Add two demos which exercise the audio server.

examples/audio_play_test/play_wav.cc

Index: examples/audio_play_test/play_wav.cc
diff --git a/examples/audio_play_test/play_wav.cc b/examples/audio_play_test/play_wav.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d4706b02c6ae74464e954831d0b4f0d6b6c4349b
--- /dev/null
+++ b/examples/audio_play_test/play_wav.cc
@@ -0,0 +1,568 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <memory>
+
+#include "mojo/public/c/system/main.h"
+#include "mojo/public/cpp/application/application_delegate.h"
+#include "mojo/public/cpp/application/application_impl.h"
+#include "mojo/public/cpp/application/application_runner.h"
+#include "mojo/public/cpp/system/data_pipe.h"
+#include "mojo/public/cpp/utility/run_loop.h"
+#include "mojo/services/media/audio/interfaces/audio_server.mojom.h"
+#include "mojo/services/media/audio/interfaces/audio_track.mojom.h"
+#include "mojo/services/media/common/cpp/circular_buffer_media_pipe_adapter.h"
+#include "mojo/services/media/common/cpp/linear_transform.h"
+#include "mojo/services/media/common/cpp/local_time.h"
+#include "mojo/services/network/interfaces/network_service.mojom.h"
+#include "mojo/services/network/interfaces/url_loader.mojom.h"
+
+#define PACKED __attribute__((packed))
+
+static inline constexpr uint32_t make_fourcc(uint8_t a, uint8_t b,
+                                             uint8_t c, uint8_t d) {
+  return (static_cast<uint32_t>(a) << 24) |
+         (static_cast<uint32_t>(b) << 16) |
+         (static_cast<uint32_t>(c) << 8)  |
+          static_cast<uint32_t>(d);
+}
+
+static inline constexpr uint32_t fetch_fourcc(const void* source) {
+  return (static_cast<uint32_t>(static_cast<const uint8_t*>(source)[0]) << 24) |
+         (static_cast<uint32_t>(static_cast<const uint8_t*>(source)[1]) << 16) |
+         (static_cast<uint32_t>(static_cast<const uint8_t*>(source)[2]) << 8) |
+          static_cast<uint32_t>(static_cast<const uint8_t*>(source)[3]);
+}
+
+namespace mojo {
+namespace media {
+namespace audio {
+namespace examples {
+
+static constexpr const char* TEST_FILE =
+  "http://localhost/test_content/piano2.wav";
+static constexpr uint32_t BUF_DEPTH_USEC    = 500000;
+static constexpr uint32_t BUF_LO_WATER_USEC = 400000;
+static constexpr uint32_t BUF_HI_WATER_USEC = 450000;
+static constexpr uint32_t CHUNK_SIZE_USEC   = 10000;
+
+class PlayWAVApp : public ApplicationDelegate {
+ public:
+  ~PlayWAVApp() override { Quit(); }
+
+  // ApplicationDelegate
+  void Initialize(ApplicationImpl* app) override;
+  void Quit() override;
+
+ private:
+  using AudioPipePtr = std::unique_ptr<CircularBufferMediaPipeAdapter>;
+  using AudioPacket  = CircularBufferMediaPipeAdapter::MappedPacket;
+  using PacketCbk    = MediaPipe::SendPacketCallback;
+
+  // TODO(johngro): endianness!
+  struct PACKED RIFFChunkHeader {
+    uint32_t  four_cc;
+    uint32_t  length;
+  };
+
+  struct PACKED WAVHeader {
+    uint32_t  wave_four_cc;
+    uint32_t  fmt_four_cc;
+    uint32_t  fmt_chunk_len;
+    uint16_t  format;
+    uint16_t  channel_count;
+    uint32_t  frame_rate;
+    uint32_t  average_byte_rate;
+    uint16_t  frame_size;
+    uint16_t  bits_per_sample;
+  };
+
+  // TODO(johngro): as mentioned before... endianness!
