| // 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. |
| |
| #include "ppapi/shared_impl/ppb_audio_config_shared.h" |
| #include "ppapi/thunk/enter.h" |
| #include "ppapi/thunk/ppb_instance_api.h" |
| |
| namespace ppapi { |
| |
| // Rounds up requested_size to the nearest multiple of minimum_size. |
| static uint32_t CalculateMultipleOfSampleFrameCount(uint32_t minimum_size, |
| uint32_t requested_size) { |
| const uint32_t multiple = (requested_size + minimum_size - 1) / minimum_size; |
| return std::min(minimum_size * multiple, |
| static_cast<uint32_t>(PP_AUDIOMAXSAMPLEFRAMECOUNT)); |
| } |
| |
| PPB_AudioConfig_Shared::PPB_AudioConfig_Shared(ResourceObjectType type, |
| PP_Instance instance) |
| : Resource(type, instance), |
| sample_rate_(PP_AUDIOSAMPLERATE_NONE), |
| sample_frame_count_(0) { |
| } |
| |
| PPB_AudioConfig_Shared::~PPB_AudioConfig_Shared() { |
| } |
| |
| PP_Resource PPB_AudioConfig_Shared::Create( |
| ResourceObjectType type, |
| PP_Instance instance, |
| PP_AudioSampleRate sample_rate, |
| uint32_t sample_frame_count) { |
| scoped_refptr<PPB_AudioConfig_Shared> object( |
| new PPB_AudioConfig_Shared(type, instance)); |
| if (!object->Init(sample_rate, sample_frame_count)) |
| return 0; |
| return object->GetReference(); |
| } |
| |
| // static |
| uint32_t PPB_AudioConfig_Shared::RecommendSampleFrameCount_1_0( |
| PP_AudioSampleRate sample_rate, |
| uint32_t requested_sample_frame_count) { |
| // Version 1.0: Don't actually query to get a value from the |
| // hardware; instead return the input for in-range values. |
| if (requested_sample_frame_count < PP_AUDIOMINSAMPLEFRAMECOUNT) |
| return PP_AUDIOMINSAMPLEFRAMECOUNT; |
| if (requested_sample_frame_count > PP_AUDIOMAXSAMPLEFRAMECOUNT) |
| return PP_AUDIOMAXSAMPLEFRAMECOUNT; |
| return requested_sample_frame_count; |
| } |
| |
| // static |
| uint32_t PPB_AudioConfig_Shared::RecommendSampleFrameCount_1_1( |
| PP_Instance instance, |
| PP_AudioSampleRate sample_rate, |
| uint32_t sample_frame_count) { |
| // Version 1.1: Query the back-end hardware for sample rate and buffer size, |
| // and recommend a best fit based on request. |
| thunk::EnterInstanceNoLock enter(instance); |
| if (enter.failed()) |
| return 0; |
| |
| // Get the hardware config. |
| PP_AudioSampleRate hardware_sample_rate = static_cast<PP_AudioSampleRate>( |
| enter.functions()->GetAudioHardwareOutputSampleRate(instance)); |
| uint32_t hardware_sample_frame_count = |
| enter.functions()->GetAudioHardwareOutputBufferSize(instance); |
| if (sample_frame_count < PP_AUDIOMINSAMPLEFRAMECOUNT) |
| sample_frame_count = PP_AUDIOMINSAMPLEFRAMECOUNT; |
| |
| // If hardware information isn't available we're connected to a fake audio |
| // output stream on the browser side, so we can use whatever sample count the |
| // client wants. |
| if (!hardware_sample_frame_count || !hardware_sample_rate) |
| return sample_frame_count; |
| |
| // Note: All the values below were determined through experimentation to |
| // minimize jitter and back-to-back callbacks from the browser. Please take |
| // care when modifying these values as they impact a large number of users. |
| // TODO(dalecurtis): Land jitter test and add documentation for updating this. |
| |
| // If client is using same sample rate as audio hardware, then recommend a |
| // multiple of the audio hardware's sample frame count. |
| if (hardware_sample_rate == sample_rate) { |
