Automatic speech recognition using Whisper and OpenVINO with Generate API#
This Jupyter notebook can be launched after a local installation only.
Whisper is an automatic speech recognition (ASR) system trained on 680,000 hours of multilingual and multitask supervised data collected from the web.
Whisper is a Transformer based encoder-decoder model, also referred to as a sequence-to-sequence model. It maps a sequence of audio spectrogram features to a sequence of text tokens. First, the raw audio inputs are converted to a log-Mel spectrogram by action of the feature extractor. Then, the Transformer encoder encodes the spectrogram to form a sequence of encoder hidden states. Finally, the decoder autoregressively predicts text tokens, conditional on both the previous tokens and the encoder hidden states.
You can see the model architecture in the diagram below:
In this tutorial, we consider how to run Whisper using OpenVINO. We will use the pre-trained model from the Hugging Face Transformers library. The Hugging Face Optimum Intel library converts the models to OpenVINO™ IR format. To simplify the user experience, we will use OpenVINO Generate API for Whisper automatic speech recognition scenarios.
Installation Instructions#
This is a self-contained example that relies solely on its own code.
We recommend running the notebook in a virtual environment. You only need a Jupyter server to start. For details, please refer to Installation Guide.
Table of contents:
Prerequisites#
%pip install -q "torch>=2.3" "torchvision>=0.18.1" --extra-index-url https://download.pytorch.org/whl/cpu
%pip install -q "transformers>=4.45" "git+https://github.com/huggingface/optimum-intel.git" --extra-index-url https://download.pytorch.org/whl/cpu
%pip install -q --pre -U "openvino" "openvino-tokenizers" "openvino-genai" --extra-index-url https://storage.openvinotoolkit.org/simple/wheels/nightly
%pip install -q datasets "gradio>=4.0" "soundfile>=0.12" "librosa" "python-ffmpeg<=1.0.16"
%pip install -q "nncf>=2.13.0" "jiwer"
import requests
from pathlib import Path
if not Path("notebook_utils.py").exists():
r = requests.get(
url="https://raw.githubusercontent.com/openvinotoolkit/openvino_notebooks/latest/utils/notebook_utils.py",
)
open("notebook_utils.py", "w").write(r.text)
if not Path("cmd_helper.py").exists():
r = requests.get(
url="https://raw.githubusercontent.com/openvinotoolkit/openvino_notebooks/latest/utils/cmd_helper.py",
)
open("cmd_helper.py", "w").write(r.text)
Load PyTorch model#
The AutoModelForSpeechSeq2Seq.from_pretrained
method is used for the
initialization of PyTorch Whisper model using the transformers library.
The model will be downloaded once during first run and this process may
require some time.
You may also choose other models from Whisper collection, more on them here.
Preprocessing and post-processing are important in this model use.
AutoProcessor
class used for initialization WhisperProcessor
is
responsible for preparing audio input data for the model, converting it
to Mel-spectrogram and decoding predicted output token_ids into string
using tokenizer. We will use pipeline
method to transcribe audios of
arbitrary length.
import ipywidgets as widgets
model_ids = {
"Multilingual models": [
"openai/whisper-large-v3-turbo",
"openai/whisper-large-v3",
"openai/whisper-large-v2",
"openai/whisper-large",
"openai/whisper-medium",
"openai/whisper-small",
"openai/whisper-base",
"openai/whisper-tiny",
],
"English-only models": [
"distil-whisper/distil-large-v2",
"distil-whisper/distil-large-v3",
"distil-whisper/distil-medium.en",
"distil-whisper/distil-small.en",
"openai/whisper-medium.en",
"openai/whisper-small.en",
"openai/whisper-base.en",
"openai/whisper-tiny.en",
],
}
model_type = widgets.Dropdown(
options=model_ids.keys(),
value="Multilingual models",
description="Model:",
disabled=False,
)
model_type
Dropdown(description='Model:', options=('Multilingual models', 'English-only models'), value='Multilingual mod…
model_id = widgets.Dropdown(
options=model_ids[model_type.value],
value=model_ids[model_type.value][-1],
description="Model:",
disabled=False,
)
model_id
Dropdown(description='Model:', index=7, options=('openai/whisper-large-v3-turbo', 'openai/whisper-large-v3', '…
from transformers import AutoProcessor, AutoModelForSpeechSeq2Seq, pipeline
from transformers.utils import logging
processor = AutoProcessor.from_pretrained(model_id.value)
pt_model = AutoModelForSpeechSeq2Seq.from_pretrained(model_id.value)
pipe_pt = pipeline(
"automatic-speech-recognition",
model=pt_model,
tokenizer=processor.tokenizer,
feature_extractor=processor.feature_extractor,
device="cpu",
)
Run PyTorch model inference#
The pipeline
expects audio data in numpy array format. We will use
.wav
file and convert it numpy array format for that purpose.
