transformers/docs/source/en/model_doc/csm.md

This model was contributed to Hugging Face Transformers on 2025-05-07.

Csm

Overview

The Conversational Speech Model (CSM) is the first open-source contextual text-to-speech model released by Sesame. It is designed to generate natural-sounding speech with or without conversational context. This context typically consists of multi-turn dialogue between speakers, represented as sequences of text and corresponding spoken audio.

Model Architecture: CSM is composed of two LLaMA-style auto-regressive transformer decoders: a backbone decoder that predicts the first codebook token and a depth decoder that generates the remaining tokens. It uses the pretrained codec model Mimi, introduced by Kyutai, to encode speech into discrete codebook tokens and decode them back into audio.

The original csm-1b checkpoint is available under the Sesame organization on Hugging Face.

Usage Tips

Without Conversational Context

CSM can be used to simply generate speech from a text prompt:

from transformers import AutoProcessor, CsmForConditionalGeneration


model_id = "sesame/csm-1b"

# load the model and the processor
processor = AutoProcessor.from_pretrained(model_id)
model = CsmForConditionalGeneration.from_pretrained(model_id, device_map="auto")

# prepare the inputs
text = "[0]The past is just a story we tell ourselves." # `[0]` for speaker id 0
inputs = processor(text, add_special_tokens=True).to(model.device)

# another equivalent way to prepare the inputs
conversation = [
    {"role": "0", "content": [{"type": "text", "text": "The past is just a story we tell ourselves."}]},
]
inputs = processor.apply_chat_template(
    conversation,
    tokenize=True,
    return_dict=True,
).to(model.device)

# infer the model
audio = model.generate(**inputs, output_audio=True)
processor.save_audio(audio, "example_without_context.wav")

With Conversational Context

CSM can be used to generate speech given a conversation, allowing consistency in the voices and content-aware generation:

from datasets import Audio, load_dataset

from transformers import AutoProcessor, CsmForConditionalGeneration


model_id = "sesame/csm-1b"

# load the model and the processor
processor = AutoProcessor.from_pretrained(model_id)
model = CsmForConditionalGeneration.from_pretrained(model_id, device_map="auto")

# prepare the inputs
ds = load_dataset("hf-internal-testing/dailytalk-dummy", split="train")
# ensure the audio is 24kHz
ds = ds.cast_column("audio", Audio(sampling_rate=24000))
conversation = []

# 1. context
for text, audio, speaker_id in zip(ds[:4]["text"], ds[:4]["audio"], ds[:4]["speaker_id"]):
    conversation.append(
        {
            "role": f"{speaker_id}",
            "content": [{"type": "text", "text": text}, {"type": "audio", "path": audio["array"]}],
        }
    )

# 2. text prompt
conversation.append({"role": f"{ds[4]['speaker_id']}", "content": [{"type": "text", "text": ds[4]["text"]}]})

inputs = processor.apply_chat_template(
    conversation,
    tokenize=True,
    return_dict=True,
).to(model.device)

# infer the model
audio = model.generate(**inputs, output_audio=True)
processor.save_audio(audio, "example_with_context.wav")

Batched Inference

CSM supports batched inference!

from datasets import Audio, load_dataset

from transformers import AutoProcessor, CsmForConditionalGeneration


model_id = "sesame/csm-1b"

# load the model and the processor
processor = AutoProcessor.from_pretrained(model_id)
model = CsmForConditionalGeneration.from_pretrained(model_id, device_map="auto")

# prepare the inputs
ds = load_dataset("hf-internal-testing/dailytalk-dummy", split="train")
# ensure the audio is 24kHz
ds = ds.cast_column("audio", Audio(sampling_rate=24000))
# here a batch with two prompts
conversation = [
    [
        {
            "role": f"{ds[0]['speaker_id']}",
            "content": [
                {"type": "text", "text": ds[0]["text"]},
                {"type": "audio", "path": ds[0]["audio"]["array"]},
            ],
        },
        {
            "role": f"{ds[1]['speaker_id']}",
            "content": [
                {"type": "text", "text": ds[1]["text"]},
            ],
        },
    ],
    [
        {
            "role": f"{ds[0]['speaker_id']}",
            "content": [
                {"type": "text", "text": ds[0]["text"]},
            ],
        }
    ],
]
inputs = processor.apply_chat_template(
    conversation,
    tokenize=True,
    return_dict=True,
).to(model.device)

audio = model.generate(**inputs, output_audio=True)
processor.save_audio(audio, [f"speech_batch_idx_{i}.wav" for i in range(len(audio))])

Making The Model Go Brrr

CSM supports full-graph compilation with CUDA graphs!

import torch
from datasets import load_dataset

from transformers import AutoProcessor, CsmForConditionalGeneration


model_id = "sesame/csm-1b"

# set logs to ensure no recompilation and graph breaks
torch._logging.set_logs(graph_breaks=True, recompiles=True, cudagraphs=True)

# load the model and the processor
processor = AutoProcessor.from_pretrained(model_id)
model = CsmForConditionalGeneration.from_pretrained(model_id, device_map="auto")

