46 lines
1.6 KiB
C++
46 lines
1.6 KiB
C++
// Copyright (c) 2012 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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// Timestamps are derived directly from the encoded media file and are commonly
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// known as the presentation timestamp (PTS). Durations are a best-guess and
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// are usually derived from the sample/frame rate of the media file.
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//
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// Due to encoding and transmission errors, it is not guaranteed that timestamps
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// arrive in a monotonically increasing order nor that the next timestamp will
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// be equal to the previous timestamp plus the duration.
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//
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// In the ideal scenario for a 25fps movie, buffers are timestamped as followed:
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//
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// Buffer0 Buffer1 Buffer2 ... BufferN
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// Timestamp: 0us 40000us 80000us ... (N*40000)us
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// Duration*: 40000us 40000us 40000us ... 40000us
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//
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// *25fps = 0.04s per frame = 40000us per frame
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#ifndef MEDIA_BASE_BUFFERS_H_
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#define MEDIA_BASE_BUFFERS_H_
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#include "base/basictypes.h"
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#include "base/memory/ref_counted.h"
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#include "base/time/time.h"
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#include "media/base/media_export.h"
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namespace media {
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// TODO(scherkus): Move the contents of this file elsewhere.
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// Indicates an invalid or missing timestamp.
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MEDIA_EXPORT extern inline base::TimeDelta kNoTimestamp() {
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return base::TimeDelta::FromMicroseconds(kint64min);
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}
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// Represents an infinite stream duration.
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MEDIA_EXPORT extern inline base::TimeDelta kInfiniteDuration() {
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return base::TimeDelta::FromMicroseconds(kint64max);
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}
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} // namespace media
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#endif // MEDIA_BASE_BUFFERS_H_
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