pub fn create_decoder_on(
codec: &str,
info: StreamInfo,
gpu_index: Option<u32>,
) -> Result<Box<dyn Decoder>>Expand description
Construct a decoder pinned to a specific gpu_index when one is
supplied. None preserves the legacy “pick the first matching
adapter” behaviour for one-shot callers (thumbnails, tests, benches)
that don’t care about distributing work across physical GPUs.
The pipeline’s per-rung decode pumps should ALWAYS pass Some(idx)
so each rung’s decode session lands on a distinct adapter — without
this, every QSV session piles onto the first physical Intel card
regardless of what the GPU pool’s lease said. See the project memo
on QSV multi-adapter session pinning.