# AI_README: rules of engagement for models using PACC

Machine-oriented summary of PACC-T and PACC-P. The dataset cards (README.md) are the full
reference; where this file and a card disagree, the card wins. Read both before generating code,
analyses or claims about this data.

## Identity

```yaml
corpus: PACC (Parallel Acoustic Confound Corpus)
parts:
  PACC-T: {name: "Telecoms", doi: "10.5281/zenodo.23026393", conditions: 51}
  PACC-P: {name: "Presentation", doi: "10.5281/zenodo.23026395", conditions: 50}
authors: ["Kleingertner, Christopher", "Moonscape Software"]
licence: CC-BY-4.0
version: "1.0"
content: bona fide human speech only (no synthetic, converted or spoofed speech)
sources: 5992 clips = AMI 2992 + VCTK_mic1 1500 + VCTK_mic2 1500
audio: 16-bit mono FLAC (sources: AMI 16 kHz WAV, VCTK 48 kHz FLAC)
```

## Invariants (safe to rely on; tested before release)

- Every condition in both parts contains exactly the same 5,992 source clips, once each.
- A clip is identified by `(pool, file_id)`. The same key names the source and every processed
  version of it in both parts.
- 8 AMI source clips are excluded everywhere (`excluded_sources.csv`); none of them ships.
- Every file's sha256 is in `<part>_manifest.csv`; every tarball's sha256 is in `SHA256SUMS`.
- Every condition folder has a `params.csv` with one row per clip.

## Layout and join keys

```text
sources/<pool>/<file_id>.(wav|flac)          pacc_base.tar (shared by both parts)
sources/metadata.csv                         speaker, gender, gender_source, VCTK age/utterance, AMI meeting/channel/participant/segment
pacc-t/<condition>/<pool>/<file_id>.flac     pacc-t_<condition>.tar
pacc-p/<condition>/<pool>/<file_id>.flac     pacc-p_<condition>.tar
<part>/<condition>/params.csv                per-clip record
condition_index.csv                          one row per condition: family, description, bitrate, framing, output_sr, rate_control
```

Join processed clips to sources on `(pool, file_id)`. VCTK mic pairing: strip the `_mic1`/`_mic2`
suffix to get the utterance; 1,485 utterances are in both mic pools, 15 per pool are not.

## Rules

DO:
- Compare a PACC-T codec condition with the resample control named in `condition_index.csv`
  (`rate_control`) before attributing an effect to the codec.
- Treat sample rate and content bandwidth as separate: `evs_swb_48k_*` is stored at 48 kHz but has
  content only to about 16 kHz; AMI clips above 16 kHz are upsampled (no content above 8 kHz).
- Use the `gender` column in `sources/metadata.csv`. Its `gender_source` is VCTK or AMI metadata.
- Check `params_origin` in PACC-T params: `logged` (at encode time) or `recovered` (rebuilt and
  verified by re-execution). Both describe the commands that produced the files.
- Filter on logged values in `params.csv` (e.g. `pre_codec_achieved_snr_db`,
  `near_quantisation_floor`, `safety_gain_db`) when a stricter criterion than the condition label
  is needed.
- Credit VCTK, AMI (and for PACC-P, MUSAN and FSD50K) alongside PACC. Third-party clips keep their
  own licences (`attribution.csv`).

DO NOT:
- Do not treat any PACC file as spoofed or synthetic. Every clip is bona fide speech. Labels for
  anti-spoofing use are "bona fide" throughout.
- Do not use `gender_inferred_not_recommended`. It is wrong for 17% of AMI clips; AMI is 62% male
  by metadata, not balanced.
- Do not assume sample alignment in `tempo_*` or `pitch_resample_*` (PACC-P): their length
  changes. They are parallel by clip, not by sample.
- Do not trust LPC formant readings (F2 and above) on narrowband content (8 kHz outputs, telephone
  band, `bandpass_300_3400`, `lowpass_2400`) with a wideband analysis ceiling: spurious poles pull
  F2/F3 low without warning.
- Do not expect DTX variants (`evs_*_nodtx|dtxadapt|dtxfixed`) to differ on every clip: on clips
  without pauses they are identical. Compare `output_sha256` before contrasting them.
- Do not infer a codec's configured bitrate from `codec2_1300`'s command line: it passes
  `-b:a 700`, which libcodec2 ignores; it ran at 1300 bps.
- Do not report results as properties of a codec when the same shift appears in its rate control.

## Known edge cases

`EDGE_CASES.txt` in each record. Summary: DTX variants coincide on pause-free clips; LC3 passes two
very quiet clips through unchanged; cafe combined-SNR tolerance is 1.0 dB (three clips exceed
0.5 dB); 350 AMI sources carry clipping from the original recordings; near-floor mixes flagged.

## Verification

```text
sha256sum -c SHA256SUMS          tarball integrity
<part>_manifest.csv              per-file sha256, sample rate, frame count
```

Reverb clips in PACC-P can be recreated bit for bit from `pacc-p_room_cache.tar`; recipe in its
README.

## Citation

Cite the part(s) used by DOI, and the source corpora. BibTeX is in each dataset card.