DASH Media Packaging SDK
 All Classes Namespaces Functions Variables Typedefs Enumerations Enumerator
packager_main.cc
1 // Copyright 2014 Google Inc. All rights reserved.
2 //
3 // Use of this source code is governed by a BSD-style
4 // license that can be found in the LICENSE file or at
5 // https://developers.google.com/open-source/licenses/bsd
6 
7 #include <gflags/gflags.h>
8 #include <iostream>
9 
10 #include "packager/app/fixed_key_encryption_flags.h"
11 #include "packager/app/hls_flags.h"
12 #include "packager/app/libcrypto_threading.h"
13 #include "packager/app/mpd_flags.h"
14 #include "packager/app/muxer_flags.h"
15 #include "packager/app/packager_util.h"
16 #include "packager/app/stream_descriptor.h"
17 #include "packager/app/vlog_flags.h"
18 #include "packager/app/widevine_encryption_flags.h"
19 #include "packager/base/at_exit.h"
20 #include "packager/base/command_line.h"
21 #include "packager/base/files/file_path.h"
22 #include "packager/base/logging.h"
23 #include "packager/base/path_service.h"
24 #include "packager/base/stl_util.h"
25 #include "packager/base/strings/string_split.h"
26 #include "packager/base/strings/stringprintf.h"
27 #include "packager/base/threading/simple_thread.h"
28 #include "packager/base/time/clock.h"
29 #include "packager/hls/base/hls_notifier.h"
30 #include "packager/hls/base/simple_hls_notifier.h"
31 #include "packager/media/base/container_names.h"
32 #include "packager/media/base/demuxer.h"
33 #include "packager/media/base/fourccs.h"
34 #include "packager/media/base/key_source.h"
35 #include "packager/media/base/muxer_options.h"
36 #include "packager/media/base/muxer_util.h"
37 #include "packager/media/event/hls_notify_muxer_listener.h"
38 #include "packager/media/event/mpd_notify_muxer_listener.h"
39 #include "packager/media/event/vod_media_info_dump_muxer_listener.h"
40 #include "packager/media/file/file.h"
41 #include "packager/media/formats/mp2t/ts_muxer.h"
42 #include "packager/media/formats/mp4/mp4_muxer.h"
43 #include "packager/media/formats/webm/webm_muxer.h"
44 #include "packager/mpd/base/dash_iop_mpd_notifier.h"
45 #include "packager/mpd/base/media_info.pb.h"
46 #include "packager/mpd/base/mpd_builder.h"
47 #include "packager/mpd/base/simple_mpd_notifier.h"
48 #include "packager/version/version.h"
49 
50 #if defined(OS_WIN)
51 #include <codecvt>
52 #include <functional>
53 #include <locale>
54 #endif // defined(OS_WIN)
55 
56 DEFINE_bool(use_fake_clock_for_muxer,
57  false,
58  "Set to true to use a fake clock for muxer. With this flag set, "
59  "creation time and modification time in outputs are set to 0. "
60  "Should only be used for testing.");
61 DEFINE_bool(override_version,
62  false,
63  "Override packager version in the generated outputs with "
64  "--test_version if it is set to true. Should be used for "
65  "testing only.");
66 DEFINE_string(test_version,
67  "",
68  "Packager version for testing. Ignored if --override_version is "
69  "false. Should be used for testing only.");
70 
71 namespace shaka {
72 namespace media {
73 namespace {
74 
75 const char kUsage[] =
76  "Packager driver program. Usage:\n\n"
77  "%s [flags] <stream_descriptor> ...\n"
78  "stream_descriptor consists of comma separated field_name/value pairs:\n"
79  "field_name=value,[field_name=value,]...\n"
80  "Supported field names are as follows:\n"
81  " - input (in): Required input/source media file path or network stream\n"
82  " URL.\n"
83  " - stream_selector (stream): Required field with value 'audio',\n"
84  " 'video', or stream number (zero based).\n"
85  " - output (out): Required output file (single file) or initialization\n"
86  " file path (multiple file).\n"
87  " - segment_template (segment): Optional value which specifies the\n"
88  " naming pattern for the segment files, and that the stream should be\n"
89  " split into multiple files. Its presence should be consistent across\n"
90  " streams.\n"
91  " - bandwidth (bw): Optional value which contains a user-specified\n"
92  " content bit rate for the stream, in bits/sec. If specified, this\n"
93  " value is propagated to the $Bandwidth$ template parameter for\n"
94  " segment names. If not specified, its value may be estimated.\n"
95  " - language (lang): Optional value which contains a user-specified\n"
96  " language tag. If specified, this value overrides any language\n"
97  " metadata in the input track.\n"
