osx_source.cc

/* -*- c++ -*- */
/*
 * Copyright 2006-2011,2013-2014 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio.
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "../audio_registry.h"
#include "osx_source.h"

#include <gnuradio/io_signature.h>
#include <gnuradio/prefs.h>
#include <stdexcept>

namespace gr {
namespace audio {

source::sptr
osx_source_fcn(int sampling_rate, const std::string& device_name, bool ok_to_block)
{
    return source::sptr(new osx_source(sampling_rate, device_name, ok_to_block));
}

static std::string default_device_name()
{
    return prefs::singleton()->get_string(
        "audio_osx", "default_input_device", "built-in");
}

osx_source::osx_source(int sample_rate, const std::string& device_name, bool ok_to_block)
    : sync_block(
          "audio_osx_source", io_signature::make(0, 0, 0), io_signature::make(0, 0, 0)),
      d_device_sample_rate(0.0),
      d_output_sample_rate(0.0),
      d_input_buffer_size_frames(0),
      d_input_buffer_size_bytes(0),
      d_output_buffer_size_frames(0),
      d_output_buffer_size_bytes(0),
      d_device_buffer_size_frames(0),
      d_device_buffer_size_bytes(0),
      d_lead_size_frames(0),
      d_lead_size_bytes(0),
      d_trail_size_frames(0),
      d_trail_size_bytes(0),
      d_extra_buffer_size_frames(0),
      d_extra_buffer_size_bytes(0),
      d_queue_sample_count(0),
      d_buffer_sample_count(0),
      d_n_available_input_frames(0),
      d_n_actual_input_frames(0),
      d_n_user_channels(0),
      d_n_dev_channels(0),
      d_ok_to_block(ok_to_block),
      d_pass_through(false),
      d_waiting_for_data(false),
      d_do_reset(false),
      d_hardware_changed(false),
      d_using_default_device(false),
      d_desired_name(device_name.empty() ? default_device_name() : device_name),
      d_input_ad_id(0),
      d_input_au(0),
      d_input_buffer(0),
      d_output_buffer(0),
      d_audio_converter(0)
{
    // set the desired output sample rate

    if (sample_rate <= 0) {
        d_logger->error("Invalid Sample Rate: {:d}", sample_rate);
        throw std::invalid_argument("audio_osx_source");
    } else {
        d_output_sample_rate = (Float64)sample_rate;
    }

    // set up for audio input using the stored desired parameters

    setup();
}

void osx_source::setup()
{
    OSStatus err = noErr;

    // set the default input audio device id to "unknown"

    d_input_ad_id = kAudioDeviceUnknown;

    // try to find the input audio device, if specified

    std::vector<AudioDeviceID> all_ad_ids;
    std::vector<std::string> all_names;

    osx::find_audio_devices(d_desired_name, true, &all_ad_ids, &all_names);

    // check number of device(s) returned

    if (d_desired_name.length() != 0) {
        if (all_ad_ids.size() == 1) {

            // exactly 1 match was found; see if it was partial

            if (all_names[0].compare(d_desired_name) != 0) {

                // yes: log the full device name
                d_logger->info("Using input audio device '{:s}'.", all_names[0]);
            }

            // store info on this device

            d_input_ad_id = all_ad_ids[0];
            d_selected_name = all_names[0];

        } else {

            // either 0 or more than 1 device was found; get all input
            // device names, print those, and error out.

            osx::find_audio_devices("", true, NULL, &all_names);

            std::string err_str("\n\nA unique input audio device name "
                                "matching the string '");
            err_str += d_desired_name;
            err_str += "' was not found.\n\n";
            err_str += "The current known input audio device name";
            err_str += ((all_names.size() > 1) ? "s are" : " is");
            err_str += ":\n";
            for (UInt32 nn = 0; nn < all_names.size(); ++nn) {
                err_str += "    " + all_names[nn] + "\n";
            }
            d_logger->error(err_str);
            throw std::runtime_error("audio_osx_source::setup");
        }
    }

    // if no input audio device id was found or no specific device
    // name was provided, use the default input audio device id as
    // set in System Preferences.

    if (d_input_ad_id == kAudioDeviceUnknown) {

        UInt32 prop_size = (UInt32)sizeof(AudioDeviceID);
        AudioObjectPropertyAddress ao_address = {
            kAudioHardwarePropertyDefaultInputDevice,
            kAudioObjectPropertyScopeGlobal,
            kAudioObjectPropertyElementMaster
        };

        err = AudioObjectGetPropertyData(
            kAudioObjectSystemObject, &ao_address, 0, NULL, &prop_size, &d_input_ad_id);
        check_error_and_throw(err,
                              "Getting the default input audio device ID failed",
                              "audio_osx_source::setup");

        {
            // retrieve the device name; max name length is 64 characters.

