whispergram 0.2.0

Transcribe Telegram voice & video messages locally with Whisper, merged into one chat transcript

whispergram

Telegram voice-to-text, locally. Transcribe Telegram voice and round video messages with Whisper (faster-whisper) and merge them into one searchable, LLM-ready chat transcript — 100% offline, no API key, no cloud.

Every line is tagged by sender and timestamp, with voice notes transcribed inline next to the text:

[2026-06-20 12:33] Alex (voice 14s): hey, just finished the thing we talked about
[2026-06-20 12:35] You: nice, send it over
[2026-06-20 12:46] Alex (video-note 8s): here it is
[2026-06-20 12:47] You (photo): looks great
[2026-06-20 12:47] Alex (sticker 👍)

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Why?

An audio-heavy Telegram chat is unreadable and unsearchable — you cannot grep a voice note, and you cannot hand a folder of .ogg files to an LLM. The alternatives are worse: Telegram Premium transcribes one message at a time by hand, and cloud speech APIs upload your private audio to a third party. whispergram transcribes every voice and video note in one pass, entirely on your own machine, and weaves them back into the text timeline as a single file you can read, search, or feed to a model.

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Features

Feature	Description
Voice + video notes	Both voice_message and round video_message notes are transcribed inline with the text
One merged file	A single merged_chat.md, chronological, every line tagged [time] sender
100% local & offline	faster-whisper runs on your machine — no upload, no API key, no account
Lossless mapping	Stickers, photos, animations, documents, music, locations, polls and contacts appear as markers — nothing content-bearing is dropped
Handles missing media	Notes excluded from the export are clearly marked [not exported], never fed to the model
All text shapes	Reconstructs plain, rich, and entity-based message text (links, mentions, custom emoji)
Dry-run	Preview the full merge with --dry-run — no model download, no GPU, instant
GPU or CPU	CUDA with automatic CPU fallback; a one-command Windows CUDA fix is built in
Auto-detect	Finds the export JSON (any filename) and the language per file
Regular videos	--video-files also transcribes ordinary video files' audio, not just round notes
Photo OCR	--ocr pulls text out of photos with local Tesseract — great for screenshots
Tested	52 offline tests on the Python 3.9–3.13 CI matrix

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Quick Start

1. Install

Via PyPI (recommended):

pip install whispergram

Or clone for development:

git clone https://github.com/davidmalko87/whispergram.git
cd whispergram
pip install -r requirements.txt

You also need ffmpeg on your PATH:

# Linux:  sudo apt install ffmpeg
# macOS:  brew install ffmpeg
# Windows: choco install ffmpeg   (or: winget install Gyan.FFmpeg)

2. Export your chat from Telegram

Telegram Desktop → open the chat → ⋮ menu → Export chat history:

• Format: JSON
• Tick Voice messages (and Video messages for round notes)

You get a folder with a .json file plus voice_messages/ and video_files/ subfolders.

3. Run

From inside the export folder:

whispergram
# or, without installing:
python whispergram.py

…or point it at the folder:

whispergram "path/to/ChatExport_2026-06-20"

The result is merged_chat.md in the export folder.

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Example output

[2026-06-20 12:33] Alex: did you get the files?
[2026-06-20 12:33] You: yep, check https://example.com thanks
[2026-06-20 12:34] Alex (voice 6s): one sec, recording the summary now ...
[2026-06-20 12:35] Alex (video-note 8s): [not exported]
[2026-06-20 12:35] You (sticker 😅)
[2026-06-20 12:36] Alex (photo): the whiteboard from today

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How each message appears

Message type	In the merged file
Text	[time] sender: message text
Voice note	[time] sender (voice 12s): <transcript>
Round video note	[time] sender (video-note 8s): <transcript>
Voice/video note with caption	[time] sender (voice 12s): <transcript> | caption: <text>
Voice/video not downloaded	[time] sender (voice 12s): [not exported]
Sticker	[time] sender (sticker 😅)
Photo (with caption)	[time] sender (photo): caption
Animation / GIF	[time] sender (animation)
Document	[time] sender (file: report.pdf): caption
Location / poll / contact	[time] sender (location) · (poll) · (contact)
Music / audio file	[time] sender (audio: Artist - Title) — transcribe with --audio-files
Regular video file	[time] sender (video) — transcribe the audio with --video-files
Photo with --ocr	[time] sender (photo, text): <text found in the image>

Markers can be turned off with --no-media-markers (voice/video notes are always transcribed).

