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How to use compressed input audio

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Reference documentation | Package (NuGet) | Additional samples on GitHub

The Speech SDK and Speech CLI use GStreamer to support different kinds of input audio formats. GStreamer decompresses the audio before it's sent over the wire to the Speech service as raw PCM.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). Outside WAV and PCM, the following compressed input formats are also supported through GStreamer:

  • MP3
  • OPUS/OGG
  • FLAC
  • ALAW in WAV container
  • MULAW in WAV container
  • ANY for MP4 container or unknown media format

GStreamer configuration

The Speech SDK can use GStreamer to handle compressed audio. For licensing reasons, GStreamer binaries aren't compiled and linked with the Speech SDK. You need to install some dependencies and plug-ins.

GStreamer binaries must be in the system path so that they can be loaded by the Speech SDK at runtime. For example, on Windows, if the Speech SDK finds libgstreamer-1.0-0.dll or gstreamer-1.0-0.dll (for the latest GStreamer) during runtime, it means the GStreamer binaries are in the system path.

Choose a platform for installation instructions.

You need to install several dependencies and plug-ins.

sudo apt install libgstreamer1.0-0 \
gstreamer1.0-plugins-base \
gstreamer1.0-plugins-good \
gstreamer1.0-plugins-bad \
gstreamer1.0-plugins-ugly

For more information, see Linux installation instructions and supported Linux distributions and target architectures.

Example

To configure the Speech SDK to accept compressed audio input, create PullAudioInputStream or PushAudioInputStream. Then, create an AudioConfig from an instance of your stream class that specifies the compression format of the stream. Find related sample code snippets in About the Speech SDK audio input stream API.

Let's assume that you have an input stream class called pullStream and are using OPUS/OGG. Your code might look like this:

using Microsoft.CognitiveServices.Speech;
using Microsoft.CognitiveServices.Speech.Audio;

// ... omitted for brevity

var speechConfig =
    SpeechConfig.FromSubscription(
        "YourSubscriptionKey",
        "YourServiceRegion");

// Create an audio config specifying the compressed
// audio format and the instance of your input stream class.
var pullStream = AudioInputStream.CreatePullStream(
    AudioStreamFormat.GetCompressedFormat(AudioStreamContainerFormat.OGG_OPUS));
var audioConfig = AudioConfig.FromStreamInput(pullStream);

using var recognizer = new SpeechRecognizer(speechConfig, audioConfig);
var result = await recognizer.RecognizeOnceAsync();

var text = result.Text;

Reference documentation | Package (NuGet) | Additional samples on GitHub

The Speech SDK and Speech CLI use GStreamer to support different kinds of input audio formats. GStreamer decompresses the audio before it's sent over the wire to the Speech service as raw PCM.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). Outside WAV and PCM, the following compressed input formats are also supported through GStreamer:

  • MP3
  • OPUS/OGG
  • FLAC
  • ALAW in WAV container
  • MULAW in WAV container
  • ANY for MP4 container or unknown media format

GStreamer configuration

The Speech SDK can use GStreamer to handle compressed audio. For licensing reasons, GStreamer binaries aren't compiled and linked with the Speech SDK. You need to install some dependencies and plug-ins.

GStreamer binaries must be in the system path so that they can be loaded by the Speech SDK at runtime. For example, on Windows, if the Speech SDK finds libgstreamer-1.0-0.dll or gstreamer-1.0-0.dll (for the latest GStreamer) during runtime, it means the GStreamer binaries are in the system path.

Choose a platform for installation instructions.

You need to install several dependencies and plug-ins.

sudo apt install libgstreamer1.0-0 \
gstreamer1.0-plugins-base \
gstreamer1.0-plugins-good \
gstreamer1.0-plugins-bad \
gstreamer1.0-plugins-ugly

For more information, see Linux installation instructions and supported Linux distributions and target architectures.