from notebook_utils import download_file
en_example_short = Path("data", "courtroom.wav")
# a wav sample
download_file(
"https://huggingface.co/datasets/Xenova/transformers.js-docs/resolve/main/courtroom.wav",
en_example_short.name,
directory=en_example_short.parent,
)
'data/courtroom.wav' already exists.
PosixPath('/home/labuser/work/notebook/openvino_notebooks/notebooks/whisper-asr-genai/data/courtroom.wav')
import librosa
en_raw_speech, samplerate = librosa.load(str(en_example_short), sr=16000)
Let’s check how to work the transcribe
task.
import copy
import IPython.display as ipd
logging.set_verbosity_error()
sample = copy.deepcopy(en_raw_speech)
display(ipd.Audio(sample, rate=samplerate))
pt_result = pipe_pt(sample)
print(f"Result: {pt_result['text']}")
/home/labuser/work/notebook/whisper_new/lib/python3.10/site-packages/transformers/models/whisper/generation_whisper.py:496: FutureWarning: The input name inputs is deprecated. Please make sure to use input_features instead. warnings.warn(
Result: Colonel Jessif, did you order the code rate? You don't have to answer that question. I'll answer the question. You want answers? I think I'm entitled. You want answers? I want the truth. You can't handle the truth.
If the multilingual model was chosen, let’s see how task translate
is working. We will use facebook/multilingual_librispeech
multilingual dataset, so you can choose the language. The model will
translate audio from the selected language into English. Conversion of
audio to numpy format is handled by Hugging Face datasets
implementation. A complete list of languages supported by the model can
be found in the paper.
import ipywidgets as widgets
languages = {"japanese": "ja_jp", "dutch": "da_dk", "french": "fr_fr", "spanish": "ca_es", "italian": "it_it", "portuguese": "pt_br", "polish": "pl_pl"}
SAMPLE_LANG = None
if model_type.value == "Multilingual models":
SAMPLE_LANG = widgets.Dropdown(
options=languages.keys(),
value="italian",
description="Dataset language:",
disabled=False,
)
SAMPLE_LANG
Dropdown(description='Dataset language:', index=4, options=('japanese', 'dutch', 'french', 'spanish', 'italian…
from datasets import load_dataset
mls_dataset = None
if model_type.value == "Multilingual models":
mls_dataset = load_dataset("google/fleurs", languages[SAMPLE_LANG.value], split="test", streaming=True, trust_remote_code=True)
mls_dataset = iter(mls_dataset) # make it iterable
mls_example = next(mls_dataset) # get one example
if model_type.value == "Multilingual models":
sample = copy.deepcopy(mls_example["audio"])
display(ipd.Audio(sample["array"], rate=sample["sampling_rate"]))
print(f"Reference: {mls_example['raw_transcription']}")
pt_result = pipe_pt(sample, generate_kwargs={"task": "translate"})
print(f"\nResult: {pt_result['text']}")
Reference: Il blog è uno strumento che si prefigge di incoraggiare la collaborazione e sviluppare l'apprendimento degli studenti ben oltre la giornata scolastica normale.
Result: The blog is our tool that is prefilled to encourage collaboration and develop the learning of the students and to attract a normal school class.
Convert model to OpenVINO IR via Optimum Intel CLI#
Listed Whisper model are available for downloading via the HuggingFace hub. We will use optimum-cli interface for exporting it into OpenVINO Intermediate Representation (IR) format.
