Whisper-Small-En: Optimized for Mobile Deployment

Automatic speech recognition (ASR) model for English transcription as well as translation

OpenAI’s Whisper ASR (Automatic Speech Recognition) model is a state-of-the-art system designed for transcribing spoken language into written text. It exhibits robust performance in realistic, noisy environments, making it highly reliable for real-world applications. Specifically, it excels in long-form transcription, capable of accurately transcribing audio clips up to 30 seconds long. Time to the first token is the encoder's latency, while time to each additional token is decoder's latency, where we assume a mean decoded length specified below.

This model is an implementation of Whisper-Small-En found here.

This repository provides scripts to run Whisper-Small-En on Qualcomm® devices. More details on model performance across various devices, can be found here.

Model Details

  • Model Type: Speech recognition
  • Model Stats:
    • Model checkpoint: small.en
    • Input resolution: 80x3000 (30 seconds audio)
    • Mean decoded sequence length: 112 tokens
    • Number of parameters (WhisperEncoder): 102M
    • Model size (WhisperEncoder): 390 MB
    • Number of parameters (WhisperDecoder): 139M
    • Model size (WhisperDecoder): 531 MB
Model Device Chipset Target Runtime Inference Time (ms) Peak Memory Range (MB) Precision Primary Compute Unit Target Model
WhisperDecoder Samsung Galaxy S23 Snapdragon® 8 Gen 2 TFLITE 29.126 ms 16 - 96 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder Samsung Galaxy S23 Snapdragon® 8 Gen 2 QNN 11.961 ms 54 - 137 MB FP16 NPU Whisper-Small-En.so
WhisperDecoder Samsung Galaxy S23 Snapdragon® 8 Gen 2 ONNX 61.425 ms 154 - 199 MB FP16 NPU Whisper-Small-En.onnx
WhisperDecoder Samsung Galaxy S24 Snapdragon® 8 Gen 3 TFLITE 23.441 ms 16 - 150 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder Samsung Galaxy S24 Snapdragon® 8 Gen 3 QNN 9.604 ms 53 - 160 MB FP16 NPU Whisper-Small-En.so
WhisperDecoder Samsung Galaxy S24 Snapdragon® 8 Gen 3 ONNX 51.698 ms 16 - 327 MB FP16 NPU Whisper-Small-En.onnx
WhisperDecoder Snapdragon 8 Elite QRD Snapdragon® 8 Elite TFLITE 18.162 ms 16 - 176 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder Snapdragon 8 Elite QRD Snapdragon® 8 Elite QNN 7.555 ms 49 - 184 MB FP16 NPU Use Export Script
WhisperDecoder Snapdragon 8 Elite QRD Snapdragon® 8 Elite ONNX 42.696 ms 86 - 408 MB FP16 NPU Whisper-Small-En.onnx
WhisperDecoder QCS8550 (Proxy) QCS8550 Proxy TFLITE 29.309 ms 16 - 101 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder QCS8550 (Proxy) QCS8550 Proxy QNN 12.213 ms 61 - 63 MB FP16 NPU Use Export Script
WhisperDecoder SA7255P ADP SA7255P TFLITE 100.26 ms 16 - 175 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder SA7255P ADP SA7255P QNN 74.87 ms 60 - 70 MB FP16 NPU Use Export Script
WhisperDecoder SA8255 (Proxy) SA8255P Proxy TFLITE 29.902 ms 16 - 101 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder SA8255 (Proxy) SA8255P Proxy QNN 12.096 ms 54 - 55 MB FP16 NPU Use Export Script
WhisperDecoder SA8295P ADP SA8295P TFLITE 31.128 ms 16 - 164 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder SA8295P ADP SA8295P QNN 14.544 ms 57 - 71 MB FP16 NPU Use Export Script
