/* Copyright 2017 The Chromium Authors
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/**
* This file defines the <code>PPB_AudioOutput_dev</code> interface, which
* provides realtime stereo audio streaming capabilities.
*/
[generate_thunk]
label Chrome {
M59 = 0.1
};
/**
* <code>PPB_AudioOutput_Callback</code> defines the type of an audio callback
* function used to fill the audio buffer with data. Please see the
* Create() function in the <code>PPB_AudioOutput</code> interface for
* more details on this callback.
*
* @param[out] sample_buffer A buffer to fill with audio data.
* @param[in] buffer_size_in_bytes The size of the buffer in bytes.
* @param[in] latency How long before the audio data is to be presented.
* @param[inout] user_data An opaque pointer that was passed into
* <code>PPB_AudioOutput.Create()</code>.
*/
typedef void PPB_AudioOutput_Callback([out] mem_t sample_buffer,
[in] uint32_t buffer_size_in_bytes,
[in] PP_TimeDelta latency,
[inout] mem_t user_data);
/**
* The <code>PPB_AudioOutput</code> interface contains pointers to several
* functions for handling audio resources.
* Please see descriptions for each <code>PPB_AudioOutput</code> and
* <code>PPB_AudioConfig</code> function for more details. A C example using
* <code>PPB_AudioOutput</code> and <code>PPB_AudioConfig</code> follows.
*
* <strong>Example: </strong>
*
* @code
* void audio_output_callback(void* sample_buffer,
* uint32_t buffer_size_in_bytes,
* PP_TimeDelta latency,
* void* user_data) {
* ... quickly fill in the buffer with samples and return to caller ...
* }
*
* ...Assume the application has cached the audio configuration interface in
* audio_config_interface and the audio interface in
* audio_output_interface...
*
* uint32_t count = audio_config_interface->RecommendSampleFrameCount(
* PP_AUDIOSAMPLERATE_44100, 4096);
* PP_Resource pp_audio_config = audio_config_interface->CreateStereo16Bit(
* pp_instance, PP_AUDIOSAMPLERATE_44100, count);
* PP_Resource pp_audio_output = audio_interface->Create(pp_instance,
* pp_audio_config, audio_callback, NULL);
* audio_interface->EnumerateDevices(pp_audio_output, output_device_list,
* callback);
* audio_interface->Open(pp_audio_output, device_ref, pp_audio_config,
* audio_output_callback, user_data, callback);
* audio_output_interface->StartPlayback(pp_audio_output);
*
* ...audio_output_callback() will now be periodically invoked on a separate
* thread...
* @endcode
*/
[macro="PPB_AUDIO_OUTPUT_DEV_INTERFACE"]
interface PPB_AudioOutput_Dev {
/**
* Creates an audio output resource.
*
* @param[in] instance A <code>PP_Instance</code> identifying one instance of
* a module.
*
* @return A <code>PP_Resource</code> corresponding to an audio output resource
* if successful, 0 if failed.
*/
PP_Resource Create(
[in] PP_Instance instance);
/**
* Determines if the given resource is an audio output resource.
*
* @param[in] resource A <code>PP_Resource</code> containing a resource.
*
* @return A <code>PP_Bool</code> containing <code>PP_TRUE</code> if the given
* resource is an audio output resource, otherwise <code>PP_FALSE</code>.
*/
PP_Bool IsAudioOutput(
[in] PP_Resource resource);
/**
* Enumerates audio output devices.
*
* @param[in] audio_output A <code>PP_Resource</code> corresponding to an audio
* output resource.
* @param[in] output An output array which will receive
* <code>PPB_DeviceRef_Dev</code> resources on success. Please note that the
* ref count of those resources has already been increased by 1 for the
* caller.
* @param[in] callback A <code>PP_CompletionCallback</code> to run on
* completion.
*
* @return An error code from <code>pp_errors.h</code>.
*/
int32_t EnumerateDevices(
[in] PP_Resource audio_output,
[in] PP_ArrayOutput output,
[in] PP_CompletionCallback callback);
/**
* Requests device change notifications.
*
* @param[in] audio_output A <code>PP_Resource</code> corresponding to an audio
* output resource.
