IndexTTS-2.5-Turkish-LoRA

IndexTTS-2.5 Turkish (v2)

Fine-tuned GPT weights that add Turkish to IndexTeam/IndexTTS-2.5 with zero-shot voice cloning. The five base languages (zh, en, ja, es, ar) are kept. Trained with index-tts-2.5-ft.

v2 cuts word errors 9×: Freya-TR-Eval WER drops from 12.36% (v1) to 1.32%. v1 swapped short Turkish words for other words (yağmur → "arkadaş mur"). The cause was text-embedding rows the base model had never trained. v2 trains exactly those rows.

Freya-TR-Eval

Freya-TR-Eval has 495 everyday Turkish sentences. We ran it with the protocol of the PatientDesk re-run: three seeded takes per sentence, an 8 kHz band, faster-whisper large-v3 (beam 5), EMA's score_norm and UTMOS22-strong. The voice reference is the same one the cloning systems used there (Anka TTS male).

• Our rows (bold and v1) were run by us on 2026-10-08. All other rows are quoted from the PatientDesk re-run of 2026-10-07; it lists 19 systems.
• Clean is the share of sentences with no word error. v2 reads 427 of the 495 sentences correctly in all three takes; v1 does so for 161.
• Speed: RTF is 0.83 on an RTX 5070 Ti (bf16, num_beams=3). This is not comparable with the L4 numbers in the re-run.
• Raw data: transcripts, UTMOS per clip and timing are in benchmark/.

v1 vs v2: listen

Same sentence, reference voice and seed (take 0). The v1 column shows what Whisper heard.

<table> <tr><th>Sentence</th><th>v1 (Whisper heard)</th><th>v1</th><th>v2</th></tr> <tr><td>Yağmur birden bastırınca hepimiz sırılsıklam olduk!</td><td><i>Arkadaş mur</i> birden bastırınca hepimiz <i>kırılsıklam</i> olduk.</td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0129_v1.wav"></audio></td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0129_v2.wav"></audio></td></tr> <tr><td>Ne demek istediğini bilmiyorum.</td><td>Ne <i>biraz geldiğimi zatım</i>.</td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0320_v1.wav"></audio></td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0320_v2.wav"></audio></td></tr> <tr><td>Akşamüstü kuaföre uğrayıp saçlarımı biraz kestirmek istiyorum.</td><td><i>Akşam düşüğü</i> kuaföre uğrayıp <i>hasırlarımı</i> biraz kestirmek istiyorum.</td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0232_v1.wav"></audio></td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0232_v2.wav"></audio></td></tr> <tr><td>Dünkü yemekten kalanları ısıtıp öğle yemeğinde afiyetle yedik.</td><td><i>Dört geçten</i> kalanları <i>sırtıp</i> öğle yemeğinde <i>afasırla</i> yedik.</td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0108_v1.wav"></audio></td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0108_v2.wav"></audio></td></tr> <tr><td>Birlikte sinemaya gitmeyeli neredeyse iki ay olmuş.</td><td><i>Artık</i> sinemaya gitmeyeli <i>söyleyse 2 ayıdır</i>.</td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0083_v1.wav"></audio></td> <td><audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/0083_v2.wav"></audio></td></tr> </table>

Reference voice: <audio controls src="https://huggingface.co/berrkkaayy/IndexTTS-2.5-Turkish-LoRA/resolve/main/samples/reference_anka_male.wav"></audio>

The reference is the AI-generated male voice of Anka TTS (not a real person), licensed CC-BY-NC-4.0. The clips in samples/ are derived from it and carry the same license.

Files

All other weights (s2mel.pth, codec, vocoder, tokenizer, …) come from IndexTeam/IndexTTS-2.5.

Quick start

git clone https://github.com/index-tts/index-tts.git && cd index-tts
uv sync --all-extras
hf download IndexTeam/IndexTTS-2.5 --local-dir=checkpoints
hf download berrkkaayy/IndexTTS-2.5-Turkish-LoRA gpt.pth --local-dir=checkpoints/tr

cd .. && git clone https://github.com/oberkayb/index-tts-2.5-ft.git && cd index-tts-2.5-ft
uv run --project ../index-tts python scripts/synthesize.py \
  --gpt-checkpoint ../index-tts/checkpoints/tr/gpt.pth \
  --lang tr --normalizer turkish --case tr_lower \
  --prompt-audio ref.wav --text "Merhaba, bugün hava çok güzel." --output out/tr.wav

Turkish needs the itts25ft text frontend (turkish normalizer + tr_lower). Training and inference must match. If you call IndexTTS2.infer directly, clean the text with the frontend and pass lang="tr", text_normalization=False. The fine-tuning repo also ships a WebUI (webui.bat) and an MCP server (mcp_server.py).

Training (v2)

Limitations

• Turkish requires the itts25ft frontend; stock webui.py does not apply it.
• Numbers are best written out as words. Long text is segmented, and prosody may reset between segments.
• UTMOS is an English-trained proxy and depends on the reference voice.
• Use is subject to the bilibili Model Use License Agreement inherited from IndexTTS-2.5.

Türkçe özet

v2, Freya-TR-Eval'de kelime hata oranını %12,36'dan %1,32'ye indirdi; doğru okunan cümle oranı %43,5'ten %92,2'ye çıktı. v1'deki kelime karışmasının sebebi, taban modelin Türkçe token satırlarını hiç eğitmemiş olmasıydı. v2 tam olarak bu 1.530 satırı eğitiyor. gpt.pth artık v2. Eski sürüm v1/ klasöründe duruyor. Kullanım için yukarıdaki Quick start bölümüne bak; Türkçe metin işleme (turkish + tr_lower) şart.

Citation

@misc{li2026indextts25technicalreport,
  title={IndexTTS 2.5 Technical Report},
  author={Yunpei Li and others},
  year={2026},
  eprint={2601.03888},
  archivePrefix={arXiv},
}
@misc{pamuk2026freyattstechnicalreport,
  title={FreyaTTS Technical Report},
  author={Ahmet Erdem Pamuk and Ömer Yentür and Ahmet Tunga Bayrak and Yavuz Alp Sencer Öztürk and Mustafa Yavuz},
  year={2026},
  eprint={2607.09530},
  archivePrefix={arXiv},
}