[vLLM backend][Feature Request] Support vLLM-Omni for native audio/video input

Problem

The vLLM backend in the official Triton image (nvcr.io/nvidia/tritonserver:*-vllm-python-py3) only supports the image modality. In backends/vllm/utils/request.py, the only multimodal branch is multi_modal_data={"image": ...} — there is no video or audio support. So even though the vLLM engine supports them, Triton users can't pass audio/video.

Request

Please add vLLM-Omni support to the official Triton vLLM backend, so Triton can natively serve omni-modal models (e.g. Qwen3-Omni) with video and audio in multi_modal_data, not just images. An official omni example model_repository would also help.

Current workaround

Custom Python pre-processing that extracts video frames with ffmpeg and sends them as multiple images — loses native temporal/audio handling and inflates tokens.

Context

• vLLM-Omni supports text/image/audio/video (v0.24.0, July 2026): https://github.com/vllm-project/vllm-omni
• Env: tritonserver:26.06-vllm-python-py3, Qwen3-VL-8B, single-node GPU