Example

To configure the Speech SDK to accept compressed audio input, create PullAudioInputStream or PushAudioInputStream. Then, create an AudioConfig from an instance of your stream class that specifies the compression format of the stream. Find related sample code in Speech SDK samples.

Let's assume that you have an input stream class called pushStream and are using OPUS/OGG. Your code might look like this:

using namespace Microsoft::CognitiveServices::Speech;
using namespace Microsoft::CognitiveServices::Speech::Audio;

// ... omitted for brevity

 auto config =
    SpeechConfig::FromSubscription(
        "YourSubscriptionKey",
        "YourServiceRegion"
    );

// Create an audio config specifying the compressed
// audio format and the instance of your input stream class.
auto pullStream = AudioInputStream::CreatePullStream(
    AudioStreamFormat::GetCompressedFormat(AudioStreamContainerFormat::OGG_OPUS));
auto audioConfig = AudioConfig::FromStreamInput(pullStream);

auto recognizer = SpeechRecognizer::FromConfig(config, audioConfig);
auto result = recognizer->RecognizeOnceAsync().get();

auto text = result->Text;

Reference documentation | Package (Go) | Additional samples on GitHub

The Speech SDK and Speech CLI use GStreamer to support different kinds of input audio formats. GStreamer decompresses the audio before it's sent over the wire to the Speech service as raw PCM.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). Outside WAV and PCM, the following compressed input formats are also supported through GStreamer:

  • MP3
  • OPUS/OGG
  • FLAC
  • ALAW in WAV container
  • MULAW in WAV container
  • ANY for MP4 container or unknown media format

GStreamer configuration

The Speech SDK can use GStreamer to handle compressed audio. For licensing reasons, GStreamer binaries aren't compiled and linked with the Speech SDK. You need to install some dependencies and plug-ins.

You need to install several dependencies and plug-ins.

sudo apt install libgstreamer1.0-0 \
gstreamer1.0-plugins-base \
gstreamer1.0-plugins-good \
gstreamer1.0-plugins-bad \
gstreamer1.0-plugins-ugly

For more information, see Linux installation instructions and supported Linux distributions and target architectures.

Example

To configure the Speech SDK to accept compressed audio input, create a PullAudioInputStream or PushAudioInputStream. Then, create an AudioConfig from an instance of your stream class that specifies the compression format of the stream.

In the following example, let's assume that your use case is to use PushStream for a compressed file.


package recognizer

import (
  "fmt"
  "time"
    "strings"

  "github.com/Microsoft/cognitive-services-speech-sdk-go/audio"
  "github.com/Microsoft/cognitive-services-speech-sdk-go/speech"
  "github.com/Microsoft/cognitive-services-speech-sdk-go/samples/helpers"
)

func RecognizeOnceFromCompressedFile(subscription string, region string, file string) {
  var containerFormat audio.AudioStreamContainerFormat
  if strings.Contains(file, ".mulaw") {
    containerFormat = audio.MULAW
  } else if strings.Contains(file, ".alaw") {
    containerFormat = audio.ALAW
  } else if strings.Contains(file, ".mp3") {
    containerFormat = audio.MP3
  } else if strings.Contains(file, ".flac") {
    containerFormat = audio.FLAC
  } else if strings.Contains(file, ".opus") {
    containerFormat = audio.OGGOPUS
  } else {
    containerFormat = audio.ANY
  }
  format, err := audio.GetCompressedFormat(containerFormat)
  if err != nil {
    fmt.Println("Got an error: ", err)
    return
  }
  defer format.Close()
  stream, err := audio.CreatePushAudioInputStreamFromFormat(format)
  if err != nil {
    fmt.Println("Got an error: ", err)
    return
  }
  defer stream.Close()
  audioConfig, err := audio.NewAudioConfigFromStreamInput(stream)
  if err != nil {
    fmt.Println("Got an error: ", err)
    return
  }
  defer audioConfig.Close()
  config, err := speech.NewSpeechConfigFromSubscription(subscription, region)
  if err != nil {
    fmt.Println("Got an error: ", err)
    return
  }
  defer config.Close()
  speechRecognizer, err := speech.NewSpeechRecognizerFromConfig(config, audioConfig)
  if err != nil {
    fmt.Println("Got an error: ", err)
    return
  }
  defer speechRecognizer.Close()
  speechRecognizer.SessionStarted(func(event speech.SessionEventArgs) {
    defer event.Close()
    fmt.Println("Session Started (ID=", event.SessionID, ")")
  })
  speechRecognizer.SessionStopped(func(event speech.SessionEventArgs) {
    defer event.Close()
    fmt.Println("Session Stopped (ID=", event.SessionID, ")")
  })
  helpers.PumpFileIntoStream(file, stream)
  task := speechRecognizer.RecognizeOnceAsync()
  var outcome speech.SpeechRecognitionOutcome
  select {
  case outcome = <-task:
  case <-time.After(40 * time.Second):
    fmt.Println("Timed out")
    return
  }
  defer outcome.Close()
  if outcome.Error != nil {
    fmt.Println("Got an error: ", outcome.Error)
  }
  fmt.Println("Got a recognition!")
  fmt.Println(outcome.Result.Text)
}

