/*!
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* COPYRIGHT (C) 2020 Emeric Grange - All Rights Reserved
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*
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* This file is part of MiniVideo.
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*
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* MiniVideo is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* MiniVideo is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with MiniVideo. If not, see <http://www.gnu.org/licenses/>.
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*
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* \author Emeric Grange <emeric.grange@gmail.com>
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* \date 2012
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*/
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#ifndef BITSTREAM_H
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#define BITSTREAM_H
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/* ************************************************************************** */
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// minivideo headers
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#include <stdio.h>
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#include "minivideo_typedef.h"
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#include <stdint.h>
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/* ************************************************************************** */
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/*!
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* \struct Bitstream_t
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* \brief Bitstream structure.
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* \todo Massive cleanup of this API, need to address the bit/byte ambiguity of the variable names and function arguments.
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*
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* The "Bitstream_t" structure and associated APU is used to map a file to a
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* bitstream data buffer that can be read bit by bit instead of byte by byte.
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* That capability is requiered to extract compressed data that aren't aligned
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* with bytes boundaries.
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*
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* Data can be read from 1 to 64 unaligned bits from a file. These data are
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* bufferized by slices of size defined by the "BITSTREAM_BUFFER_SIZE" variable.
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*
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* Size and offset of the bitstream are stored using int64_t. This structure
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* should be able to handle files up to 1073741824 GiB if "Large File Support"
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* is enabled during compilation with -D_LARGEFILE64_SOURCE. Overwise only files
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* of 2 GiB will work.
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*
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* During a bitstream initialization, a MediaStream_t structure can be used. It
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* allows the bitstream to easily move the current bitstream offset from the end
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* of a frame directly to the start of the next frame one.
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*/
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typedef struct Bitstream_t
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{
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FILE *bitstream_file; //!< File pointer
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int64_t bitstream_size; //!< Bitstream size (in byte)
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int64_t bitstream_offset; //!< Current offset into the bitstream (in byte)
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uint32_t buffer_size_saved; //!< Data buffer size (in byte)
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uint8_t *buffer; //!< Current data buffer
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uint32_t buffer_size; //!< Current data buffer size (in byte)
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uint32_t buffer_offset; //!< Current offset into the buffer (in bit)
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uint32_t buffer_discarded_bytes; //!< Current number of byte(s) removed during NAL Unit read ahead
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} Bitstream_t;
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/* ************************************************************************** */
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struct MediaFile_t;
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Bitstream_t *init_bitstream0(MediaFile_t *media, int64_t bitstream_offset, uint32_t buffer_size);
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Bitstream_t *init_bitstream(MediaFile_t *media);
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void free_bitstream(Bitstream_t **bitstr_ptr);
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int buffer_feed_manual(Bitstream_t *bitstr, int64_t bitstream_offset, int64_t size);
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int buffer_feed_dynamic(Bitstream_t *bitstr, int64_t new_bitstream_offset);
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int read_chunk(Bitstream_t* bitstr, uint8_t* chunk, const uint32_t size);
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// Bits operations
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uint32_t read_bit(Bitstream_t *bitstr);
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uint32_t read_bits(Bitstream_t *bitstr, const unsigned int n);
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uint64_t read_bits_64(Bitstream_t *bitstr, const unsigned int n);
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uint32_t next_bit(Bitstream_t *bitstr);
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uint32_t next_bits(Bitstream_t *bitstr, const unsigned int n);
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uint32_t read_byte_aligned(Bitstream_t *bitstr);
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uint32_t next_byte_aligned(Bitstream_t *bitstr);
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// Move into the bitstream
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int skip_bits(Bitstream_t *bitstr, const unsigned int n);
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int rewind_bits(Bitstream_t *bitstr, const unsigned int n);
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int bitstream_goto_offset(Bitstream_t *bitstr, const int64_t n);
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// Various operations
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int64_t bitstream_get_full_size(Bitstream_t *bitstr);
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int64_t bitstream_get_absolute_byte_offset(Bitstream_t *bitstr);
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int64_t bitstream_get_absolute_bit_offset(Bitstream_t *bitstr);
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/* ************************************************************************** */
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#endif // BITSTREAM_H
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