text: /*
   * Live smooth streaming fragmenter
   * Copyright (c) 2012 Martin Storsjo
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "config.h"
  
  #include <float.h>
  
  #include "avformat.h"
  #include "internal.h"
  #include "os_support.h"
  
  #if HAVE_UNISTD_H
  #include <unistd.h>
  #endif
  
  #include "avc.h"
  #include "url.h"
  #include "isom.h"
  
  #include "libavutil/opt.h"
  #include "libavutil/avstring.h"
  #include "libavutil/mathematics.h"
  #include "libavutil/intreadwrite.h"
  
  typedef struct {
      char file[1024];
      char infofile[1024];
      int64_t start_time, duration;
      int n;
      int64_t start_pos, size;
  } Fragment;
  
  typedef struct {
      AVFormatContext *ctx;
      int ctx_inited;
      char dirname[1024];
      uint8_t iobuf[32768];
      URLContext *out;  // Current output stream where all output is written
      URLContext *out2; // Auxiliary output stream where all output is also written
      URLContext *tail_out; // The actual main output stream, if we're currently seeked back to write elsewhere
      int64_t tail_pos, cur_pos, cur_start_pos;
      int packets_written;
      const char *stream_type_tag;
      int nb_fragments, fragments_size, fragment_index;
      Fragment **fragments;
  
      const char *fourcc;
      char *private_str;
      int packet_size;
      int audio_tag;
  } OutputStream;
  
  typedef struct {
      const AVClass *class;  /* Class for private options. */
      int window_size;
      int extra_window_size;
      int lookahead_count;
      int min_frag_duration;
      int remove_at_exit;
      OutputStream *streams;
      int has_video, has_audio;
      int nb_fragments;
  } SmoothStreamingContext;
  
  static int ism_write(void *opaque, uint8_t *buf, int buf_size)
  {
      OutputStream *os = opaque;
      if (os->out)
          ffurl_write(os->out, buf, buf_size);
      if (os->out2)
          ffurl_write(os->out2, buf, buf_size);
      os->cur_pos += buf_size;
      if (os->cur_pos >= os->tail_pos)
          os->tail_pos = os->cur_pos;
      return buf_size;
  }
  
  static int64_t ism_seek(void *opaque, int64_t offset, int whence)
  {
      OutputStream *os = opaque;
      int i;
      if (whence != SEEK_SET)
          return AVERROR(ENOSYS);
      if (os->tail_out) {
          if (os->out) {
              ffurl_close(os->out);
          }
          if (os->out2) {
              ffurl_close(os->out2);
          }
          os->out = os->tail_out;
          os->out2 = NULL;
          os->tail_out = NULL;
      }
      if (offset >= os->cur_start_pos) {
          if (os->out)
              ffurl_seek(os->out, offset - os->cur_start_pos, SEEK_SET);
          os->cur_pos = offset;
          return offset;
      }
      for (i = os->nb_fragments - 1; i >= 0; i--) {
          Fragment *frag = os->fragments[i];
          if (offset >= frag->start_pos && offset < frag->start_pos + frag->size) {
              int ret;
              AVDictionary *opts = NULL;
              os->tail_out = os->out;
              av_dict_set(&opts, "truncate", "0", 0);
              ret = ffurl_open(&os->out, frag->file, AVIO_FLAG_READ_WRITE, &os->ctx->interrupt_callback, &opts);
              av_dict_free(&opts);
              if (ret < 0) {
                  os->out = os->tail_out;
                  os->tail_out = NULL;
                  return ret;
              }
              av_dict_set(&opts, "truncate", "0", 0);
              ffurl_open(&os->out2, frag->infofile, AVIO_FLAG_READ_WRITE, &os->ctx->interrupt_callback, &opts);
              av_dict_free(&opts);
              ffurl_seek(os->out, offset - frag->start_pos, SEEK_SET);
              if (os->out2)
                  ffurl_seek(os->out2, offset - frag->start_pos, SEEK_SET);
              os->cur_pos = offset;
              return offset;
          }
      }
      return AVERROR(EIO);
  }
  
