# Results

All six clips: 768x1344, 124 frames, 50 steps, seed 1101, same prompt, one RTX 5090.
Runs 1–5 are NVFP4 W4A4 through the Nunchaku runtime with the `smooth_factor` interleave fix.

## Offline, per modality — the measurement that decides it

Relative L2 of the quantized layer output against bf16, median over 312 layers, 4096 sampled rows
per modality per layer, rank-32 branch included, same NVFP4 fake-quantizer the calibration used.

| modality | lambda=1 | lambda=all | lambda=video | lambda=text |
| --- | --- | --- | --- | --- |
| video | 0.0980 | 0.0976 | **0.0937** | 0.0981 |
| text | 0.0891 | **0.0871** | 0.1140 | **0.0871** |
| audio | 0.0875 | **0.0857** | 0.0975 | 0.0874 |

vs no smoothing: `lambda=all` −0.4 % / −2.2 % / −2.1 %; `lambda=video` **−4.3 % / +27.9 % /
+11.5 %**; `lambda=text` +0.1 % / −2.2 % / −0.2 %.

`lambda=all` is the only candidate that is not negative-sum. This is 312 layers x 3 modalities of
independent measurements and it is the basis for the recommendation.

## End to end, one prompt

| run | mean RGB | per-frame lo–hi | span | std | Δmean | PSNR vs BF16 | corr vs BF16 |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 0 BF16 | 36.27 | 27.78–45.96 | 18.18 | 43.90 | — | — | — |
| 1 plain W4A4 | 28.42 | 27.40–29.11 | 1.71 | 41.60 | −7.85 | 15.02 | 0.438 |
| 2 lambda=1 +LoRA | 30.43 | 25.50–33.72 | 8.21 | 42.76 | −5.84 | 15.12 | 0.436 |
| 3 lambda=all | **36.67** | 31.64–43.28 | 11.64 | 46.14 | **+0.40** | 14.84 | **0.449** |
| 4 lambda=video | 24.59 | 21.62–26.69 | 5.07 | 27.07 | −11.67 | 14.50 | 0.139 |
| 5 lambda=text | 24.58 | 21.73–26.99 | 5.26 | 29.73 | −11.69 | 14.56 | 0.196 |

**Read this table as a coarse split, not a ranking.** All five quantized runs produce coherent
video — none is degraded or noisy; see `contact_sheet.png`. What differs is which sample the run
lands in. Runs 1, 2 and 3 stay in BF16's bedroom framing (`corr` 0.44–0.45); runs 4 and 5 both go
to a different floor-level scene (`corr` 0.14–0.20, and `corr` 0.645 to *each other* — they are
closer to one another than either is to BF16).

Two limits worth stating rather than papering over:

* **n = 1 prompt.** Which basin a run falls into is close to a coin flip at this sample size. The
  table cannot separate run 1 from run 3, and it should not be read as doing so.
* **`lambda=text` diverges end to end while being benign offline.** The offline table says it is
  harmless; this clip says it moved. One clip is not enough to call that a real effect.

What the end-to-end runs *do* establish: run 3 is the only one whose mean RGB, per-frame spread and
std all land on BF16's, and the two runs that diverged are not the two that the calibration's own
error column ranked best. That is consistent with the offline per-modality table and inconsistent
with the proportional one.

## The trap this repeats

The calibration's own error column — the one in `svdquant_calib_768p*.pt` — ranks the runs:

| | lambda=1 | lambda=1 +LoRA | lambda=all | lambda=video | lambda=text |
| --- | --- | --- | --- | --- | --- |
| median `err_smooth_lowrank` | 0.1019 | 0.0951 | 0.0942 | **0.0903** | 0.0953 |

`lambda=video` wins it. That column is measured on rows drawn uniformly from the packed sequence,
and video is 98.6 % of them, so it is a video error — it cannot see the 27.9 % it charged text.
Picking a calibration by that number alone selects the configuration this study rejects.

## Files

`0_bf16.mp4` … `5_lambda_text.mp4`, `grid.mp4` (all six on one timeline, captioned),
`contact_sheet.png` (5 frames each), `README.md` (what each run is and why).

Scripts, on the H100 side: `calib_stats_modal.py`, `calib_sample_modal.py`,
`score_modal_lambda.py`, `score_modal_report.py`, `diag_lambda_crossmodal.py`,
`lambda_exps_report.py`, `mk_lambda_grid.py`.