sample_muxer: added WebVTT support

Change-Id: If72d31ca4828adf39e4637003979a314e5dda98e

sample_muxer_metadata.cc

@@ -0,0 +1,236 @@
+#include "sample_muxer_metadata.h"
+#include <string>
+#include "vttreader.h"
+
+using std::string;
+
+SampleMuxerMetadata::SampleMuxerMetadata() : segment_(NULL) {
+}
+
+void SampleMuxerMetadata::Init(mkvmuxer::Segment* s) {
+  segment_ = s;
+}
+
+bool SampleMuxerMetadata::Load(const char* file, Kind kind) {
+  mkvmuxer::uint64 track_num;
+
+  if (!AddTrack(kind, &track_num)) {
+    printf("Unable to add track for WebVTT file \"%s\"\n", file);
+    return false;
+  }
+
+  return Parse(file, kind, track_num);
+}
+
+bool SampleMuxerMetadata::Write(mkvmuxer::int64 time_ns) {
+  typedef cues_set_t::iterator iter_t;
+
+  iter_t i = cues_set_.begin();
+  const iter_t j = cues_set_.end();
+
+  while (i != j) {
+    const cues_set_t::value_type& v = *i;
+
+    if (time_ns >= 0 && v > time_ns)
+      return true;  // nothing else to do just yet
+
+    if (!v.Write(segment_)) {
+      printf("\nCould not add metadata.\n");
+      return false;  // error
+    }
+
+    cues_set_.erase(i++);
+  }
+
+  return true;
+}
+
+bool SampleMuxerMetadata::AddTrack(
+    Kind kind,
+    mkvmuxer::uint64* track_num) {
+  *track_num = 0;
+
+  // Track number value 0 means "let muxer choose track number"
+  mkvmuxer::Track* const track = segment_->AddTrack(0);
+
+  if (track == NULL)  // error
+    return false;
+
+  // Return the track number value chosen by the muxer
+  *track_num = track->number();
+
+  int type;
+  const char* codec_id;
+
+  switch (kind) {
+  case kSubtitles:
+    type = 0x11;
+    codec_id = "D_WEBVTT/SUBTITLES";
+    break;
+
+  case kCaptions:
+    type = 0x11;
+    codec_id = "D_WEBVTT/CAPTIONS";
+    break;
+
+  case kDescriptions:
+    type = 0x21;
+    codec_id = "D_WEBVTT/DESCRIPTIONS";
+    break;
+
+  case kMetadata:
+    type = 0x21;
+    codec_id = "D_WEBVTT/METADATA";
+    break;
+
+  default:
+    return false;
+  }
+
+  track->set_type(type);
+  track->set_codec_id(codec_id);
+
+  // TODO(matthewjheaney): set name and language
+
+  return true;
+}
+
+bool SampleMuxerMetadata::Parse(
+    const char* file,
+    Kind /* kind */,
+    mkvmuxer::uint64 track_num) {
+  libwebvtt::VttReader r;
+  int e = r.Open(file);
+
+  if (e) {
+    printf("Unable to open WebVTT file: \"%s\"\n", file);
+    return false;
+  }
+
+  libwebvtt::Parser p(&r);
+
+  e = p.Init();
+
+  if (e < 0) {  // error
+    printf("Error parsing WebVTT file: \"%s\"\n", file);
+    return false;
+  }
+
+  SortableCue cue;
+  cue.track_num = track_num;
+
+  libwebvtt::Time t;
+  t.hours = -1;
+
+  for (;;) {
+    cue_t& c = cue.cue;
+    e = p.Parse(&c);
+
+    if (e < 0) {  // error
+      printf("Error parsing WebVTT file: \"%s\"\n", file);
+      return false;
+    }
+
+    if (e > 0)  // EOF
+      return true;
+
+    if (c.start_time >= t) {
+      t = c.start_time;
+    } else {
+      printf("bad WebVTT cue timestamp (out-of-order)\n");
+      return false;
+    }
+
+    if (c.stop_time < c.start_time) {
+      printf("bad WebVTT cue timestamp (stop < start)\n");
+      return false;
+    }
+
+    cues_set_.insert(cue);
+  }
+}
+
+void SampleMuxerMetadata::MakeFrame(const cue_t& c, string* pf) {
+  pf->clear();
+  WriteCueIdentifier(c.identifier, pf);
+  WriteCueSettings(c.settings, pf);
+  WriteCuePayload(c.payload, pf);
+}
+
+void SampleMuxerMetadata::WriteCueIdentifier(
+    const string& identifier,
+    string* pf) {
+  pf->append(identifier);
+  pf->push_back('\x0A');  // LF
+}
+
+void SampleMuxerMetadata::WriteCueSettings(
+    const cue_t::settings_t& settings,
+    string* pf) {
+  if (settings.empty()) {
+    pf->push_back('\x0A');  // LF
+    return;
+  }
+
+  typedef cue_t::settings_t::const_iterator iter_t;
+
+  iter_t i = settings.begin();
+  const iter_t j = settings.end();
+
+  for (;;) {
+    const libwebvtt::Setting& setting = *i++;
+
+    pf->append(setting.name);
+    pf->push_back(':');
+    pf->append(setting.value);
+
+    if (i == j)
+      break;
+
+    pf->push_back(' ');  // separate settings with whitespace
+  }
+
+  pf->push_back('\x0A');  // LF
+}
+
+void SampleMuxerMetadata::WriteCuePayload(
+    const cue_t::payload_t& payload,
+    string* pf) {
+  typedef cue_t::payload_t::const_iterator iter_t;
+
+  iter_t i = payload.begin();
+  const iter_t j = payload.end();
+
+  while (i != j) {
+    const string& line = *i++;
+    pf->append(line);
+    pf->push_back('\x0A');  // LF
+  }
+}
+
+bool SampleMuxerMetadata::SortableCue::Write(
+    mkvmuxer::Segment* segment) const {
+  // Cue start time expressed in milliseconds
+  const mkvmuxer::int64 start_ms = cue.start_time.presentation();
+
+  // Cue start time expressed in nanoseconds (MKV time)
+  const mkvmuxer::int64 start_ns = start_ms * 1000000;
+
+  // Cue stop time expressed in milliseconds
+  const mkvmuxer::int64 stop_ms = cue.stop_time.presentation();
+
+  // Cue stop time expressed in nanonseconds
+  const mkvmuxer::int64 stop_ns = stop_ms * 1000000;
+
+  // Metadata blocks always specify the block duration.
+  const mkvmuxer::int64 duration_ns = stop_ns - start_ns;
+
+  string frame;
+  MakeFrame(cue, &frame);
+
+  typedef const mkvmuxer::uint8* data_t;
+  const data_t buf = reinterpret_cast<data_t>(frame.data());
+  const mkvmuxer::uint64 len = frame.length();
+
+  return segment->AddMetadata(buf, len, track_num, start_ns, duration_ns);
+}