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// Copyright (c) 2010 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_C_DEV_PPB_AUDIO_CONFIG_DEV_H_
#define PPAPI_C_DEV_PPB_AUDIO_CONFIG_DEV_H_
#include "ppapi/c/pp_bool.h"
#include "ppapi/c/pp_macros.h"
#include "ppapi/c/pp_module.h"
#include "ppapi/c/pp_resource.h"
#include "ppapi/c/pp_stdint.h"
#define PPB_AUDIO_CONFIG_DEV_INTERFACE "PPB_AudioConfig(Dev);0.3"
enum {
PP_AUDIOMINSAMPLEFRAMECOUNT = 64,
PP_AUDIOMAXSAMPLEFRAMECOUNT = 32768
};
typedef enum {
PP_AUDIOSAMPLERATE_NONE = 0,
PP_AUDIOSAMPLERATE_44100 = 44100,
PP_AUDIOSAMPLERATE_48000 = 48000
} PP_AudioSampleRate_Dev;
PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_AudioSampleRate_Dev, 4);
/**
* Audio configuration. This base configuration interface supports only stereo
* 16bit output. This class is not mutable, therefore it is okay to access
* instances from different threads.
*/
struct PPB_AudioConfig_Dev {
/**
* Create a 16 bit stereo config with the given sample rate. We guarantee
* that PP_AUDIOSAMPLERATE_44100 and PP_AUDIOSAMPLERATE_48000 sample rates
* are supported. The |sample_frame_count| should be the result of calling
* RecommendSampleFrameCount. If the sample frame count or bit rate aren'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:
* int16_t *buffer16;
* buffer16[0] is the first left channel sample
* buffer16[1] is the first right channel sample
* buffer16[2] is the second left channel sample
* buffer16[3] is the second right channel sample
* ...
* buffer16[2 * (sample_frame_count - 1)] is the last left channel sample
* buffer16[2 * (sample_frame_count - 1) + 1] is the last right channel sample
* Data will always be in the native endian format of the platform.
*/
PP_Resource (*CreateStereo16Bit)(PP_Module module,
PP_AudioSampleRate_Dev sample_rate,
uint32_t sample_frame_count);
/*
* Returns a supported sample frame count closest to the given 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 PP_AUDIOMINSAMPLEFRAMECOUNT
* and greater than PP_AUDIOMAXSAMPLEFRAMECOUNT 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.
*
* If you pass 0 as the requested sample count, the recommended sample for
* the local system is returned.
*/
uint32_t (*RecommendSampleFrameCount)(uint32_t requested_sample_frame_count);
/**
* Returns true if the given resource is an AudioConfig object.
*/
PP_Bool (*IsAudioConfig)(PP_Resource resource);
/**
* Returns the sample rate for the given AudioConfig resource. If the
* resource is invalid, this will return PP_AUDIOSAMPLERATE_NONE.
*/
PP_AudioSampleRate_Dev (*GetSampleRate)(PP_Resource config);
/**
* Returns the sample frame count for the given AudioConfig resource. If the
* resource is invalid, this will return 0. See RecommendSampleFrameCount for
* more on sample frame counts.
*/
uint32_t (*GetSampleFrameCount)(PP_Resource config);
};
#endif // PPAPI_C_DEV_PPB_AUDIO_CONFIG_DEV_H_
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