Optimum CLI interface for converting models supports export to OpenVINO (supported starting optimum-intel 1.12 version). General command format:
optimum-cli export openvino --model <model_id_or_path> --task <task> <output_dir>
where --model
argument is model id from HuggingFace Hub or local
directory with model (saved using .save_pretrained
method),
--task
is one of supported
task
that exported model should solve. For LLMs it will be
automatic-speech-recognition-with-past
. If model initialization
requires to use remote code, --trust-remote-code
flag additionally
should be passed. Full list of supported arguments available via
--help
For more details and examples of usage, please check optimum
documentation.
import logging
import nncf
from cmd_helper import optimum_cli
nncf.set_log_level(logging.ERROR)
model_path = Path(model_id.value.split("/")[1])
optimum_cli(model_id.value, model_path)
print(f"✅ {model_id.value} model converted and can be found in {model_path}")
Run inference OpenVINO model with WhisperPipeline#
To simplify user experience we will use OpenVINO Generate
API.
Firstly we will create pipeline with WhisperPipeline
. You can
construct it straight away from the folder with the converted model. It
will automatically load the model
, tokenizer
, detokenizer
and default generation configuration
.
from notebook_utils import device_widget
device = device_widget(default="CPU", exclude=["NPU"])
device
Dropdown(description='Device:', options=('CPU', 'AUTO'), value='CPU')
import openvino_genai
ov_pipe = openvino_genai.WhisperPipeline(str(model_path), device=device.value)
Let’s run the transcribe
task. We just call generate
for that
and put array as input.
genai_result = ov_pipe.generate(en_raw_speech)
display(ipd.Audio(en_raw_speech, rate=samplerate))
print(f"Result: {genai_result}")
Result: Colonel Jessif, did you order the code rate? You don't have to answer that question. I'll answer the question. You want answers? I think I'm entitled. You want answers? I want the truth. You can't handle the truth.
Whisper could provide a phrase-level timestamps for audio. Let’s try
this scenario, we will specify return_timestamps=True
for
generate
method.
generate
method with return_timestamps
set to True
will
return chunks
, which contain attributes: text
, start_ts
and
end_ts
in seconds.
genai_result_timestamps = ov_pipe.generate(en_raw_speech, return_timestamps=True)
for segment in genai_result_timestamps.chunks:
print(f"{segment.start_ts}sec. ---> {segment.end_ts}sec.")
print(f"{segment.text}\n")
0.0sec. ---> 3.0sec.
Colonel Jessif, did you order the code rate?
3.0sec. ---> 4.5sec.
You don't have to answer that question.
4.5sec. ---> 6.5sec.
I'll answer the question.
6.5sec. ---> 8.0sec.
You want answers?
8.0sec. ---> 9.0sec.
I think I'm entitled.
9.0sec. ---> 10.0sec.
You want answers?
10.0sec. ---> 11.0sec.
I want the truth.
11.0sec. ---> 13.0sec.
You can't handle the truth.
Let’s see how to work the translate
task. It supports for
multilingual models only. For that case we will specify language
and
task
options. We can do this in different ways. We can get default
config with get_generation_config()
, setup parameters and put config
directly to generate()
. It’s also possible to specify the needed
options just as inputs in the generate()
method and we will use this
way. Then we just run generate
method and get the output in text
format.
languages_genai = {
"japanese": "<|ja|>",
"dutch": "<|da|>",
"french": "<|fr|>",
"spanish": "<|es|>",
"italian": "<|it|>",
"portuguese": "<|pt|>",
"polish": "<|pl|>",
}
if model_type.value == "Multilingual models":
sample = mls_example["audio"]
genai_result_ml = ov_pipe.generate(sample["array"], max_new_tokens=100, task="translate", language=languages_genai[SAMPLE_LANG.value])
display(ipd.Audio(sample["array"], rate=sample["sampling_rate"]))
print(f"Reference: {mls_example['raw_transcription']}")
print(f"\nResult: {genai_result_ml}")
Reference: Il blog è uno strumento che si prefigge di incoraggiare la collaborazione e sviluppare l'apprendimento degli studenti ben oltre la giornata scolastica normale.
Result: The blog is our tool that is prefilled to encourage collaboration and develop the learning of the students and to attract a normal school class.
