import torch
from transformers import AutoModelForCausalLM, AutoTokenizer, BitsAndBytesConfig
from snac import SNAC
import soundfile as sf

Model configuration for 4-bit inference

quantization_config = BitsAndBytesConfig(
load_in_4bit=True,
bnb_4bit_quant_type="nf4",
bnb_4bit_compute_dtype=torch.bfloat16,
bnb_4bit_use_double_quant=True,
)

Load model and tokenizer

model = AutoModelForCausalLM.from_pretrained(
"maya-research/veena-tts",
quantization_config=quantization_config,
device_map="cuda",
trust_remote_code=True,
)
tokenizer = AutoTokenizer.from_pretrained("maya-research/veena-tts", trust_remote_code=True)

Initialize SNAC decoder

snac_model = SNAC.from_pretrained("hubertsiuzdak/snac_24khz").eval().cuda()

Control token IDs (fixed for Veena)

START_OF_SPEECH_TOKEN = 128257
END_OF_SPEECH_TOKEN = 128258
START_OF_HUMAN_TOKEN = 128259
END_OF_HUMAN_TOKEN = 128260
START_OF_AI_TOKEN = 128261
END_OF_AI_TOKEN = 128262
AUDIO_CODE_BASE_OFFSET = 128266

Available speakers

speakers = ["kavya", "agastya", "maitri", "vinaya"]

def generate_speech(text, speaker="kavya", temperature=0.4, top_p=0.9):
"""Generate speech from text using specified speaker voice"""

# Prepare input with speaker token
prompt = f"<spk_{speaker}> {text}"
prompt_tokens = tokenizer.encode(prompt, add_special_tokens=False)

# Construct full sequence: [HUMAN] <spk_speaker> text [/HUMAN] [AI] [SPEECH]
input_tokens = [
    START_OF_HUMAN_TOKEN,
    *prompt_tokens,
    END_OF_HUMAN_TOKEN,
    START_OF_AI_TOKEN,
    START_OF_SPEECH_TOKEN
]

#input_ids = torch.tensor([input_tokens], device=model.device)
input_ids = torch.tensor([input_tokens], device="cuda")
# Calculate max tokens based on text length
max_tokens = min(int(len(text) * 1.3) * 7 + 21, 700)

# Generate audio tokens
with torch.no_grad():
    output = model.generate(
        input_ids,
        use_cache=True,
        max_new_tokens=max_tokens,
        do_sample=True,
        temperature=temperature,
        top_p=top_p,
        repetition_penalty=1.05,
        pad_token_id=tokenizer.pad_token_id,
        eos_token_id=[END_OF_SPEECH_TOKEN, END_OF_AI_TOKEN]
    )

# Extract SNAC tokens
generated_ids = output[0][len(input_tokens):].tolist()
snac_tokens = [
    token_id for token_id in generated_ids
    if AUDIO_CODE_BASE_OFFSET <= token_id < (AUDIO_CODE_BASE_OFFSET + 7 * 4096)
]

if not snac_tokens:
    raise ValueError("No audio tokens generated")

# Decode audio
audio = decode_snac_tokens(snac_tokens, snac_model)
return audio

def decode_snac_tokens(snac_tokens, snac_model):
"""De-interleave and decode SNAC tokens to audio"""
if not snac_tokens or len(snac_tokens) % 7 != 0:
return None

# De-interleave tokens into 3 hierarchical levels
codes_lvl = [[] for _ in range(3)]
llm_codebook_offsets = [AUDIO_CODE_BASE_OFFSET + i * 4096 for i in range(7)]

for i in range(0, len(snac_tokens), 7):
    # Level 0: Coarse (1 token)
    codes_lvl[0].append(snac_tokens[i] - llm_codebook_offsets[0])
    # Level 1: Medium (2 tokens)
    codes_lvl[1].append(snac_tokens[i+1] - llm_codebook_offsets[1])
    codes_lvl[1].append(snac_tokens[i+4] - llm_codebook_offsets[4])
    # Level 2: Fine (4 tokens)
    codes_lvl[2].append(snac_tokens[i+2] - llm_codebook_offsets[2])
    codes_lvl[2].append(snac_tokens[i+3] - llm_codebook_offsets[3])
    codes_lvl[2].append(snac_tokens[i+5] - llm_codebook_offsets[5])
    codes_lvl[2].append(snac_tokens[i+6] - llm_codebook_offsets[6])

# Convert to tensors for SNAC decoder
hierarchical_codes = []
for lvl_codes in codes_lvl:
    #tensor = torch.tensor(lvl_codes, dtype=torch.int32, device=snac_model.device).unsqueeze(0)
    tensor = torch.tensor(lvl_codes, dtype=torch.int32, device="cuda").unsqueeze(0)
    if torch.any((tensor < 0) | (tensor > 4095)):
        raise ValueError("Invalid SNAC token values")
    hierarchical_codes.append(tensor)

# Decode with SNAC
with torch.no_grad():
    audio_hat = snac_model.decode(hierarchical_codes)

return audio_hat.squeeze().clamp(-1, 1).cpu().numpy()

--- Example Usage ---

audio = generate_speech("presentation", speaker="maitri")

Code-mixed

from time import time
start=time()
text_mixed = "मैं तो पूरा presentation prepare कर चुका हूं! कल रात को ही मैंने पूरा code base चेक किया।"
audio = generate_speech(text_mixed, speaker="maitri")
end=time()
print(end-start)
sf.write("output_mixed_maitri.wav", audio, 24000)

i am using this code to run this model on A100 gpu but but its taking 31 seconds, am i missing something for sub 200ms runtime @DheemanthReddy