Files
hao-ai-lab-FastVideo/examples/inference/basic/basic_cosmos3_t2vs_new_api.py
SolitaryThinker 1ec268cf80 [feat] cosmos3 PR2: t2vs pipeline (joint denoise + AVAE decode + AV mux)
Wire text-to-video+sound end-to-end, completing the audio PR.

- CFG velocity (`cosmos3_get_cfg_velocity`) + `Cosmos3DenoiseEngine` take an
  optional `sound_specs`: the denoise latent becomes a combined [vision | sound]
  flat vector; each step packs vision+sound, forwards the DiT, zeros the
  prediction on conditioning frames for both, and returns the concatenated
  velocity. The UniPC scheduler steps the joint vector. `Cosmos3SoundSpec` +
  `_split_sound_latent` added.
- `Cosmos3DenoisingStage` t2vs path (gated on `COSMOS3_T2VS`): size the sound
  latent from the video duration (framework `create_placeholder_audio` +
  `get_latent_num_samples`), append sound noise, joint-denoise, split, AVAE-decode
  the sound latent, and set `batch.extra["audio"]` / `["audio_sample_rate"]` so
  the generator muxes a stereo 48 kHz AAC track into the mp4. Sound AVAE is
  lazy-loaded from `<model_path>/sound_tokenizer` (`_get_sound_vae`).
- Parity (`test_cosmos3_sound_parity::test_t2vs_cfg_velocity_matches_framework`):
  the combined [vision|sound] sequential-CFG velocity vs a framework-DiT oracle —
  max abs diff = 0.0, mean abs diff = 0.0 across t2vs/i2vs cases.
- Example `basic_cosmos3_t2vs_new_api.py`.

Verified on B200 (real weights, 1280x704, 29f, 35 steps): coherent ocean/sunset
video WITH a real stereo 48 kHz audio track (mean -10.2 dB, peak -0.4 dB; not
silence). Full cosmos3 suite: 130 passed, 0 skipped.
2026-07-13 03:23:42 -07:00

68 lines
2.2 KiB
Python

import os
import time
# t2vs (text -> video + sound). The Cosmos3 denoise stage generates a joint
# [vision | sound] latent and AVAE-decodes the sound to a waveform muxed into the
# mp4. The joint-sound path is gated on COSMOS3_T2VS (set here for the example).
os.environ.setdefault("COSMOS3_T2VS", "1")
from fastvideo import VideoGenerator # noqa: E402
from fastvideo.api import ( # noqa: E402
EngineConfig,
GenerationRequest,
GeneratorConfig,
OffloadConfig,
OutputConfig,
SamplingConfig,
)
OUTPUT_PATH = "video_samples_cosmos3_t2vs"
def main():
model_name = os.environ.get("COSMOS3_MODEL_PATH", "nvidia/Cosmos3-Nano")
generator_config = GeneratorConfig(
model_path=model_name,
engine=EngineConfig(
num_gpus=1,
use_fsdp_inference=False,
offload=OffloadConfig(text_encoder=True, pin_cpu_memory=True, dit=False, vae=False),
),
)
load_start = time.perf_counter()
generator = VideoGenerator.from_config(generator_config)
load_time = time.perf_counter() - load_start
prompt = (
"Ocean waves crash against a rocky shore at sunset, white foam spraying "
"into the air as seagulls wheel overhead. Golden light, cinematic wide "
"shot, the rhythmic roar of the surf."
)
request = GenerationRequest(
prompt=prompt,
sampling=SamplingConfig(
num_frames=int(os.environ.get("COSMOS3_NUM_FRAMES", "189")),
height=int(os.environ.get("COSMOS3_HEIGHT", "704")),
width=int(os.environ.get("COSMOS3_WIDTH", "1280")),
num_inference_steps=int(os.environ.get("COSMOS3_STEPS", "35")),
guidance_scale=6.0,
fps=24,
seed=1024,
),
output=OutputConfig(output_path=OUTPUT_PATH, save_video=True, return_frames=False),
)
start = time.perf_counter()
result = generator.generate(request)
gen_time = time.perf_counter() - start
print(f"Time taken to load model: {load_time} seconds")
print(f"Time taken to generate video+sound: {gen_time} seconds")
print(f"Output written to: {result.video_path}")
if __name__ == "__main__":
main()