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// Copyright (c) 2006-2008 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.
// FilterHost describes an interface for individual filters to access and
// modify global playback information. Every filter is given a filter host
// reference as part of initialization.
//
// This interface is intentionally verbose to cover the needs for the different
// types of filters (see media/base/filters.h for filter definitionss). Filters
// typically use parts of the interface that are relevant to their function.
// For example, an audio renderer filter typically calls SetTime as it feeds
// data to the audio hardware. A video renderer filter typically calls GetTime
// to synchronize video with audio. An audio and video decoder would typically
// have no need to call either SetTime or GetTime.
//
// The reasoning behind providing PostTask is to discourage filters from
// implementing their own threading. The overall design is that many filters
// can share few threads and that notifications return quickly by scheduling
// processing with PostTask.
#ifndef MEDIA_BASE_FILTER_HOST_H_
#define MEDIA_BASE_FILTER_HOST_H_
#include "base/task.h"
#include "media/base/pipeline.h"
namespace media {
class FilterHost {
public:
// The PipelineStatus class allows read-only access to the pipeline state.
// This is the same object that is used by the pipeline client to examine
// the state of the running pipeline. The lifetime of the PipelineStatus
// interface is the same as the lifetime of the FilterHost interface, so
// it is acceptable for filters to use the returned pointer until their
// Stop method has been called.
virtual const PipelineStatus* GetPipelineStatus() const = 0;
// Registers a callback to receive global clock update notifications. The
// callback will be called repeatedly and filters do not need to re-register
// after each invocation of the callback. To remove the callback, filters
// may call this method passing NULL for the callback argument.
//
// Callback arguments:
// base::TimeDelta - the new pipeline time, in microseconds.
virtual void SetTimeUpdateCallback(Callback1<base::TimeDelta>::Type* cb) = 0;
// Request that the time callback be called at the specified stream
// time. This will set a timer specific to the filter that will be fired
// no sooner than the specified time based on the interpolated time. Note
// that, becuase the callback will be made with the interpolated time, it is
// possible for time to move "backward" slightly when the audio device updates
// the pipeline time though the SetTime method.
virtual void ScheduleTimeUpdateCallback(base::TimeDelta time) = 0;
// Filters must call this method to indicate that their initialization is
// complete. They may call this from within their Initialize() method or may
// choose call it after processing some data.
virtual void InitializationComplete() = 0;
// Posts a task to be executed asynchronously on the pipeline's thread.
virtual void PostTask(Task* task) = 0;
// Stops execution of the pipeline due to a fatal error.
virtual void Error(PipelineError error) = 0;
// Sets the current time. Any filters that have registered a callback through
// the SetTimeUpdateCallback method will be notified of the change.
virtual void SetTime(base::TimeDelta time) = 0;
// Get the duration of the media in microseconds. If the duration has not
// been determined yet, then returns 0.
virtual void SetDuration(base::TimeDelta duration) = 0;
// Set the approximate amount of playable data buffered so far in micro-
// seconds.
virtual void SetBufferedTime(base::TimeDelta buffered_time) = 0;
// Set the total size of the media file.
virtual void SetTotalBytes(int64 total_bytes) = 0;
// Sets the total number of bytes that are buffered on the client and ready to
// be played.
virtual void SetBufferedBytes(int64 buffered_bytes) = 0;
// Sets the size of the video output in pixel units.
virtual void SetVideoSize(size_t width, size_t height) = 0;
protected:
virtual ~FilterHost() {}
};
} // namespace media
#endif // MEDIA_BASE_FILTER_HOST_H_
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