  static void get_private_data(OutputStream *os)
  {
      AVCodecContext *codec = os->ctx->streams[0]->codec;
      uint8_t *ptr = codec->extradata;
      int size = codec->extradata_size;
      int i;
      if (codec->codec_id == AV_CODEC_ID_H264) {
          ff_avc_write_annexb_extradata(ptr, &ptr, &size);
          if (!ptr)
              ptr = codec->extradata;
      }
      if (!ptr)
          return;
      os->private_str = av_mallocz(2*size + 1);
      if (!os->private_str)
          goto fail;
      for (i = 0; i < size; i++)
          snprintf(&os->private_str[2*i], 3, "%02x", ptr[i]);
  fail:
      if (ptr != codec->extradata)
          av_free(ptr);
  }
  
  static void ism_free(AVFormatContext *s)
  {
      SmoothStreamingContext *c = s->priv_data;
      int i, j;
      if (!c->streams)
          return;
      for (i = 0; i < s->nb_streams; i++) {
          OutputStream *os = &c->streams[i];
          ffurl_close(os->out);
          ffurl_close(os->out2);
          ffurl_close(os->tail_out);
          os->out = os->out2 = os->tail_out = NULL;
          if (os->ctx && os->ctx_inited)
              av_write_trailer(os->ctx);
          if (os->ctx && os->ctx->pb)
              av_free(os->ctx->pb);
          if (os->ctx)
              avformat_free_context(os->ctx);
          av_free(os->private_str);
          for (j = 0; j < os->nb_fragments; j++)
              av_free(os->fragments[j]);
          av_free(os->fragments);
      }
      av_freep(&c->streams);
  }
  
  static void output_chunk_list(OutputStream *os, AVIOContext *out, int final, int skip, int window_size)
  {
      int removed = 0, i, start = 0;
      if (os->nb_fragments <= 0)
          return;
      if (os->fragments[0]->n > 0)
          removed = 1;
      if (final)
          skip = 0;
      if (window_size)
          start = FFMAX(os->nb_fragments - skip - window_size, 0);
      for (i = start; i < os->nb_fragments - skip; i++) {
          Fragment *frag = os->fragments[i];
          if (!final || removed)
              avio_printf(out, "<c t=\"%"PRIu64"\" d=\"%"PRIu64"\" />\n", frag->start_time, frag->duration);
          else
              avio_printf(out, "<c n=\"%d\" d=\"%"PRIu64"\" />\n", frag->n, frag->duration);
      }
  }
  
  static int write_manifest(AVFormatContext *s, int final)
  {
      SmoothStreamingContext *c = s->priv_data;
      AVIOContext *out;
      char filename[1024], temp_filename[1024];
      int ret, i, video_chunks = 0, audio_chunks = 0, video_streams = 0, audio_streams = 0;
      int64_t duration = 0;
  
