Function open_track_stream_at 

pub fn open_track_stream_at<R: AudioSectorReader>(
    src: &R,
    start_lba: u32,
    sectors: u32,
) -> AudioTrackStream<'_, R>

Open a streaming reader over an explicit absolute sector range (start_lba .. start_lba + sectors), bypassing TOC bounds resolution.

For backings that compute their own track layout — e.g. reading [start_lba(n) .. start_lba(n + 1)) from a contiguous extract — this is the zero-policy primitive: no TOC lookup, no CD-Extra rule, and no failure mode.