Add a bit of silence between batches of phonemes

[j-venerable]

Describe the feature

Removing all silence between batches of phonemes results in an unnatural speech flow. I'm talking about this code specifically:

kokoro-onnx/src/kokoro_onnx/__init__.py

Line 179 in 281999e

audio_part, _ = librosa.effects.trim(audio_part)

As an experiment I tried to add one second of silence between every batch and it sounded much better IMO. I can make a pull request if you want, adding an extra argument to the create() method so users can choose the duration of silence they want between batches.

[thewh1teagle]

Removing all silence between batches of phonemes results in an unnatural speech flow.

Can you show example sentence?

[j-venerable]

In my opinion, this is an issue with every long text I have tried. It was more pronounced before upgrading to Kokoro 1.0, so I have adjusted the pause to 0.8s. 0.5s or 0.6s might be a better default. Here is the beginning of Moby Dick:

text = "Some years ago — never mind how long precisely — having little or no money in my purse, and nothing particular to interest me on shore, " \
       "I thought I would sail about a little and see the watery part of the world. It is a way I have of driving off the spleen and regulating the circulation. " \
       "Whenever I find myself growing grim about the mouth; whenever it is a damp, drizzly November in my soul; " \
       "whenever I find myself involuntarily pausing before coffin warehouses, and bringing up the rear of every funeral I meet; " \
       "and especially whenever my hypos get such an upper hand of me, that it requires a strong moral principle to prevent me from deliberately stepping into the street, " \
       "and methodically knocking people’s hats off—then, I account it high time to get to sea as soon as I can. " \
       "This is my substitute for pistol and ball. With a philosophical flourish Cato throws himself upon his sword; " \
       "I quietly take to the ship. There is nothing surprising in this. If they but knew it, almost all men in their degree, some time or other, " \
       "cherish very nearly the same feelings towards the ocean with me."

audio, _ = KOKORO.create(text, voice="af_sarah", speed=0.84, lang="en-us")

Notice the cut after "whenever I find myself involuntarily pausing before coffin warehouses," and "I quietly take to the ship."

Without silence between batches:

mobydick-no-silence.webm

With 0.8 seconds of silence between batches:

mobydick-silence.webm