* @param[in] callback The callback to receive notifications. If not NULL, it
* will be called once for the currently available devices, and then every
* time the list of available devices changes. All calls will happen on the
* same thread as the one on which MonitorDeviceChange() is called. It will
* receive notifications until <code>audio_output</code> is destroyed or
* <code>MonitorDeviceChange()</code> is called to set a new callback for
* <code>audio_output</code>. You can pass NULL to cancel sending
* notifications.
* @param[inout] user_data An opaque pointer that will be passed to
* <code>callback</code>.
*
* @return An error code from <code>pp_errors.h</code>.
*/
int32_t MonitorDeviceChange(
[in] PP_Resource audio_output,
[in] PP_MonitorDeviceChangeCallback callback,
[inout] mem_t user_data);
/**
* Open() opens an audio output device. No sound will be heard until
* StartPlayback() is called. The callback is called with the buffer address
* and given user data whenever the buffer needs to be filled. From within the
* callback, you should not call <code>PPB_AudioOutput</code> functions. The
* callback will be called on a different thread than the one which created
* the interface. For performance-critical applications (i.e. low-latency
* audio), the callback should avoid blocking or calling functions that can
* obtain locks, such as malloc. The layout and the size of the buffer passed
* to the audio callback will be determined by the device configuration and is
* specified in the <code>AudioConfig</code> documentation.
*
* @param[in] audio_output A <code>PP_Resource</code> corresponding to an audio
* output resource.
* @param[in] device_ref Identifies an audio output device. It could be one of
* the resource in the array returned by EnumerateDevices(), or 0 which means
* the default device.
* @param[in] config A <code>PPB_AudioConfig</code> audio configuration
* resource.
* @param[in] audio_output_callback A <code>PPB_AudioOutput_Callback</code>
* function that will be called when audio buffer needs to be filled.
* @param[inout] user_data An opaque pointer that will be passed into
* <code>audio_output_callback</code>.
* @param[in] callback A <code>PP_CompletionCallback</code> to run when this
* open operation is completed.
*
* @return An error code from <code>pp_errors.h</code>.
*/
int32_t Open(
[in] PP_Resource audio_output,
[in] PP_Resource device_ref,
[in] PP_Resource config,
[in] PPB_AudioOutput_Callback audio_output_callback,
[inout] mem_t user_data,
[in] PP_CompletionCallback callback);
/**
* GetCurrrentConfig() returns an audio config resource for the given audio
* output resource.
*
* @param[in] config A <code>PP_Resource</code> corresponding to an audio
* output resource.
*
* @return A <code>PP_Resource</code> containing the audio config resource if
* successful.
*/
PP_Resource GetCurrentConfig(
[in] PP_Resource audio_output);
/**
* StartPlayback() starts the playback of the audio output resource and begins
* periodically calling the callback.
*
* @param[in] config A <code>PP_Resource</code> corresponding to an audio
* output resource.
*
* @return A <code>PP_Bool</code> containing <code>PP_TRUE</code> if
* successful, otherwise <code>PP_FALSE</code>. Also returns
* <code>PP_TRUE</code> (and be a no-op) if called while playback is already
* in progress.
*/
PP_Bool StartPlayback(
[in] PP_Resource audio_output);
/**
* StopPlayback() stops the playback of the audio resource.
*
* @param[in] config A <code>PP_Resource</code> corresponding to an audio
* output resource.
*
* @return A <code>PP_Bool</code> containing <code>PP_TRUE</code> if
* successful, otherwise <code>PP_FALSE</code>. Also returns
* <code>PP_TRUE</code> (and is a no-op) if called while playback is already
* stopped. If a callback is in progress, StopPlayback() will block until the
* callback completes.
*/
PP_Bool StopPlayback(
[in] PP_Resource audio_output);
/**
* Close() closes the audio output device, and stops playback if necessary. It is
* not valid to call Open() again after a call to this method.
* If an audio output resource is destroyed while a device is still open, then
* it will be implicitly closed, so you are not required to call this method.
*
* @param[in] audio_output A <code>PP_Resource</code> corresponding to an audio
* output resource.
*/
void Close(
[in] PP_Resource audio_output);
};
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