      snprintf(filename, sizeof(filename), "%s/Manifest", s->filename);
      snprintf(temp_filename, sizeof(temp_filename), "%s/Manifest.tmp", s->filename);
      ret = avio_open2(&out, temp_filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
      if (ret < 0) {
          av_log(s, AV_LOG_ERROR, "Unable to open %s for writing\n", temp_filename);
          return ret;
      }
      avio_printf(out, "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n");
      for (i = 0; i < s->nb_streams; i++) {
          OutputStream *os = &c->streams[i];
          if (os->nb_fragments > 0) {
              Fragment *last = os->fragments[os->nb_fragments - 1];
              duration = last->start_time + last->duration;
          }
          if (s->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
              video_chunks = os->nb_fragments;
              video_streams++;
          } else {
              audio_chunks = os->nb_fragments;
              audio_streams++;
          }
      }
      if (!final) {
          duration = 0;
          video_chunks = audio_chunks = 0;
      }
      if (c->window_size) {
          video_chunks = FFMIN(video_chunks, c->window_size);
          audio_chunks = FFMIN(audio_chunks, c->window_size);
      }
      avio_printf(out, "<SmoothStreamingMedia MajorVersion=\"2\" MinorVersion=\"0\" Duration=\"%"PRIu64"\"", duration);
      if (!final)
          avio_printf(out, " IsLive=\"true\" LookAheadFragmentCount=\"%d\" DVRWindowLength=\"0\"", c->lookahead_count);
      avio_printf(out, ">\n");
      if (c->has_video) {
          int last = -1, index = 0;
          avio_printf(out, "<StreamIndex Type=\"video\" QualityLevels=\"%d\" Chunks=\"%d\" Url=\"QualityLevels({bitrate})/Fragments(video={start time})\">\n", video_streams, video_chunks);
          for (i = 0; i < s->nb_streams; i++) {
              OutputStream *os = &c->streams[i];
              if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_VIDEO)
                  continue;
              last = i;
              avio_printf(out, "<QualityLevel Index=\"%d\" Bitrate=\"%d\" FourCC=\"%s\" MaxWidth=\"%d\" MaxHeight=\"%d\" CodecPrivateData=\"%s\" />\n", index, s->streams[i]->codec->bit_rate, os->fourcc, s->streams[i]->codec->width, s->streams[i]->codec->height, os->private_str);
              index++;
          }
          output_chunk_list(&c->streams[last], out, final, c->lookahead_count, c->window_size);
          avio_printf(out, "</StreamIndex>\n");
      }
      if (c->has_audio) {
          int last = -1, index = 0;
          avio_printf(out, "<StreamIndex Type=\"audio\" QualityLevels=\"%d\" Chunks=\"%d\" Url=\"QualityLevels({bitrate})/Fragments(audio={start time})\">\n", audio_streams, audio_chunks);
          for (i = 0; i < s->nb_streams; i++) {
              OutputStream *os = &c->streams[i];
              if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
                  continue;
              last = i;
              avio_printf(out, "<QualityLevel Index=\"%d\" Bitrate=\"%d\" FourCC=\"%s\" SamplingRate=\"%d\" Channels=\"%d\" BitsPerSample=\"16\" PacketSize=\"%d\" AudioTag=\"%d\" CodecPrivateData=\"%s\" />\n", index, s->streams[i]->codec->bit_rate, os->fourcc, s->streams[i]->codec->sample_rate, s->streams[i]->codec->channels, os->packet_size, os->audio_tag, os->private_str);
              index++;
          }
          output_chunk_list(&c->streams[last], out, final, c->lookahead_count, c->window_size);
          avio_printf(out, "</StreamIndex>\n");
      }
      avio_printf(out, "</SmoothStreamingMedia>\n");
      avio_flush(out);
      avio_close(out);
      rename(temp_filename, filename);
      return 0;
  }
  
  static int ism_write_header(AVFormatContext *s)
  {
      SmoothStreamingContext *c = s->priv_data;
      int ret = 0, i;
      AVOutputFormat *oformat;
  
      if (mkdir(s->filename, 0777) == -1 && errno != EEXIST) {
          av_log(s, AV_LOG_ERROR, "mkdir failed\n");
          ret = AVERROR(errno);
          goto fail;
      }
  
      oformat = av_guess_format("ismv", NULL, NULL);
      if (!oformat) {
          ret = AVERROR_MUXER_NOT_FOUND;
          goto fail;
      }
  
      c->streams = av_mallocz_array(s->nb_streams, sizeof(*c->streams));
      if (!c->streams) {
          ret = AVERROR(ENOMEM);
          goto fail;
      }
  
      for (i = 0; i < s->nb_streams; i++) {
          OutputStream *os = &c->streams[i];
          AVFormatContext *ctx;
          AVStream *st;
          AVDictionary *opts = NULL;
  
          if (!s->streams[i]->codec->bit_rate) {
              av_log(s, AV_LOG_ERROR, "No bit rate set for stream %d\n", i);
              ret = AVERROR(EINVAL);
              goto fail;
          }
          snprintf(os->dirname, sizeof(os->dirname), "%s/QualityLevels(%d)", s->filename, s->streams[i]->codec->bit_rate);
          if (mkdir(os->dirname, 0777) == -1 && errno != EEXIST) {
              ret = AVERROR(errno);
              av_log(s, AV_LOG_ERROR, "mkdir failed\n");
              goto fail;
          }
  
          ctx = avformat_alloc_context();
          if (!ctx) {
              ret = AVERROR(ENOMEM);
              goto fail;
          }
          os->ctx = ctx;
          ctx->oformat = oformat;
          ctx->interrupt_callback = s->interrupt_callback;
  
