chromium/media/base/encryption_pattern.h

// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_BASE_ENCRYPTION_PATTERN_H_
#define MEDIA_BASE_ENCRYPTION_PATTERN_H_

#include <stdint.h>
#include <ostream>

#include "media/base/media_export.h"

namespace media {

// CENC 3rd Edition adds pattern encryption, through two new protection
// schemes: 'cens' (with AES-CTR) and 'cbcs' (with AES-CBC).
// The pattern applies independently to each 'encrypted' part of the frame (as
// defined by the relevant subsample entries), and reduces further the
// actual encryption applied through a repeating pattern of (encrypt:skip)
// 16 byte blocks. For example, in a (1:9) pattern, the first block is
// encrypted, and the next nine are skipped. This pattern is applied
// repeatedly until the end of the last 16-byte block in the subsample.
// Any remaining bytes are left clear.
// TODO(jrummell): Use std::optional<EncryptionPattern> everywhere.
class MEDIA_EXPORT EncryptionPattern { … };

// For logging use only.
MEDIA_EXPORT std::ostream& operator<<(
    std::ostream& os,
    const EncryptionPattern& encryption_pattern);

}  // namespace media

#endif  // MEDIA_BASE_ENCRYPTION_PATTERN_H_