Reference documentation | Additional samples on GitHub

The Speech SDK and Speech CLI use GStreamer to support different kinds of input audio formats. GStreamer decompresses the audio before it's sent over the wire to the Speech service as raw PCM.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). Outside WAV and PCM, the following compressed input formats are also supported through GStreamer:

  • MP3
  • OPUS/OGG
  • FLAC
  • ALAW in WAV container
  • MULAW in WAV container
  • ANY for MP4 container or unknown media format

GStreamer configuration

The Speech SDK can use GStreamer to handle compressed audio. For licensing reasons, GStreamer binaries aren't compiled and linked with the Speech SDK. You need to install some dependencies and plug-ins.

GStreamer binaries must be in the system path so that they can be loaded by the Speech SDK at runtime. For example, on Windows, if the Speech SDK finds libgstreamer-1.0-0.dll or gstreamer-1.0-0.dll (for the latest GStreamer) during runtime, it means the GStreamer binaries are in the system path.

Choose a platform for installation instructions.

Handling compressed audio is implemented by using GStreamer. For licensing reasons, GStreamer binaries aren't compiled and linked with the Speech SDK. Instead, you need to use the prebuilt binaries for Android. To download the prebuilt libraries, see Installing for Android development.

The libgstreamer_android.so object is required. Make sure that all the GStreamer plug-ins (from the Android.mk file that follows) are linked in libgstreamer_android.so. When you use the Speech SDK with GStreamer version 1.18.3, libc++_shared.so is also required to be present from android ndk.

GSTREAMER_PLUGINS := coreelements app audioconvert mpg123 \
    audioresample audioparsers ogg opusparse \
    opus wavparse alaw mulaw flac

An example Android.mk and Application.mk file are provided here. Follow these steps to create the gstreamer shared object:libgstreamer_android.so.

# Android.mk
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := dummy
LOCAL_SHARED_LIBRARIES := gstreamer_android
include $(BUILD_SHARED_LIBRARY)

ifndef GSTREAMER_ROOT_ANDROID
$(error GSTREAMER_ROOT_ANDROID is not defined!)
endif

ifndef APP_BUILD_SCRIPT
$(error APP_BUILD_SCRIPT is not defined!)
endif

ifndef TARGET_ARCH_ABI
$(error TARGET_ARCH_ABI is not defined!)
endif

ifeq ($(TARGET_ARCH_ABI),armeabi)
GSTREAMER_ROOT        := $(GSTREAMER_ROOT_ANDROID)/arm
else ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
GSTREAMER_ROOT        := $(GSTREAMER_ROOT_ANDROID)/armv7
else ifeq ($(TARGET_ARCH_ABI),arm64-v8a)
GSTREAMER_ROOT        := $(GSTREAMER_ROOT_ANDROID)/arm64
else ifeq ($(TARGET_ARCH_ABI),x86)
GSTREAMER_ROOT        := $(GSTREAMER_ROOT_ANDROID)/x86
else ifeq ($(TARGET_ARCH_ABI),x86_64)
GSTREAMER_ROOT        := $(GSTREAMER_ROOT_ANDROID)/x86_64
else
$(error Target arch ABI not supported: $(TARGET_ARCH_ABI))
endif