          if (!(st = avformat_new_stream(ctx, NULL))) {
              ret = AVERROR(ENOMEM);
              goto fail;
          }
          avcodec_copy_context(st->codec, s->streams[i]->codec);
          st->sample_aspect_ratio = s->streams[i]->sample_aspect_ratio;
  
          ctx->pb = avio_alloc_context(os->iobuf, sizeof(os->iobuf), AVIO_FLAG_WRITE, os, NULL, ism_write, ism_seek);
          if (!ctx->pb) {
              ret = AVERROR(ENOMEM);
              goto fail;
          }
  
          av_dict_set_int(&opts, "ism_lookahead", c->lookahead_count, 0);
          av_dict_set(&opts, "movflags", "frag_custom", 0);
          if ((ret = avformat_write_header(ctx, &opts)) < 0) {
               goto fail;
          }
          os->ctx_inited = 1;
          avio_flush(ctx->pb);
          av_dict_free(&opts);
          s->streams[i]->time_base = st->time_base;
          if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
              c->has_video = 1;
              os->stream_type_tag = "video";
              if (st->codec->codec_id == AV_CODEC_ID_H264) {
                  os->fourcc = "H264";
              } else if (st->codec->codec_id == AV_CODEC_ID_VC1) {
                  os->fourcc = "WVC1";
              } else {
                  av_log(s, AV_LOG_ERROR, "Unsupported video codec\n");
                  ret = AVERROR(EINVAL);
                  goto fail;
              }
          } else {
              c->has_audio = 1;
              os->stream_type_tag = "audio";
              if (st->codec->codec_id == AV_CODEC_ID_AAC) {
                  os->fourcc = "AACL";
                  os->audio_tag = 0xff;
              } else if (st->codec->codec_id == AV_CODEC_ID_WMAPRO) {
                  os->fourcc = "WMAP";
                  os->audio_tag = 0x0162;
              } else {
                  av_log(s, AV_LOG_ERROR, "Unsupported audio codec\n");
                  ret = AVERROR(EINVAL);
                  goto fail;
              }
              os->packet_size = st->codec->block_align ? st->codec->block_align : 4;
          }
          get_private_data(os);
      }
  
      if (!c->has_video && c->min_frag_duration <= 0) {
          av_log(s, AV_LOG_WARNING, "no video stream and no min frag duration set\n");
          ret = AVERROR(EINVAL);
      }
      ret = write_manifest(s, 0);
  
  fail:
      if (ret)
          ism_free(s);
      return ret;
  }
  
  static int parse_fragment(AVFormatContext *s, const char *filename, int64_t *start_ts, int64_t *duration, int64_t *moof_size, int64_t size)
  {
      AVIOContext *in;
      int ret;
      uint32_t len;
      if ((ret = avio_open2(&in, filename, AVIO_FLAG_READ, &s->interrupt_callback, NULL)) < 0)
          return ret;
      ret = AVERROR(EIO);
      *moof_size = avio_rb32(in);
      if (*moof_size < 8 || *moof_size > size)
          goto fail;
      if (avio_rl32(in) != MKTAG('m','o','o','f'))
          goto fail;
      len = avio_rb32(in);
      if (len > *moof_size)
          goto fail;
      if (avio_rl32(in) != MKTAG('m','f','h','d'))
          goto fail;
      avio_seek(in, len - 8, SEEK_CUR);
      avio_rb32(in); /* traf size */
      if (avio_rl32(in) != MKTAG('t','r','a','f'))
          goto fail;
      while (avio_tell(in) < *moof_size) {
          uint32_t len = avio_rb32(in);
          uint32_t tag = avio_rl32(in);
          int64_t end = avio_tell(in) + len - 8;
          if (len < 8 || len >= *moof_size)
              goto fail;
          if (tag == MKTAG('u','u','i','d')) {
              static const uint8_t tfxd[] = {
                  0x6d, 0x1d, 0x9b, 0x05, 0x42, 0xd5, 0x44, 0xe6,
                  0x80, 0xe2, 0x14, 0x1d, 0xaf, 0xf7, 0x57, 0xb2
              };
              uint8_t uuid[16];
              avio_read(in, uuid, 16);
              if (!memcmp(uuid, tfxd, 16) && len >= 8 + 16 + 4 + 16) {
                  avio_seek(in, 4, SEEK_CUR);
                  *start_ts = avio_rb64(in);
                  *duration = avio_rb64(in);
                  ret = 0;
                  break;
              }
          }
          avio_seek(in, end, SEEK_SET);
      }
  fail:
      avio_close(in);
      return ret;
  }
  
