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100 lines
3.6 KiB
100 lines
3.6 KiB
// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef CAST_STREAMING_ENCODED_FRAME_H_
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#define CAST_STREAMING_ENCODED_FRAME_H_
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#include <stdint.h>
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#include <chrono>
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#include <vector>
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#include "absl/types/span.h"
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#include "cast/streaming/frame_id.h"
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#include "cast/streaming/rtp_time.h"
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#include "platform/api/time.h"
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#include "platform/base/macros.h"
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namespace openscreen {
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namespace cast {
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// A combination of metadata and data for one encoded frame. This can contain
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// audio data or video data or other.
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struct EncodedFrame {
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enum Dependency : int8_t {
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// "null" value, used to indicate whether |dependency| has been set.
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UNKNOWN_DEPENDENCY,
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// Not decodable without the reference frame indicated by
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// |referenced_frame_id|.
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DEPENDS_ON_ANOTHER,
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// Independently decodable.
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INDEPENDENTLY_DECODABLE,
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// Independently decodable, and no future frames will depend on any frames
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// before this one.
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KEY_FRAME,
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};
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EncodedFrame();
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~EncodedFrame();
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EncodedFrame(EncodedFrame&&) noexcept;
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EncodedFrame& operator=(EncodedFrame&&);
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// Copies all members except |data| to |dest|. Does not modify |dest->data|.
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void CopyMetadataTo(EncodedFrame* dest) const;
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// This frame's dependency relationship with respect to other frames.
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Dependency dependency = UNKNOWN_DEPENDENCY;
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// The label associated with this frame. Implies an ordering relative to
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// other frames in the same stream.
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FrameId frame_id;
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// The label associated with the frame upon which this frame depends. If
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// this frame does not require any other frame in order to become decodable
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// (e.g., key frames), |referenced_frame_id| must equal |frame_id|.
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FrameId referenced_frame_id;
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// The stream timestamp, on the timeline of the signal data. For example, RTP
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// timestamps for audio are usually defined as the total number of audio
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// samples encoded in all prior frames. A playback system uses this value to
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// detect gaps in the stream, and otherwise stretch the signal to gradually
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// re-align towards playout targets when too much drift has occurred (see
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// |reference_time|, below).
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RtpTimeTicks rtp_timestamp;
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// The common reference clock timestamp for this frame. Over a sequence of
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// frames, this time value is expected to drift with respect to the elapsed
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// time implied by the RTP timestamps; and this may not necessarily increment
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// with precise regularity.
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//
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// This value originates from a sender, and is the time at which the frame was
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// captured/recorded. In the receiver context, this value is the computed
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// target playout time, which is used for guiding the timing of presentation
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// (see |rtp_timestamp|, above). It is also meant to be used to synchronize
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// the presentation of multiple streams (e.g., audio and video), commonly
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// known as "lip-sync." It is NOT meant to be a mandatory/exact playout time.
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Clock::time_point reference_time;
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// Playout delay for this and all future frames. Used by the Adaptive
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// Playout delay extension. Non-positive values means no change.
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std::chrono::milliseconds new_playout_delay{};
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// Pointer to a buffer containing the encoded signal data for the frame. In
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// the sender context, this points to the data to be sent, and nothing will be
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// mutated. In the receiver context, this is set to the region of a
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// client-provided buffer that was populated.
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absl::Span<uint8_t> data;
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OSP_DISALLOW_COPY_AND_ASSIGN(EncodedFrame);
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};
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} // namespace cast
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} // namespace openscreen
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#endif // CAST_STREAMING_ENCODED_FRAME_H_
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