// Copyright 2023 The MediaPipe Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef MEDIAPIPE_FRAMEWORK_STREAM_HANDLER_TIMESTAMP_ALIGN_INPUT_STREAM_HANDLER_H_
#define MEDIAPIPE_FRAMEWORK_STREAM_HANDLER_TIMESTAMP_ALIGN_INPUT_STREAM_HANDLER_H_
#include <functional>
#include <memory>
#include <vector>
#include "absl/base/thread_annotations.h"
#include "absl/status/status.h"
#include "absl/synchronization/mutex.h"
#include "mediapipe/framework/calculator_context_manager.h"
#include "mediapipe/framework/calculator_framework.h"
#include "mediapipe/framework/collection_item_id.h"
#include "mediapipe/framework/input_stream_handler.h"
#include "mediapipe/framework/stream_handler/timestamp_align_input_stream_handler.pb.h"
#include "mediapipe/framework/timestamp.h"
namespace mediapipe {
// The input streams must have the same time unit but may have different time
// origins (also called epochs). The timestamp_base_tag_index option
// designates an input stream as the timestamp base.
//
// TimestampAlignInputStreamHandler operates in two phases:
//
// 1. Pre-initialization: In this phase, the input stream handler passes
// through input packets in the timestamp base input stream, but buffers the
// input packets in all other input streams. This phase ends when the input
// stream handler has an input packet in every input stream. It uses the
// the timestamps of these input packets to calculate the timestamp offset of
// each input stream with respect to the timestamp base input stream. The
// timestamp offsets are saved for use in the next phase.
//
// 2. Post-initialization: In this phase, the input stream handler behaves
// like the DefaultInputStreamHandler, except that timestamp offsets are
// applied to the packet timestamps.
class TimestampAlignInputStreamHandler : public InputStreamHandler {
public:
TimestampAlignInputStreamHandler() = delete;
TimestampAlignInputStreamHandler(std::shared_ptr<tool::TagMap> tag_map,
CalculatorContextManager* cc_manager,
const mediapipe::MediaPipeOptions& options,
bool calculator_run_in_parallel);
void PrepareForRun(std::function<void()> headers_ready_callback,
std::function<void()> notification_callback,
std::function<void(CalculatorContext*)> schedule_callback,
std::function<void(absl::Status)> error_callback) override;
protected:
// In TimestampAlignInputStreamHandler, a node is "ready" if:
// - before the timestamp offsets are initialized: we have received a packet
// in the timestamp base input stream, or
// - after the timestamp offsets are initialized: the minimum bound (over
// all empty streams) is greater than the smallest timestamp of any
// stream, which means we have received all the packets that will be
// available at the next timestamp, or
// - all streams are done (need to call Close() in this case).
// Note that all packet timestamps and timestamp bounds are aligned with the
// timestamp base.
NodeReadiness GetNodeReadiness(Timestamp* min_stream_timestamp) override;
// Only invoked when associated GetNodeReadiness() returned kReadyForProcess.
void FillInputSet(Timestamp input_timestamp,
InputStreamShardSet* input_set) override;
private:
CollectionItemId timestamp_base_stream_id_;
absl::Mutex mutex_;
bool offsets_initialized_ ABSL_GUARDED_BY(mutex_) = false;
std::vector<TimestampDiff> timestamp_offsets_;
};
} // namespace mediapipe
#endif // MEDIAPIPE_FRAMEWORK_STREAM_HANDLER_TIMESTAMP_ALIGN_INPUT_STREAM_HANDLER_H_
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