+  static constexpr uint32_t RIFF_FOUR_CC = make_fourcc('R', 'I', 'F', 'F');
+  static constexpr uint32_t WAVE_FOUR_CC = make_fourcc('W', 'A', 'V', 'E');
+  static constexpr uint32_t FMT_FOUR_CC  = make_fourcc('f', 'm', 't', ' ');
+  static constexpr uint32_t DATA_FOUR_CC = make_fourcc('d', 'a', 't', 'a');
+
+  static constexpr uint16_t FORMAT_LPCM  = 0x0001;
+  static constexpr uint16_t FORMAT_MULAW = 0x0101;
+  static constexpr uint16_t FORMAT_ALAW  = 0x0102;
+  static constexpr uint16_t FORMAT_ADPCM = 0x0103;
+
+  static const std::set<std::string> VALID_MIME_TYPES;
+  static const std::set<uint16_t>    VALID_FRAME_RATES;
+  static const std::set<uint16_t>    VALID_BITS_PER_SAMPLES;
+
+  bool BlockingRead(void* buf, uint32_t len);
+  void ProcessHTTPResponse(URLResponsePtr resp);
+
+  bool ReadAndValidateRIFFHeader();
+  bool ReadAndValidateWAVHeader();
+  bool ReadAndValidateDATAHeader();
+
+  bool OnNeedsData(MediaResult res);
+  void OnPlayoutComplete(MediaResult res);
+  void OnConnectionError(const std::string& connection_name);
+  void BeginShutdown();
+
+  uint32_t USecToFrames(uint32_t usec) {
+    uint64_t ret = (static_cast<uint64_t>(usec) * wav_info_.frame_rate)
+                 / 1000000;
+    MOJO_DCHECK(ret < std::numeric_limits<uint32_t>::max());
+    return ret;
+  }
+
+  uint32_t USecToBytes(uint32_t usec) {
+    uint32_t frames = USecToFrames(usec);
+
+    MOJO_DCHECK(wav_info_.frame_size);
+    MOJO_DCHECK(frames <
+                std::numeric_limits<uint32_t>::max() / wav_info_.frame_size);
+
+    return frames * wav_info_.frame_size;
+  }
+
+  AudioServerPtr               audio_server_;
+  AudioTrackPtr                audio_track_;
+  AudioPipePtr                 audio_pipe_;
+  RateControlPtr               rate_control_;
+  AudioPacket                  audio_packet_;
+  PacketCbk                    playout_complete_cbk_;
+  NetworkServicePtr            network_service_;
+  URLLoaderPtr                 url_loader_;
+  ScopedDataPipeConsumerHandle payload_;
+  uint32_t                     payload_len_;
+  RIFFChunkHeader              riff_hdr_;
+  WAVHeader                    wav_info_;
+  RIFFChunkHeader              data_hdr_;
+  bool                         sent_first_packet_ = false;
+  bool                         clock_started_     = false;
+  bool                         shutting_down_     = false;
+};
+
+const std::set<std::string> PlayWAVApp::VALID_MIME_TYPES({
+  "audio/x-wav",
+  "audio/wav",
+});
+
+const std::set<uint16_t> PlayWAVApp::VALID_FRAME_RATES({
+  8000, 16000, 24000, 32000, 48000,
+  11025, 22050, 44100,
+});
+
+const std::set<uint16_t> PlayWAVApp::VALID_BITS_PER_SAMPLES({
+  8, 16,
+});
+
+void PlayWAVApp::Initialize(ApplicationImpl* app) {
+  app->ConnectToService("mojo:audio_server", &audio_server_);
+  audio_server_.set_connection_error_handler([this]() {
+    OnConnectionError("audio_server");
+  });
+
+  app->ConnectToService("mojo:network_service", &network_service_);
+  audio_server_.set_connection_error_handler([this]() {
+    OnConnectionError("network_service");
+  });
+
+  network_service_->CreateURLLoader(GetProxy(&url_loader_));
+  url_loader_.set_connection_error_handler([this]() {
+    OnConnectionError("url_loader");
+  });
+
+  playout_complete_cbk_ = PacketCbk([this](MediaResult res) {
+                                      this->OnPlayoutComplete(res);
