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# Speech2Text2

## Overview

The Speech2Text2 model is used together with [Wav2Vec2](wav2vec2) for Speech Translation models proposed in
[Large-Scale Self- and Semi-Supervised Learning for Speech Translation](https://arxiv.org/abs/2104.06678) by
Changhan Wang, Anne Wu, Juan Pino, Alexei Baevski, Michael Auli, Alexis Conneau.

Speech2Text2 is a *decoder-only* transformer model that can be used with any speech *encoder-only*, such as
[Wav2Vec2](wav2vec2) or [HuBERT](hubert) for Speech-to-Text tasks. Please refer to the
[SpeechEncoderDecoder](speech-encoder-decoder) class on how to combine Speech2Text2 with any speech *encoder-only*
model.

This model was contributed by [Patrick von Platen](https://huggingface.co/patrickvonplaten).

The original code can be found [here](https://github.com/pytorch/fairseq/blob/1f7ef9ed1e1061f8c7f88f8b94c7186834398690/fairseq/models/wav2vec/wav2vec2_asr.py#L266).


Tips:

- Speech2Text2 achieves state-of-the-art results on the CoVoST Speech Translation dataset. For more information, see
  the [official models](https://huggingface.co/models?other=speech2text2) .
- Speech2Text2 is always used within the [SpeechEncoderDecoder](speech-encoder-decoder) framework.
- Speech2Text2's tokenizer is based on [fastBPE](https://github.com/glample/fastBPE).

## Inference

Speech2Text2's [`SpeechEncoderDecoderModel`] model accepts raw waveform input values from speech and
makes use of [`~generation_utils.GenerationMixin.generate`] to translate the input speech
autoregressively to the target language.

The [`Wav2Vec2FeatureExtractor`] class is responsible for preprocessing the input speech and
[`Speech2Text2Tokenizer`] decodes the generated target tokens to the target string. The
[`Speech2Text2Processor`] wraps [`Wav2Vec2FeatureExtractor`] and
[`Speech2Text2Tokenizer`] into a single instance to both extract the input features and decode the
predicted token ids.

- Step-by-step Speech Translation

```python
>>> import torch
>>> from transformers import Speech2Text2Processor, SpeechEncoderDecoderModel
>>> from datasets import load_dataset
>>> import soundfile as sf

>>> model = SpeechEncoderDecoderModel.from_pretrained("facebook/s2t-wav2vec2-large-en-de")
>>> processor = Speech2Text2Processor.from_pretrained("facebook/s2t-wav2vec2-large-en-de")


>>> def map_to_array(batch):
...     speech, _ = sf.read(batch["file"])
...     batch["speech"] = speech
...     return batch


>>> ds = load_dataset("hf-internal-testing/librispeech_asr_dummy", "clean", split="validation")
>>> ds = ds.map(map_to_array)

>>> inputs = processor(ds["speech"][0], sampling_rate=16_000, return_tensors="pt")
>>> generated_ids = model.generate(inputs=inputs["input_values"], attention_mask=inputs["attention_mask"])

>>> transcription = processor.batch_decode(generated_ids)
```

- Speech Translation via Pipelines

  The automatic speech recognition pipeline can also be used to translate speech in just a couple lines of code

```python
>>> from datasets import load_dataset
>>> from transformers import pipeline

>>> librispeech_en = load_dataset("hf-internal-testing/librispeech_asr_dummy", "clean", split="validation")
>>> asr = pipeline(
...     "automatic-speech-recognition",
...     model="facebook/s2t-wav2vec2-large-en-de",
...     feature_extractor="facebook/s2t-wav2vec2-large-en-de",
... )

>>> translation_de = asr(librispeech_en[0]["file"])
```

See [model hub](https://huggingface.co/models?filter=speech2text2) to look for Speech2Text2 checkpoints.


## Speech2Text2Config

[[autodoc]] Speech2Text2Config

## Speech2TextTokenizer

[[autodoc]] Speech2Text2Tokenizer
    - batch_decode
    - decode
    - save_vocabulary

## Speech2Text2Processor

[[autodoc]] Speech2Text2Processor
    - __call__
    - from_pretrained
    - save_pretrained
    - batch_decode
    - decode
    - as_target_processor

## Speech2Text2ForCausalLM

[[autodoc]] Speech2Text2ForCausalLM
    - forward