WhisperDecoder SA8650 (Proxy) SA8650P Proxy TFLITE 29.982 ms 14 - 97 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder SA8650 (Proxy) SA8650P Proxy QNN 12.14 ms 57 - 59 MB FP16 NPU Use Export Script
WhisperDecoder SA8775P ADP SA8775P TFLITE 33.024 ms 16 - 175 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder SA8775P ADP SA8775P QNN 14.735 ms 57 - 66 MB FP16 NPU Use Export Script
WhisperDecoder QCS8450 (Proxy) QCS8450 Proxy TFLITE 33.055 ms 16 - 140 MB FP16 NPU Whisper-Small-En.tflite
WhisperDecoder QCS8450 (Proxy) QCS8450 Proxy QNN 16.795 ms 53 - 172 MB FP16 NPU Use Export Script
WhisperDecoder Snapdragon X Elite CRD Snapdragon® X Elite QNN 10.56 ms 61 - 61 MB FP16 NPU Use Export Script
WhisperDecoder Snapdragon X Elite CRD Snapdragon® X Elite ONNX 52.337 ms 232 - 232 MB FP16 NPU Whisper-Small-En.onnx
WhisperEncoder Samsung Galaxy S23 Snapdragon® 8 Gen 2 TFLITE 807.519 ms 79 - 160 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder Samsung Galaxy S23 Snapdragon® 8 Gen 2 QNN 804.747 ms 0 - 211 MB FP16 NPU Whisper-Small-En.so
WhisperEncoder Samsung Galaxy S24 Snapdragon® 8 Gen 3 TFLITE 602.309 ms 110 - 200 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder Samsung Galaxy S24 Snapdragon® 8 Gen 3 QNN 597.586 ms 0 - 837 MB FP16 NPU Whisper-Small-En.so
WhisperEncoder Samsung Galaxy S24 Snapdragon® 8 Gen 3 ONNX 869.225 ms 0 - 1429 MB FP16 NPU Whisper-Small-En.onnx
WhisperEncoder Snapdragon 8 Elite QRD Snapdragon® 8 Elite TFLITE 544.489 ms 111 - 141 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder Snapdragon 8 Elite QRD Snapdragon® 8 Elite QNN 515.742 ms 0 - 906 MB FP16 NPU Use Export Script
WhisperEncoder Snapdragon 8 Elite QRD Snapdragon® 8 Elite ONNX 677.156 ms 172 - 1609 MB FP16 NPU Whisper-Small-En.onnx
WhisperEncoder QCS8550 (Proxy) QCS8550 Proxy TFLITE 1255.513 ms 18 - 221 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder QCS8550 (Proxy) QCS8550 Proxy QNN 675.441 ms 1 - 3 MB FP16 NPU Use Export Script
WhisperEncoder SA7255P ADP SA7255P TFLITE 4429.057 ms 109 - 142 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder SA7255P ADP SA7255P QNN 3217.361 ms 1 - 11 MB FP16 NPU Use Export Script
WhisperEncoder SA8255 (Proxy) SA8255P Proxy TFLITE 685.501 ms 110 - 158 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder SA8255 (Proxy) SA8255P Proxy QNN 687.338 ms 1 - 3 MB FP16 NPU Use Export Script
WhisperEncoder SA8295P ADP SA8295P TFLITE 657.369 ms 110 - 142 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder SA8295P ADP SA8295P QNN 700.793 ms 0 - 15 MB FP16 NPU Use Export Script
WhisperEncoder SA8650 (Proxy) SA8650P Proxy TFLITE 686.08 ms 50 - 129 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder SA8650 (Proxy) SA8650P Proxy QNN 674.708 ms 0 - 3 MB FP16 NPU Use Export Script
WhisperEncoder SA8775P ADP SA8775P TFLITE 1287.541 ms 88 - 121 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder SA8775P ADP SA8775P QNN 604.581 ms 1 - 10 MB FP16 NPU Use Export Script
WhisperEncoder QCS8450 (Proxy) QCS8450 Proxy TFLITE 983.989 ms 58 - 157 MB FP16 GPU Whisper-Small-En.tflite
WhisperEncoder Snapdragon X Elite CRD Snapdragon® X Elite QNN 505.395 ms 0 - 0 MB FP16 NPU Use Export Script
WhisperEncoder Snapdragon X Elite CRD Snapdragon® X Elite ONNX 1340.942 ms 237 - 237 MB FP16 NPU Whisper-Small-En.onnx