GSTREAMER_NDK_BUILD_PATH  := $(GSTREAMER_ROOT)/share/gst-android/ndk-build/
include $(GSTREAMER_NDK_BUILD_PATH)/plugins.mk
GSTREAMER_PLUGINS         :=  $(GSTREAMER_PLUGINS_CORE) \ 
                              $(GSTREAMER_PLUGINS_CODECS) \ 
                              $(GSTREAMER_PLUGINS_PLAYBACK) \
                              $(GSTREAMER_PLUGINS_CODECS_GPL) \
                              $(GSTREAMER_PLUGINS_CODECS_RESTRICTED)
GSTREAMER_EXTRA_LIBS      := -liconv -lgstbase-1.0 -lGLESv2 -lEGL
include $(GSTREAMER_NDK_BUILD_PATH)/gstreamer-1.0.mk

# Application.mk
APP_STL = c++_shared
APP_PLATFORM = android-21
APP_BUILD_SCRIPT = Android.mk

You can build libgstreamer_android.so by using the following command on Ubuntu 18.04 or 20.04. The following command lines have been tested for [GStreamer Android version 1.14.4] with Android NDK b16b.

# Assuming wget and unzip are already installed on the system
mkdir buildLibGstreamer
cd buildLibGstreamer
wget https://dl.google.com/android/repository/android-ndk-r16b-linux-x86_64.zip
unzip -q -o android-ndk-r16b-linux-x86_64.zip
export PATH=$PATH:$(pwd)/android-ndk-r16b
export NDK_PROJECT_PATH=$(pwd)/android-ndk-r16b
wget https://gstreamer.freedesktop.org/download/
mkdir gstreamer_android
tar -xjf gstreamer-1.0-android-universal-1.14.4.tar.bz2 -C $(pwd)/gstreamer_android/
export GSTREAMER_ROOT_ANDROID=$(pwd)/gstreamer_android

mkdir gstreamer
# Copy the Application.mk and Android.mk from the documentation above and put it inside $(pwd)/gstreamer

# Enable only one of the following at one time to create the shared object for the targeted ABI
echo "building for armeabi-v7a. libgstreamer_android.so will be placed in $(pwd)/armeabi-v7a"
ndk-build -C $(pwd)/gstreamer "NDK_APPLICATION_MK=Application.mk" APP_ABI=armeabi-v7a NDK_LIBS_OUT=$(pwd)

#echo "building for arm64-v8a. libgstreamer_android.so will be placed in $(pwd)/arm64-v8a"
#ndk-build -C $(pwd)/gstreamer "NDK_APPLICATION_MK=Application.mk" APP_ABI=arm64-v8a NDK_LIBS_OUT=$(pwd)

#echo "building for x86_64. libgstreamer_android.so will be placed in $(pwd)/x86_64"
#ndk-build -C $(pwd)/gstreamer "NDK_APPLICATION_MK=Application.mk" APP_ABI=x86_64 NDK_LIBS_OUT=$(pwd)

#echo "building for x86. libgstreamer_android.so will be placed in $(pwd)/x86"
#ndk-build -C $(pwd)/gstreamer "NDK_APPLICATION_MK=Application.mk" APP_ABI=x86 NDK_LIBS_OUT=$(pwd)

After the shared object (libgstreamer_android.so) is built, place the shared object in the Android app so that the Speech SDK can load it.

Example

To configure the Speech SDK to accept compressed audio input, create a PullAudioInputStream or PushAudioInputStream. Then, create an AudioConfig from an instance of your stream class that specifies the compression format of the stream. Find related sample code in Speech SDK samples.