  static int add_fragment(OutputStream *os, const char *file, const char *infofile, int64_t start_time, int64_t duration, int64_t start_pos, int64_t size)
  {
      int err;
      Fragment *frag;
      if (os->nb_fragments >= os->fragments_size) {
          os->fragments_size = (os->fragments_size + 1) * 2;
          if ((err = av_reallocp(&os->fragments, sizeof(*os->fragments) *
                                 os->fragments_size)) < 0) {
              os->fragments_size = 0;
              os->nb_fragments = 0;
              return err;
          }
      }
      frag = av_mallocz(sizeof(*frag));
      if (!frag)
          return AVERROR(ENOMEM);
      av_strlcpy(frag->file, file, sizeof(frag->file));
      av_strlcpy(frag->infofile, infofile, sizeof(frag->infofile));
      frag->start_time = start_time;
      frag->duration = duration;
      frag->start_pos = start_pos;
      frag->size = size;
      frag->n = os->fragment_index;
      os->fragments[os->nb_fragments++] = frag;
      os->fragment_index++;
      return 0;
  }
  
  static int copy_moof(AVFormatContext *s, const char* infile, const char *outfile, int64_t size)
  {
      AVIOContext *in, *out;
      int ret = 0;
      if ((ret = avio_open2(&in, infile, AVIO_FLAG_READ, &s->interrupt_callback, NULL)) < 0)
          return ret;
      if ((ret = avio_open2(&out, outfile, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL)) < 0) {
          avio_close(in);
          return ret;
      }
      while (size > 0) {
          uint8_t buf[8192];
          int n = FFMIN(size, sizeof(buf));
          n = avio_read(in, buf, n);
          if (n <= 0) {
              ret = AVERROR(EIO);
              break;
          }
          avio_write(out, buf, n);
          size -= n;
      }
      avio_flush(out);
      avio_close(out);
      avio_close(in);
      return ret;
  }
  
  static int ism_flush(AVFormatContext *s, int final)
  {
      SmoothStreamingContext *c = s->priv_data;
      int i, ret = 0;
  
      for (i = 0; i < s->nb_streams; i++) {
          OutputStream *os = &c->streams[i];
          char filename[1024], target_filename[1024], header_filename[1024];
          int64_t start_pos = os->tail_pos, size;
          int64_t start_ts, duration, moof_size;
          if (!os->packets_written)
              continue;
  
          snprintf(filename, sizeof(filename), "%s/temp", os->dirname);
          ret = ffurl_open(&os->out, filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
          if (ret < 0)
              break;
          os->cur_start_pos = os->tail_pos;
          av_write_frame(os->ctx, NULL);
          avio_flush(os->ctx->pb);
          os->packets_written = 0;
          if (!os->out || os->tail_out)
              return AVERROR(EIO);
  
          ffurl_close(os->out);
          os->out = NULL;
          size = os->tail_pos - start_pos;
          if ((ret = parse_fragment(s, filename, &start_ts, &duration, &moof_size, size)) < 0)
              break;
          snprintf(header_filename, sizeof(header_filename), "%s/FragmentInfo(%s=%"PRIu64")", os->dirname, os->stream_type_tag, start_ts);
          snprintf(target_filename, sizeof(target_filename), "%s/Fragments(%s=%"PRIu64")", os->dirname, os->stream_type_tag, start_ts);
          copy_moof(s, filename, header_filename, moof_size);
          rename(filename, target_filename);
          add_fragment(os, target_filename, header_filename, start_ts, duration, start_pos, size);
      }
  