            UInt32 prop_size = 65;
            char c_name_buf[prop_size];
            memset((void*)c_name_buf, 0, (size_t)prop_size);
            --prop_size;

            AudioObjectPropertyAddress ao_address = { kAudioDevicePropertyDeviceName,
                                                      kAudioDevicePropertyScopeInput,
                                                      0 };

            if ((err = AudioObjectGetPropertyData(d_input_ad_id,
                                                  &ao_address,
                                                  0,
                                                  NULL,
                                                  &prop_size,
                                                  (void*)c_name_buf)) != noErr) {

                check_error(err, "Unable to retrieve input audio device name");

            } else {

                d_logger->info("\n\nUsing input audio device '{:s}'.\n  ... "
                               "which is the current default input audio"
                               " device.\n  Changing the default input"
                               " audio device in the System Preferences"
                               " will \n  result in changing it here, too "
                               "(with an internal reconfiguration).\n",
                               std::string(c_name_buf));
            }

            d_selected_name = c_name_buf;
        }

        d_using_default_device = true;
    }

    // retrieve the total number of channels for the selected input
    // audio device

    osx::get_num_channels_for_audio_device_id(d_input_ad_id, &d_n_dev_channels, NULL);

    // set the block output signature, if not already set
    // (d_n_user_channels is set in check_topology, which is called
    // before the flow-graph is running)

    if (d_n_user_channels == 0) {
        set_output_signature(io_signature::make(1, d_n_dev_channels, sizeof(float)));
    }

    // set the interim buffer size; to work with the GR scheduler,
    // must be at least 16kB.  Pick 50 kB since that's plenty yet
    // not very much.

    d_buffer_sample_count =
        (d_output_sample_rate < 50000.0 ? 50000 : (UInt32)d_output_sample_rate);

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("source(): max # samples = {:d}", d_buffer_sample_count);
#endif

    // create the default AudioUnit for input

    // Open the default input unit

    AudioComponentDescription desc;

    desc.componentType = kAudioUnitType_Output;
    desc.componentSubType = kAudioUnitSubType_HALOutput;
    desc.componentManufacturer = kAudioUnitManufacturer_Apple;
    desc.componentFlags = 0;
    desc.componentFlagsMask = 0;

    AudioComponent comp = AudioComponentFindNext(NULL, &desc);
    if (!comp) {
        d_logger->fatal("AudioComponentFindNext Failed");
        throw std::runtime_error("audio_osx_source::setup");
    }
    err = AudioComponentInstanceNew(comp, &d_input_au);
    check_error_and_throw(
        err, "AudioComponentInstanceNew Failed", "audio_osx_source::setup");

    // must enable the AUHAL for input and disable output
    // before setting the AUHAL's current device

    // Enable input on the AUHAL

    UInt32 enable_io = 1;
    err = AudioUnitSetProperty(d_input_au,
                               kAudioOutputUnitProperty_EnableIO,
                               kAudioUnitScope_Input,
                               1, // input element
                               &enable_io,
                               sizeof(enable_io));
    check_error_and_throw(
        err, "AudioUnitSetProperty Input Enable", "audio_osx_source::setup");

    // Disable output on the AUHAL

    enable_io = 0;
    err = AudioUnitSetProperty(d_input_au,
                               kAudioOutputUnitProperty_EnableIO,
                               kAudioUnitScope_Output,
                               0, // output element
                               &enable_io,
                               sizeof(enable_io));
    check_error_and_throw(
        err, "AudioUnitSetProperty Output Disable", "audio_osx_source::setup");

    // set the selected device ID as the current input device

    err = AudioUnitSetProperty(d_input_au,
                               kAudioOutputUnitProperty_CurrentDevice,
                               kAudioUnitScope_Global,
                               0,
                               &d_input_ad_id,
                               sizeof(d_input_ad_id));
    check_error_and_throw(err,
                          "Setting selected input device as current failed",
                          "audio_osx_source::setup");

    // Set up a callback function to retrieve input from the Audio Device

    AURenderCallbackStruct au_callback = { reinterpret_cast<AURenderCallback>(
                                               &osx_source::au_input_callback),
                                           reinterpret_cast<void*>(this) };
    UInt32 prop_size = (UInt32)sizeof(au_callback);

    err = AudioUnitSetProperty(d_input_au,
                               kAudioOutputUnitProperty_SetInputCallback,
                               kAudioUnitScope_Global,
                               0,
                               &au_callback,
                               prop_size);
    check_error_and_throw(err, "Set Input Callback", "audio_osx_source::setup");

    // Get the Stream Format (device side; cannot generally be changed)

    prop_size = (UInt32)sizeof(d_asbd_device);
    memset((void*)(&d_asbd_device), 0, (size_t)prop_size);
    err = AudioUnitGetProperty(d_input_au,
                               kAudioUnitProperty_StreamFormat,
                               kAudioUnitScope_Input,
                               1,
                               &d_asbd_device,
                               &prop_size);
    check_error_and_throw(
        err, "Get Device Input Stream Format (before) failed", "audio_osx_source::setup");

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("\n---- Device Stream Format (before) ----\n{:s}\n",
                          d_asbd_device);
#endif

    // try to set the device (input) side of the audio device to the
    // sample rate of this source.  This will likely fail, and
    // that's OK; just ignore the error since we can accomplish
    // audio input in other ways.

    prop_size = (UInt32)sizeof(d_asbd_device);
    d_asbd_device.mSampleRate = d_output_sample_rate;
    err = AudioUnitSetProperty(d_input_au,
                               kAudioUnitProperty_StreamFormat,
                               kAudioUnitScope_Input,
                               1,
                               &d_asbd_device,
                               prop_size);
#if _OSX_AU_DEBUG_
    check_error(err, "Set Device Input Stream Format failed (expected)");
#endif

    memset((void*)(&d_asbd_device), 0, (size_t)prop_size);
    err = AudioUnitGetProperty(d_input_au,
                               kAudioUnitProperty_StreamFormat,
                               kAudioUnitScope_Input,
                               1,
                               &d_asbd_device,
                               &prop_size);
    check_error_and_throw(
        err, "Get Device Input Stream Format (after) failed", "audio_osx_source::setup");

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("\n---- Device Stream Format (after) ----\n{:s}\n",
                          d_asbd_device);
#endif

    d_device_sample_rate = d_asbd_device.mSampleRate;

