1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/content/media/webspeech/recognition/endpointer.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,180 @@
1.4 +// Copyright (c) 2013 The Chromium Authors. All rights reserved.
1.5 +//
1.6 +// Redistribution and use in source and binary forms, with or without
1.7 +// modification, are permitted provided that the following conditions are
1.8 +// met:
1.9 +//
1.10 +// * Redistributions of source code must retain the above copyright
1.11 +// notice, this list of conditions and the following disclaimer.
1.12 +// * Redistributions in binary form must reproduce the above
1.13 +// copyright notice, this list of conditions and the following disclaimer
1.14 +// in the documentation and/or other materials provided with the
1.15 +// distribution.
1.16 +// * Neither the name of Google Inc. nor the names of its
1.17 +// contributors may be used to endorse or promote products derived from
1.18 +// this software without specific prior written permission.
1.19 +//
1.20 +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
1.21 +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
1.22 +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
1.23 +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
1.24 +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
1.25 +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
1.26 +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
1.27 +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
1.28 +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
1.29 +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
1.30 +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.31 +
1.32 +#ifndef CONTENT_BROWSER_SPEECH_ENDPOINTER_ENDPOINTER_H_
1.33 +#define CONTENT_BROWSER_SPEECH_ENDPOINTER_ENDPOINTER_H_
1.34 +
1.35 +#include "energy_endpointer.h"
1.36 +
1.37 +namespace mozilla {
1.38 +
1.39 +struct AudioChunk;
1.40 +
1.41 +// A simple interface to the underlying energy-endpointer implementation, this
1.42 +// class lets callers provide audio as being recorded and let them poll to find
1.43 +// when the user has stopped speaking.
1.44 +//
1.45 +// There are two events that may trigger the end of speech:
1.46 +//
1.47 +// speechInputPossiblyComplete event:
1.48 +//
1.49 +// Signals that silence/noise has been detected for a *short* amount of
1.50 +// time after some speech has been detected. It can be used for low latency
1.51 +// UI feedback. To disable it, set it to a large amount.
1.52 +//
1.53 +// speechInputComplete event:
1.54 +//
1.55 +// This event is intended to signal end of input and to stop recording.
1.56 +// The amount of time to wait after speech is set by
1.57 +// speech_input_complete_silence_length_ and optionally two other
1.58 +// parameters (see below).
1.59 +// This time can be held constant, or can change as more speech is detected.
1.60 +// In the latter case, the time changes after a set amount of time from the
1.61 +// *beginning* of speech. This is motivated by the expectation that there
1.62 +// will be two distinct types of inputs: short search queries and longer
1.63 +// dictation style input.
1.64 +//
1.65 +// Three parameters are used to define the piecewise constant timeout function.
1.66 +// The timeout length is speech_input_complete_silence_length until
1.67 +// long_speech_length, when it changes to
1.68 +// long_speech_input_complete_silence_length.
1.69 +class Endpointer {
1.70 + public:
1.71 + explicit Endpointer(int sample_rate);
1.72 +
1.73 + // Start the endpointer. This should be called at the beginning of a session.
1.74 + void StartSession();
1.75 +
1.76 + // Stop the endpointer.
1.77 + void EndSession();
1.78 +
1.79 + // Start environment estimation. Audio will be used for environment estimation
1.80 + // i.e. noise level estimation.
1.81 + void SetEnvironmentEstimationMode();
1.82 +
1.83 + // Start user input. This should be called when the user indicates start of
1.84 + // input, e.g. by pressing a button.
1.85 + void SetUserInputMode();
1.86 +
1.87 + // Process a segment of audio, which may be more than one frame.
1.88 + // The status of the last frame will be returned.
1.89 + EpStatus ProcessAudio(const AudioChunk& raw_audio, float* rms_out);
1.90 +
1.91 + // Get the status of the endpointer.
1.92 + EpStatus Status(int64_t *time_us);
1.93 +
1.94 + // Get the expected frame size for audio chunks. Audio chunks are expected
1.95 + // to contain a number of samples that is a multiple of this number, and extra
1.96 + // samples will be dropped.