Compare performance PyTorch vs OpenVINO#
import time
import numpy as np
from tqdm.notebook import tqdm
def measure_perf(pipe, n=10, model_type="ov"):
timers = []
for _ in tqdm(range(n), desc="Measuring performance"):
sample = copy.deepcopy(en_raw_speech)
start = time.perf_counter()
if model_type == "pt":
pipe(sample)
elif model_type == "ov":
pipe.generate(sample)
end = time.perf_counter()
timers.append(end - start)
return np.median(timers)
perf_torch = measure_perf(pipe_pt, model_type="pt")
perf_ov = measure_perf(ov_pipe)
Measuring performance: 0%| | 0/10 [00:00<?, ?it/s]
Measuring performance: 0%| | 0/10 [00:00<?, ?it/s]
print(f"Mean torch {model_id.value} generation time: {perf_torch:.3f}s")
print(f"Mean openvino {model_id.value} generation time: {perf_ov:.3f}s")
print(f"Performance {model_id.value} openvino speedup: {perf_torch / perf_ov:.3f}")
Mean torch openai/whisper-tiny generation time: 0.564s
Mean openvino openai/whisper-tiny generation time: 0.311s
Performance openai/whisper-tiny openvino speedup: 1.815
Quantization#
NNCF enables post-training quantization by adding the quantization layers into the model graph and then using a subset of the training dataset to initialize the parameters of these additional quantization layers. The framework is designed so that modifications to your original training code are minor.
The optimization process contains the following steps:
Create a calibration dataset for quantization.
Run
nncf.quantize
to obtain quantized encoder and decoder models.Serialize the
INT8
model usingopenvino.save_model
function.
Note: Quantization is time and memory consuming operation. Running quantization code below may take some time.
Please select below whether you would like to run Whisper quantization.
from notebook_utils import quantization_widget
to_quantize = quantization_widget()
to_quantize
Checkbox(value=True, description='Quantization')
# Fetch `skip_kernel_extension` module
import requests
r = requests.get(
url="https://raw.githubusercontent.com/openvinotoolkit/openvino_notebooks/latest/utils/skip_kernel_extension.py",
)
open("skip_kernel_extension.py", "w").write(r.text)
%load_ext skip_kernel_extension
Let’s load converted OpenVINO model format using Optimum-Intel to easily quantize it.
Optimum Intel can be used to load optimized models from the Hugging
Face Hub or
local folder to create pipelines to run an inference with OpenVINO
Runtime using Hugging Face APIs. The Optimum Inference models are API
compatible with Hugging Face Transformers models. This means we just
need to replace the AutoModelForXxx
class with the corresponding
OVModelForXxx
class.
Below is an example of the whisper-tiny model
-from transformers import AutoModelForSpeechSeq2Seq
+from optimum.intel.openvino import OVModelForSpeechSeq2Seq
from transformers import AutoTokenizer, pipeline
model_id = "openai/whisper-tiny"
-model = AutoModelForSpeechSeq2Seq.from_pretrained(model_id)
+model = OVModelForSpeechSeq2Seq.from_pretrained(model_id, export=True)
Like the original PyTorch model, the OpenVINO model is also compatible
with HuggingFace
pipeline
interface for automatic-speech-recognition
.
from optimum.intel.openvino import OVModelForSpeechSeq2Seq
ov_model = OVModelForSpeechSeq2Seq.from_pretrained(str(model_path), device=device.value)
ov_processor = AutoProcessor.from_pretrained(str(model_path))
Prepare calibration datasets#
First step is to prepare calibration datasets for quantization. Since we
quantize whisper encoder and decoder separately, we need to prepare a
calibration dataset for each of the models. We import an
InferRequestWrapper
class that will intercept model inputs and
collect them to a list. Then we run model inference on some small amount
of audio samples. Generally, increasing the calibration dataset size
improves quantization quality.
%%skip not $to_quantize.value
from itertools import islice
from optimum.intel.openvino.quantization import InferRequestWrapper
def collect_calibration_dataset(ov_model: OVModelForSpeechSeq2Seq, calibration_dataset_size: int):
# Overwrite model request properties, saving the original ones for restoring later
encoder_calibration_data = []
decoder_calibration_data = []
ov_model.encoder.request = InferRequestWrapper(ov_model.encoder.request, encoder_calibration_data, apply_caching=True)
ov_model.decoder_with_past.request = InferRequestWrapper(ov_model.decoder_with_past.request,
decoder_calibration_data,
apply_caching=True)
pipe = pipeline(
"automatic-speech-recognition",
model=ov_model,
chunk_length_s=30,
tokenizer=ov_processor.tokenizer,
feature_extractor=ov_processor.feature_extractor)
try:
calibration_dataset = dataset = load_dataset("openslr/librispeech_asr", "clean", split="validation", streaming=True, trust_remote_code=True)
for sample in tqdm(islice(calibration_dataset, calibration_dataset_size), desc="Collecting calibration data",
total=calibration_dataset_size):
pipe(sample["audio"], return_timestamps=True)
finally:
ov_model.encoder.request = ov_model.encoder.request.request
ov_model.decoder_with_past.request = ov_model.decoder_with_past.request.request
return encoder_calibration_data, decoder_calibration_data
Quantize Whisper encoder and decoder models#
Below we run the quantize
function which calls nncf.quantize
on
Whisper encoder and decoder-with-past models. We don’t quantize
first-step-decoder because its share in whole inference time is
negligible.
