RIVA ASR StreamingRecognition low confidence for word transcripts

R0MAN · November 20, 2023, 11:12am

I am trying to implement RIVA ASR StreamingRecognition in my conversational AI application.

This is the asr client method:

def stream_transcribe_audio(channel, audio_chunk):
    stub = riva_asr_pb2_grpc.RivaSpeechRecognitionStub(channel)
    
    # Prepare the streaming recognition configuration
    streaming_config = riva_asr_pb2.StreamingRecognitionConfig(
        config=riva_asr_pb2.RecognitionConfig(
            encoding=riva_audio_pb2.AudioEncoding.LINEAR_PCM,
            sample_rate_hertz=16000,
            language_code="en-US",
            max_alternatives=1,
            enable_automatic_punctuation=True,
        ),
    )

    # Create a generator for streaming requests
    def request_generator(config, audio):
        yield riva_asr_pb2.StreamingRecognizeRequest(streaming_config=config)
        yield riva_asr_pb2.StreamingRecognizeRequest(audio_content=audio)

    try: 
        responses = stub.StreamingRecognize(request_generator(streaming_config, audio_chunk))
        print("Server response received, starting to process...")
    except Exception as e:
        print(f"Exception during streaming: {e}")  # To log exceptions
        return ""

    transcript = ""
    try:
        for response in responses:
            # Detailed logging of each response
            print(f"Response received: {response}")

            if hasattr(response, 'error') and response.error.code != 0:
                print(f"Error in response: {response.error.message}")
                break

            if hasattr(response, 'results') and response.results:
                result = response.results[0]
                if result.is_final:
                    transcript_part = result.alternatives[0].transcript
                    print(f"Transcript part: {transcript_part}")  # Log each transcript part
                    transcript += transcript_part + " "
    except Exception as e:
        print(f"Error in streaming transcription: {e}")
        print("Detailed error information:")
        print(type(e).__name__)
        print(e.args)

    print(f"Final Transcript: {transcript}")  # Log the final transcript
    return transcript

Script Response Logs:

Please speak...
Recording... Press Enter to stop.
Received audio chunk: 16384 bytes
ASRThread running, processing audio queue
Sending audio chunk of size 16384 to RIVA ASR
Server response received, starting to process...
Response received:
Response received:
Response received:
Response received:
Final Transcript:
Received audio chunk: 16384 bytes
ASRThread running, processing audio queue
Sending audio chunk of size 16384 to RIVA ASR
Server response received, starting to process...
Response received:
Response received:
Response received:
Response received: results {
  alternatives {
    transcript: "Hello. "
    confidence: -1.613735556602478
  }
  is_final: true
  channel_tag: 1
  audio_processed: 0.6399999856948853
}

Transcript part: Hello.
Final Transcript: Hello.
Received audio chunk: 16384 bytes
ASRThread running, processing audio queue
Sending audio chunk of size 16384 to RIVA ASR
Server response received, starting to process...
Response received:
Response received:
Response received:
Response received: results {
  alternatives {
    transcript: "Can somebody "
    confidence: -1.8710156679153442
  }
  is_final: true
  channel_tag: 1
  audio_processed: 0.6399999856948853
}

Transcript part: Can somebody
Final Transcript: Can somebody
Received audio chunk: 16384 bytes
ASRThread running, processing audio queue
Sending audio chunk of size 16384 to RIVA ASR
Server response received, starting to process...
Response received:
Response received:
Response received:
Response received: results {
  alternatives {
    transcript: "You hear me right. "
    confidence: -1.8283002376556396
  }
  is_final: true
  channel_tag: 1
  audio_processed: 0.6399999856948853
}

Transcript part: You hear me right.
Final Transcript: You hear me right.
Received audio chunk: 16384 bytes
ASRThread running, processing audio queue
Sending audio chunk of size 16384 to RIVA ASR
Server response received, starting to process...
Response received:
Response received:
Response received:
Response received: results {
  alternatives {
    transcript: "Right now. "
    confidence: -1.4808837175369263
  }
  is_final: true
  channel_tag: 1
  audio_processed: 0.6399999856948853
}

Transcript part: Right now.
Final Transcript: Right now.
Received audio chunk: 16384 bytes
ASRThread running, processing audio queue
Sending audio chunk of size 16384 to RIVA ASR
Server response received, starting to process...
Response received:
Response received:
Response received:
Response received:
Final Transcript:

Received audio chunk: 16384 bytes
Stopped recording.
Received transcription:
Please speak...
Recording... Press Enter to stop.
Received audio chunk: 16384 bytes
Stopped recording.

