Reduce Text-to-speech hallucination

[johnson-liang]

From 2023/10/11 meeting https://g0v.hackmd.io/t9ypB87SQBuMjjW_PheZVg#Comm-AI-transcript

The current implementation for speech-to-text (based on Whisper API) suffers from hallucination problems. Some of the examples are:

https://cofacts.tw/article/TvR6AosBAjOeMOklfe-g
原來 train data 是來自群眾協作字幕的社群呀

無聲
https://cofacts.tw/article/JvRhAosBAjOeMOklpe-v

我會希望他不要翻譯耶其實
雖然他翻得還 OK
https://cofacts.tw/article/FPRXAosBAjOeMOklXO9y

前面好好的
後面沒聲音開始起肖
https://cofacts.tw/article/m_S3AosBAjOeMOkls-_a

慘叫
https://cofacts.tw/article/jvSIBYsBAjOeMOklDvOv

無法解釋
明明有這麼明顯的口白
https://cofacts.tw/article/MvTSCosBAjOeMOklBvlJ

We should investigate:

• Measures to reduce or cancel hallucination, such as voice activity detection (VAD).
• Experiment with a different prompt.
• Experiment with a replacement of Whisper API
• Assess the feasibility of solutions above, including the operation costs.

References

Precious research on Whisper and mitigation to it's hallucination
https://g0v.hackmd.io/wkx286lmTDaFUpgRhnUawQ#Whisper

[MrOrz]

Tried to remove apparent hallucination in #323