+                                    });
+
+  URLRequestPtr req(URLRequest::New());
+  req->url    = TEST_FILE;
+  req->method = "GET";
+
+  auto cbk = [this](URLResponsePtr resp) { ProcessHTTPResponse(resp.Pass()); };
+  url_loader_->Start(req.Pass(), URLLoader::StartCallback(cbk));
+}
+
+void PlayWAVApp::Quit() {
+  if (audio_packet_.packet()) {
+    MOJO_DCHECK(audio_pipe_);
+    audio_pipe_->CancelMediaPacket(&audio_packet_);
+  }
+
+  payload_.reset();
+  url_loader_.reset();
+  network_service_.reset();
+  audio_pipe_.reset();
+  rate_control_.reset();
+  audio_track_.reset();
+  audio_server_.reset();
+}
+
+bool PlayWAVApp::BlockingRead(void* buf, uint32_t op_len) {
+  MojoResult res;
+  uint32_t amt;
+
+  while (true) {
+    amt = op_len;
+    res = ReadDataRaw(payload_.get(), buf, &amt,
+                      MOJO_READ_DATA_FLAG_ALL_OR_NONE);
+
+    if ((res == MOJO_RESULT_SHOULD_WAIT) ||
+        (res == MOJO_RESULT_OUT_OF_RANGE)) {
+      Wait(payload_.get(),
+           MOJO_HANDLE_SIGNAL_READABLE,
+           MOJO_DEADLINE_INDEFINITE,
+           nullptr);
+      continue;
+    }
+
+    break;
+  }
+
+  return ((res == MOJO_RESULT_OK) && (amt == op_len));
+}
+
+void PlayWAVApp::ProcessHTTPResponse(URLResponsePtr resp) {
+  if (resp->mime_type.is_null() ||
+     (VALID_MIME_TYPES.find(resp->mime_type) == VALID_MIME_TYPES.end())) {
+    MOJO_LOG(ERROR) << "Bad MimeType \""
+                    << (resp->mime_type.is_null() ? "<null>" : resp->mime_type)
+                    << "\"";
+    BeginShutdown();
+    return;
+  }
+
+  payload_ = resp->body.Pass();
+
+  if (!ReadAndValidateRIFFHeader() ||
+      !ReadAndValidateWAVHeader() ||
+      !ReadAndValidateDATAHeader()) {
+    BeginShutdown();
+    return;
+  }
+
+  MOJO_LOG(INFO) << "Preparing to play...";
+  MOJO_LOG(INFO) << "File : " << TEST_FILE;
+  MOJO_LOG(INFO) << "Rate : " << wav_info_.frame_rate;
+  MOJO_LOG(INFO) << "Chan : " << wav_info_.channel_count;
+  MOJO_LOG(INFO) << "BPS  : " << wav_info_.bits_per_sample;
+
+  // Create the audio sink we will use to play this WAV file and start to
+  // configure it.
+  audio_server_->CreateTrack(GetProxy(&audio_track_));
+
+  LinearTransform::Ratio audio_rate(wav_info_.frame_rate, 1);
+  LinearTransform::Ratio local_rate(LocalDuration::period::num,
+                                    LocalDuration::period::den);
+  LinearTransform::Ratio tmp;
+  bool success = LinearTransform::Ratio::Compose(audio_rate, local_rate, &tmp);
+  MOJO_DCHECK(success);
+
+  AudioTrackConfigurationPtr cfg;
+  cfg = AudioTrackConfiguration::New();
+  cfg->max_frames = USecToFrames(BUF_DEPTH_USEC);
+  cfg->audio_frame_ratio = tmp.numerator;
+  cfg->media_time_ratio  = tmp.denominator;
+
+  LpcmMediaTypeDetailsPtr pcm_cfg = LpcmMediaTypeDetails::New();
+  pcm_cfg->sample_format = (wav_info_.bits_per_sample == 8)
+                         ? LpcmSampleFormat::UNSIGNED_8
+                         : LpcmSampleFormat::SIGNED_16;
+  pcm_cfg->samples_per_frame = wav_info_.channel_count;
+  pcm_cfg->frames_per_second = wav_info_.frame_rate;
+
+  cfg->media_type = MediaType::New();
+  cfg->media_type->scheme = MediaTypeScheme::LPCM;
+  cfg->media_type->details = MediaTypeDetails::New();
+  cfg->media_type->details->set_lpcm(pcm_cfg.Pass());
+
+  // Configure the track based on the WAV header information.