Installation

This model can be installed as a Python package via pip.

pip install "qai-hub-models[whisper_small_en]"

Configure Qualcomm® AI Hub to run this model on a cloud-hosted device

Sign-in to Qualcomm® AI Hub with your Qualcomm® ID. Once signed in navigate to Account -> Settings -> API Token.

With this API token, you can configure your client to run models on the cloud hosted devices.

qai-hub configure --api_token API_TOKEN

Navigate to docs for more information.

Demo off target

The package contains a simple end-to-end demo that downloads pre-trained weights and runs this model on a sample input.

python -m qai_hub_models.models.whisper_small_en.demo

The above demo runs a reference implementation of pre-processing, model inference, and post processing.

NOTE: If you want running in a Jupyter Notebook or Google Colab like environment, please add the following to your cell (instead of the above).

%run -m qai_hub_models.models.whisper_small_en.demo

Run model on a cloud-hosted device

In addition to the demo, you can also run the model on a cloud-hosted Qualcomm® device. This script does the following:

  • Performance check on-device on a cloud-hosted device
  • Downloads compiled assets that can be deployed on-device for Android.
  • Accuracy check between PyTorch and on-device outputs.
python -m qai_hub_models.models.whisper_small_en.export
Profiling Results
------------------------------------------------------------
WhisperDecoder
Device                          : Samsung Galaxy S23 (13)
Runtime                         : TFLITE                 
Estimated inference time (ms)   : 29.1                   
Estimated peak memory usage (MB): [16, 96]               
Total # Ops                     : 2573                   
Compute Unit(s)                 : NPU (2573 ops)         

------------------------------------------------------------
WhisperEncoder
Device                          : Samsung Galaxy S23 (13)   
Runtime                         : TFLITE                    
Estimated inference time (ms)   : 807.5                     
Estimated peak memory usage (MB): [79, 160]                 
Total # Ops                     : 911                       
Compute Unit(s)                 : GPU (900 ops) CPU (11 ops)

How does this work?

This export script leverages Qualcomm® AI Hub to optimize, validate, and deploy this model on-device. Lets go through each step below in detail:

Step 1: Compile model for on-device deployment

To compile a PyTorch model for on-device deployment, we first trace the model in memory using the jit.trace and then call the submit_compile_job API.

import torch

import qai_hub as hub
from qai_hub_models.models.whisper_small_en import Model

# Load the model
model = Model.from_pretrained()
decoder_model = model.decoder
encoder_model = model.encoder

# Device
device = hub.Device("Samsung Galaxy S23")

# Trace model
decoder_input_shape = decoder_model.get_input_spec()
decoder_sample_inputs = decoder_model.sample_inputs()

traced_decoder_model = torch.jit.trace(decoder_model, [torch.tensor(data[0]) for _, data in decoder_sample_inputs.items()])

# Compile model on a specific device
decoder_compile_job = hub.submit_compile_job(
    model=traced_decoder_model ,
    device=device,
    input_specs=decoder_model.get_input_spec(),
)

# Get target model to run on-device
decoder_target_model = decoder_compile_job.get_target_model()
# Trace model
encoder_input_shape = encoder_model.get_input_spec()
encoder_sample_inputs = encoder_model.sample_inputs()

traced_encoder_model = torch.jit.trace(encoder_model, [torch.tensor(data[0]) for _, data in encoder_sample_inputs.items()])

# Compile model on a specific device
encoder_compile_job = hub.submit_compile_job(
    model=traced_encoder_model ,
    device=device,
    input_specs=encoder_model.get_input_spec(),
)

# Get target model to run on-device
encoder_target_model = encoder_compile_job.get_target_model()

Step 2: Performance profiling on cloud-hosted device

After compiling models from step 1. Models can be profiled model on-device using the target_model. Note that this scripts runs the model on a device automatically provisioned in the cloud. Once the job is submitted, you can navigate to a provided job URL to view a variety of on-device performance metrics.

decoder_profile_job = hub.submit_profile_job(
    model=decoder_target_model,
    device=device,
)
encoder_profile_job = hub.submit_profile_job(
    model=encoder_target_model,
    device=device,
)

Step 3: Verify on-device accuracy

To verify the accuracy of the model on-device, you can run on-device inference on sample input data on the same cloud hosted device.

decoder_input_data = decoder_model.sample_inputs()
decoder_inference_job = hub.submit_inference_job(
    model=decoder_target_model,
    device=device,
    inputs=decoder_input_data,
)
decoder_inference_job.download_output_data()
encoder_input_data = encoder_model.sample_inputs()
encoder_inference_job = hub.submit_inference_job(
    model=encoder_target_model,
    device=device,
    inputs=encoder_input_data,
)
encoder_inference_job.download_output_data()

With the output of the model, you can compute like PSNR, relative errors or spot check the output with expected output.

Note: This on-device profiling and inference requires access to Qualcomm® AI Hub. Sign up for access.

Deploying compiled model to Android

The models can be deployed using multiple runtimes:

  • TensorFlow Lite (.tflite export): This tutorial provides a guide to deploy the .tflite model in an Android application.

  • QNN (.so export ): This sample app provides instructions on how to use the .so shared library in an Android application.

View on Qualcomm® AI Hub

Get more details on Whisper-Small-En's performance across various devices here. Explore all available models on Qualcomm® AI Hub

License

  • The license for the original implementation of Whisper-Small-En can be found here.
  • The license for the compiled assets for on-device deployment can be found here

References

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