename);
197 if (ret < 0)
198 goto fail;
199 if (wc->http_method)
200 if ((ret = av_dict_set(&options, "method", wc->http_method, 0)) < 0)
201 goto fail;
202 ret = s->io_open(s, &pb, filename.str, AVIO_FLAG_WRITE, &options);
203 av_dict_free(&options);
204 if (ret < 0)
205 goto fail;
206 avio_write(pb, buffer, buffer_size);
207 ff_format_io_close(s, &pb);
208 fail:
209 av_bprint_finalize(&filename, NULL);
210 av_free(buffer);
211 return (ret < 0) ? ret : 0;
212 }
213
214 static int webm_chunk_write_packet(AVFormatContext *s, AVPacket *pkt)
215 {
216 WebMChunkContext *wc = s->priv_data;
217 AVFormatContext *oc = wc->avf;
218 AVStream *st = s->streams[pkt->stream_index];
219 int ret;
220
221 if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
222 if (wc->prev_pts != AV_NOPTS_VALUE)
223 wc->duration_written += av_rescale_q(pkt->pts - wc->prev_pts,
224 st->time_base,
225 (AVRational) {1, 1000});
226 wc->prev_pts = pkt->pts;
227 }
228
229 // For video, a new chunk is started only on key frames. For audio, a new
230 // chunk is started based on chunk_duration. Also, a new chunk is started
231 // unconditionally if there is no currently open chunk.
232 if (!oc->pb || (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
233 (pkt->flags & AV_PKT_FLAG_KEY)) ||
234 (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
235 wc->duration_written >= wc->chunk_duration)) {
236 wc->duration_written = 0;
237 if ((ret = chunk_end(s, 1)) < 0 || (ret = chunk_start(s)) < 0) {
238 return ret;
239 }
240 }
241
242 // We only have one stream, so use the non-interleaving av_write_frame.
243 return av_write_frame(oc, pkt);
244 }
245
246 static int webm_chunk_write_trailer(AVFormatContext *s)
247 {
248 WebMChunkContext *wc = s->priv_data;
249 AVFormatContext *oc = wc->avf;
250 int ret;
251
252 if (!oc->pb) {
253 ret = chunk_start(s);
254 if (ret < 0)
255 return ret;
256 }
257 ret = av_write_trailer(oc);
258 if (ret < 0)
259 return ret;
260 return chunk_end(s, 0);
261 }
262
263 static void webm_chunk_deinit(AVFormatContext *s)
264 {
265 WebMChunkContext *wc = s->priv_data;
266
267 if (!wc->avf)
268 return;
269
270 if (wc->header_written)
271 ffio_free_dyn_buf(&wc->avf->pb);
272 else
273 ff_format_io_close(s, &wc->avf->pb);
274 avformat_free_context(wc->avf);
275 wc->avf = NULL;
276 }
277
278 #define OFFSET(x) offsetof(WebMChunkContext, x)
279 static const AVOption options[] = {
280 { "chunk_start_index", "start index of the chunk", OFFSET(chunk_index), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
281 { "header", "filename of the header where the initialization data will be written", OFFSET(header_filename), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
282 { "audio_chunk_duration", "duration of each chunk in milliseconds", OFFSET(chunk_duration), AV_OPT_TYPE_INT, {.i64 = 5000}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
283 { "method", "set the HTTP method", OFFSET(http_method), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
284 { NULL },
285 };
286
287 static const AVClass webm_chunk_class = {
288 .class_name = "WebM Chunk Muxer",
289 .item_name = av_default_item_name,
290 .option = options,
291 .version = LIBAVUTIL_VERSION_INT,
292 };
293
294 const FFOutputFormat ff_webm_chunk_muxer = {
295 .p.name = "webm_chunk",
296 .p.long_name = NULL_IF_CONFIG_SMALL("WebM Chunk Muxer"),
297 .p.mime_type = "video/webm",
298 .p.extensions = "chk",
299 .p.flags = AVFMT_NOFILE | AVFMT_GLOBALHEADER | AVFMT_NEEDNUMBER |
300 AVFMT_TS_NONSTRICT,
301 .p.priv_class = &webm_chunk_class,
302 .priv_data_size = sizeof(WebMChunkContext),
303 .init = webm_chunk_init,
304 .write_header = webm_chunk_write_header,
305 .write_packet = webm_chunk_write_packet,
306 .write_trailer = webm_chunk_write_trailer,
307 .deinit = webm_chunk_deinit,
308 };
309