Add C++ and Python API for Kokoro TTS models.

[csukuangfj]

Generated samples

0 af	1 af_bella	2 af_nicole
https://github.com/user-attachments/assets/6d0c0cb4-6b5b-48f4-a9e4-1eaaab86327a	https://github.com/user-attachments/assets/70596402-a74f-4775-abcb-1f2b4fcaba60	https://github.com/user-attachments/assets/c76cf8fc-efa7-4f03-b356-7e1759eebea8

3 af_sarah	4 af_sky	5 am_adam
https://github.com/user-attachments/assets/3f160a11-05c4-47ed-b356-7a160e836ecc	https://github.com/user-attachments/assets/1443e0a0-1c92-4ac2-9e5d-56c0a0dbf4af	https://github.com/user-attachments/assets/153abc1a-421d-4e08-b62b-9fcb401fbfec

6 am_michael	7 bf_emma	8 bf_isabella
https://github.com/user-attachments/assets/6372c7d5-a2d5-4b8c-9e56-7f9957f592cc	https://github.com/user-attachments/assets/6e9ccccd-de74-43e4-8594-f44121277d7a	https://github.com/user-attachments/assets/5f56e847-6527-4eaf-be96-e2c9ad04366b

9 bm_george	10 bm_lewis
https://github.com/user-attachments/assets/54edffe5-9264-42ed-bc71-7de94f724706	https://github.com/user-attachments/assets/f4d33446-38c7-420d-bb1c-852203f18443

kokoro-0.mov

kokoro-1.mov

kokoro-10.mov

kokoro-9.mov

kokoro-8.mov

kokoro-7.mov

kokoro-6.mov

kokoro-5.mov

kokoro-4.mov

kokoro-3.mov

kokoro-2.mov

Usage with C++ binaries

curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/kokoro-en-v0_19.tar.bz2
tar xf kokoro-en-v0_19.tar.bz2
rm kokoro-en-v0_19.tar.bz2

# mapping of sid to voice name
# 0->af, 1->af_bella, 2->af_nicole, 3->af_sarah, 4->af_sky, 5->am_adam
# 6->am_michael, 7->bf_emma, 8->bf_isabella, 9->bm_george, 10->bm_lewis

for sid in $(seq 0 10); do
  ./build/bin/sherpa-onnx-offline-tts \
    --debug=1 \
    --kokoro-model=./kokoro-en-v0_19/model.onnx \
    --kokoro-voices=./kokoro-en-v0_19/voices.bin \
    --kokoro-tokens=./kokoro-en-v0_19/tokens.txt \
    --kokoro-data-dir=./kokoro-en-v0_19/espeak-ng-data \
    --num-threads=2 \
    --sid=$sid \
    --output-filename="./tts/kokoro-$sid.wav" \
    "Today as always, men fall into two groups: slaves and free men. Whoever does not have two-thirds of his day for himself, is a slave, whatever he may be  a statesman, a businessman, an official, or a scholar."
done

Usage with Python APIs

curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/kokoro-en-v0_19.tar.bz2
tar xf kokoro-en-v0_19.tar.bz2
rm kokoro-en-v0_19.tar.bz2

# mapping of sid to voice name
# 0->af, 1->af_bella, 2->af_nicole, 3->af_sarah, 4->af_sky, 5->am_adam
# 6->am_michael, 7->bf_emma, 8->bf_isabella, 9->bm_george, 10->bm_lewis

for sid in $(seq 0 10); do
  python3 ./python-api-examples/offline-tts.py \
    --debug=1 \
    --kokoro-model=./kokoro-en-v0_19/model.onnx \
    --kokoro-voices=./kokoro-en-v0_19/voices.bin \
    --kokoro-tokens=./kokoro-en-v0_19/tokens.txt \
    --kokoro-data-dir=./kokoro-en-v0_19/espeak-ng-data \
    --num-threads=2 \
    --sid=$sid \
    --output-filename="./tts/kokoro-$sid.wav" \
    "Today as always, men fall into two groups: slaves and free men. Whoever does not have two-thirds of his day for himself, is a slave, whatever he may be  a statesman, a businessman, an official, or a scholar."
done

[csukuangfj]

CC @thewh1teagle @giannik

Fixes #1679