+  MediaPipePtr media_pipe;
+  audio_track_->Configure(cfg.Pass(), GetProxy(&media_pipe),
+      [this](MediaResult res) {
+        if (res != MediaResult::OK) {
+          MOJO_LOG(ERROR) << "Failed to configure audio track (res = "
+                          << res << ")";
+          BeginShutdown();
+        }
+      });
+
+  // Grab the rate control interface for our audio renderer.
+  audio_track_->GetRateControl(GetProxy(&rate_control_),
+      [this](MediaResult res) {
+        if (res != MediaResult::OK) {
+          MOJO_LOG(ERROR) << "Failed to fetch rate control interface "
+                          << "(res = " << res << ")";
+          BeginShutdown();
+        }
+      });
+
+  // Set up our connection error handlers for the various interfaces we are
+  // holding on to.  Right now, we make no attempt to recover from a closed
+  // connection.  If one of our connections is closed, its time to shut down.
+  //
+  // TODO(johngro): when there is some better diagnostic information made
+  // available to us, make sure that we log it so we have some way to proceed
+  // with debugging.
+  audio_track_.set_connection_error_handler([this]() {
+    OnConnectionError("audio_track");
+  });
+
+  // TODO(johngro): Once the media pipe adapter (audio_pipe) has been changed to
+  // be the owner of the connection error handler on the media_pipe object,
+  // remove this.  Use the error handler in the adapter instead.
+  media_pipe.set_connection_error_handler([this]() {
+    OnConnectionError("media_pipe");
+  });
+
+  rate_control_.set_connection_error_handler([this]() {
+    OnConnectionError("rate_control");
+  });
+
+  // Set up our media pipe helper, configure its callback and water marks to
+  // kick off the playback process.
+  audio_pipe_.reset(new CircularBufferMediaPipeAdapter(media_pipe.Pass()));
+  audio_pipe_->SetWatermarks(USecToBytes(BUF_HI_WATER_USEC),
+                             USecToBytes(BUF_LO_WATER_USEC));
+  audio_pipe_->SetSignalCallback(
+      [this](MediaResult res) -> bool {
+        return OnNeedsData(res);
+      });
+}
+
+bool PlayWAVApp::ReadAndValidateRIFFHeader() {
+  // Read and sanity check the top level RIFF header
+  if (!BlockingRead(&riff_hdr_, sizeof(riff_hdr_))) {
+    MOJO_LOG(ERROR) << "Failed to read top level RIFF header!";
+    return false;
+  }
+
+  if (fetch_fourcc(&riff_hdr_.four_cc) != RIFF_FOUR_CC) {
+    MOJO_LOG(ERROR) << "Missing expected 'RIFF' 4CC "
+                    << "(expected 0x " << std::hex << RIFF_FOUR_CC
+                    << " got 0x"       << std::hex
+                    << fetch_fourcc(&riff_hdr_.four_cc)
+                    << ")";
+    return false;
+  }
+
+  return true;
+}
+
+bool PlayWAVApp::ReadAndValidateWAVHeader() {
+  // Read the WAVE header along with its required format chunk.
+  if (!BlockingRead(&wav_info_, sizeof(wav_info_))) {
+    MOJO_LOG(ERROR) << "Failed to read top level WAVE header!";
+    return false;
+  }
+
+  if (fetch_fourcc(&wav_info_.wave_four_cc) != WAVE_FOUR_CC) {
+    MOJO_LOG(ERROR) << "Missing expected 'WAVE' 4CC "
+                    << "(expected 0x " << std::hex << WAVE_FOUR_CC
+                    << " got 0x"
+                    << std::hex << fetch_fourcc(&wav_info_.wave_four_cc)
+                    << ")";
+    return false;
+  }
+
+  if (fetch_fourcc(&wav_info_.fmt_four_cc) != FMT_FOUR_CC) {
+    MOJO_LOG(ERROR) << "Missing expected 'fmt ' 4CC "
+                    << "(expected 0x " << std::hex << FMT_FOUR_CC
+                    << " got 0x"
+                    << std::hex << fetch_fourcc(&wav_info_.fmt_four_cc)
+                    << ")";
+    return false;
+  }
+
+  // Sanity check the format of the wave file.  This demo only support a limited
+  // subset of the possible formats.