    // Get the Stream Format (client side; might be changeable)

    prop_size = (UInt32)sizeof(d_asbd_client);
    memset((void*)(&d_asbd_client), 0, (size_t)prop_size);
    err = AudioUnitGetProperty(d_input_au,
                               kAudioUnitProperty_StreamFormat,
                               kAudioUnitScope_Output,
                               1,
                               &d_asbd_client,
                               &prop_size);
    check_error_and_throw(err,
                          "Get Device Output Stream Format (before) failed",
                          "audio_osx_source::setup");

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("---- Client Stream Format (Before) ----\n{:s}\n",
                          d_asbd_client);
#endif

    // Set the format of all the AUs to the
    // input/output devices channel count

    d_asbd_client.mFormatID = kAudioFormatLinearPCM;
    d_asbd_client.mFormatFlags = (kAudioFormatFlagIsFloat | kAudioFormatFlagIsPacked |
                                  kAudioFormatFlagIsNonInterleaved);
    if ((d_asbd_client.mFormatID == kAudioFormatLinearPCM) && (d_n_dev_channels == 1)) {
        d_asbd_client.mFormatFlags &= ~kLinearPCMFormatFlagIsNonInterleaved;
    }
    d_asbd_client.mBytesPerFrame = (UInt32)sizeof(float);
    d_asbd_client.mFramesPerPacket = 1;
    d_asbd_client.mBitsPerChannel = d_asbd_client.mBytesPerFrame * 8;
    d_asbd_client.mChannelsPerFrame = d_n_dev_channels;
    d_asbd_client.mBytesPerPacket = d_asbd_client.mBytesPerFrame;

    // according to Apple docs [see, e.g., Apple Technical Note
    // TN2091 "Device input using the HAL Output Audio Unit"], the
    // device input and output sample rate must be the same; do
    // sample rate conversion elsewhere.

    d_asbd_client.mSampleRate = d_asbd_device.mSampleRate;
    err = AudioUnitSetProperty(d_input_au,
                               kAudioUnitProperty_StreamFormat,
                               kAudioUnitScope_Output,
                               1,
                               &d_asbd_client,
                               prop_size);
    check_error_and_throw(
        err, "Set Device Output Stream Format failed", "audio_osx_source::setup");

    // Get the Stream Format (client side), again

    prop_size = (UInt32)sizeof(d_asbd_client);
    memset((void*)(&d_asbd_client), 0, (size_t)prop_size);
    err = AudioUnitGetProperty(d_input_au,
                               kAudioUnitProperty_StreamFormat,
                               kAudioUnitScope_Output,
                               1,
                               &d_asbd_client,
                               &prop_size);
    check_error_and_throw(
        err, "Get Device Output Stream Format (after) failed", "audio_osx_source::setup");

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("---- Client Stream Format (After) ----\n{:s}\n",
                          d_asbd_client);
#endif

    d_pass_through = (d_asbd_client.mSampleRate == d_output_sample_rate);

    if (d_pass_through) {

        // no need to do conversion if d_asbd_client matches user wants
        d_lead_size_frames = d_trail_size_frames = 0L;

    } else {

        // create an ASBD for the user's wants

        memset((void*)(&d_asbd_user), 0, sizeof(d_asbd_user));
        d_asbd_user.mSampleRate = d_output_sample_rate;
        d_asbd_user.mFormatID = kAudioFormatLinearPCM;
        d_asbd_user.mFormatFlags =
            (kLinearPCMFormatFlagIsFloat | GR_PCM_ENDIANNESS |
             kLinearPCMFormatFlagIsPacked | kAudioFormatFlagIsNonInterleaved);
        d_asbd_user.mBytesPerPacket = (UInt32)sizeof(float);
        d_asbd_user.mFramesPerPacket = 1;
        d_asbd_user.mBytesPerFrame = d_asbd_user.mBytesPerPacket;
        d_asbd_user.mChannelsPerFrame = d_n_dev_channels;
        d_asbd_user.mBitsPerChannel = d_asbd_user.mBytesPerPacket * 8;

        // Create the audio converter

        err = AudioConverterNew(&d_asbd_client, &d_asbd_user, &d_audio_converter);
        check_error_and_throw(err, "AudioConverterNew failed", "audio_osx_source::setup");

        // Set the audio converter sample rate quality to "max" ...
        // requires more samples, but should sound nicer

        UInt32 ac_quality = kAudioConverterQuality_Max;
        prop_size = (UInt32)sizeof(ac_quality);
        err = AudioConverterSetProperty(d_audio_converter,
                                        kAudioConverterSampleRateConverterQuality,
                                        prop_size,
                                        &ac_quality);
        check_error_and_throw(
            err, "Set Sample Rate Converter Quality failed", "audio_osx_source::setup");

        // set the audio converter's prime method to "pre",
        // which uses both leading and trailing frames
        // from the "current input".  All of this is handled
        // internally by the AudioConverter; we just supply
        // the frames for conversion.

