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Merge pull request #530 from ksooo/aac_rds
Add support for RDS data contained in AAC streams
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| /* | ||
| * Copyright (C) 2005-2021 Team Kodi | ||
| * https://kodi.tv | ||
| * | ||
| * SPDX-License-Identifier: GPL-2.0-or-later | ||
| * See LICENSE.md for more information. | ||
| */ | ||
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| #include "BitStream.h" | ||
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| #include <stdexcept> | ||
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| using namespace aac; | ||
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| BitStream::BitStream(const uint8_t* data, unsigned int dataLen) : m_data(data), m_dataLen(dataLen) | ||
| { | ||
| } | ||
|
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| int BitStream::GetBitsLeft() const | ||
| { | ||
| return 8 * (m_dataLen - m_pos) + m_bitsCached; | ||
| } | ||
|
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| int BitStream::ReadBit() | ||
| { | ||
| int result; | ||
|
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| if (m_bitsCached > 0) | ||
| { | ||
| m_bitsCached--; | ||
| } | ||
| else | ||
| { | ||
| m_cache = ReadCache(); | ||
| m_bitsCached = 31; | ||
| } | ||
|
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| result = (m_cache >> m_bitsCached) & 0x1; | ||
| m_bitsRead++; | ||
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| return result; | ||
| } | ||
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| int BitStream::ReadBits(int n) | ||
| { | ||
| if (n > 32) | ||
| throw std::invalid_argument("aac::BitStream::ReadBits - Attempt to read more than 32 bits"); | ||
|
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| int result; | ||
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| if (m_bitsCached >= n) | ||
| { | ||
| m_bitsCached -= n; | ||
| result = (m_cache >> m_bitsCached) & MaskBits(n); | ||
| } | ||
| else | ||
| { | ||
| const uint32_t c = m_cache & MaskBits(m_bitsCached); | ||
| const int left = n - m_bitsCached; | ||
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| m_cache = ReadCache(); | ||
| m_bitsCached = 32 - left; | ||
| result = ((m_cache >> m_bitsCached) & MaskBits(left)) | (c << left); | ||
| } | ||
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| m_bitsRead += n; | ||
| return result; | ||
| } | ||
|
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| void BitStream::SkipBit() | ||
| { | ||
| m_bitsRead++; | ||
| if (m_bitsCached > 0) | ||
| { | ||
| m_bitsCached--; | ||
| } | ||
| else | ||
| { | ||
| m_cache = ReadCache(); | ||
| m_bitsCached = 31; | ||
| } | ||
| } | ||
|
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| void BitStream::SkipBits(int n) | ||
| { | ||
| m_bitsRead += n; | ||
| if (n <= m_bitsCached) | ||
| { | ||
| m_bitsCached -= n; | ||
| } | ||
| else | ||
| { | ||
| n -= m_bitsCached; | ||
|
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| while (n >= 32) | ||
| { | ||
| n -= 32; | ||
| ReadCache(); | ||
| } | ||
|
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| if (n > 0) | ||
| { | ||
| m_cache = ReadCache(); | ||
| m_bitsCached = 32 - n; | ||
| } | ||
| else | ||
| { | ||
| m_cache = 0; | ||
| m_bitsCached = 0; | ||
| } | ||
| } | ||
| } | ||
|
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| void BitStream::ByteAlign() | ||
| { | ||
| const int toFlush = m_bitsCached & 0x7; | ||
| if (toFlush > 0) | ||
| SkipBits(toFlush); | ||
| } | ||
|
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| uint32_t BitStream::ReadCache() | ||
| { | ||
| if (m_pos == m_dataLen) | ||
| { | ||
| throw std::out_of_range("aac::BitStream::ReadCache - Attempt to read past end of stream"); | ||
| } | ||
| else if (m_pos > m_dataLen - 4) | ||
| { | ||
| // read near end of stream; read last 1 to 3 bytes | ||
| int toRead = m_dataLen - m_pos; | ||
| int i = 0; | ||
| if (toRead-- > 0) | ||
| i = ((m_data[m_pos] & 0xFF) << 24); | ||
| if (toRead-- > 0) | ||
| i |= ((m_data[m_pos + 1] & 0xFF) << 16); | ||
| if (toRead-- > 0) | ||
| i |= ((m_data[m_pos + 2] & 0xFF) << 8); | ||
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| m_pos = m_dataLen; | ||
| return i; | ||
| } | ||
| else | ||
| { | ||
| // read next 4 bytes | ||
| const uint32_t i = ((m_data[m_pos] & 0xFF) << 24) | ((m_data[m_pos + 1] & 0xFF) << 16) | | ||
| ((m_data[m_pos + 2] & 0xFF) << 8) | (m_data[m_pos + 3] & 0xFF); | ||
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| m_pos += 4; | ||
| return i; | ||
| } | ||
| } | ||
|
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| int BitStream::MaskBits(int n) | ||
| { | ||
| return (n == 32) ? -1 : (1 << n) - 1; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,49 @@ | ||
| /* | ||
| * Copyright (C) 2005-2021 Team Kodi | ||
| * https://kodi.tv | ||
| * | ||
| * SPDX-License-Identifier: GPL-2.0-or-later | ||
| * See LICENSE.md for more information. | ||
| */ | ||
|
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| #pragma once | ||
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| #include <cstdint> | ||
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| namespace aac | ||
| { | ||
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| class BitStream | ||
| { | ||
| public: | ||
| BitStream() = delete; | ||
| BitStream(const uint8_t* data, unsigned int dataLen); | ||
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| unsigned int GetLength() const { return m_dataLen; } | ||
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| int GetBitsLeft() const; | ||
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| int ReadBit(); | ||
| int ReadBits(int n); | ||
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| bool ReadBool() { return (ReadBit() & 0x1) != 0; } | ||
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| void SkipBit(); | ||
| void SkipBits(int n); | ||
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| void ByteAlign(); | ||
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| private: | ||
| uint32_t ReadCache(); | ||
| int MaskBits(int n); | ||
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| const uint8_t* m_data = nullptr; | ||
| const unsigned int m_dataLen = 0; | ||
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| unsigned int m_pos = 0; // offset in the data array | ||
| uint32_t m_cache = 0; // current 4 bytes, that are read from data | ||
| unsigned int m_bitsCached = 0; // remaining bits in current cache | ||
| unsigned int m_bitsRead = 0; // number of total bits read | ||
| }; | ||
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| } // namespace aac |
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