v0.0.55

### Added

- Added a new `start_metadata` field to `PipelineParams`. The provided metadata will be set to the initial `StartFrame` being pushed from the `PipelineTask`.

- Added new fields to `PipelineParams` to control audio input and output sample rates for the whole pipeline. This allows controlling sample rates from a single place instead of having to specify sample rates in each service. Setting a sample rate to a service is still possible and will override the value from `PipelineParams`.

- Introduce audio resamplers (`BaseAudioResampler`). This is just a base class to implement audio resamplers. Currently, two implementations are provided `SOXRAudioResampler` and `ResampyResampler`. A new `create_default_resampler()` has been added (replacing the now deprecated `resample_audio()`).

- It is now possible to specify the asyncio event loop that a `PipelineTask` and all the processors should run on by passing it as a new argument to the `PipelineRunner`. This could allow running pipelines in multiple threads each one with its own event loop.

- Added a new `utils.TaskManager`. Instead of a global task manager we now have a task manager per `PipelineTask`. In the previous version the task manager was global, so running multiple simultaneous `PipelineTask`s could result in dangling task warnings which were not actually true. In order, for all the processors to know about the task manager, we pass it through the `StartFrame`. This means that processors should create tasks when they receive a `StartFrame` but not before (because they don't have a task manager yet).

- Added `TelnyxFrameSerializer` to support Telnyx calls. A full running example has also been added to `examples/telnyx-chatbot`.

- Allow pushing silence audio frames before `TTSStoppedFrame`. This might be useful for testing purposes, for example, passing bot audio to an STT service which usually needs additional audio data to detect the utterance stopped.

- `TwilioSerializer` now supports transport message frames. With this we can create Twilio emulators.

- Added a new transport: `WebsocketClientTransport`.

- Added a `metadata` field to `Frame` which makes it possible to pass custom data to all frames.

- Added `test/utils.py` inside of pipecat package.

### Changed

- `GatedOpenAILLMContextAggregator` now require keyword arguments. Also, a new `start_open` argument has been added to set the initial state of the gate.

- Added `organization` and `project` level authentication to `OpenAILLMService`.

- Improved the language checking logic in `ElevenLabsTTSService` and `ElevenLabsHttpTTSService` to properly handle language codes based on model compatibility, with appropriate warnings when language codes cannot be applied.

- Updated `GoogleLLMContext` to support pushing `LLMMessagesUpdateFrame`s that contain a combination of function calls, function call responses, system messages, or just messages.

- `InputDTMFFrame` is now based on `DTMFFrame`. There's also a new `OutputDTMFFrame` frame.

### Deprecated

- `resample_audio()` is now deprecated, use `create_default_resampler()` instead.

### Removed

- `AudioBufferProcessor.reset_audio_buffers()` has been removed, use `AudioBufferProcessor.start_recording()` and `AudioBufferProcessor.stop_recording()` instead.

### Fixed

- Fixed a `AudioBufferProcessor` that would cause crackling in some recordings.

- Fixed an issue in `AudioBufferProcessor` where user callback would not be called on task cancellation.

- Fixed an issue in `AudioBufferProcessor` that would cause wrong silence padding in some cases.

- Fixed an issue where `ElevenLabsTTSService` messages would return a 1009 websocket error by increasing the max message size limit to 16MB.

- Fixed a `DailyTransport` issue that would cause events to be triggered before join finished.

- Fixed a `PipelineTask` issue that was preventing processors to be cleaned up after cancelling the task.

- Fixed an issue where queuing a `CancelFrame` to a pipeline task would not cause the task to finish. However, using `PipelineTask.cancel()` is still the recommended way to cancel a task.

### Other

- Improved Unit Test `run_test()` to use `PipelineTask` and `PipelineRunner`. There's now also some control around `StartFrame` and `EndFrame`. The `EndTaskFrame` has been removed since it doesn't seem necessary with this new approach.

- Updated `twilio-chatbot` with a few new features: use 8000 sample rate and avoid resampling, a new client useful for stress testing and testing locally without the need to make phone calls. Also, added audio recording on both the client and the server to make sure the audio sounds good.

- Updated examples to use `task.cancel()` to immediately exit the example when a participant leaves or disconnects, instead of pushing an `EndFrame`. Pushing an `EndFrame` causes the bot to run through everything that is internally queued (which could take some seconds). Note that using `task.cancel()` might not always be the best option and pushing an `EndFrame` could still be desirable to make sure all the pipeline is flushed.