        UInt32 ac_prime_method = kConverterPrimeMethod_Pre;
        prop_size = (UInt32)sizeof(ac_prime_method);
        err = AudioConverterSetProperty(
            d_audio_converter, kAudioConverterPrimeMethod, prop_size, &ac_prime_method);
        check_error_and_throw(err, "Set Prime Method failed", "audio_osx_source::setup");

        // Get the size of the priming I/O buffer space to allow for
        // pre-allocated buffers

        AudioConverterPrimeInfo ac_prime_info = { 0, 0 };
        prop_size = (UInt32)sizeof(ac_prime_info);
        err = AudioConverterGetProperty(
            d_audio_converter, kAudioConverterPrimeInfo, &prop_size, &ac_prime_info);
        check_error_and_throw(err, "Get Prime Info failed", "audio_osx_source::setup");

        d_lead_size_frames = ac_prime_info.leadingFrames;
        d_trail_size_frames = ac_prime_info.trailingFrames;
    }

    d_lead_size_bytes = d_lead_size_frames * sizeof(float);
    d_trail_size_bytes = d_trail_size_frames * sizeof(float);

    prop_size = (UInt32)sizeof(d_device_buffer_size_frames);
    err = AudioUnitGetProperty(d_input_au,
                               kAudioDevicePropertyBufferFrameSize,
                               kAudioUnitScope_Global,
                               0,
                               &d_device_buffer_size_frames,
                               &prop_size);
    check_error_and_throw(err, "Get Buffer Frame Size failed", "audio_osx_source::setup");

    d_device_buffer_size_bytes = (d_device_buffer_size_frames * sizeof(float));
    d_input_buffer_size_bytes = (d_device_buffer_size_bytes + d_lead_size_bytes);
    d_input_buffer_size_frames = (d_device_buffer_size_frames + d_lead_size_frames);

    // outBufSizeBytes = floor (inBufSizeBytes * rate_out / rate_in)
    // since this is rarely exact, we need another buffer to hold
    // "extra" samples not processed at any given sampling period
    // this buffer must be at least 4 floats in size, but generally
    // follows the rule that
    // extraBufSize =  ceil (rate_in / rate_out)*sizeof(float)

    d_extra_buffer_size_frames =
        ((UInt32)ceil(d_device_sample_rate / d_output_sample_rate) * sizeof(float));
    if (d_extra_buffer_size_frames < 4)
        d_extra_buffer_size_frames = 4;
    d_extra_buffer_size_bytes = d_extra_buffer_size_frames * sizeof(float);

    d_output_buffer_size_frames =
        (UInt32)ceil(((Float64)d_input_buffer_size_frames) * d_output_sample_rate /
                     d_device_sample_rate);
    d_output_buffer_size_bytes = d_output_buffer_size_frames * sizeof(float);
    d_input_buffer_size_frames += d_extra_buffer_size_frames;

    // pre-alloc all CoreAudio buffers

    alloc_audio_buffer_list(&d_input_buffer, d_n_dev_channels, d_input_buffer_size_bytes);
    if (!d_pass_through) {
        alloc_audio_buffer_list(
            &d_output_buffer, d_n_dev_channels, d_output_buffer_size_bytes);
    } else {
        d_output_buffer = d_input_buffer;
    }

    // allocate the output circular buffer(s), one per device
    // channel (the user may select fewer channels; those buffers
    // just won't get used).

    d_buffers.resize(d_n_dev_channels);
    for (UInt32 nn = 0; nn < d_n_dev_channels; ++nn) {
        d_buffers[nn] = new circular_buffer<float>(d_buffer_sample_count, false, false);
    }

    // clear the RunLoop (whatever that is); needed, for some
    // reason, before a listener will work.

    {
        CFRunLoopRef the_run_loop = NULL;
        AudioObjectPropertyAddress property = { kAudioHardwarePropertyRunLoop,
                                                kAudioObjectPropertyScopeGlobal,
                                                kAudioObjectPropertyElementMaster };
        prop_size = (UInt32)sizeof(the_run_loop);
        err = AudioObjectSetPropertyData(
            kAudioObjectSystemObject, &property, 0, NULL, prop_size, &the_run_loop);
        check_error(err,
                    "Clearing RunLoop failed; "
                    "Audio Input Device Listener might not work.");
    }

    // set up listeners

    {

        // set up a listener if hardware changes (at all)

        AudioObjectPropertyAddress property = { kAudioHardwarePropertyDevices,
                                                kAudioObjectPropertyScopeGlobal,
                                                kAudioObjectPropertyElementMaster };

        err = AudioObjectAddPropertyListener(
            kAudioObjectSystemObject,
            &property,
            reinterpret_cast<AudioObjectPropertyListenerProc>(
                &osx_source::hardware_listener),
            reinterpret_cast<void*>(this));
        check_error(err, "Adding Audio Hardware Listener failed");
    }

    if (d_using_default_device) {

        // set up a listener if default hardware input device changes

        AudioObjectPropertyAddress property = { kAudioHardwarePropertyDefaultInputDevice,
                                                kAudioObjectPropertyScopeGlobal,
                                                kAudioObjectPropertyElementMaster };

        err = AudioObjectAddPropertyListener(
            kAudioObjectSystemObject,
            &property,
            reinterpret_cast<AudioObjectPropertyListenerProc>(
                &osx_source::default_listener),
            reinterpret_cast<void*>(this));
        check_error(err, "Adding Default Input Audio Listener failed");
    }

    // initialize the AU for input, so that it is ready to be used

    err = AudioUnitInitialize(d_input_au);
    check_error_and_throw(err, "AudioUnitInitialize", "audio_osx_source::check_channels");