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✅ Round-trip Validated

The merge has been validated against a real 770-message Telegram export (a live, audio-heavy chat — not a synthetic fixture). Every dimension was diffed against the source JSON:

Dimension	In export	In merged file	Result
Voice notes (downloaded)	4	4 transcribed	✅
Round video notes (not downloaded)	5	5 [not exported]	✅
Other media (stickers, photos, animations, videos, audio, …)	107	107 markers	✅
Text messages	654	654	✅
Messages dropped	—	0	✅

All 770 messages map to 770 lines — the per-type counts match the source exactly, and not-exported notes are never sent to the model. (An earlier version silently dropped 88 of those messages — every sticker, photo, and caption-less media item — leaving misleading gaps. The round-trip is what surfaced it.)

That export is private, so these counts were measured locally and are not reproducible from this repo. The synthetic export under tests/fixtures/ reproduces the same lossless mapping across every media type and guards it automatically in CI. A faithful merge is only proven once it has been run end-to-end and the output diffed back against every message type — structural validity alone is not enough.

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Known Limitations

These follow from the Telegram export format and from speech recognition itself — not from a lack of effort in the tool:

Area	Status	Notes
Round video notes	Audio only, if downloaded	Telegram often excludes the binary; those show [not exported]
Music / audio_file	Off by default	Opt in with --audio-files; songs are otherwise not run through ASR
Photo OCR	Text-in-image only	--ocr reads visible text (great for screenshots), not a description of the scene; needs Tesseract + language packs
Photo descriptions	Roadmap	A local vision model (--describe) to caption a photo's content/meaning is planned — kept local to preserve the no-cloud promise
Speaker labels	Sender only	Each note is attributed to its Telegram sender; no in-audio diarization
Timestamps	Minute resolution	Telegram exports YYYY-MM-DDThh:mm; seconds are not shown
Reactions / edits / replies	Not represented	The merged file is a clean reading transcript, not a full forensic dump
Transcription accuracy	Model-dependent	large-v3 is best for uk/ru; --lang forces a language if auto-detect slips

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Options

whispergram --device cpu --model large-v3-turbo   # no GPU, fast
whispergram --lang uk                             # force a language
whispergram --dry-run                             # preview the merge, no transcription
whispergram --audio-files                         # also transcribe music/long audio files
whispergram --video-files                         # also transcribe regular videos' audio
whispergram --ocr --ocr-lang ukr+rus+eng          # read text from photos (local Tesseract)
whispergram --out result.md                       # custom output path

Flag	Default	Notes
--device	cuda	cuda or cpu; auto-falls back to CPU if the GPU fails
--model	large-v3	try large-v3-turbo or medium if CPU is slow
--lang	auto	force a code like uk, ru, en if auto-detect mislabels
--out	merged_chat.md	output file
--audio-files	off	also transcribe audio_file messages (music, long memos)
--video-files	off	also transcribe regular video files' audio track
--ocr	off	extract text from photos with local Tesseract OCR
--ocr-lang	eng	Tesseract language(s), e.g. ukr+rus+eng
--no-media-markers	off	omit (sticker) / (photo) / (file) markers
--dry-run	off	map the chat without loading a model or transcribing
--setup-cuda-windows	—	copy CUDA DLLs next to ctranslate2, then exit (Windows GPU fix)

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GPU (CUDA) setup

Linux / macOS: with a working CUDA install it runs as-is on --device cuda.

