libavformat/webm_chunk.c

   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
  32 #include "libavutil/log.h"
  33 #include "libavutil/opt.h"
  34 #include "libavutil/mathematics.h"
  35
  36 #define MAX_FILENAME_SIZE 1024
  37
  38 typedef struct WebMChunkContext {
  39     const AVClass *class;
  40     char *header_filename;
  41     int chunk_duration;
  42     int chunk_index;
  43     char *http_method;
  44     uint64_t duration_written;
  45     int64_t prev_pts;
  46     AVFormatContext *avf;
  47     int header_written;
  48 } WebMChunkContext;
  49
  50 static int webm_chunk_init(AVFormatContext *s)
  51 {
  52     WebMChunkContext *wc = s->priv_data;
  53     ff_const59 AVOutputFormat *oformat;
  54     AVFormatContext *oc;
  55     AVStream *st, *ost = s->streams[0];
  56     AVDictionary *dict = NULL;
  57     int ret;
  58
  59     // DASH Streams can only have one track per file.
  60     if (s->nb_streams != 1)
  61         return AVERROR(EINVAL);
  62
  63     if (!wc->header_filename) {
  64         av_log(s, AV_LOG_ERROR, "No header filename provided\n");
  65         return AVERROR(EINVAL);
  66     }
  67
  68     wc->prev_pts = AV_NOPTS_VALUE;
  69
  70     oformat = av_guess_format("webm", s->url, "video/webm");
  71     if (!oformat)
  72         return AVERROR_MUXER_NOT_FOUND;
  73
  74     ret = avformat_alloc_output_context2(&wc->avf, oformat, NULL, NULL);
  75     if (ret < 0)
  76         return ret;
  77     oc = wc->avf;
  78
  79     ff_format_set_url(oc, wc->header_filename);
  80     wc->header_filename = NULL;
  81
  82     oc->interrupt_callback    = s->interrupt_callback;
  83     oc->max_delay             = s->max_delay;
  84     oc->flags                 = s->flags & ~AVFMT_FLAG_FLUSH_PACKETS;
  85     oc->strict_std_compliance = s->strict_std_compliance;
  86     oc->avoid_negative_ts     = s->avoid_negative_ts;
  87
  88     oc->flush_packets         = 0;
  89
  90     if ((ret = av_dict_copy(&oc->metadata, s->metadata, 0)) < 0)
  91         return ret;
  92
  93     if (!(st = avformat_new_stream(oc, NULL)))
  94         return AVERROR(ENOMEM);
  95
  96     if ((ret = avcodec_parameters_copy(st->codecpar, ost->codecpar)) < 0 ||
  97         (ret = av_dict_copy(&st->metadata, ost->metadata, 0))        < 0)
  98         return ret;
  99
 100     st->sample_aspect_ratio = ost->sample_aspect_ratio;
 101     st->disposition         = ost->disposition;
 102     avpriv_set_pts_info(st, ost->pts_wrap_bits, ost->time_base.num,
 103                                                 ost->time_base.den);
 104
 105     if (wc->http_method)
 106         if ((ret = av_dict_set(&dict, "method", wc->http_method, 0)) < 0)
 107             return ret;
 108     ret = s->io_open(s, &oc->pb, oc->url, AVIO_FLAG_WRITE, &dict);
 109     av_dict_free(&dict);
 110     if (ret < 0)
 111         return ret;
 112     oc->pb->seekable = 0;
 113
 114     if ((ret = av_dict_set_int(&dict, "dash", 1, 0))   < 0 ||
 115         (ret = av_dict_set_int(&dict, "cluster_time_limit",
 116                                wc->chunk_duration, 0)) < 0 ||
 117         (ret = av_dict_set_int(&dict, "live", 1, 0))   < 0)
 118         goto fail;
 119
 120     ret = avformat_init_output(oc, &dict);
 121 fail:
 122     av_dict_free(&dict);
 123     if (ret < 0)
 124         return ret;
 125
 126     // Copy the timing info back to the original stream
 127     // so that the timestamps of the packets are directly usable
 128     avpriv_set_pts_info(ost, st->pts_wrap_bits, st->time_base.num,
 129                                                 st->time_base.den);
 130
 131     // This ensures that the timestamps will already be properly shifted
 132     // when the packets arrive here, so we don't need to shift again.
 133     s->avoid_negative_ts  = oc->avoid_negative_ts;
 134     s->internal->avoid_negative_ts_use_pts =
 135         oc->internal->avoid_negative_ts_use_pts;
 136     oc->avoid_negative_ts = 0;
 137
 138     return 0;
 139 }
 140
 141 static int get_chunk_filename(AVFormatContext *s, char filename[MAX_FILENAME_SIZE])
 142 {
 143     WebMChunkContext *wc = s->priv_data;
 144     if (!filename) {
 145         return AVERROR(EINVAL);
 146     }
 147     if (av_get_frame_filename(filename, MAX_FILENAME_SIZE,
 148                               s->url, wc->chunk_index - 1) < 0) {
 149         av_log(s, AV_LOG_ERROR, "Invalid chunk filename template '%s'\n", s->url);
 150         return AVERROR(EINVAL);
 151     }
 152     return 0;
 153 }
 154
 155 static int webm_chunk_write_header(AVFormatContext *s)
 156 {
 157     WebMChunkContext *wc = s->priv_data;
 158     AVFormatContext *oc = wc->avf;
 159     int ret;
 160
 161     ret = avformat_write_header(oc, NULL);
 162     ff_format_io_close(s, &oc->pb);
 163     wc->header_written = 1;
 164     if (ret < 0)
 165         return ret;
 166     return 0;
 167 }
 168
 169 static int chunk_start(AVFormatContext *s)
 170 {
 171     WebMChunkContext *wc = s->priv_data;
 172     AVFormatContext *oc = wc->avf;
 173     int ret;
 174
 175     ret = avio_open_dyn_buf(&oc->pb);
 176     if (ret < 0)
 177         return ret;
 178     wc->chunk_index++;
 179     return 0;
 180 }
 181
 182 static int chunk_end(AVFormatContext *s, int flush)
 183 {
 184     WebMChunkContext *wc = s->priv_data;
 185     AVFormatContext *oc = wc->avf;
 186     int ret;
 187     int buffer_size;
 188     uint8_t *buffer;
 189     AVIOContext *pb;
 190     char filename[MAX_FILENAME_SIZE];
 191     AVDictionary *options = NULL;
 192
 193     if (!oc->pb)
 194         return 0;
 195
 196     if (flush)
 197         // Flush the cluster in WebM muxer.