+  if (wav_info_.format != FORMAT_LPCM) {
+    MOJO_LOG(ERROR) << "Unsupported format (0x"
+                    << std::hex << wav_info_.format
+                    << ") must be LPCM (0x"
+                    << std::hex << FORMAT_LPCM
+                    << ")";
+    return false;
+  }
+
+  if ((wav_info_.channel_count != 1) && (wav_info_.channel_count != 2)) {
+    MOJO_LOG(ERROR) << "Unsupported channel count ("
+                    << wav_info_.channel_count
+                    << ") must be either mono or stereo";
+    return false;
+  }
+
+  if (VALID_FRAME_RATES.find(wav_info_.frame_rate) == VALID_FRAME_RATES.end()) {
+    MOJO_LOG(ERROR) << "Unsupported frame_rate ("
+                    << wav_info_.frame_rate << ")";
+    return false;
+  }
+
+  if (VALID_BITS_PER_SAMPLES.find(wav_info_.bits_per_sample) ==
+      VALID_BITS_PER_SAMPLES.end()) {
+    MOJO_LOG(ERROR) << "Unsupported bits per sample ("
+                    << wav_info_.bits_per_sample << ")";
+    return false;
+  }
+
+  uint16_t expected_frame_size;
+  expected_frame_size = (wav_info_.channel_count * wav_info_.bits_per_sample)
+                        >> 3;
+  if (wav_info_.frame_size != expected_frame_size) {
+    MOJO_LOG(ERROR) << "Frame size sanity check failed.  (expected "
+                    << expected_frame_size << " got "
+                    << wav_info_.frame_size << ")";
+    return false;
+  }
+
+  return true;
+}
+
+bool PlayWAVApp::ReadAndValidateDATAHeader() {
+  // Technically, there could be format specific member of the wave format
+  // chunk, or other riff chunks which could come after this, but for this demo,
+  // we only handle getting the 'data' chunk at this point.
+  if (!BlockingRead(&data_hdr_, sizeof(data_hdr_))) {
+    MOJO_LOG(ERROR) << "Failed to read data header!";
+    return false;
+  }
+
+  if (fetch_fourcc(&data_hdr_.four_cc) != DATA_FOUR_CC) {
+    MOJO_LOG(ERROR) << "Missing expected 'data' 4CC "
+                    << "(expected 0x " << std::hex << DATA_FOUR_CC
+                    << " got 0x"       << std::hex
+                    << fetch_fourcc(&data_hdr_.four_cc)
+                    << ")";
+    return false;
+  }
+
+  if ((data_hdr_.length + sizeof(WAVHeader) + sizeof(RIFFChunkHeader))
+      != riff_hdr_.length) {
+    MOJO_LOG(ERROR) << "Header length sanity check failure ("
+                    << data_hdr_.length << " + "
+                    << sizeof(WAVHeader) + sizeof(RIFFChunkHeader) << " != "
+                    << riff_hdr_.length << ")";
+    return false;
+  }
+
+  // If the length of the data chunk is not a multiple of the frame size, log a
+  // warning and truncate the length.