Let's assume that you have an input stream class called pullAudio and are using MP3. Your code might look like this:

String filePath = "whatstheweatherlike.mp3";
PullAudioInputStream pullAudio = AudioInputStream.createPullStream(new BinaryAudioStreamReader(filePath),
    AudioStreamFormat.getCompressedFormat(AudioStreamContainerFormat.MP3));
AudioConfig audioConfig = AudioConfig.fromStreamInput(pullAudio);

Reference documentation | Package (npm) | Additional samples on GitHub | Library source code

The Speech SDK for JavaScript does not support compressed audio.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). To input a compressed audio file (such as mp3), you must first convert it to a WAV file in the default input format. To stream compressed audio, you must first decode the audio buffers to the default input format. For more information, see How to use the audio input stream.

Reference documentation | Package (download) | Additional samples on GitHub

The Speech SDK for Objective-C does not support compressed audio.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). To input a compressed audio file (such as mp3), you must first convert it to a WAV file in the default input format. To stream compressed audio, you must first decode the audio buffers to the default input format. For more information, see How to use the audio input stream.

Reference documentation | Package (download) | Additional samples on GitHub

The Speech SDK for Swift does not support compressed audio.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). To input a compressed audio file (such as mp3), you must first convert it to a WAV file in the default input format. To stream compressed audio, you must first decode the audio buffers to the default input format. For more information, see How to use the audio input stream.

Reference documentation | Package (PyPi) | Additional samples on GitHub

The Speech SDK and Speech CLI use GStreamer to support different kinds of input audio formats. GStreamer decompresses the audio before it's sent over the wire to the Speech service as raw PCM.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). Outside WAV and PCM, the following compressed input formats are also supported through GStreamer:

  • MP3
  • OPUS/OGG
  • FLAC
  • ALAW in WAV container
  • MULAW in WAV container
  • ANY for MP4 container or unknown media format

GStreamer configuration

The Speech SDK can use GStreamer to handle compressed audio. For licensing reasons, GStreamer binaries aren't compiled and linked with the Speech SDK. You need to install some dependencies and plug-ins.

GStreamer binaries must be in the system path so that they can be loaded by the Speech SDK at runtime. For example, on Windows, if the Speech SDK finds libgstreamer-1.0-0.dll or gstreamer-1.0-0.dll (for the latest GStreamer) during runtime, it means the GStreamer binaries are in the system path.

Choose a platform for installation instructions.

You need to install several dependencies and plug-ins.

sudo apt install libgstreamer1.0-0 \
gstreamer1.0-plugins-base \
gstreamer1.0-plugins-good \
gstreamer1.0-plugins-bad \
gstreamer1.0-plugins-ugly

For more information, see Linux installation instructions and supported Linux distributions and target architectures.

Example

To configure the Speech SDK to accept compressed audio input, create PullAudioInputStream or PushAudioInputStream. Then, create an AudioConfig from an instance of your stream class that specifies the compression format of the stream.

Let's assume that your use case is to use PullStream for an MP3 file. Your code might look like this:


import azure.cognitiveservices.speech as speechsdk

class BinaryFileReaderCallback(speechsdk.audio.PullAudioInputStreamCallback):
    def __init__(self, filename: str):
        super().__init__()
        self._file_h = open(filename, "rb")

    def read(self, buffer: memoryview) -> int:
        print('trying to read {} frames'.format(buffer.nbytes))
        try:
            size = buffer.nbytes
            frames = self._file_h.read(size)

            buffer[:len(frames)] = frames
            print('read {} frames'.format(len(frames)))

            return len(frames)
        except Exception as ex:
            print('Exception in `read`: {}'.format(ex))
            raise

    def close(self) -> None:
        print('closing file')
        try:
            self._file_h.close()
        except Exception as ex:
            print('Exception in `close`: {}'.format(ex))
            raise