Server Logs:

I1120 11:02:22.489441  5775 grpc_riva_asr.cc:1579] ASRService.StreamingRecognize called.
I1120 11:02:22.489544  5775 grpc_riva_asr.cc:1794] Using model conformer-en-US-asr-streaming from Triton localhost:8001
I1120 11:02:22.489671  5775 riva_asr_stream.cc:226] Detected format: encoding = 1 RAW numchannels = 1 samplerate = 16000 bitspersample = 16
I1120 11:02:22.570063  5775 grpc_riva_asr.cc:1910] ASRService.StreamingRecognize returning OK
I1120 11:02:22.570289  5775 stats_builder.h:100] {"specversion":"1.0","type":"riva.asr.streamingrecognize.v1","source":"","subject":"","id":"e9010209-07b6-41bd-93a6-5c938bc28d03","datacontenttype":"application/json","time":"2023-11-20T11:02:22.489424783+00:00","data":{"release_version":"2.13.0","customer_uuid":"","ngc_org":"","ngc_team":"","ngc_org_team":"","container_uuid":"","language_code":"en-US","request_count":1,"audio_duration":0.5120000243186951,"speech_duration":0.0,"status":0,"err_msg":""}}
I1120 11:02:23.008147  5798 grpc_riva_asr.cc:1579] ASRService.StreamingRecognize called.
I1120 11:02:23.008957  5798 grpc_riva_asr.cc:1794] Using model conformer-en-US-asr-streaming from Triton localhost:8001
I1120 11:02:23.009198  5798 riva_asr_stream.cc:226] Detected format: encoding = 1 RAW numchannels = 1 samplerate = 16000 bitspersample = 16
E1120 11:02:23.088802 11998 normalize.cc:150] Class hints empty.
E1120 11:02:23.088826 11998 normalize.cc:156] normalizer failed to apply speechhints 'hello'. Returning output unchanged.
I1120 11:02:23.120199  5798 grpc_riva_asr.cc:1910] ASRService.StreamingRecognize returning OK
I1120 11:02:23.120492  5798 stats_builder.h:100] {"specversion":"1.0","type":"riva.asr.streamingrecognize.v1","source":"","subject":"","id":"1bad763d-67ac-4a75-ab1e-512c972f509b","datacontenttype":"application/json","time":"2023-11-20T11:02:23.008127535+00:00","data":{"release_version":"2.13.0","customer_uuid":"","ngc_org":"","ngc_team":"","ngc_org_team":"","container_uuid":"","language_code":"en-US","request_count":1,"audio_duration":0.5120000243186951,"speech_duration":0.0,"status":0,"err_msg":""}}
I1120 11:02:23.513077  5775 grpc_riva_asr.cc:1579] ASRService.StreamingRecognize called.
I1120 11:02:23.513692  5775 grpc_riva_asr.cc:1794] Using model conformer-en-US-asr-streaming from Triton localhost:8001
I1120 11:02:23.513990  5775 riva_asr_stream.cc:226] Detected format: encoding = 1 RAW numchannels = 1 samplerate = 16000 bitspersample = 16
E1120 11:02:23.567021 12001 normalize.cc:150] Class hints empty.
E1120 11:02:23.567047 12001 normalize.cc:156] normalizer failed to apply speechhints 'can somebody'. Returning output unchanged.
I1120 11:02:23.578464  5775 grpc_riva_asr.cc:1910] ASRService.StreamingRecognize returning OK
I1120 11:02:23.578678  5775 stats_builder.h:100] {"specversion":"1.0","type":"riva.asr.streamingrecognize.v1","source":"","subject":"","id":"0d9c4423-bcc4-4f9d-ac4a-02641344ca5d","datacontenttype":"application/json","time":"2023-11-20T11:02:23.513060427+00:00","data":{"release_version":"2.13.0","customer_uuid":"","ngc_org":"","ngc_team":"","ngc_org_team":"","container_uuid":"","language_code":"en-US","request_count":1,"audio_duration":0.5120000243186951,"speech_duration":0.0,"status":0,"err_msg":""}}