Windows — the common pitfall is RuntimeError: Library cublas64_12.dll is not found:

1. Install the CUDA runtime wheels (no full CUDA Toolkit needed):

   pip install nvidia-cublas-cu12 nvidia-cudnn-cu12
   pip install -U "ctranslate2>=4.5"
   

2. If it still can't find the DLL, copy them next to CTranslate2 (the reliable fix):

   python whispergram.py --setup-cuda-windows
   

3. Or skip the GPU entirely: --device cpu --model large-v3-turbo.

CTranslate2 loads cuBLAS/cuDNN lazily in native code that ignores os.add_dll_directory, which is why placing the DLLs inside the package dir is the dependable solution.

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FAQ

How do I transcribe Telegram voice messages? Export the chat from Telegram Desktop as JSON (with voice messages), then run whispergram in the export folder. Every voice note is transcribed with Whisper and merged into the text chat.

Is it private / offline? Does my audio leave my machine? Yes, it is offline. Transcription runs locally with faster-whisper and needs no account or API key. The tool makes no network calls with your data; faster-whisper downloads the speech model once on first run, then works fully offline. Your chat audio and transcripts never leave your machine.

Do I need a GPU? No. It runs on CPU (--device cpu); use --model large-v3-turbo for speed. A CUDA GPU is faster.

Does it handle round video messages / video notes? Yes — round video_message notes are transcribed from their audio, just like voice notes. Regular video files are transcribed too with --video-files.

Can it read text from photos / screenshots? Yes — --ocr runs local Tesseract over photos and drops the extracted text inline as (photo, text): .... It reads text in the image (ideal for screenshots); describing a photo's scene is on the roadmap via a local vision model. Everything stays offline.

Which languages work? Any language Whisper supports. large-v3 handles Ukrainian and Russian well; use --lang uk (or ru, en, …) to force one if auto-detection slips.

How is this different from Telegram Premium's transcription? Premium transcribes one message at a time, by hand, in the app. whispergram transcribes the entire chat in one pass, offline, and produces a single searchable file.

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Project Structure

whispergram/
├── whispergram.py             # The tool: text reconstruction, mapping, transcription, CLI
├── requirements.txt           # Runtime dependency (faster-whisper)
├── pyproject.toml             # Packaging + ruff + pytest configuration
├── CHANGELOG.md
├── CONTRIBUTING.md
├── LICENSE
├── README.md
│
├── .github/
│   ├── workflows/
│   │   ├── ci.yml             # ruff + pytest on Python 3.9–3.13 (no transcription deps)
│   │   └── publish.yml        # tag v* → verify version → build → PyPI (trusted publishing)
│   ├── ISSUE_TEMPLATE/
│   └── dependabot.yml
│
└── tests/
    ├── test_whispergram.py    # 52 offline tests — no model download or GPU required
    └── fixtures/
        └── sample_export/
            └── result.json    # synthetic export (safe to commit; used by tests + CI)

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⚠️ Privacy

This tool processes private conversations, and the transcripts it produces are just as sensitive as the audio. Two rules:

• Nothing leaves your machine. Transcription is fully local; the tool makes no network calls with your data and needs no credentials.
• Never commit your exports or transcripts. The included .gitignore blocks chat data (*.json, audio files, merged_chat.md, ChatExport_*/) by default — keep it. Build your repo in a folder separate from any export, keep any --out path inside the export folder, and run git status before pushing to confirm only code is staged. The only data file in this repo is the synthetic fixture under tests/fixtures/.

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Requirements

• Python 3.9+
• ffmpeg on your PATH
• faster-whisper >= 1.0 (pip install -r requirements.txt)
• For NVIDIA GPU on Windows: nvidia-cublas-cu12, nvidia-cudnn-cu12, ctranslate2>=4.5
• For --ocr (optional): the Tesseract binary on your PATH (with language packs, e.g. ukr, rus) plus pip install whispergram[ocr]

The test suite needs none of the above — only ruff and pytest.

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Changelog

See CHANGELOG.md for the full version history.

Contributing

See CONTRIBUTING.md for the development setup, the privacy rule, and the versioning / release policy.

License

MIT