def compressed_stream_helper(compressed_format,
        mp3_file_path,
        default_speech_auth):
    callback = BinaryFileReaderCallback(mp3_file_path)
    stream = speechsdk.audio.PullAudioInputStream(stream_format=compressed_format, pull_stream_callback=callback)

    speech_config = speechsdk.SpeechConfig(**default_speech_auth)
    audio_config = speechsdk.audio.AudioConfig(stream=stream)

    speech_recognizer = speechsdk.SpeechRecognizer(speech_config=speech_config, audio_config=audio_config)

    done = False

    def stop_cb(evt):
        """callback that signals to stop continuous recognition upon receiving an event `evt`"""
        print('CLOSING on {}'.format(evt))
        nonlocal done
        done = True

    # Connect callbacks to the events fired by the speech recognizer
    speech_recognizer.recognizing.connect(lambda evt: print('RECOGNIZING: {}'.format(evt)))
    speech_recognizer.recognized.connect(lambda evt: print('RECOGNIZED: {}'.format(evt)))
    speech_recognizer.session_started.connect(lambda evt: print('SESSION STARTED: {}'.format(evt)))
    speech_recognizer.session_stopped.connect(lambda evt: print('SESSION STOPPED {}'.format(evt)))
    speech_recognizer.canceled.connect(lambda evt: print('CANCELED {}'.format(evt)))
    # stop continuous recognition on either session stopped or canceled events
    speech_recognizer.session_stopped.connect(stop_cb)
    speech_recognizer.canceled.connect(stop_cb)

    # Start continuous speech recognition
    speech_recognizer.start_continuous_recognition()
    while not done:
        time.sleep(.5)

    speech_recognizer.stop_continuous_recognition()

def pull_audio_input_stream_compressed_mp3(mp3_file_path: str,
        default_speech_auth):
    # Create a compressed format
    compressed_format = speechsdk.audio.AudioStreamFormat(compressed_stream_format=speechsdk.AudioStreamContainerFormat.MP3)
    compressed_stream_helper(compressed_format, mp3_file_path, default_speech_auth)

Speech to text REST API reference | Speech to text REST API for short audio reference | Additional samples on GitHub

You can use the REST API for compressed audio, but we haven't yet included a guide here. Please select another programming language to get started and learn about the concepts.

The Speech SDK and Speech CLI use GStreamer to support different kinds of input audio formats. GStreamer decompresses the audio before it's sent over the wire to the Speech service as raw PCM.

The default audio streaming format is WAV (16 kHz or 8 kHz, 16-bit, and mono PCM). Outside WAV and PCM, the following compressed input formats are also supported through GStreamer:

  • MP3
  • OPUS/OGG
  • FLAC
  • ALAW in WAV container
  • MULAW in WAV container
  • ANY for MP4 container or unknown media format

GStreamer configuration

The Speech CLI can use GStreamer to handle compressed audio. For licensing reasons, GStreamer binaries aren't compiled and linked with the Speech CLI. You need to install some dependencies and plug-ins.

GStreamer binaries must be in the system path so that they can be loaded by the Speech CLI at runtime. For example, on Windows, if the Speech CLI finds libgstreamer-1.0-0.dll or gstreamer-1.0-0.dll (for the latest GStreamer) during runtime, it means the GStreamer binaries are in the system path.

Choose a platform for installation instructions.

You need to install several dependencies and plug-ins.

sudo apt install libgstreamer1.0-0 \
gstreamer1.0-plugins-base \
gstreamer1.0-plugins-good \
gstreamer1.0-plugins-bad \
gstreamer1.0-plugins-ugly

For more information, see Linux installation instructions and supported Linux distributions and target architectures.

Example

The --format option specifies the container format for the audio file being recognized. For an mp4 file, set the format to any as shown in the following command:

spx recognize --file YourAudioFile.mp4 --format any

To get a list of supported audio formats, run the following command:

spx help recognize format

Next steps