98  " - output_format (format): Optional value which specifies the format\n"
99  " of the output files (MP4 or WebM). If not specified, it will be\n"
100  " derived from the file extension of the output file.\n"
101  " - hls_name: Required for audio when outputting HLS.\n"
102  " name of the output stream. This is not (necessarily) the same as\n"
103  " output. This is used as the NAME attribute for EXT-X-MEDIA\n"
104  " - hls_group_id: Required for audio when outputting HLS.\n"
105  " The group ID for the output stream. For HLS this is used as the\n"
106  " GROUP-ID attribute for EXT-X-MEDIA.\n"
107  " - playlist_name: Required for HLS output.\n"
108  " Name of the playlist for the stream. Usually ends with '.m3u8'.\n";
109 
110 const char kMediaInfoSuffix[] = ".media_info";
111 
112 enum ExitStatus {
113  kSuccess = 0,
114  kArgumentValidationFailed,
115  kPackagingFailed,
116  kInternalError,
117 };
118 
119 // TODO(rkuroiwa): Write TTML and WebVTT parser (demuxing) for a better check
120 // and for supporting live/segmenting (muxing). With a demuxer and a muxer,
121 // CreateRemuxJobs() shouldn't treat text as a special case.
122 std::string DetermineTextFileFormat(const std::string& file) {
123  std::string content;
124  if (!File::ReadFileToString(file.c_str(), &content)) {
125  LOG(ERROR) << "Failed to open file " << file
126  << " to determine file format.";
127  return "";
128  }
129  MediaContainerName container_name = DetermineContainer(
130  reinterpret_cast<const uint8_t*>(content.data()), content.size());
131  if (container_name == CONTAINER_WEBVTT) {
132  return "vtt";
133  } else if (container_name == CONTAINER_TTML) {
134  return "ttml";
135  }
136 
137  return "";
138 }
139 
140 FourCC GetProtectionScheme(const std::string& protection_scheme) {
141  if (protection_scheme == "cenc") {
142  return FOURCC_cenc;
143  } else if (protection_scheme == "cens") {
144  return FOURCC_cens;
145  } else if (protection_scheme == "cbc1") {
146  return FOURCC_cbc1;
147  } else if (protection_scheme == "cbcs") {
148  return FOURCC_cbcs;
149  } else {
150  LOG(ERROR) << "Unknown protection scheme: " << protection_scheme;
151  return FOURCC_NULL;
152  }
153 }
154 
155 } // namespace
156 
157 // A fake clock that always return time 0 (epoch). Should only be used for
158 // testing.
159 class FakeClock : public base::Clock {
160  public:
161  base::Time Now() override { return base::Time(); }
162 };
163 
164 // Demux, Mux(es) and worker thread used to remux a source file/stream.
165 class RemuxJob : public base::SimpleThread {
166  public:
167  RemuxJob(std::unique_ptr<Demuxer> demuxer)
168  : SimpleThread("RemuxJob"), demuxer_(std::move(demuxer)) {}
169 
170  ~RemuxJob() override {
171  STLDeleteElements(&muxers_);
172  }
173 
174  void AddMuxer(std::unique_ptr<Muxer> mux) {
175  muxers_.push_back(mux.release());
176  }
177 
178  Demuxer* demuxer() { return demuxer_.get(); }
179  Status status() { return status_; }
180 
181  private:
182  void Run() override {
183  DCHECK(demuxer_);
184  status_ = demuxer_->Run();
185  }
186 
187  std::unique_ptr<Demuxer> demuxer_;
188  std::vector<Muxer*> muxers_;
189  Status status_;
190 
191  DISALLOW_COPY_AND_ASSIGN(RemuxJob);
192 };
193 
194 bool StreamInfoToTextMediaInfo(const StreamDescriptor& stream_descriptor,
195  const MuxerOptions& stream_muxer_options,
196  MediaInfo* text_media_info) {
197  const std::string& language = stream_descriptor.language;
198  std::string format = DetermineTextFileFormat(stream_descriptor.input);
199  if (format.empty()) {
200  LOG(ERROR) << "Failed to determine the text file format for "
201  << stream_descriptor.input;
202  return false;
203  }
204 
205  if (!File::Copy(stream_descriptor.input.c_str(),
206  stream_muxer_options.output_file_name.c_str())) {
207  LOG(ERROR) << "Failed to copy the input file (" << stream_descriptor.input
208  << ") to output file (" << stream_muxer_options.output_file_name
209  << ").";
210  return false;
211  }
212 
213  text_media_info->set_media_file_name(stream_muxer_options.output_file_name);
214  text_media_info->set_container_type(MediaInfo::CONTAINER_TEXT);
215 
216  if (stream_muxer_options.bandwidth != 0) {
217  text_media_info->set_bandwidth(stream_muxer_options.bandwidth);
218  } else {
219  // Text files are usually small and since the input is one file; there's no
220  // way for the player to do ranged requests. So set this value to something
221  // reasonable.
