mzML export

OpenSXRaw doesn't ship a dedicated export binary yet, but since Reader implements openmassspec_core::SpectrumSource, it can be written to mzML using the same writer every reader in the OpenMassSpec stack uses, so output is consistent across vendors:

use opensxraw::reader::Reader;
use openmassspec_core::write_mzml;

let mut reader = Reader::open("sample.wiff")?;
let mut out = std::fs::File::create("output.mzML")?;
let summary = write_mzml(&mut reader, &mut out)?;
println!("{} spectra written", summary.spectra_written);

write_mzml stops at the first spectrum that fails to decode and returns that error. To write the readable spectra and skip the rest, use write_mzml_with_options with RecordErrorPolicy::Skip and report the skipped count from the returned WriteSummary.

write_mzml iterates the reader's spectra via SpectrumSource (the same stream described in Reader) and emits PSI-MS CV-annotated mzML - MS:1000562 (ABI WIFF format) as the source-file format term, with per-spectrum retention time, MS level, and precursor information carried through where the reader populated it. Given the current reader limitations (TOF m/z not accurate, QTRAP m/z in raw bins, every TripleTOF/ZenoTOF scan labelled MS2 with no precursor m/z), exported mzML will carry those same gaps until the underlying fields are decoded.