# use static cache, enabling automatically torch compile with fullgraph and reduce-overhead
model.generation_config.max_length = 250 # big enough to avoid recompilation
model.generation_config.max_new_tokens = None # would take precedence over max_length
model.generation_config.cache_implementation = "static"
model.depth_decoder.generation_config.cache_implementation = "static"

# generation kwargs
gen_kwargs = {
    "do_sample": False,
    "depth_decoder_do_sample": False,
    "temperature": 1.0,
    "depth_decoder_temperature": 1.0,
}

# Define a timing decorator
class TimerContext:
    def __init__(self, name="Execution"):
        self.name = name
        self.start_event = None
        self.end_event = None

    def __enter__(self):
        # Use CUDA events for more accurate GPU timing
        self.start_event = torch.cuda.Event(enable_timing=True)
        self.end_event = torch.cuda.Event(enable_timing=True)
        self.start_event.record()
        return self

    def __exit__(self, *args):
        self.end_event.record()
        torch.cuda.synchronize()
        elapsed_time = self.start_event.elapsed_time(self.end_event) / 1000.0
        print(f"{self.name} time: {elapsed_time:.4f} seconds")

# prepare the inputs
ds = load_dataset("hf-internal-testing/dailytalk-dummy", split="train")

conversation = [
    {
        "role": f"{ds[0]['speaker_id']}",
        "content": [
            {"type": "text", "text": ds[0]["text"]},
            {"type": "audio", "path": ds[0]["audio"]["array"]},
        ],
    },
    {
        "role": f"{ds[1]['speaker_id']}",
        "content": [
            {"type": "text", "text": ds[1]["text"]},
            {"type": "audio", "path": ds[1]["audio"]["array"]},
        ],
    },
    {
        "role": f"{ds[2]['speaker_id']}",
        "content": [
            {"type": "text", "text": ds[2]["text"]},
        ],
    },
]

padded_inputs_1 = processor.apply_chat_template(
    conversation,
    tokenize=True,
    return_dict=True,
).to(model.device)

print("\n" + "="*50)
print("First generation - compiling and recording CUDA graphs...")
with TimerContext("First generation"):
    _ = model.generate(**padded_inputs_1, **gen_kwargs)
print("="*50)

print("\n" + "="*50)
print("Second generation - fast !!!")
with TimerContext("Second generation"):
    _ = model.generate(**padded_inputs_1, **gen_kwargs)
print("="*50)

# now with different inputs
conversation = [
    {
        "role": f"{ds[0]['speaker_id']}",
        "content": [
            {"type": "text", "text": ds[2]["text"]},
            {"type": "audio", "path": ds[2]["audio"]["array"]},
        ],
    },
    {
        "role": f"{ds[1]['speaker_id']}",
        "content": [
            {"type": "text", "text": ds[3]["text"]},
            {"type": "audio", "path": ds[3]["audio"]["array"]},
        ],
    },
    {
        "role": f"{ds[2]['speaker_id']}",
        "content": [
            {"type": "text", "text": ds[4]["text"]},
        ],
    },
]
padded_inputs_2 = processor.apply_chat_template(
    conversation,
    tokenize=True,
    return_dict=True,
).to(model.device)

print("\n" + "="*50)
print("Generation with other inputs!")
with TimerContext("Generation with different inputs"):
    _ = model.generate(**padded_inputs_2, **gen_kwargs)
print("="*50)

Training

CSM Transformers integration supports training!

from datasets import Audio, load_dataset

from transformers import AutoProcessor, CsmForConditionalGeneration


model_id = "sesame/csm-1b"

# load the model and the processor
processor = AutoProcessor.from_pretrained(model_id)
model = CsmForConditionalGeneration.from_pretrained(model_id, device_map="auto")
model.train()
model.codec_model.eval()

ds = load_dataset("hf-internal-testing/dailytalk-dummy", split="train")
# ensure the audio is 24kHz
ds = ds.cast_column("audio", Audio(sampling_rate=24000))
conversation = []

# context
for text, audio, speaker_id in zip(ds[:4]["text"], ds[:4]["audio"], ds[:4]["speaker_id"]):
    conversation.append(
        {
            "role": f"{speaker_id}",
            "content": [{"type": "text", "text": text}, {"type": "audio", "path": audio["array"]}],
        }
    )

inputs = processor.apply_chat_template(
    conversation,
    tokenize=True,
    return_dict=True,
    output_labels=True,
).to(model.device)

out = model(**inputs)
out.loss.backward()

This model was contributed by Eustache Le Bihan. The original code can be found here.

CsmConfig

autodoc CsmConfig

CsmDepthDecoderConfig

autodoc CsmDepthDecoderConfig

CsmProcessor

autodoc CsmProcessor - call

CsmForConditionalGeneration

autodoc CsmForConditionalGeneration - forward - generate

CsmDepthDecoderForCausalLM

autodoc CsmDepthDecoderForCausalLM

CsmDepthDecoderModel

autodoc CsmDepthDecoderModel

CsmBackboneModel

autodoc CsmBackboneModel