222  text_media_info->set_bandwidth(256);
223  }
224 
225  MediaInfo::TextInfo* text_info = text_media_info->mutable_text_info();
226  text_info->set_format(format);
227  if (!language.empty())
228  text_info->set_language(language);
229 
230  return true;
231 }
232 
233 std::unique_ptr<Muxer> CreateOutputMuxer(const MuxerOptions& options,
234  MediaContainerName container) {
235  if (container == CONTAINER_WEBM) {
236  return std::unique_ptr<Muxer>(new webm::WebMMuxer(options));
237  } else if (container == CONTAINER_MPEG2TS) {
238  return std::unique_ptr<Muxer>(new mp2t::TsMuxer(options));
239  } else {
240  DCHECK_EQ(container, CONTAINER_MOV);
241  return std::unique_ptr<Muxer>(new mp4::MP4Muxer(options));
242  }
243 }
244 
245 bool CreateRemuxJobs(const StreamDescriptorList& stream_descriptors,
246  const MuxerOptions& muxer_options,
247  FakeClock* fake_clock,
248  KeySource* key_source,
249  MpdNotifier* mpd_notifier,
250  hls::HlsNotifier* hls_notifier,
251  std::vector<RemuxJob*>* remux_jobs) {
252  // No notifiers OR (mpd_notifier XOR hls_notifier); which is NAND.
253  DCHECK(!(mpd_notifier && hls_notifier));
254  DCHECK(remux_jobs);
255 
256  std::string previous_input;
257  int stream_number = 0;
258  for (StreamDescriptorList::const_iterator
259  stream_iter = stream_descriptors.begin();
260  stream_iter != stream_descriptors.end();
261  ++stream_iter, ++stream_number) {
262  // Process stream descriptor.
263  MuxerOptions stream_muxer_options(muxer_options);
264  stream_muxer_options.output_file_name = stream_iter->output;
265  if (!stream_iter->segment_template.empty()) {
266  if (!ValidateSegmentTemplate(stream_iter->segment_template)) {
267  LOG(ERROR) << "ERROR: segment template with '"
268  << stream_iter->segment_template << "' is invalid.";
269  return false;
270  }
271  stream_muxer_options.segment_template = stream_iter->segment_template;
272  if (stream_muxer_options.single_segment) {
273  LOG(WARNING) << "Segment template and single segment are incompatible, "
274  "setting single segment to false.";
275  stream_muxer_options.single_segment = false;
276  }
277  }
278  stream_muxer_options.bandwidth = stream_iter->bandwidth;
279 
280  // Handle text input.
281  if (stream_iter->stream_selector == "text") {
282  MediaInfo text_media_info;
283  if (!StreamInfoToTextMediaInfo(*stream_iter, stream_muxer_options,
284  &text_media_info)) {
285  return false;
286  }
287 
288  if (mpd_notifier) {
289  uint32 unused;
290  if (!mpd_notifier->NotifyNewContainer(text_media_info, &unused)) {
291  LOG(ERROR) << "Failed to process text file " << stream_iter->input;
292  } else {
293  mpd_notifier->Flush();
294  }
295  } else if (FLAGS_output_media_info) {
297  text_media_info,
298  stream_muxer_options.output_file_name + kMediaInfoSuffix);
299  } else {
300  NOTIMPLEMENTED()
301  << "--mpd_output or --output_media_info flags are "
302  "required for text output. Skipping manifest related output for "
303  << stream_iter->input;
304  }
305  continue;
306  }
307 
308  if (stream_iter->input != previous_input) {
309  // New remux job needed. Create demux and job thread.