1.97 + int32_t FrameSize() const {
1.98 + return frame_size_;
1.99 + }
1.100 +
1.101 + // Returns true if the endpointer detected reasonable audio levels above
1.102 + // background noise which could be user speech, false if not.
1.103 + bool DidStartReceivingSpeech() const {
1.104 + return speech_previously_detected_;
1.105 + }
1.106 +
1.107 + bool IsEstimatingEnvironment() const {
1.108 + return energy_endpointer_.estimating_environment();
1.109 + }
1.110 +
1.111 + void set_speech_input_complete_silence_length(int64_t time_us) {
1.112 + speech_input_complete_silence_length_us_ = time_us;
1.113 + }
1.114 +
1.115 + void set_long_speech_input_complete_silence_length(int64_t time_us) {
1.116 + long_speech_input_complete_silence_length_us_ = time_us;
1.117 + }
1.118 +
1.119 + void set_speech_input_possibly_complete_silence_length(int64_t time_us) {
1.120 + speech_input_possibly_complete_silence_length_us_ = time_us;
1.121 + }
1.122 +
1.123 + void set_long_speech_length(int64_t time_us) {
1.124 + long_speech_length_us_ = time_us;
1.125 + }
1.126 +
1.127 + bool speech_input_complete() const {
1.128 + return speech_input_complete_;
1.129 + }
1.130 +
1.131 + // RMS background noise level in dB.
1.132 + float NoiseLevelDb() const { return energy_endpointer_.GetNoiseLevelDb(); }
1.133 +
1.134 + private:
1.135 + // Reset internal states. Helper method common to initial input utterance
1.136 + // and following input utternaces.
1.137 + void Reset();
1.138 +
1.139 + // Minimum allowable length of speech input.
1.140 + int64_t speech_input_minimum_length_us_;
1.141 +
1.142 + // The speechInputPossiblyComplete event signals that silence/noise has been
1.143 + // detected for a *short* amount of time after some speech has been detected.
1.144 + // This proporty specifies the time period.
1.145 + int64_t speech_input_possibly_complete_silence_length_us_;
1.146 +
1.147 + // The speechInputComplete event signals that silence/noise has been
1.148 + // detected for a *long* amount of time after some speech has been detected.
1.149 + // This property specifies the time period.
1.150 + int64_t speech_input_complete_silence_length_us_;
1.151 +
1.152 + // Same as above, this specifies the required silence period after speech
1.153 + // detection. This period is used instead of
1.154 + // speech_input_complete_silence_length_ when the utterance is longer than
1.155 + // long_speech_length_. This parameter is optional.
1.156 + int64_t long_speech_input_complete_silence_length_us_;
1.157 +
1.158 + // The period of time after which the endpointer should consider
1.159 + // long_speech_input_complete_silence_length_ as a valid silence period
1.160 + // instead of speech_input_complete_silence_length_. This parameter is
1.161 + // optional.
1.162 + int64_t long_speech_length_us_;
1.163 +
1.164 + // First speech onset time, used in determination of speech complete timeout.
1.165 + int64_t speech_start_time_us_;
1.166 +
1.167 + // Most recent end time, used in determination of speech complete timeout.
1.168 + int64_t speech_end_time_us_;
1.169 +
1.170 + int64_t audio_frame_time_us_;
1.171 + EpStatus old_ep_status_;
1.172 + bool waiting_for_speech_possibly_complete_timeout_;
1.173 + bool waiting_for_speech_complete_timeout_;
1.174 + bool speech_previously_detected_;
1.175 + bool speech_input_complete_;
1.176 + EnergyEndpointer energy_endpointer_;
1.177 + int sample_rate_;
1.178 + int32_t frame_size_;
1.179 +};
1.180 +
1.181 +} // namespace mozilla
1.182 +
1.183 +#endif // CONTENT_BROWSER_SPEECH_ENDPOINTER_ENDPOINTER_H_
