Audio playback needs silence stream

[dariopellegrino00]

Title

Audio Playback Requires Silence Stream

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Background

When playing back audio responses from the OpenAI Realtime API, the channel currently requires a looped silence_stream toward the caller leg.
This workaround is functional but not ideal, as it depends on an external application. We should handle the playback flow entirely within the module.

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Expected Behavior

Audio playback should start correctly without requiring an external silence_stream.

The media path toward the caller should open automatically when playback begins.

Actual Behavior

Playback only works if a looped silence_stream is running toward the caller leg.

Without it, the media path does not open properly.

Steps to Reproduce

1. Start audio playback of Realtime API responses without a silence_stream.
2. Observe that the media path toward the caller fails to open.
3. Start a silence_stream and retry — playback works.

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Possible Solutions / Investigation Ideas

1. Start the silence_stream internally within the module when invoking start.
2. Investigate why the media path fails to open toward the caller without it, and implement a cleaner, self-contained solution.

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Notes

We haven’t fully identified the root cause yet — the quick workaround using the silence_stream was used initially to unblock audio playback. Further investigation is required.