310  std::unique_ptr<Demuxer> demuxer(new Demuxer(stream_iter->input));
311  if (FLAGS_enable_widevine_decryption ||
312  FLAGS_enable_fixed_key_decryption) {
313  std::unique_ptr<KeySource> key_source(CreateDecryptionKeySource());
314  if (!key_source)
315  return false;
316  demuxer->SetKeySource(std::move(key_source));
317  }
318  Status status = demuxer->Initialize();
319  if (!status.ok()) {
320  LOG(ERROR) << "Demuxer failed to initialize: " << status.ToString();
321  return false;
322  }
323  if (FLAGS_dump_stream_info) {
324  printf("\nFile \"%s\":\n", stream_iter->input.c_str());
325  DumpStreamInfo(demuxer->streams());
326  if (stream_iter->output.empty())
327  continue; // just need stream info.
328  }
329  remux_jobs->push_back(new RemuxJob(std::move(demuxer)));
330  previous_input = stream_iter->input;
331  }
332  DCHECK(!remux_jobs->empty());
333 
334  std::unique_ptr<Muxer> muxer(
335  CreateOutputMuxer(stream_muxer_options, stream_iter->output_format));
336  if (FLAGS_use_fake_clock_for_muxer) muxer->set_clock(fake_clock);
337 
338  if (key_source) {
339  muxer->SetKeySource(key_source,
340  FLAGS_max_sd_pixels,
341  FLAGS_clear_lead,
342  FLAGS_crypto_period_duration,
343  GetProtectionScheme(FLAGS_protection_scheme));
344  }
345 
346  std::unique_ptr<MuxerListener> muxer_listener;
347  DCHECK(!(FLAGS_output_media_info && mpd_notifier));
348  if (FLAGS_output_media_info) {
349  const std::string output_media_info_file_name =
350  stream_muxer_options.output_file_name + kMediaInfoSuffix;
351  std::unique_ptr<VodMediaInfoDumpMuxerListener>
352  vod_media_info_dump_muxer_listener(
353  new VodMediaInfoDumpMuxerListener(output_media_info_file_name));
354  muxer_listener = std::move(vod_media_info_dump_muxer_listener);
355  }
356  if (mpd_notifier) {
357  std::unique_ptr<MpdNotifyMuxerListener> mpd_notify_muxer_listener(
358  new MpdNotifyMuxerListener(mpd_notifier));
359  muxer_listener = std::move(mpd_notify_muxer_listener);
360  }
361 
362  if (hls_notifier) {
363  // TODO(rkuroiwa): Do some smart stuff to group the audios, e.g. detect
364  // languages.
365  std::string group_id = stream_iter->hls_group_id;
366  std::string name = stream_iter->hls_name;
367  std::string hls_playlist_name = stream_iter->hls_playlist_name;
368  if (group_id.empty())
369  group_id = "audio";
370  if (name.empty())
371  name = base::StringPrintf("stream_%d", stream_number);
372  if (hls_playlist_name.empty())
373  hls_playlist_name = base::StringPrintf("stream_%d.m3u8", stream_number);
374 
375  muxer_listener.reset(new HlsNotifyMuxerListener(hls_playlist_name, name,
376  group_id, hls_notifier));
377  }
378 
379  if (muxer_listener)
380  muxer->SetMuxerListener(std::move(muxer_listener));
381 
382  if (!AddStreamToMuxer(remux_jobs->back()->demuxer()->streams(),
383  stream_iter->stream_selector,
384  stream_iter->language,
385  muxer.get())) {
386  return false;
387  }
388  remux_jobs->back()->AddMuxer(std::move(muxer));
389  }
390 
391  return true;
392 }
393 
394 Status RunRemuxJobs(const std::vector<RemuxJob*>& remux_jobs) {
395  // Start the job threads.
396  for (std::vector<RemuxJob*>::const_iterator job_iter = remux_jobs.begin();
397  job_iter != remux_jobs.end();
398  ++job_iter) {
399  (*job_iter)->Start();
400  }
401 
402  // Wait for all jobs to complete or an error occurs.
