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AllMusic/core/decoder/flac/FlacLowLevelInput.java
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2025-06-23 13:15:56 +08:00

105 lines
5.6 KiB
Java

/*
* FLAC library (Java)
* Copyright (c) Project Nayuki
* https://www.nayuki.io/page/flac-library-java
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public License
* along with this program (see COPYING.txt and COPYING.LESSER.txt).
* If not, see <http://www.gnu.org/licenses/>.
*/
package com.coloryr.allmusic.server.core.decoder.flac;
import java.io.IOException;
/**
* A low-level input stream tailored to the needs of FLAC decoding. An overview of methods includes
* bit reading, CRC calculation, Rice decoding, and positioning and seeking (partly optional).
*
* @see SeekableFileFlacInput
* @see FrameDecoder
*/
public interface FlacLowLevelInput extends AutoCloseable {
/*---- Stream position ----*/
// Returns the total number of bytes in the FLAC file represented by this input stream.
// This number should not change for the lifetime of this object. Implementing this is optional;
// it's intended to support blind seeking without the use of seek tables, such as binary searching
// the whole file. A class may choose to throw UnsupportedOperationException instead,
// such as for a non-seekable network input stream of unknown length.
public long getLength();
// Returns the current byte position in the stream, a non-negative value.
// This increments after every 8 bits read, and a partially read byte is treated as unread.
// This value is 0 initially, is set directly by seekTo(), and potentially increases
// after every call to a read*() method. Other methods do not affect this value.
public long getPosition();
// Returns the current number of consumed bits in the current byte. This starts at 0,
// increments for each bit consumed, maxes out at 7, then resets to 0 and repeats.
public int getBitPosition();
/*---- Reading bitwise integers ----*/
// Reads the next given number of bits (0 <= n <= 32) as an unsigned integer (i.e. zero-extended to int32).
// However in the case of n = 32, the result will be a signed integer that represents a uint32.
public int readUint(int n) throws IOException;
// Reads the next given number of bits (0 <= n <= 32) as an signed integer (i.e. sign-extended to int32).
public int readSignedInt(int n) throws IOException;
// Reads and decodes the next batch of Rice-coded signed integers. Note that any Rice-coded integer might read a
// large
// number of bits from the underlying stream (but not in practice because it would be a very inefficient encoding).
// Every new value stored into the array is guaranteed to fit into a signed int53 - see FrameDecoder.restoreLpc()
// for an explanation of why this is a necessary (but not sufficient) bound on the range of decoded values.
public void readRiceSignedInts(int param, long[] result, int start, int end) throws IOException;
/*---- Reading bytes ----*/
// Returns the next unsigned byte value (in the range [0, 255]) or -1 for EOF.
// Must be called at a byte boundary (i.e. getBitPosition() == 0), otherwise IllegalStateException is thrown.
public int readByte() throws IOException;
// Discards any partial bits, then reads the given array fully or throws EOFException.
// Must be called at a byte boundary (i.e. getBitPosition() == 0), otherwise IllegalStateException is thrown.
public void readFully(byte[] b) throws IOException;
/*---- CRC calculations ----*/
// Marks the current byte position as the start of both CRC calculations.
// The effect of resetCrcs() is implied at the beginning of stream and when seekTo() is called.
// Must be called at a byte boundary (i.e. getBitPosition() == 0), otherwise IllegalStateException is thrown.
public void resetCrcs();
// Returns the CRC-8 hash of all the bytes read since the most recent time one of these
// events occurred: a call to resetCrcs(), a call to seekTo(), the beginning of stream.
// Must be called at a byte boundary (i.e. getBitPosition() == 0), otherwise IllegalStateException is thrown.
public int getCrc8();
// Returns the CRC-16 hash of all the bytes read since the most recent time one of these
// events occurred: a call to resetCrcs(), a call to seekTo(), the beginning of stream.
// Must be called at a byte boundary (i.e. getBitPosition() == 0), otherwise IllegalStateException is thrown.
public int getCrc16();
/*---- Miscellaneous ----*/
// Closes underlying objects / native resources, and possibly discards memory buffers.
// Generally speaking, this operation invalidates this input stream, so calling methods
// (other than close()) or accessing fields thereafter should be forbidden.
// The close() method must be idempotent and safe when called more than once.
// If an implementation does not have native or time-sensitive resources, it is okay for the class user
// to skip calling close() and simply let the object be garbage-collected. But out of good habit, it is
// recommended to always close a FlacLowLevelInput stream so that the logic works correctly on all types.
public void close() throws IOException;
}