# EasyCom open-stream context: 8 seconds versus 20 seconds

Recorded on **2026-08-23**. This is a single-run experiment snapshot, not a
final multi-seed paper result.

## Experiment contract

- Dataset: EasyCom with EgoSpeak's official split.
- Train sessions: 7, 11, 10, 6, 9, 4, 8, 5, and 12.
- Test sessions: 3, 2, and 1.
- Representation: frozen Qwen2.5-Omni-3B Thinker, open-stream replay.
- Head: MLP `2048 -> 1024 -> 30`, reshaped to `10 x 3`.
- Video sampling: 2 FPS.
- Prediction rate: 5 Hz.
- Context budgets: 8 seconds and 20 seconds.
- Targets: ten future horizons from 0.2 through 2.0 seconds.
- Loss/evaluation: EgoSpeak LSTR MCE and Table 2 frame AP/mAP protocol.

The heads were trained separately for their corresponding representations. A
head trained on the 20-second states was not reused on the 8-second states.

## Summary

All values are percentages.

| Protocol | 8 seconds | 20 seconds | 8s minus 20s |
|---|---:|---:|---:|
| EgoSpeak full timeline | **58.51937** | 58.316 | **+0.20337** |
| Strict causal valid only | **58.53015** | 58.326 | **+0.20415** |

The full-timeline per-horizon comparison is:

| Horizon | Time | 8s mAP | 20s mAP | 8s minus 20s |
|---:|---:|---:|---:|---:|
| 1 | 0.2s | **71.99768** | 69.756 | **+2.24168** |
| 2 | 0.4s | **66.74289** | 65.163 | **+1.57989** |
| 3 | 0.6s | **62.38972** | 61.578 | **+0.81172** |
| 4 | 0.8s | **59.12229** | 58.783 | **+0.33929** |
| 5 | 1.0s | 56.71380 | **56.913** | -0.19920 |
| 6 | 1.2s | 55.36300 | **55.727** | -0.36400 |
| 7 | 1.4s | 54.21297 | **54.819** | -0.60603 |
| 8 | 1.6s | 53.43221 | **53.957** | -0.52479 |
| 9 | 1.8s | 52.84703 | **53.459** | -0.61197 |
| 10 | 2.0s | 52.37207 | **53.002** | -0.62993 |
| Mean | — | **58.51937** | 58.316 | **+0.20337** |

For the full-timeline protocol, averaging AP over the ten horizons gives:

| Class | 8s mean AP | 20s mean AP | 8s minus 20s |
|---|---:|---:|---:|
| Background | 39.63094 | **40.49350** | -0.86256 |
| Camera wearer speaking | **58.91206** | 58.59400 | +0.31806 |
| Other people speaking | **77.01510** | 75.85970 | +1.15540 |

## Interpretation

The aggregate 8-second advantage is only 0.20 mAP, but it is not distributed
uniformly. The 8-second representation is substantially stronger at 0.2--0.6
seconds, while the 20-second representation becomes stronger from 1.0 seconds
onward. This looks like a short/long-horizon tradeoff rather than evidence that
one context budget is uniformly better.

The class pattern is also mixed: 8 seconds improves the two speaking classes,
especially other-person speech, but reduces background AP. Because the heads
were trained once and the aggregate difference is small, training variance
could plausibly reverse the mean comparison. Identical multi-seed runs are
required before selecting the context budget for the paper.

## Files and provenance

- `raw_8s_console.txt` preserves the reported 8-second console output.
- `metrics.csv` contains both contexts, protocols, horizons, and classes.
- `summary.json` contains the machine-readable aggregate comparison.
- The 20-second values come from the previously archived
  `easycom_open_stream_vs_causal_prefix_2026-08-19` snapshot and therefore
  have only three-decimal precision.
- Aggregate differences use the separately reported aggregate means. Averaging
  differences reconstructed from the rounded 20-second horizon rows can vary
  slightly from those aggregate differences.
- The original remote `metrics.json` files have not yet been copied here.