#if _OSX_AU_DEBUG_
    d_debug_logger->debug(R"EOF(
audio_osx_source Parameters:
  Device Sample Rate is {:d}
  Client Sample Rate is {:d}
  User Sample Rate is {:d}
  Do Passthrough is {:s}
  Max Sample Count is {:d}
  # Device Channels is {:d}
  Device Buffer Size in Frames = {:d}
  Lead Size in Frames = {:d}
  Trail Size in Frames = {:d}
  Input Buffer Size in Frames = {:d}
  Output Buffer Size in Frames = {:d}
)EOF",
                          d_device_sample_rate,
                          d_pass_through ? d_output_sample_rate : d_device_sample_rate,
                          d_output_sample_rate,
                          d_pass_through ? "true" : "false",
                          d_buffer_sample_count,
                          d_n_dev_channels,
                          d_device_buffer_size_frames,
                          d_lead_size_frames,
                          d_trail_size_frames,
                          d_input_buffer_size_frames,
                          d_output_buffer_size_frames);
#endif
}

void osx_source::alloc_audio_buffer_list(AudioBufferList** t_abl,
                                         UInt32 n_channels,
                                         UInt32 input_buffer_size_bytes)
{
    free_audio_buffer_list(t_abl);
    UInt32 prop_size =
        (offsetof(AudioBufferList, mBuffers[0]) + (sizeof(AudioBuffer) * n_channels));
    *t_abl = (AudioBufferList*)calloc(1, prop_size);
    (*t_abl)->mNumberBuffers = n_channels;

    int counter = n_channels;

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("alloc_audio_buffer_list: (#chan, #bytes) == ({:d}, {:d})",
                          n_channels,
                          input_buffer_size_bytes);
#endif

    while (--counter >= 0) {
        AudioBuffer* t_ab = &((*t_abl)->mBuffers[counter]);
        t_ab->mNumberChannels = 1;
        t_ab->mDataByteSize = input_buffer_size_bytes;
        t_ab->mData = calloc(1, input_buffer_size_bytes);
    }
}

void osx_source::free_audio_buffer_list(AudioBufferList** t_abl)
{
    // free pre-allocated audio buffer, if it exists
    if (*t_abl) {
        int counter = (*t_abl)->mNumberBuffers;
        while (--counter >= 0) {
            AudioBuffer* t_ab = &((*t_abl)->mBuffers[counter]);
            free(t_ab->mData);
            t_ab->mData = 0;
        }
        free(*t_abl);
        (*t_abl) = 0;
    }
}

bool osx_source::is_running()
{
    UInt32 au_running = 0;
    if (d_input_au) {

        UInt32 prop_size = (UInt32)sizeof(au_running);
        OSStatus err = AudioUnitGetProperty(d_input_au,
                                            kAudioOutputUnitProperty_IsRunning,
                                            kAudioUnitScope_Global,
                                            0,
                                            &au_running,
                                            &prop_size);
        check_error_and_throw(
            err, "AudioUnitGetProperty IsRunning", "audio_osx_source::is_running");
    }

    return (au_running != 0);
}

bool osx_source::start()
{
#if _OSX_AU_DEBUG_
    d_debug_logger->debug("{:p} : audio_osx_source::start: Starting.",
                          (void*)pthread_self());
#endif

    if ((!is_running()) && d_input_au) {

#if _OSX_AU_DEBUG_
        d_debug_logger->debug("{:p} : audio_osx_source::start: Starting Audio Unit.",
                              (void*)pthread_self());
#endif

        // reset buffers before starting

        for (UInt32 nn = 0; nn < d_buffers.size(); ++nn) {
            d_buffers[nn]->reset();
        }

        // start the audio unit

        OSStatus err = AudioOutputUnitStart(d_input_au);
        check_error_and_throw(err, "AudioOutputUnitStart", "audio_osx_source::start");

        // clear reset (will sometimes be necessary, and it has to
        // happen after AudioOutputUnitStart)

        d_do_reset = false;
    }

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("{:p} : audio_osx_source::start: Returning.",
                          (void*)pthread_self());

#endif

    return (true);
}

bool osx_source::stop()
{
#if _OSX_AU_DEBUG_
    d_debug_logger->debug("{:p} : audio_osx_source::stop: Starting.",
                          (void*)pthread_self());
#endif
    if (is_running()) {

#if _OSX_AU_DEBUG_
        d_debug_logger->debug("{:p} : audio_osx_source::stop: stopping audio unit.",
                              (void*)pthread_self());
#endif

        // stop the audio unit

        OSStatus err = AudioOutputUnitStop(d_input_au);
        check_error_and_throw(err, "AudioOutputUnitStart", "audio_osx_source::stop");

        // abort all buffers

        for (UInt32 nn = 0; nn < d_n_user_channels; ++nn) {
            d_buffers[nn]->abort();
        }
    }

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("{:p} : audio_osx_source::stop: Returning.",
                          (void*)pthread_self());
#endif

    return (true);
}

void osx_source::teardown()
{
#if _OSX_AU_DEBUG_
    d_debug_logger->debug("{:p} : audio_osx_source::teardown: Starting.",
                          (void*)pthread_self());
#endif

    OSStatus err = noErr;

    // stop the AudioUnit

    stop();