| return CalculateMultipleOfSampleFrameCount( |
| hardware_sample_frame_count, sample_frame_count); |
| } |
| |
| // Should track the value reported by XP and ALSA backends. |
| const uint32_t kHighLatencySampleFrameCount = 2048; |
| |
| // If the hardware requires a high latency buffer or we're at a low sample |
| // rate w/ a buffer that's larger than 10ms, choose the nearest multiple of |
| // the high latency sample frame count. An example of too low and too large |
| // is 16kHz and a sample frame count greater than 160 frames. |
| if (hardware_sample_frame_count >= kHighLatencySampleFrameCount || |
| (hardware_sample_rate < 44100 && |
| hardware_sample_frame_count > hardware_sample_rate / 100u)) { |
| return CalculateMultipleOfSampleFrameCount( |
| sample_frame_count, |
| std::max(kHighLatencySampleFrameCount, hardware_sample_frame_count)); |
| } |
| |
| // All low latency clients should be able to handle a 512 frame buffer with |
| // resampling from 44.1kHz and 48kHz to higher sample rates. |
| // TODO(dalecurtis): We may need to investigate making the callback thread |
| // high priority to handle buffers at the absolute minimum w/o glitching. |
| const uint32_t kLowLatencySampleFrameCount = 512; |
| |
| // Special case for 48kHz -> 44.1kHz and buffer sizes greater than 10ms. In |
| // testing most buffer sizes > 10ms led to glitching, so we choose a size we |
| // know won't cause jitter. |
| int min_sample_frame_count = kLowLatencySampleFrameCount; |
| if (hardware_sample_rate == 44100 && sample_rate == 48000 && |
| hardware_sample_frame_count > hardware_sample_rate / 100u) { |
| min_sample_frame_count = std::max( |
| 2 * kLowLatencySampleFrameCount, hardware_sample_frame_count); |
| } |
| |
| return CalculateMultipleOfSampleFrameCount( |
| min_sample_frame_count, sample_frame_count); |
| } |
| |
| // static |
| PP_AudioSampleRate PPB_AudioConfig_Shared::RecommendSampleRate( |
| PP_Instance instance) { |
| thunk::EnterInstanceNoLock enter(instance); |
| if (enter.failed()) |
| return PP_AUDIOSAMPLERATE_NONE; |
| PP_AudioSampleRate hardware_sample_rate = static_cast<PP_AudioSampleRate>( |
| enter.functions()->GetAudioHardwareOutputSampleRate(instance)); |
| return hardware_sample_rate; |
| } |
| |
| thunk::PPB_AudioConfig_API* PPB_AudioConfig_Shared::AsPPB_AudioConfig_API() { |
| return this; |
| } |
| |
| PP_AudioSampleRate PPB_AudioConfig_Shared::GetSampleRate() { |
| return sample_rate_; |
| } |
| |
| uint32_t PPB_AudioConfig_Shared::GetSampleFrameCount() { |
| return sample_frame_count_; |
| } |
| |
| bool PPB_AudioConfig_Shared::Init(PP_AudioSampleRate sample_rate, |
| uint32_t sample_frame_count) { |
| // TODO(brettw): Currently we don't actually check what the hardware |
| // supports, so just allow sample rates of the "guaranteed working" ones. |
| // TODO(dalecurtis): If sample rates are added RecommendSampleFrameCount_1_1() |
| // must be updated to account for the new rates. |
| if (sample_rate != PP_AUDIOSAMPLERATE_44100 && |
| sample_rate != PP_AUDIOSAMPLERATE_48000) |
| return false; |
| |
| // TODO(brettw): Currently we don't actually query to get a value from the |
| // hardware, so just validate the range. |
| if (sample_frame_count > PP_AUDIOMAXSAMPLEFRAMECOUNT || |
| sample_frame_count < PP_AUDIOMINSAMPLEFRAMECOUNT) |
| return false; |
| |
| sample_rate_ = sample_rate; |
| sample_frame_count_ = sample_frame_count; |
| return true; |
| } |
| |
| } // namespace ppapi |