%%skip not $to_quantize.value
import gc
import shutil
import nncf
import openvino as ov
from datasets import load_dataset
from tqdm.notebook import tqdm
CALIBRATION_DATASET_SIZE = 30
quantized_model_path = Path(f"{model_path}-quantized")
def quantize(ov_model: OVModelForSpeechSeq2Seq, calibration_dataset_size: int):
if not quantized_model_path.exists():
encoder_calibration_data, decoder_calibration_data = collect_calibration_dataset(
ov_model, calibration_dataset_size
)
print("Quantizing encoder")
quantized_encoder = nncf.quantize(
ov_model.encoder.model,
nncf.Dataset(encoder_calibration_data),
subset_size=len(encoder_calibration_data),
model_type=nncf.ModelType.TRANSFORMER,
# Smooth Quant algorithm reduces activation quantization error; optimal alpha value was obtained through grid search
advanced_parameters=nncf.AdvancedQuantizationParameters(smooth_quant_alpha=0.80)
)
ov.save_model(quantized_encoder, quantized_model_path / "openvino_encoder_model.xml")
del quantized_encoder
del encoder_calibration_data
gc.collect()
print("Quantizing decoder with past")
quantized_decoder_with_past = nncf.quantize(
ov_model.decoder_with_past.model,
nncf.Dataset(decoder_calibration_data),
subset_size=len(decoder_calibration_data),
model_type=nncf.ModelType.TRANSFORMER,
# Smooth Quant algorithm reduces activation quantization error; optimal alpha value was obtained through grid search
advanced_parameters=nncf.AdvancedQuantizationParameters(smooth_quant_alpha=0.96)
)
ov.save_model(quantized_decoder_with_past, quantized_model_path / "openvino_decoder_with_past_model.xml")
del quantized_decoder_with_past
del decoder_calibration_data
gc.collect()
# Copy the config file and the first-step-decoder manually
shutil.copy(model_path / "config.json", quantized_model_path / "config.json")
shutil.copy(model_path / "generation_config.json", quantized_model_path / "generation_config.json")
shutil.copy(model_path / "openvino_decoder_model.xml", quantized_model_path / "openvino_decoder_model.xml")
shutil.copy(model_path / "openvino_decoder_model.bin", quantized_model_path / "openvino_decoder_model.bin")
shutil.copy(model_path / "openvino_tokenizer.xml", quantized_model_path / "openvino_tokenizer.xml")
shutil.copy(model_path / "openvino_tokenizer.bin", quantized_model_path / "openvino_tokenizer.bin")
shutil.copy(model_path / "openvino_detokenizer.xml", quantized_model_path / "openvino_detokenizer.xml")
shutil.copy(model_path / "openvino_detokenizer.bin", quantized_model_path / "openvino_detokenizer.bin")
shutil.copy(model_path / "tokenizer_config.json", quantized_model_path / "tokenizer_config.json")
shutil.copy(model_path / "tokenizer.json", quantized_model_path / "tokenizer.json")
shutil.copy(model_path / "vocab.json", quantized_model_path / "vocab.json")
shutil.copy(model_path / "preprocessor_config.json", quantized_model_path / "preprocessor_config.json")
shutil.copy(model_path / "special_tokens_map.json", quantized_model_path / "special_tokens_map.json")
shutil.copy(model_path / "normalizer.json", quantized_model_path / "normalizer.json")
shutil.copy(model_path / "merges.txt", quantized_model_path / "merges.txt")
shutil.copy(model_path / "added_tokens.json", quantized_model_path / "added_tokens.json")
quantized_ov_pipe = openvino_genai.WhisperPipeline(str(quantized_model_path), device=device.value)
return quantized_ov_pipe
ov_quantized_pipe = quantize(ov_model, CALIBRATION_DATASET_SIZE)
Run quantized model inference#
Let’s compare the transcription results for original and quantized models.