    // remove the listeners

    {
        AudioObjectPropertyAddress property = { kAudioHardwarePropertyDevices,
                                                kAudioObjectPropertyScopeGlobal,
                                                kAudioObjectPropertyElementMaster };

        err = AudioObjectRemovePropertyListener(
            kAudioObjectSystemObject,
            &property,
            reinterpret_cast<AudioObjectPropertyListenerProc>(
                &osx_source::hardware_listener),
            reinterpret_cast<void*>(this));
#if _OSX_AU_DEBUG_
        check_error(err,
                    "teardown: AudioObjectRemovePropertyListener "
                    "hardware failed");
#endif
    }

    if (d_using_default_device) {

        AudioObjectPropertyAddress property = { kAudioHardwarePropertyDefaultInputDevice,
                                                kAudioObjectPropertyScopeGlobal,
                                                kAudioObjectPropertyElementMaster };

        err = AudioObjectRemovePropertyListener(
            kAudioObjectSystemObject,
            &property,
            reinterpret_cast<AudioObjectPropertyListenerProc>(
                &osx_source::default_listener),
            reinterpret_cast<void*>(this));
#if _OSX_AU_DEBUG_
        check_error(err, "AudioObjectRemovePropertyListener default");
#endif

        d_using_default_device = false;
    }

    // free pre-allocated audio buffers
    free_audio_buffer_list(&d_input_buffer);

    if (!d_pass_through) {
        err = AudioConverterDispose(d_audio_converter);
#if _OSX_AU_DEBUG_
        check_error(err, "~audio_osx_source: AudioConverterDispose");
#endif
        free_audio_buffer_list(&d_output_buffer);
    }

    // remove the audio unit
    err = AudioUnitUninitialize(d_input_au);
#if _OSX_AU_DEBUG_
    check_error(err, "~audio_osx_source: AudioUnitUninitialize");
#endif

    err = AudioComponentInstanceDispose(d_input_au);
#if _OSX_AU_DEBUG_
    check_error(err, "~audio_osx_source: AudioComponentInstanceDispose");
#endif

    // empty and delete the queues

    for (UInt32 nn = 0; nn < d_buffers.size(); ++nn) {
        delete d_buffers[nn];
        d_buffers[nn] = 0;
    }
    d_buffers.resize(0);

    // clear important variables; not # user channels

    d_queue_sample_count = 0;
    d_device_sample_rate = 0;
    d_n_dev_channels = 0;
    d_input_ad_id = 0;
    d_input_au = 0;
    d_input_buffer = d_output_buffer = 0;
    d_audio_converter = 0;
    d_using_default_device = false;

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("{:p} : audio_osx_source::teardown: Returning.",
                          (void*)pthread_self());
#endif
}

bool osx_source::check_topology(int ninputs, int noutputs)
{
    // check # inputs to make sure it's valid
    if (ninputs != 0) {

        d_logger->fatal("check_topology(): number of input "
                        "streams provided ({:d}) should be 0.",
                        ninputs);
        throw std::runtime_error("audio_osx_source::check_topology");
    }

    // check # outputs to make sure it's valid
    if ((noutputs < 1) | (noutputs > (int)d_n_dev_channels)) {

        d_logger->fatal("check_topology(): number of output "
                        "streams provided ({:d}) should be in [1,{:d}] "
                        "for the selected input audio device.",
                        noutputs,
                        d_n_dev_channels);
        throw std::runtime_error("audio_osx_source::check_topology");
    }

    // save the actual number of output (user) channels

    d_n_user_channels = noutputs;

#if _OSX_AU_DEBUG_
    d_debug_logger->debug("chk_topo: Actual # user output channels = {:d}", noutputs);
#endif

    return (true);
}

int osx_source::work(int noutput_items,
                     gr_vector_const_void_star& input_items,
                     gr_vector_void_star& output_items)
{
#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("{:p} : audio_osx_source::work: Starting.",
                          (void*)pthread_self());
#endif
    if (d_do_reset) {
        if (d_hardware_changed) {

            // see if the current AudioDeviceID is still available

            std::vector<AudioDeviceID> all_ad_ids;
            osx::find_audio_devices(d_desired_name, true, &all_ad_ids, NULL);
            bool found = false;
            for (UInt32 nn = 0; (nn < all_ad_ids.size()) && (!found); ++nn) {
                found = (all_ad_ids[nn] == d_input_ad_id);
            }
            if (!found) {

                d_logger->fatal("The selected input audio device ('{:s}') "
                                "is no longer available.\n",
                                d_selected_name);
                return (gr::block::WORK_DONE);
            }

            d_do_reset = d_hardware_changed = false;

        } else {

#if _OSX_AU_DEBUG_RENDER_
            d_debug_logger->debug("audio_osx_source::work: doing reset.");
#endif

            d_logger->warn("\n\nThe default input audio device has "
                           "changed; resetting audio.\nThere may "
                           "be a sound glitch while resetting.\n");

            // for any changes, just tear down the current
            // configuration, then set it up again using the user's
            // parameters to try to make selections.

            teardown();

            gr::thread::scoped_lock l(d_internal);

#if _OSX_AU_DEBUG_RENDER_
            d_debug_logger->debug("audio_osx_source::work: mutex locked.");
#endif

            setup();
            start();

#if _OSX_AU_DEBUG_RENDER_
            d_debug_logger->debug("audio_osx_source::work: returning after reset.");
#endif
            return (0);
        }
    }

    gr::thread::scoped_lock l(d_internal);

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("audio_osx_source::work: mutex locked.");

    d_debug_logger->debug("work1: SC={:d}, #OI={:d}, #Chan={:d}",
                          d_queue_sample_count,
                          noutput_items,
                          output_items.size());
#endif

    // set the actual # of output items to the 'desired' amount then
    // verify that data is available; if not enough data is
    // available, either wait until it is (is "ok_to_block" is
    // true), return (0) is no data is available and "ok_to_block"
    // is false, or process the actual amount of available data.