I1120 11:02:24.033721  5798 grpc_riva_asr.cc:1579] ASRService.StreamingRecognize called.
I1120 11:02:24.034348  5798 grpc_riva_asr.cc:1794] Using model conformer-en-US-asr-streaming from Triton localhost:8001
I1120 11:02:24.034597  5798 riva_asr_stream.cc:226] Detected format: encoding = 1 RAW numchannels = 1 samplerate = 16000 bitspersample = 16
E1120 11:02:24.088775 12004 normalize.cc:150] Class hints empty.
E1120 11:02:24.088806 12004 normalize.cc:156] normalizer failed to apply speechhints 'you hear me right'. Returning output unchanged.
I1120 11:02:24.100689  5798 grpc_riva_asr.cc:1910] ASRService.StreamingRecognize returning OK
I1120 11:02:24.100970  5798 stats_builder.h:100] {"specversion":"1.0","type":"riva.asr.streamingrecognize.v1","source":"","subject":"","id":"980d827d-c5cc-4322-b078-bcf5739baf5f","datacontenttype":"application/json","time":"2023-11-20T11:02:24.033702957+00:00","data":{"release_version":"2.13.0","customer_uuid":"","ngc_org":"","ngc_team":"","ngc_org_team":"","container_uuid":"","language_code":"en-US","request_count":1,"audio_duration":0.5120000243186951,"speech_duration":0.0,"status":0,"err_msg":""}}
I1120 11:02:24.602605  5798 grpc_riva_asr.cc:1579] ASRService.StreamingRecognize called.
I1120 11:02:24.603236  5798 grpc_riva_asr.cc:1794] Using model conformer-en-US-asr-streaming from Triton localhost:8001
I1120 11:02:24.603442  5798 riva_asr_stream.cc:226] Detected format: encoding = 1 RAW numchannels = 1 samplerate = 16000 bitspersample = 16
E1120 11:02:24.656375 12007 normalize.cc:150] Class hints empty.
E1120 11:02:24.656402 12007 normalize.cc:156] normalizer failed to apply speechhints 'right now'. Returning output unchanged.
I1120 11:02:24.669127  5798 grpc_riva_asr.cc:1910] ASRService.StreamingRecognize returning OK
I1120 11:02:24.669392  5798 stats_builder.h:100] {"specversion":"1.0","type":"riva.asr.streamingrecognize.v1","source":"","subject":"","id":"34d678f4-4524-4bbe-98c5-07522fe99dd8","datacontenttype":"application/json","time":"2023-11-20T11:02:24.602589539+00:00","data":{"release_version":"2.13.0","customer_uuid":"","ngc_org":"","ngc_team":"","ngc_org_team":"","container_uuid":"","language_code":"en-US","request_count":1,"audio_duration":0.5120000243186951,"speech_duration":0.0,"status":0,"err_msg":""}}
I1120 11:02:25.062372  5798 grpc_riva_asr.cc:1579] ASRService.StreamingRecognize called.
I1120 11:02:25.063171  5798 grpc_riva_asr.cc:1794] Using model conformer-en-US-asr-streaming from Triton localhost:8001
I1120 11:02:25.063496  5798 riva_asr_stream.cc:226] Detected format: encoding = 1 RAW numchannels = 1 samplerate = 16000 bitspersample = 16
I1120 11:02:25.149184  5798 grpc_riva_asr.cc:1910] ASRService.StreamingRecognize returning OK
I1120 11:02:25.149407  5798 stats_builder.h:100] {"specversion":"1.0","type":"riva.asr.streamingrecognize.v1","source":"","subject":"","id":"87d549be-8b77-491b-9083-528b21971f9b","datacontenttype":"application/json","time":"2023-11-20T11:02:25.062354469+00:00","data":{"release_version":"2.13.0","customer_uuid":"","ngc_org":"","ngc_team":"","ngc_org_team":"","container_uuid":"","language_code":"en-US","request_count":1,"audio_duration":0.5120000243186951,"speech_duration":0.0,"status":0,"err_msg":""}}

