| // Copyright (c) 2012 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. |
| |
| #ifndef PPAPI_CPP_AUDIO_CONFIG_H_ |
| #define PPAPI_CPP_AUDIO_CONFIG_H_ |
| |
| #include "ppapi/c/ppb_audio_config.h" |
| #include "ppapi/c/pp_stdint.h" |
| #include "ppapi/cpp/resource.h" |
| |
| /// @file |
| /// This file defines the interface for establishing an |
| /// audio configuration resource within the browser. |
| |
| namespace pp { |
| |
| class InstanceHandle; |
| |
| /// A 16 bit stereo AudioConfig resource. Refer to the |
| /// <a href="/native-client/devguide/coding/audio.html">Audio |
| /// </a>chapter in the Developer's Guide for information on using this |
| /// interface. |
| /// |
| /// A single sample frame on a stereo device means one value for the left |
| /// channel and one value for the right channel. |
| /// |
| /// Buffer layout for a stereo int16 configuration: |
| /// |
| /// <code>int16_t *buffer16;</code> |
| /// <code>buffer16[0]</code> is the first left channel sample. |
| /// <code>buffer16[1]</code> is the first right channel sample. |
| /// <code>buffer16[2]</code> is the second left channel sample. |
| /// <code>buffer16[3]</code> is the second right channel sample. |
| /// <code>...</code> |
| /// <code>buffer16[2 * (sample_frame_count - 1)]</code> is the last left |
| /// channel sample. |
| /// <code>buffer16[2 * (sample_frame_count - 1) + 1]</code> is the last right |
| /// channel sample. |
| /// Data will always be in the native endian format of the platform. |
| /// |
| /// <strong>Example:</strong> |
| /// @code |
| /// |
| /// // Create an audio config with a supported frame count. |
| /// uint32_t sample_frame_count = AudioConfig::RecommendSampleFrameCount( |
| /// PP_AUDIOSAMPLERATE_44100, 4096); |
| /// AudioConfig config(PP_AUDIOSAMPLERATE_44100, sample_frame_count); |
| /// if (config.is_null()) |
| /// return false; // Couldn't configure audio. |
| /// |
| /// // Then use the config to create your audio resource. |
| /// Audio audio(instance, config, callback, user_data); |
| /// if (audio.is_null()) |
| /// return false; // Couldn't create audio. |
| /// @endcode |
| class AudioConfig : public Resource { |
| public: |
| /// An empty constructor for an <code>AudioConfig</code> resource. |
| AudioConfig(); |
| |
| /// A constructor that creates an audio config based on the given sample rate |
| /// and frame count. If the rate and frame count aren't supported, the |
| /// resulting resource will be is_null(). You can pass the result of |
| /// RecommendSampleFrameCount() as the sample frame count. |
| /// |
| /// @param[in] instance The instance associated with this resource. |
| /// |
| /// @param[in] sample_rate A <code>PP_AudioSampleRate</code> which is either |
| /// <code>PP_AUDIOSAMPLERATE_44100</code> or |
| /// <code>PP_AUDIOSAMPLERATE_48000</code>. |
| /// |
| /// @param[in] sample_frame_count A uint32_t frame count returned from the |
| /// <code>RecommendSampleFrameCount</code> function. |
| AudioConfig(const InstanceHandle& instance, |
| PP_AudioSampleRate sample_rate, |
| uint32_t sample_frame_count); |
| |
| /// RecommendSampleRate() returns the native sample rate used by the |
| /// audio system. Applications that use the recommended sample rate might |
| /// obtain lower latency and higher fidelity output. |
| /// |
| /// @param[in] instance The instance associated with this resource. |
| static PP_AudioSampleRate RecommendSampleRate( |
| const InstanceHandle& instance); |
| |
| /// RecommendSampleFrameCount() returns a supported frame count closest to |
| /// the requested count. The sample frame count determines the overall |
| /// latency of audio. Smaller frame counts will yield lower latency, but |
| /// higher CPU utilization. Supported sample frame counts will vary by |
| /// hardware and system (consider that the local system might be anywhere |
| /// from a cell phone or a high-end audio workstation). Sample counts less |
| /// than <code>PP_AUDIOMINSAMPLEFRAMECOUNT</code> and greater than |
| /// <code>PP_AUDIOMAXSAMPLEFRAMECOUNT</code> are never supported on any |
| /// system, but values in between aren't necessarily valid. This function |
| /// will return a supported count closest to the requested value for use in |
| /// the constructor. |
| /// |
| /// @param[in] instance The instance associated with this resource. |
| /// @param[in] sample_rate A <code>PP_AudioSampleRate</code> which is either |
| /// <code>PP_AUDIOSAMPLERATE_44100</code> or |
| /// <code>PP_AUDIOSAMPLERATE_48000</code>. |
| /// @param[in] requested_sample_frame_count A uint32_t requested frame count. |
| /// |
| /// @return A uint32_t containing the recommended sample frame count if |
| /// successful. If the sample frame count or bit rate is not supported, |
| /// this function will fail and return 0. |
| static uint32_t RecommendSampleFrameCount( |
| const InstanceHandle& instance, |
| PP_AudioSampleRate sample_rate, |
| uint32_t requested_sample_frame_count); |
| |
| /// Getter function for returning the internal |
| /// <code>PP_AudioSampleRate</code> enum. |
| /// |
| /// @return The <code>PP_AudioSampleRate</code> enum. |
| PP_AudioSampleRate sample_rate() const { return sample_rate_; } |
| |
| /// Getter function for returning the internal sample frame count. |
| /// |
| /// @return A uint32_t containing the sample frame count. |
| uint32_t sample_frame_count() const { return sample_frame_count_; } |
| |
| private: |
| PP_AudioSampleRate sample_rate_; |
| uint32_t sample_frame_count_; |
| }; |
| |
| } // namespace pp |
| |
| #endif // PPAPI_CPP_AUDIO_CONFIG_H_ |
| |