    UInt32 actual_noutput_items = noutput_items;

    if (d_queue_sample_count < actual_noutput_items) {
        if (d_queue_sample_count == 0) {
            // no data; ok_to_block decides what to do
            if (d_ok_to_block == true) {
                // block until there is data to return, or on reset
                while (d_queue_sample_count == 0) {
                    // release control so-as to allow data to be retrieved;
                    // block until there is data to return
#if _OSX_AU_DEBUG_RENDER_
                    d_debug_logger->debug("audio_osx_source::work: waiting.");
#endif
                    d_waiting_for_data = true;
                    d_cond_data.wait(l);
                    d_waiting_for_data = false;
#if _OSX_AU_DEBUG_RENDER_
                    d_debug_logger->debug("audio_osx_source::work: done waiting.");
#endif
                    // the condition's 'notify' was called; acquire control to
                    // keep thread safe

                    // if doing a reset, just return here; reset will pick
                    // up the next time this method is called.
                    if (d_do_reset) {
#if _OSX_AU_DEBUG_RENDER_
                        d_debug_logger->debug(
                            "audio_osx_source::work: returning for reset.");
#endif
                        return (0);
                    }
                }
            } else {
                // no data & not blocking; return nothing
#if _OSX_AU_DEBUG_RENDER_
                d_debug_logger->debug(
                    "audio_osx_source::work: no data & not blocking; returning 0.");
#endif
                return (0);
            }
        }

        // use the actual amount of available data
        actual_noutput_items = d_queue_sample_count;
    }

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("audio_osx_source::work: copying {:d} items per channel",
                          actual_noutput_items);
#endif

    // number of channels
    int l_counter = (int)output_items.size();

    // copy the items from the circular buffer(s) to 'work's output
    // buffers; verify that the number copied out is as expected.

    while (--l_counter >= 0) {

        size_t t_n_output_items = actual_noutput_items;
        d_buffers[l_counter]->dequeue((float*)output_items[l_counter], &t_n_output_items);

        if (t_n_output_items != actual_noutput_items) {

            d_logger->fatal("work(): ERROR: number of available "
                            "items changing unexpectedly; expecting {:d}, got {:d}.",
                            actual_noutput_items,
                            t_n_output_items);
            throw std::runtime_error("audio_osx_source::work()");
        }
    }

    // subtract the actual number of items removed from the buffer(s)
    // from the local accounting of the number of available samples

    d_queue_sample_count -= actual_noutput_items;

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("work2: SC = {:d}, act#OI = {:d}\nReturning.",
                          d_queue_sample_count,
                          actual_noutput_items);
#endif
#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("audio_osx_source::work: returning.");
#endif

    return (actual_noutput_items);
}

OSStatus osx_source::converter_callback(AudioConverterRef in_audio_converter,
                                        UInt32* io_number_data_packets,
                                        AudioBufferList* io_data,
                                        AudioStreamPacketDescription** out_aspd,
                                        void* in_user_data)
{
    // This callback is for us to provide the buffers to CoreAudio
    // for conversion.  We need to set the buffers in the provided
    // buffer list (io_data) to the buffers we know about and use to
    // do data input (d_input_buffers).

    osx_source* This = static_cast<osx_source*>(in_user_data);
    AudioBufferList* l_input_abl = This->d_input_buffer;
    UInt32 total_input_buffer_size_bytes = ((*io_number_data_packets) * sizeof(float));
    int counter = This->d_n_dev_channels;
    io_data->mNumberBuffers = This->d_n_dev_channels;
    This->d_n_actual_input_frames = (*io_number_data_packets);

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("cc1: io#DP = {:d}, TIBSB = {:d}, #C = {:d}",
                          *io_number_data_packets,
                          total_input_buffer_size_bytes,
                          counter);
#endif

    while (--counter >= 0) {
        AudioBuffer* t_ab = &(io_data->mBuffers[counter]);
        t_ab->mNumberChannels = 1;
        t_ab->mData = l_input_abl->mBuffers[counter].mData;
        t_ab->mDataByteSize = total_input_buffer_size_bytes;
    }

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("cc2: Returning.");
#endif

    return (noErr);
}

OSStatus osx_source::au_input_callback(void* in_ref_con,
                                       AudioUnitRenderActionFlags* io_action_flags,
                                       const AudioTimeStamp* in_time_stamp,
                                       UInt32 in_bus_number,
                                       UInt32 in_number_frames,
                                       AudioBufferList* io_data)
{
#if _OSX_AU_DEBUG_RENDER_
    // This->d_debug_logger->debug("{:p} : audio_osx_source::au_input_callback:
    //                             Starting.",
    //                             (void*)pthread_self());
#endif

    osx_source* This = reinterpret_cast<osx_source*>(in_ref_con);
    gr::thread::scoped_lock l(This->d_internal);
    gr::logger_ptr d_logger = This->d_logger;
    gr::logger_ptr d_debug_logger = This->d_debug_logger;

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("audio_osx_source::au_input_callback: mutex locked.");
#endif

    OSStatus err = noErr;

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("cb0: in#Fr = {:d}, inBus# = {:d}, idD = {:p}, d_ib = {:p}, "
                          "d_ib#c = {:d}, SC = {:d}",
                          in_number_frames,
                          in_bus_number,
                          (void*)io_data,
                          (void*)(This->d_input_buffer),
                          This->d_input_buffer->mNumberBuffers,
                          This->d_queue_sample_count);
#endif

    if (This->d_do_reset) {

        // clear audio data; do not render since it will generate an error

        AudioBufferList* t_abl = This->d_input_buffer;
        for (UInt32 nn = 0; nn < t_abl->mNumberBuffers; ++nn) {
            AudioBuffer* t_ab = &(t_abl->mBuffers[nn]);
            memset(t_ab->mData,
                   0,
                   (size_t)((t_ab->mDataByteSize) * (t_ab->mNumberChannels)));
        }
    } else {