      if (c->window_size || (final && c->remove_at_exit)) {
          for (i = 0; i < s->nb_streams; i++) {
              OutputStream *os = &c->streams[i];
              int j;
              int remove = os->nb_fragments - c->window_size - c->extra_window_size - c->lookahead_count;
              if (final && c->remove_at_exit)
                  remove = os->nb_fragments;
              if (remove > 0) {
                  for (j = 0; j < remove; j++) {
                      unlink(os->fragments[j]->file);
                      unlink(os->fragments[j]->infofile);
                      av_free(os->fragments[j]);
                  }
                  os->nb_fragments -= remove;
                  memmove(os->fragments, os->fragments + remove, os->nb_fragments * sizeof(*os->fragments));
              }
              if (final && c->remove_at_exit)
                  rmdir(os->dirname);
          }
      }
  
      if (ret >= 0)
          ret = write_manifest(s, final);
      return ret;
  }
  
  static int ism_write_packet(AVFormatContext *s, AVPacket *pkt)
  {
      SmoothStreamingContext *c = s->priv_data;
      AVStream *st = s->streams[pkt->stream_index];
      OutputStream *os = &c->streams[pkt->stream_index];
      int64_t end_dts = (c->nb_fragments + LLN(1)) * c->min_frag_duration;
      int ret;
  
      if (st->first_dts == AV_NOPTS_VALUE)
          st->first_dts = pkt->dts;
  
  	if ((!c->has_video || st->codec->codec_type == AVMEDIA_TYPE_VIDEO) &&
          av_compare_ts(pkt->dts - st->first_dts, st->time_base,
                        end_dts, AV_TIME_BASE_Q) >= 0 &&
          pkt->flags & AV_PKT_FLAG_KEY && os->packets_written) {
  
          if ((ret = ism_flush(s, 0)) < 0)
              return ret;
          c->nb_fragments++;
      }
  
      os->packets_written++;
      return ff_write_chained(os->ctx, 0, pkt, s, 0);
  }
  
  static int ism_write_trailer(AVFormatContext *s)
  {
      SmoothStreamingContext *c = s->priv_data;
      ism_flush(s, 1);
  
      if (c->remove_at_exit) {
          char filename[1024];
          snprintf(filename, sizeof(filename), "%s/Manifest", s->filename);
          unlink(filename);
          rmdir(s->filename);
      }
  
      ism_free(s);
      return 0;
  }
  
  #define OFFSET(x) offsetof(SmoothStreamingContext, x)
  #define E AV_OPT_FLAG_ENCODING_PARAM
  static const AVOption options[] = {
  	{ "window_size", "number of fragments kept in the manifest", OFFSET(window_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, E },
      { "extra_window_size", "number of fragments kept outside of the manifest before removing from disk", OFFSET(extra_window_size), AV_OPT_TYPE_INT, { .i64 = 5 }, 0, INT_MAX, E },
      { "lookahead_count", "number of lookahead fragments", OFFSET(lookahead_count), AV_OPT_TYPE_INT, { .i64 = 2 }, 0, INT_MAX, E },
      { "min_frag_duration", "minimum fragment duration (in microseconds)", OFFSET(min_frag_duration), AV_OPT_TYPE_INT64, { .i64 = 5000000 }, 0, INT_MAX, E },
      { "remove_at_exit", "remove all fragments when finished", OFFSET(remove_at_exit), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
  	{ NULL },
  };
  
  static const AVClass ism_class = {
  	.class_name = "smooth streaming muxer",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  AVOutputFormat ff_smoothstreaming_muxer = {
  	.name           = "smoothstreaming",
      .long_name      = NULL_IF_CONFIG_SMALL("Smooth Streaming Muxer"),
      .priv_data_size = sizeof(SmoothStreamingContext),
      .audio_codec    = AV_CODEC_ID_AAC,
      .video_codec    = AV_CODEC_ID_H264,
      .flags          = AVFMT_GLOBALHEADER | AVFMT_NOFILE,
      .write_header   = ism_write_header,
      .write_packet   = ism_write_packet,
      .write_trailer  = ism_write_trailer,
      .codec_tag      = (const AVCodecTag* const []){ ff_mp4_obj_type, 0 },
      .priv_class     = &ism_class,
  };
  