1 /*
2 mkvmerge -- utility for splicing together matroska files
3 from component media subtypes
4
5 Distributed under the GPL v2
6 see the file COPYING for details
7 or visit https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
8
9 header removal compressor
10
11 Written by Moritz Bunkus <moritz@bunkus.org>.
12 */
13
14 #include "common/common_pch.h"
15
16 #include "common/ac3.h"
17 #include "common/dirac.h"
18 #include "common/dts.h"
19 #include "common/endian.h"
20 #include "common/compression/header_removal.h"
21
header_removal_compressor_c()22 header_removal_compressor_c::header_removal_compressor_c()
23 : compressor_c(COMPRESSION_HEADER_REMOVAL)
24 {
25 }
26
27 memory_cptr
do_decompress(unsigned char const * buffer,std::size_t size)28 header_removal_compressor_c::do_decompress(unsigned char const *buffer,
29 std::size_t size) {
30 if (!m_bytes || (0 == m_bytes->get_size()))
31 return memory_c::clone(buffer, size);
32
33 memory_cptr new_buffer = memory_c::alloc(size + m_bytes->get_size());
34
35 memcpy(new_buffer->get_buffer(), m_bytes->get_buffer(), m_bytes->get_size());
36 memcpy(new_buffer->get_buffer() + m_bytes->get_size(), buffer, size);
37
38 return new_buffer;
39 }
40
41 memory_cptr
do_compress(unsigned char const * buffer,std::size_t size)42 header_removal_compressor_c::do_compress(unsigned char const *buffer,
43 std::size_t size) {
44 if (!m_bytes || (0 == m_bytes->get_size()))
45 return memory_c::clone(buffer, size);
46
47 size_t to_remove_size = m_bytes->get_size();
48 if (size < to_remove_size)
49 throw mtx::compression_x(fmt::format(Y("Header removal compression not possible because the buffer contained {0} bytes "
50 "which is less than the size of the headers that should be removed, {1}."), size, to_remove_size));
51
52 auto bytes_ptr = m_bytes->get_buffer();
53
54 if (memcmp(buffer, bytes_ptr, to_remove_size)) {
55 std::string b_buffer, b_bytes;
56 size_t i;
57
58 for (i = 0; to_remove_size > i; ++i) {
59 b_buffer += fmt::format(" {0:02x}", static_cast<unsigned int>(buffer[i]));
60 b_bytes += fmt::format(" {0:02x}", static_cast<unsigned int>(bytes_ptr[i]));
61 }
62 throw mtx::compression_x(fmt::format(Y("Header removal compression not possible because the buffer did not start with the bytes that should be removed. "
63 "Wanted bytes:{0}; found:{1}."), b_bytes, b_buffer));
64 }
65
66 return memory_c::clone(buffer + size, size - to_remove_size);
67 }
68
69 void
set_track_headers(libmatroska::KaxContentEncoding & c_encoding)70 header_removal_compressor_c::set_track_headers(libmatroska::KaxContentEncoding &c_encoding) {
71 compressor_c::set_track_headers(c_encoding);
72
73 // Set compression parameters.
74 GetChild<libmatroska::KaxContentCompSettings>(GetChild<libmatroska::KaxContentCompression>(c_encoding)).CopyBuffer(m_bytes->get_buffer(), m_bytes->get_size());
75 }
76
77 // ------------------------------------------------------------
78
analyze_header_removal_compressor_c()79 analyze_header_removal_compressor_c::analyze_header_removal_compressor_c()
80 : compressor_c(COMPRESSION_ANALYZE_HEADER_REMOVAL)
81 , m_packet_counter(0)
82 {
83 }
84
~analyze_header_removal_compressor_c()85 analyze_header_removal_compressor_c::~analyze_header_removal_compressor_c() {
86 if (!m_bytes)
87 mxinfo("Analysis failed: no packet encountered\n");
88
89 else if (m_bytes->get_size() == 0)
90 mxinfo("Analysis complete but no similarities found.\n");
91
92 else {
93 mxinfo(fmt::format("Analysis complete. {0} identical byte(s) at the start of each of the {1} packet(s). Hex dump of the content:\n", m_bytes->get_size(), m_packet_counter));
94 debugging_c::hexdump(m_bytes->get_buffer(), m_bytes->get_size());
95 }
96 }
97
98 memory_cptr
do_decompress(unsigned char const *,std::size_t)99 analyze_header_removal_compressor_c::do_decompress(unsigned char const *,
100 std::size_t) {
101 mxerror("analyze_header_removal_compressor_c::do_decompress(): not supported\n");
102 return {};
103 }
104
105 memory_cptr
do_compress(unsigned char const * buffer,std::size_t size)106 analyze_header_removal_compressor_c::do_compress(unsigned char const *buffer,
107 std::size_t size) {
108 ++m_packet_counter;
109
110 if (!m_bytes) {
111 m_bytes = memory_c::clone(buffer, size);
112 return memory_c::clone(buffer, size);
113 }
114
115 auto saved = m_bytes->get_buffer();
116 size_t i, new_size = 0;
117
118 for (i = 0; i < std::min(size, m_bytes->get_size()); ++i, ++new_size)
119 if (buffer[i] != saved[i])
120 break;
121
122 m_bytes->set_size(new_size);
123
124 return memory_c::clone(buffer, size);
125 }
126
127 void
set_track_headers(libmatroska::KaxContentEncoding &)128 analyze_header_removal_compressor_c::set_track_headers(libmatroska::KaxContentEncoding &) {
129 }
130
131 // ------------------------------------------------------------
132
mpeg4_p2_compressor_c()133 mpeg4_p2_compressor_c::mpeg4_p2_compressor_c() {
134 memory_cptr bytes = memory_c::alloc(3);
135 put_uint24_be(bytes->get_buffer(), 0x000001);
136 set_bytes(bytes);
137 }
138
mpeg4_p10_compressor_c()139 mpeg4_p10_compressor_c::mpeg4_p10_compressor_c() {
140 memory_cptr bytes = memory_c::alloc(1);
141 bytes->get_buffer()[0] = 0;
142 set_bytes(bytes);
143 }
144
dirac_compressor_c()145 dirac_compressor_c::dirac_compressor_c() {
146 memory_cptr bytes = memory_c::alloc(4);
147 put_uint32_be(bytes->get_buffer(), mtx::dirac::SYNC_WORD);
148 set_bytes(bytes);
149 }
150
dts_compressor_c()151 dts_compressor_c::dts_compressor_c() {
152 memory_cptr bytes = memory_c::alloc(4);
153 put_uint32_be(bytes->get_buffer(), static_cast<uint32_t>(mtx::dts::sync_word_e::core));
154 set_bytes(bytes);
155 }
156
ac3_compressor_c()157 ac3_compressor_c::ac3_compressor_c() {
158 memory_cptr bytes = memory_c::alloc(2);
159 put_uint16_be(bytes->get_buffer(), mtx::ac3::SYNC_WORD);
160 set_bytes(bytes);
161 }
162
mp3_compressor_c()163 mp3_compressor_c::mp3_compressor_c() {
164 memory_cptr bytes = memory_c::alloc(1);
165 bytes->get_buffer()[0] = 0xff;
166 set_bytes(bytes);
167 }
168