403  Status status;
404  bool all_joined;
405  do {
406  all_joined = true;
407  for (std::vector<RemuxJob*>::const_iterator job_iter = remux_jobs.begin();
408  job_iter != remux_jobs.end();
409  ++job_iter) {
410  if ((*job_iter)->HasBeenJoined()) {
411  status = (*job_iter)->status();
412  if (!status.ok())
413  break;
414  } else {
415  all_joined = false;
416  (*job_iter)->Join();
417  }
418  }
419  } while (!all_joined && status.ok());
420 
421  return status;
422 }
423 
424 bool RunPackager(const StreamDescriptorList& stream_descriptors) {
425  const FourCC protection_scheme = GetProtectionScheme(FLAGS_protection_scheme);
426  if (protection_scheme == FOURCC_NULL)
427  return false;
428 
429  if (!AssignFlagsFromProfile())
430  return false;
431 
432  if (FLAGS_output_media_info && !FLAGS_mpd_output.empty()) {
433  NOTIMPLEMENTED() << "ERROR: --output_media_info and --mpd_output do not "
434  "work together.";
435  return false;
436  }
437  if (FLAGS_output_media_info && !FLAGS_single_segment) {
438  // TODO(rkuroiwa, kqyang): Support partial media info dump for live.
439  NOTIMPLEMENTED() << "ERROR: --output_media_info is only supported if "
440  "--single_segment is true.";
441  return false;
442  }
443 
444  // Since there isn't a muxer listener that can output both MPD and HLS,
445  // disallow specifying both MPD and HLS flags.
446  if (!FLAGS_mpd_output.empty() && !FLAGS_hls_master_playlist_output.empty()) {
447  LOG(ERROR) << "Cannot output both MPD and HLS.";
448  return false;
449  }
450 
451  // Get basic muxer options.
452  MuxerOptions muxer_options;
453  if (!GetMuxerOptions(&muxer_options))
454  return false;
455 
456  MpdOptions mpd_options;
457  if (!GetMpdOptions(&mpd_options))
458  return false;
459 
460  // Create encryption key source if needed.
461  std::unique_ptr<KeySource> encryption_key_source;
462  if (FLAGS_enable_widevine_encryption || FLAGS_enable_fixed_key_encryption) {
463  encryption_key_source = CreateEncryptionKeySource();
464  if (!encryption_key_source)
465  return false;
466  }
467 
468  std::unique_ptr<MpdNotifier> mpd_notifier;
469  if (!FLAGS_mpd_output.empty()) {
470  DashProfile profile =
471  FLAGS_single_segment ? kOnDemandProfile : kLiveProfile;
472  std::vector<std::string> base_urls;
473  base::SplitString(FLAGS_base_urls, ',', &base_urls);
474  if (FLAGS_generate_dash_if_iop_compliant_mpd) {
475  mpd_notifier.reset(new DashIopMpdNotifier(profile, mpd_options, base_urls,
476  FLAGS_mpd_output));
477  } else {
478  mpd_notifier.reset(new SimpleMpdNotifier(profile, mpd_options, base_urls,
479  FLAGS_mpd_output));
480  }
481  if (!mpd_notifier->Init()) {
482  LOG(ERROR) << "MpdNotifier failed to initialize.";
483  return false;
484  }
485  }
486 
487  std::unique_ptr<hls::HlsNotifier> hls_notifier;
488  if (!FLAGS_hls_master_playlist_output.empty()) {
489  base::FilePath master_playlist_path(
490  base::FilePath::FromUTF8Unsafe(FLAGS_hls_master_playlist_output));
491  base::FilePath master_playlist_name = master_playlist_path.BaseName();
492 
493  hls_notifier.reset(new hls::SimpleHlsNotifier(
494  hls::HlsNotifier::HlsProfile::kOnDemandProfile, FLAGS_hls_base_url,
495  master_playlist_path.DirName().AsEndingWithSeparator().AsUTF8Unsafe(),
496  master_playlist_name.AsUTF8Unsafe()));
497  }
498 
499  std::vector<RemuxJob*> remux_jobs;
500  STLElementDeleter<std::vector<RemuxJob*> > scoped_jobs_deleter(&remux_jobs);
501  FakeClock fake_clock;
502  if (!CreateRemuxJobs(stream_descriptors, muxer_options, &fake_clock,
503  encryption_key_source.get(), mpd_notifier.get(),
504  hls_notifier.get(), &remux_jobs)) {
505  return false;
506  }
507 
508  Status status = RunRemuxJobs(remux_jobs);
509  if (!status.ok()) {
510  LOG(ERROR) << "Packaging Error: " << status.ToString();
511  return false;
512  }
513 
514  if (hls_notifier) {
515  if (!hls_notifier->Flush())
516  return false;
517  }
518  if (mpd_notifier) {
519  if (!mpd_notifier->Flush())
520  return false;
521  }
522 
523  printf("Packaging completed successfully.\n");
524  return true;
525 }
526 
527 int PackagerMain(int argc, char** argv) {
528  base::AtExitManager exit;
529  // Needed to enable VLOG/DVLOG through --vmodule or --v.