+  uint16_t leftover;
+  payload_len_ = data_hdr_.length;
+  leftover     = payload_len_ % wav_info_.frame_size;
+  if (leftover) {
+    MOJO_LOG(WARNING)
+      << "Data chunk length (" << payload_len_
+      << ") not a multiple of frame size (" << wav_info_.frame_size
+      << ")";
+    payload_len_ -= leftover;
+  }
+
+  return true;
+}
+
+bool PlayWAVApp::OnNeedsData(MediaResult res) {
+  if (res != MediaResult::OK) {
+    MOJO_LOG(ERROR) << "Error during playback!  (res = " << res << ")";
+    BeginShutdown();
+    return false;
+  }
+
+  uint64_t bytes = USecToBytes(CHUNK_SIZE_USEC);
+  if (bytes > payload_len_) {
+    bytes = payload_len_;
+  }
+
+  res = audio_pipe_->CreateMediaPacket(bytes, false, &audio_packet_);
+  if (res != MediaResult::OK) {
+    MOJO_LOG(ERROR) << "Failed to create " << bytes << " byte media packet!  "
+                    << "(res = " << res << ")";
+    BeginShutdown();
+    return false;
+  }
+
+  if (!sent_first_packet_) {
+    MOJO_DCHECK(audio_packet_.packet());
+    audio_packet_.packet()->pts = 0;
+    sent_first_packet_ = true;
+  }
+
+  for (size_t i = 0; i < AudioPacket::kMaxRegions; ++i) {
+    if (audio_packet_.data(i)) {
+      MOJO_DCHECK(audio_packet_.length(i));
+      MOJO_DCHECK(audio_packet_.length(i) <= payload_len_);
+
+      if (!BlockingRead(audio_packet_.data(i),
+                        audio_packet_.length(i))) {
+        MOJO_LOG(ERROR) << "Failed to read source, shutting down...";
+        BeginShutdown();
+        return false;
+      }
+
+      payload_len_ -= audio_packet_.length(i);
+    }
+  }
+
+  if (payload_len_) {
+    res = audio_pipe_->SendMediaPacket(&audio_packet_);
+  } else {
+    res = audio_pipe_->SendMediaPacket(&audio_packet_, playout_complete_cbk_);
+  }
+
+  if (res != MediaResult::OK) {
+    MOJO_LOG(ERROR) << "Failed to send media packet!  "
+               << "(res = " << res << ")";
+    BeginShutdown();
+    return false;
+  }
+
+  if (!clock_started_ && (audio_pipe_->AboveHiWater() || !payload_len_)) {
+    LocalTime sched = LocalClock::now() + local_time::from_msec(50);
+    rate_control_->SetRateAtTargetTime(1, 1, sched.time_since_epoch().count());
+    clock_started_ = true;
+  }
+
+  return (payload_len_ != 0);
+}
+
+void PlayWAVApp::OnPlayoutComplete(MediaResult res) {
+  MOJO_DCHECK(!audio_pipe_->GetPending());
+  BeginShutdown();
+}
+
+void PlayWAVApp::OnConnectionError(const std::string& connection_name) {
+  if (!shutting_down_) {
+    MOJO_LOG(ERROR) << connection_name << " connection closed unexpectedly!";
+    BeginShutdown();
+  }
+}
+
+// TODO(johngro): remove this when we can.  Right now, the proper way to cleanly
+// shut down a running mojo application is a bit unclear to me.  Calling
+// RunLoop::current()->Quit() seems like the best option, but the run loop does
+// not seep to call our application's quit method.  Instead, it starts to close
+// all of our connections (triggering all of our connection error handlers we
+// have registered on interfaces) before finally destroying our application
+// object.
+//
+// The net result is that we end up spurrious "connection closed unexpectedly"
+// error messages when we are actually shutting down cleanly.  For now, we
+// suppress this by having a shutting_down_ flag and suppressing the error
+// message which show up after shutdown has been triggered.  When the proper
+// pattern for shutting down an app has been established, come back here and
+// remove all this junk.
+void PlayWAVApp::BeginShutdown() {
+  if (!shutting_down_) {
+    shutting_down_ = true;
+    RunLoop::current()->Quit();
+  }
+}
+
+}  // namespace examples
+}  // namespace audio
+}  // namespace media
+}  // namespace mojo
+
+MojoResult MojoMain(MojoHandle app_request) {
+  mojo::ApplicationRunner runner(new mojo::media::audio::examples::PlayWAVApp);
+  return runner.Run(app_request);
+}