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76 lines
3.4 KiB
ReStructuredText
76 lines
3.4 KiB
ReStructuredText
Automatic Speech Recognition (ASR)
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==================================
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Automatic Speech Recognition (ASR), also known as Speech To Text (STT), refers to the problem of automatically transcribing spoken language.
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NeMo provides open-sourced pretrained models in 25+ languages. Browse the full list in :doc:`ASR Model Checkpoints <./asr_checkpoints>`.
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Quick Start
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-----------
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After :ref:`installing NeMo<installation>`, transcribe an audio file in 3 lines:
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.. code-block:: python
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import nemo.collections.asr as nemo_asr
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asr_model = nemo_asr.models.ASRModel.from_pretrained("nvidia/parakeet-tdt-0.6b-v2")
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transcript = asr_model.transcribe(["path/to/audio_file.wav"])[0].text
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Timestamps
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^^^^^^^^^^
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Obtain word, segment, or character timestamps with any Parakeet model (CTC/RNNT/TDT):
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.. code-block:: python
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hypotheses = asr_model.transcribe(["path/to/audio_file.wav"], timestamps=True)
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for stamp in hypotheses[0].timestamp['word']:
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print(f"{stamp['start']}s - {stamp['end']}s : {stamp['word']}")
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See :doc:`Inference <./inference>` for full details on timestamps, long audio, streaming, and multi-task inference.
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Key Features
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------------
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**50+ Pretrained Models** — NeMo offers open-source checkpoints across 14+ languages, available on `HuggingFace <https://huggingface.co/nvidia>`__ and `NGC <https://catalog.ngc.nvidia.com/models?query=nemo>`__. Browse the full list in :doc:`All Checkpoints <./asr_checkpoints>`.
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**Timestamps** — Character, word, and segment-level timestamps are supported for all Parakeet models with CTC, RNNT, and TDT decoders.
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**Streaming** — Real-time transcription with cache-aware streaming Conformer models, supporting configurable latency-accuracy tradeoffs. See :ref:`cache-aware streaming conformer`.
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**Multi-task (Canary)** — The Canary model family supports ASR and speech translation (AST) across 25 European languages, with built-in punctuation and capitalization. See :doc:`Featured Models <./featured_models>`.
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**Language Modeling** — GPU-accelerated n-gram LM fusion (NGPU-LM) for CTC, RNN-T, TDT, and AED models improves transcription accuracy without retraining. See :ref:`asr_language_modeling_and_customization`.
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**Word Boosting** — Bias decoding toward specific words or phrases without retraining. Supports global and per-stream (per-utterance) boosting. See :ref:`word_boosting`.
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**Multitalker** — Streaming multi-speaker ASR with speaker kernel injection handles overlapping speech in real time. See `Multitalker Parakeet <https://huggingface.co/nvidia/multitalker-parakeet-streaming-0.6b-v1>`__.
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**Long Audio** — Inference on audio over 1 hour via local attention or buffered chunked processing.
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**Decoder Types** — NeMo supports CTC, RNN-T, TDT, AED, and Hybrid decoders. For a comparison of decoder types, see :ref:`asr_language_modeling_and_customization`.
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ASR Customization
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-----------------
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NeMo supports decoding-time customization techniques to improve accuracy without retraining, including GPU-accelerated language model fusion (NGPU-LM), neural rescoring, and word boosting (GPU-PB, per-stream, Flashlight, CTC-WS). See :ref:`asr_language_modeling_and_customization` for full documentation.
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Further Reading
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---------------
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.. toctree::
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:maxdepth: 1
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featured_models
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asr_checkpoints
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inference
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fine_tuning
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datasets
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asr_language_modeling_and_customization
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configs
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api
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featured_community_checkpoints
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