 198         av_write_frame(oc, NULL);
 199     buffer_size = avio_close_dyn_buf(oc->pb, &buffer);
 200     oc->pb = NULL;
 201     ret = get_chunk_filename(s, filename);
 202     if (ret < 0)
 203         goto fail;
 204     if (wc->http_method)
 205         if ((ret = av_dict_set(&options, "method", wc->http_method, 0)) < 0)
 206             goto fail;
 207     ret = s->io_open(s, &pb, filename, AVIO_FLAG_WRITE, &options);
 208     av_dict_free(&options);
 209     if (ret < 0)
 210         goto fail;
 211     avio_write(pb, buffer, buffer_size);
 212     ff_format_io_close(s, &pb);
 213 fail:
 214     av_free(buffer);
 215     return (ret < 0) ? ret : 0;
 216 }
 217
 218 static int webm_chunk_write_packet(AVFormatContext *s, AVPacket *pkt)
 219 {
 220     WebMChunkContext *wc = s->priv_data;
 221     AVFormatContext *oc = wc->avf;
 222     AVStream *st = s->streams[pkt->stream_index];
 223     int ret;
 224
 225     if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
 226         if (wc->prev_pts != AV_NOPTS_VALUE)
 227             wc->duration_written += av_rescale_q(pkt->pts - wc->prev_pts,
 228                                                  st->time_base,
 229                                                  (AVRational) {1, 1000});
 230         wc->prev_pts = pkt->pts;
 231     }
 232
 233     // For video, a new chunk is started only on key frames. For audio, a new
 234     // chunk is started based on chunk_duration. Also, a new chunk is started
 235     // unconditionally if there is no currently open chunk.
 236     if (!oc->pb || (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
 237          (pkt->flags & AV_PKT_FLAG_KEY)) ||
 238         (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
 239          wc->duration_written >= wc->chunk_duration)) {
 240         wc->duration_written = 0;
 241         if ((ret = chunk_end(s, 1)) < 0 || (ret = chunk_start(s)) < 0) {
 242             return ret;
 243         }
 244     }
 245
 246     // We only have one stream, so use the non-interleaving av_write_frame.
 247     return av_write_frame(oc, pkt);
 248 }
 249
 250 static int webm_chunk_write_trailer(AVFormatContext *s)
 251 {
 252     WebMChunkContext *wc = s->priv_data;
 253     AVFormatContext *oc = wc->avf;
 254     int ret;
 255
 256     if (!oc->pb) {
 257         ret = chunk_start(s);
 258         if (ret < 0)
 259             return ret;
 260     }
 261     ret = av_write_trailer(oc);
 262     if (ret < 0)
 263         return ret;
 264     return chunk_end(s, 0);
 265 }
 266
 267 static void webm_chunk_deinit(AVFormatContext *s)
 268 {
 269     WebMChunkContext *wc = s->priv_data;
 270
 271     if (!wc->avf)
 272         return;
 273
 274     if (wc->header_written)
 275         ffio_free_dyn_buf(&wc->avf->pb);
 276     else
 277         ff_format_io_close(s, &wc->avf->pb);
 278     avformat_free_context(wc->avf);
 279     wc->avf = NULL;
 280 }
 281
 282 #define OFFSET(x) offsetof(WebMChunkContext, x)
 283 static const AVOption options[] = {
 284     { "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 },
 285     { "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 },
 286     { "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 },
 287     { "method", "set the HTTP method", OFFSET(http_method), AV_OPT_TYPE_STRING, {.str = NULL},  0, 0, AV_OPT_FLAG_ENCODING_PARAM },
 288     { NULL },
 289 };
 290
 291 static const AVClass webm_chunk_class = {
 292     .class_name = "WebM Chunk Muxer",
 293     .item_name  = av_default_item_name,
 294     .option     = options,
 295     .version    = LIBAVUTIL_VERSION_INT,
 296 };
 297
 298 AVOutputFormat ff_webm_chunk_muxer = {
 299     .name           = "webm_chunk",
 300     .long_name      = NULL_IF_CONFIG_SMALL("WebM Chunk Muxer"),
 301     .mime_type      = "video/webm",
 302     .extensions     = "chk",
 303     .flags          = AVFMT_NOFILE | AVFMT_GLOBALHEADER | AVFMT_NEEDNUMBER |
 304                       AVFMT_TS_NONSTRICT,
 305     .priv_data_size = sizeof(WebMChunkContext),
 306     .init           = webm_chunk_init,
 307     .write_header   = webm_chunk_write_header,
 308     .write_packet   = webm_chunk_write_packet,
 309     .write_trailer  = webm_chunk_write_trailer,
 310     .deinit         = webm_chunk_deinit,
 311     .priv_class     = &webm_chunk_class,
 312 };