The microphone has a great quality and audio recording was tested and works correctly in the application!

I tried smaller chunk sizes than 8192 which yielded worse or no results.

Sample rate is set to 16000.

Still the confidence values for the received transcription responses seem to always be negative.

Recording Code:

def record_audio(self, asr_thread):
        # Start recording in a separate thread
        recording_thread = threading.Thread(target=self._record_audio_thread, args=(asr_thread,))
        recording_thread.start()

        input("Recording... Press Enter to stop.\n")
        asr_thread.stop()  # Signal the ASR thread to stop processing
        recording_thread.join()  # Wait for the recording thread to finish

    def _record_audio_thread(self, asr_thread):
        with MicrophoneStream(rate=16000, chunk=8192) as stream:
            for audio_chunk in stream:
                if not asr_thread.running:
                    break
                asr_thread.audio_queue.put(audio_chunk)
            print("Stopped recording.")

Chunk processing and call of streaming transcription client method:

class ASRThread(threading.Thread):
    def __init__(self):
        super().__init__()
        self.channel = create_channel()
        self.audio_queue = queue.Queue()
        self.running = True
        self.latest_transcription = ""

    def run(self):
        while self.running:
            # Check if there are audio chunks and stream them
            while not self.audio_queue.empty():
                audio_chunk = self.audio_queue.get()
                print("ASRThread running, processing audio queue")  # To confirm thread is processing
                # Ensure audio_chunk is raw audio bytes
                self.stream_transcribe_audio(audio_chunk)


    def stream_transcribe_audio(self, audio_chunk):
        try:
            print(f"Sending audio chunk of size {len(audio_chunk)} to RIVA ASR")  # To check size of audio being sent
            transcript = stream_transcribe_audio(self.channel, audio_chunk)
            self.latest_transcription = transcript
        except Exception as e:
            print(f"Error during transcription: {e}")

    def get_latest_transcription(self):
            return self.latest_transcription

    def stop(self):
        self.running = False

I appreciate help to figure out how to set this up correctly, thanks!

Hardware - GPU RTX 4090
Hardware - CPU
Operating System Windows11
Riva Version 2.13.0
TLT Version (if relevant)
How to reproduce the issue ? (This is for errors. Please share the command and the detailed log here)

rvinobha · November 29, 2023, 5:57am

Hi @R0MAN

We can improve the confidence by performing word boosting

Word boosting is one of the customizations Riva offers. It allows you to bias the ASR engine to recognize particular words of interest at request time by giving them a higher score when decoding the output of the acoustic model.

Please find the Demo Tutorial Notebook below to perform word boosting

github.com

nvidia-riva/tutorials/blob/stable/asr-wordboosting.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "2bf1191b",
   "metadata": {},
   "source": [
    "<img src=\"http://developer.download.nvidia.com/notebooks/dlsw-notebooks/rivaasrasr-wordboosting/nvidia_logo.png\" style=\"width: 90px; float: right;\">\n",
    "\n",
    "# How do I boost specific words at runtime with word boosting?\n",
    "\n",
    "This tutorial walks you through some of the advanced features for customization of Riva Speech Skills ASR Services at runtime with word boosting."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "bcfba84d",
   "metadata": {},
   "source": [
    "## NVIDIA Riva Overview\n",

This file has been truncated. show original

Thanks

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RIVA ASR StreamingRecognition low confidence for word transcripts

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