%%skip not $to_quantize.value
genai_result = ov_pipe.generate(en_raw_speech)
quantized_genai_result = ov_quantized_pipe.generate(en_raw_speech)
display(ipd.Audio(en_raw_speech, rate=samplerate))
print(f"Original : {genai_result}")
print(f"Quantized: {quantized_genai_result}")
Original : Colonel Jessif, did you order the code rate? You don't have to answer that question. I'll answer the question. You want answers? I think I'm entitled. You want answers? I want the truth. You can't handle the truth.
Quantized: Don, I'll just, if you order the code right. You don have to answer that question. I'll answer the question. You want answers. I think I'm entitled you want answer. I want the truth. You can't handle the truth. You can't handle the truth.
Compare performance and accuracy of the original and quantized models#
Finally, we compare original and quantized Whisper models from accuracy and performance stand-points.
To measure accuracy, we use 1 - WER
as a metric, where WER stands
for Word Error Rate.
%%skip not $to_quantize.value
import time
from contextlib import contextmanager
from jiwer import wer, wer_standardize
TEST_DATASET_SIZE = 50
def calculate_transcription_time_and_accuracy(ov_model, test_samples):
whole_infer_times = []
ground_truths = []
predictions = []
for data_item in tqdm(test_samples, desc="Measuring performance and accuracy"):
start_time = time.perf_counter()
transcription = ov_model.generate(data_item["audio"]["array"])
end_time = time.perf_counter()
whole_infer_times.append(end_time - start_time)
ground_truths.append(data_item["text"])
predictions.append(transcription.texts[0])
word_accuracy = (1 - wer(ground_truths, predictions, reference_transform=wer_standardize,
hypothesis_transform=wer_standardize)) * 100
mean_whole_infer_time = sum(whole_infer_times)
return word_accuracy, mean_whole_infer_time
test_dataset = load_dataset("openslr/librispeech_asr", "clean", split="test", streaming=True, trust_remote_code=True)
test_dataset = test_dataset.shuffle(seed=42).take(TEST_DATASET_SIZE)
test_samples = [sample for sample in test_dataset]
accuracy_original, times_original = calculate_transcription_time_and_accuracy(ov_pipe, test_samples)
accuracy_quantized, times_quantized = calculate_transcription_time_and_accuracy(ov_quantized_pipe, test_samples)
print(f"Whole pipeline performance speedup: {times_original / times_quantized:.3f}")
print(f"Whisper transcription word accuracy. Original model: {accuracy_original:.2f}%. Quantized model: {accuracy_quantized:.2f}%.")
print(f"Accuracy drop: {accuracy_original - accuracy_quantized:.2f}%.")
Measuring performance and accuracy: 0%| | 0/50 [00:00<?, ?it/s]
Measuring performance and accuracy: 0%| | 0/50 [00:00<?, ?it/s]
Whole pipeline performance speedup: 1.350
Whisper transcription word accuracy. Original model: 82.88%. Quantized model: 84.13%.
Accuracy drop: -1.25%.
Interactive demo#
We are also providing an interactive demo using the Gradio interface, where you can test model capabilities on your own audio data (using the upload button) or record using your microphone.
import requests
if not Path("gradio_helper.py").exists():
r = requests.get(url="https://raw.githubusercontent.com/openvinotoolkit/openvino_notebooks/latest/notebooks/whisper-asr-genai/gradio_helper.py")
open("gradio_helper.py", "w").write(r.text)
from gradio_helper import make_demo, GradioPipeline
pipe = ov_quantized_pipe if to_quantize.value else ov_pipe
gr_pipeline = GradioPipeline(pipe, model_id.value, quantized=to_quantize.value)
demo = make_demo(gr_pipeline)
try:
demo.launch(debug=True)
except Exception:
demo.launch(share=True, debug=True)
# if you are launching remotely, specify server_name and server_port
# demo.launch(server_name='your server name', server_port='server port in int')
# Read more in the docs: https://gradio.app/docs/