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 #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 };