blob: 765c4c2de64a540a36ce11f862e6bd156a9a4400 [file] [log] [blame]
// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <memory>
#include "media_pipeline_backend.h"
namespace chromecast {
namespace media {
// Interface for output audio stream. Used by the mixer to play mixed stream.
class MixerOutputStream {
static constexpr int kInvalidSampleRate = 0;
// Creates a default MixerOutputStream.
static std::unique_ptr<MixerOutputStream> Create();
virtual ~MixerOutputStream() {}
// Start the stream. Caller must call GetSampleRate() to get the actual sample
// rate selected for the stream. It may be different from
// |requested_sample_rate|, e.g. if IsFixedSampleRate() is true, or the device
// doesn't support |requested_sample_rate|.
virtual bool Start(int requested_sample_rate, int channels) = 0;
// Returns number of channels expected to be passed to Write().
virtual int GetNumChannels() = 0;
// Returns current sample rate.
virtual int GetSampleRate() = 0;
// Returns current rendering delay for the stream.
virtual MediaPipelineBackend::AudioDecoder::RenderingDelay
GetRenderingDelay() = 0;
// Returns the optimal number of frames to pass to Write(). For ALSA, this is
// the period size.
virtual int OptimalWriteFramesCount() = 0;
// |data_size| is size of |data|. Should be divided by number of channels
// to get number of frames.
// The current implementation of the mixer relies on ALSA specific behavior
// where Write blocks if there is not enough space in the buffer. Until
// this is changed other implementation must follow the same behavior.
virtual bool Write(const float* data,
int data_size,
bool* out_playback_interrupted) = 0;
// Stops the stream. After being stopped the stream can be restarted by
// calling Start().
virtual void Stop() = 0;
} // namespace media
} // namespace chromecast