---
license: cc-by-sa-4.0
language:
- pl
pretty_name: PJM sentence clips (CrocoSign, unfiltered)
size_categories:
- 10K<n<100K
task_categories:
- translation
tags:
- sign-language
- polish-sign-language
- pjm
- webdataset
---

# PJM sentence clips (unfiltered)

All 39,817 sentence clips cut from the [Open Repository of the PJM Corpus](https://www.korpuspjm.uw.edu.pl/)
(Sign Language Linguistics Lab, University of Warsaw), each with its Polish transcript, as WebDataset shards.
This is the step before selection: the ready-to-train dataset of 29,928 pairs, with English translations,
splits and features, is [CrocoSign/pjm-data](https://huggingface.co/datasets/CrocoSign/pjm-data).

## Format

89 tar shards, `train-000000.tar` to `train-000088.tar`, about 25 GB in all. Each clip is two members:

- `{key}.mp4`: the video of one sentence, one signer, H.264. Despite the extension, the container is MPEG-TS; browsers need it remuxed to MP4 (`ffmpeg -i clip.mp4 -c copy -movflags +faststart out.mp4`).
- `{key}.txt`: the Polish transcript of that sentence, UTF-8, as cut from the corpus subtitles (the corrected texts of the 29,928 dataset clips are in `pjm-data/texts/texts_fixed.csv`).

The key, such as `004_000_M`, is `{recording}_{sentence}_{side}`, where the side is `L` or `R` for a half of a dialogue recording and `M` for a monologue. It is the same key as in pjm-data, so it joins the clips with the splits, features and poses there.

```python
from datasets import Value, load_dataset

clips = load_dataset("CrocoSign/pjm-segments", split="train", streaming=True)
clips = clips.cast_column("mp4", Value("binary"))  # raw bytes; decoding video would need torchcodec
first = next(iter(clips))
print(first["__key__"], first["txt"])  # 004_000_M Wiesz, kot i ptak w klatce.
video = first["mp4"]["bytes"]
```

Streaming reads the shards in order, so finding one clip by key this way scans the dataset. To fetch a single clip, request its byte range from the shard instead. `clip_index.csv` gives, for every clip, the shard and the offset and size of its `.mp4` member:

```bash
# 682_073_R,train-000085.tar,352468480,471880
curl -L -r 352468480-352940359 -o 682_073_R.ts \
  https://huggingface.co/datasets/CrocoSign/pjm-segments/resolve/main/train-000085.tar
```

## What was left out of pjm-data, and why

| Reason | Clips |
|---|---|
| one-word sentence | 5,527 |
| fewer than three words (final quality filter) | 3,603 |
| only very common words (final quality filter) | 362 |
| dominated by rare words (seen at most three times) | 362 |
| longer than 60 sub-word tokens | 19 |
| translation flagged as invalid | 10 |
| broken video (one to five frames) | 4 |
| empty sentence | 2 |

## Licence and attribution

CC BY-SA 4.0, as the corpus. The clips show the faces of the signers who recorded themselves for the corpus. Cite the corpus (Wójcicka, Kuder, Mostowski, Rutkowski (eds.), *Otwarte Repozytorium Korpusu Polskiego Języka Migowego*, University of Warsaw, 2020, ISBN 978-83-66400-21-4) and our work (Sieńko, Kovalenko, Śledzianowski, *A Polish Sign Language to Text Dataset and Benchmark*, 2026, in preparation); BibTeX for both is in the [pjm-data card](https://huggingface.co/datasets/CrocoSign/pjm-data).