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/* 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.
*/
/**
* This file defines the PPB_AudioConfig interface for establishing an
* audio configuration resource within the browser.
*/
label Chrome {
M14 = 1.0,
M19 = 1.1
};
/**
* This enumeration contains audio frame count constants.
* <code>PP_AUDIOMINSAMPLEFRAMECOUNT</code> is the minimum possible frame
* count. <code>PP_AUDIOMAXSAMPLEFRAMECOUNT</code> is the maximum possible
* frame count.
*/
[unnamed] enum PP_AudioFrameSize {
PP_AUDIOMINSAMPLEFRAMECOUNT = 64,
PP_AUDIOMAXSAMPLEFRAMECOUNT = 32768
};
/**
* PP_AudioSampleRate is an enumeration of the different audio sampling rates.
* <code>PP_AUDIOSAMPLERATE_44100</code> is the sample rate used on CDs and
* <code>PP_AUDIOSAMPLERATE_48000</code> is the sample rate used on DVDs and
* Digital Audio Tapes.
*/
[assert_size(4)]
enum PP_AudioSampleRate {
PP_AUDIOSAMPLERATE_NONE = 0,
PP_AUDIOSAMPLERATE_44100 = 44100,
PP_AUDIOSAMPLERATE_48000 = 48000
} ;
/**
* The <code>PPB_AudioConfig</code> interface contains pointers to several
* functions for establishing your audio configuration within the browser.
* This interface only supports 16-bit stereo output.
*
* 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.
*/
[macro="PPB_AUDIO_CONFIG_INTERFACE"]
interface PPB_AudioConfig {
/**
* CreateStereo16bit() creates a 16 bit audio configuration resource. The
* <code>sample_rate</code> should be the result of calling
* <code>RecommendSampleRate</code> and <code>sample_frame_count</code> should
* be the result of calling <code>RecommendSampleFrameCount</code>. If the
* sample frame count or bit rate isn't supported, this function will fail and
* return a null resource.
*
* 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>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.
*
* @param[in] instance A <code>PP_Instance</code> identifying one instance
* of a module.
* @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 <code>uint32_t</code> frame count returned
* from the <code>RecommendSampleFrameCount</code> function.
*
* @return A <code>PP_Resource</code> containing the
* <code>PPB_Audio_Config</code> if successful or a null resource if the
* sample frame count or bit rate are not supported.
*/
PP_Resource CreateStereo16Bit(
[in] PP_Instance instance,
[in] PP_AudioSampleRate sample_rate,
[in] uint32_t sample_frame_count);
/**
* This comment block applies to version 1.0, which is deprecated in favor of
* the same function but with slightly different signature and behavior.
*
* RecommendSampleFrameCount() returns the supported sample frame count
* closest to the requested count. The sample frame count determines the
* overall latency of audio. Since one "frame" is always buffered in advance,
* smaller frame counts will yield lower latency, but higher CPU utilization.
* For best audio performance, use the value returned by RecommendSampleRate
* as the input sample rate, then use the RecommendSampleFrameCount return
* value when creating the audio configuration resource.
*
* 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 glitch-free.
*
* @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 <code>uint_32t</code> requested
* frame count.
*
* @return A <code>uint32_t</code> containing the recommended sample frame
* count if successful.
*/
[deprecate=1.1]
uint32_t RecommendSampleFrameCount(
[in] PP_AudioSampleRate sample_rate,
[in] uint32_t requested_sample_frame_count);
/**
* RecommendSampleFrameCount() returns the supported sample frame count
* closest to the requested count. The sample frame count determines the
* overall latency of audio. Since one "frame" is always buffered in advance,
* 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 frame count.
*
* RecommendSampleFrameCount() result is intended for audio output devices.
*
* @param[in] instance
* @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 <code>uint_32t</code> requested
* frame count.
*
* @return A <code>uint32_t</code> containing the recommended sample frame
* count if successful.
*/
[version=1.1]
uint32_t RecommendSampleFrameCount(
[in] PP_Instance instance,
[in] PP_AudioSampleRate sample_rate,
[in] uint32_t requested_sample_frame_count);
/**
* IsAudioConfig() determines if the given resource is a
* <code>PPB_Audio_Config</code>.
*
* @param[in] resource A <code>PP_Resource</code> corresponding to an audio
* config resource.
*
* @return A <code>PP_Bool</code> containing <code>PP_TRUE</code> if the given
* resource is an <code>AudioConfig</code> resource, otherwise
* <code>PP_FALSE</code>.
*/
PP_Bool IsAudioConfig(
[in] PP_Resource resource);
/**
* GetSampleRate() returns the sample rate for the given
* <code>PPB_Audio_Config</code>.
*
* @param[in] config A <code>PP_Resource</code> corresponding to a
* <code>PPB_Audio_Config</code>.
*
* @return A <code>PP_AudioSampleRate</code> containing sample rate or
* <code>PP_AUDIOSAMPLERATE_NONE</code> if the resource is invalid.
*/
PP_AudioSampleRate GetSampleRate(
[in] PP_Resource config);
/**
* GetSampleFrameCount() returns the sample frame count for the given
* <code>PPB_Audio_Config</code>.
*
* @param[in] config A <code>PP_Resource</code> corresponding to an audio
* config resource.
*
* @return A <code>uint32_t</code> containing sample frame count or
* 0 if the resource is invalid. Refer to
* RecommendSampleFrameCount() for more on sample frame counts.
*/
uint32_t GetSampleFrameCount(
[in] PP_Resource config);
/**
* RecommendSampleRate() returns the native sample rate that the browser
* is using in the backend. Applications that use the recommended sample
* rate will have potentially better latency and fidelity. The return value
* is intended for audio output devices. If the output sample rate cannot be
* determined, this function can return PP_AUDIOSAMPLERATE_NONE.
*
* @param[in] instance
*
* @return A <code>uint32_t</code> containing the recommended sample frame
* count if successful.
*/
[version=1.1]
PP_AudioSampleRate RecommendSampleRate(
[in] PP_Instance instance);
};
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