530  base::CommandLine::Init(argc, argv);
531 
532  // Set up logging.
533  logging::LoggingSettings log_settings;
534  base::FilePath log_filename;
535  PathService::Get(base::DIR_EXE, &log_filename);
536  log_filename = log_filename.AppendASCII("packager.log");
537  log_settings.logging_dest = logging::LOG_TO_ALL;
538  log_settings.log_file = log_filename.value().c_str();
539  log_settings.delete_old = logging::DELETE_OLD_LOG_FILE;
540  CHECK(logging::InitLogging(log_settings));
541 
542  google::SetUsageMessage(base::StringPrintf(kUsage, argv[0]));
543  google::ParseCommandLineFlags(&argc, &argv, true);
544  if (argc < 2) {
545  const std::string version_string = base::StringPrintf(
546  "shaka-packager version %s", GetPackagerVersion().c_str());
547  google::ShowUsageWithFlags(version_string.c_str());
548  return kSuccess;
549  }
550 
552  return kArgumentValidationFailed;
553 
554  if (FLAGS_override_version)
555  SetPackagerVersionForTesting(FLAGS_test_version);
556 
557  LibcryptoThreading libcrypto_threading;
558  // TODO(tinskip): Make InsertStreamDescriptor a member of
559  // StreamDescriptorList.
560  StreamDescriptorList stream_descriptors;
561  for (int i = 1; i < argc; ++i) {
562  if (!InsertStreamDescriptor(argv[i], &stream_descriptors))
563  return kArgumentValidationFailed;
564  }
565  return RunPackager(stream_descriptors) ? kSuccess : kPackagingFailed;
566 }
567 
568 } // namespace media
569 } // namespace shaka
570 
571 #if defined(OS_WIN)
572 // Windows wmain, which converts wide character arguments to UTF-8.
573 int wmain(int argc, wchar_t* argv[], wchar_t* envp[]) {
574  std::unique_ptr<char* [], std::function<void(char**)>> utf8_argv(
575  new char*[argc], [argc](char** utf8_args) {
576  // TODO(tinskip): This leaks, but if this code is enabled, it crashes.
577  // Figure out why. I suspect gflags does something funny with the
578  // argument array.
579  // for (int idx = 0; idx < argc; ++idx)
580  // delete[] utf8_args[idx];
581  delete[] utf8_args;
582  });
583  std::wstring_convert<std::codecvt_utf8<wchar_t>> converter;
584  for (int idx = 0; idx < argc; ++idx) {
585  std::string utf8_arg(converter.to_bytes(argv[idx]));
586  utf8_arg += '\0';
587  utf8_argv[idx] = new char[utf8_arg.size()];
588  memcpy(utf8_argv[idx], &utf8_arg[0], utf8_arg.size());
589  }
590  return shaka::media::PackagerMain(argc, utf8_argv.get());
591 }
592 #else
593 int main(int argc, char** argv) {
594  return shaka::media::PackagerMain(argc, argv);
595 }
596 #endif // defined(OS_WIN)
static bool Copy(const char *from_file_name, const char *to_file_name)
Definition: file.cc:204
bool ValidateWidevineCryptoFlags()
static bool WriteMediaInfoToFile(const MediaInfo &media_info, const std::string &output_file_path)
static bool ReadFileToString(const char *file_name, std::string *contents)
Definition: file.cc:186
bool ValidateFixedCryptoFlags()