        // Get the new audio data from the input device

        err = AudioUnitRender(This->d_input_au,
                              io_action_flags,
                              in_time_stamp,
                              1, // inBusNumber,
                              in_number_frames,
                              This->d_input_buffer);
        check_error_and_throw(
            err, "AudioUnitRender", "audio_osx_source::au_input_callback");
    }

    UInt32 available_input_frames = This->d_n_available_input_frames = in_number_frames;

    // get the number of actual output frames,
    // either via converting the buffer or not

    UInt32 actual_output_frames = available_input_frames;

    if (!This->d_pass_through) {
        UInt32 available_input_bytes = available_input_frames * sizeof(float);
        UInt32 available_output_bytes = available_input_bytes;
        UInt32 prop_size = sizeof(available_output_bytes);
        err = AudioConverterGetProperty(This->d_audio_converter,
                                        kAudioConverterPropertyCalculateOutputBufferSize,
                                        &prop_size,
                                        &available_output_bytes);
        check_error_and_throw(
            err, "Get Output Buffer Size failed", "audio_osx_source::au_input_callback");

        UInt32 available_output_frames = available_output_bytes / sizeof(float);

#if 0
        // when decimating too much, the output sounds warbly due to
        // fluctuating # of output frames
        // This should not be a surprise, but there's probably some
        // clever programming that could lessed the effect ...
        // like finding the "ideal" # of output frames, and keeping
        // that number constant no matter the # of input frames

        UInt32 l_input_bytes = available_output_bytes;
        prop_size = sizeof(available_output_bytes);
        err = AudioConverterGetProperty
	  (This->d_audio_converter,
	   kAudioConverterPropertyCalculateInputBufferSize,
	   &prop_size, &l_input_bytes);
        check_error_and_throw
	  (err, "Get Input Buffer Size failed",
	   "audio_osx_source::au_input_callback");

        if(l_input_bytes < available_input_bytes) {
          // OK to zero pad the input a little
          ++available_output_frames;
          available_output_bytes = available_output_frames * sizeof(float);
        }

#endif

#if _OSX_AU_DEBUG_RENDER_
        d_debug_logger->debug("cb1:  avail: #IF = {:d}, #OF = {:d}",
                              available_input_frames,
                              available_output_frames);
#endif
        actual_output_frames = available_output_frames;

        // convert the data to the correct rate; on input,
        // actual_output_frames is the number of available output frames

        err = AudioConverterFillComplexBuffer(
            This->d_audio_converter,
            reinterpret_cast<AudioConverterComplexInputDataProc>(
                &(This->converter_callback)),
            in_ref_con,
            &actual_output_frames,
            This->d_output_buffer,
            NULL);
        check_error_and_throw(err,
                              "AudioConverterFillComplexBuffer failed",
                              "audio_osx_source::au_input_callback");

        // on output, actual_output_frames is the actual number of
        // output frames

#if _OSX_AU_DEBUG_RENDER_
        d_debug_logger->debug("cb2: actual: #IF = {:d}, #OF = {:d}",
                              This->d_n_actual_input_frames,
                              actual_output_frames);

        if (This->d_n_actual_input_frames != available_input_frames)
            d_debug_logger->warn("cb2.1: (avail#IF = {:d}) != (actual#IF = {:d})",
                                 available_input_frames,
                                 This->d_n_actual_input_frames);
#endif
    }

    // add the output frames to the buffers' queue, checking for overflow

    int counter = This->d_n_user_channels;
    int res = 0;

    while (--counter >= 0) {
        float* in_buffer = (float*)This->d_output_buffer->mBuffers[counter].mData;

#if _OSX_AU_DEBUG_RENDER_
        d_debug_logger->debug("cb3: enqueuing audio data.");
#endif

        int l_res = This->d_buffers[counter]->enqueue(in_buffer, actual_output_frames);
        if (l_res == -1)
            res = -1;
    }

    if (res == -1) {
        // data coming in too fast
        // drop oldest buffer
        fputs("aO", stderr);
        fflush(stderr);
        // set the local number of samples available to the max
        This->d_queue_sample_count = This->d_buffers[0]->buffer_length_items();
    } else {
        // keep up the local sample count
        This->d_queue_sample_count += actual_output_frames;
    }

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("cb4: #OI = {:d}, #Cnt = {:d}, mSC = {:d}",
                          actual_output_frames,
                          This->d_queue_sample_count,
                          This->d_buffer_sample_count);
#endif

    // signal that data is available, if appropriate

    if (This->d_waiting_for_data) {
        This->d_cond_data.notify_one();
    }

#if _OSX_AU_DEBUG_RENDER_
    d_debug_logger->debug("cb5: returning.");
#endif

    return (err);
}

OSStatus osx_source::hardware_listener(AudioObjectID in_object_id,
                                       UInt32 in_num_addresses,
                                       const AudioObjectPropertyAddress in_addresses[],
                                       void* in_client_data)
{
    osx_source* This = reinterpret_cast<osx_source*>(in_client_data);
    This->reset(true);
    return (noErr);
}

OSStatus osx_source::default_listener(AudioObjectID in_object_id,
                                      UInt32 in_num_addresses,
                                      const AudioObjectPropertyAddress in_addresses[],
                                      void* in_client_data)
{
    osx_source* This = reinterpret_cast<osx_source*>(in_client_data);
    This->reset(false);
    return (noErr);
}

} /* namespace audio */
} /* namespace gr */