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[lhc/web/www.git] / www / plugins-dist / medias / lib / getid3 / module.audio-video.mpeg.php
1 <?php
2
3 /////////////////////////////////////////////////////////////////
4 /// getID3() by James Heinrich <info@getid3.org> //
5 // available at https://github.com/JamesHeinrich/getID3 //
6 // or https://www.getid3.org //
7 // or http://getid3.sourceforge.net //
8 // see readme.txt for more details //
9 /////////////////////////////////////////////////////////////////
10 // //
11 // module.audio-video.mpeg.php //
12 // module for analyzing MPEG files //
13 // dependencies: module.audio.mp3.php //
14 // ///
15 /////////////////////////////////////////////////////////////////
16
17 if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
18 exit;
19 }
20 getid3_lib::IncludeDependency(GETID3_INCLUDEPATH.'module.audio.mp3.php', __FILE__, true);
21
22 class getid3_mpeg extends getid3_handler
23 {
24
25 const START_CODE_BASE = "\x00\x00\x01";
26 const VIDEO_PICTURE_START = "\x00\x00\x01\x00";
27 const VIDEO_USER_DATA_START = "\x00\x00\x01\xB2";
28 const VIDEO_SEQUENCE_HEADER = "\x00\x00\x01\xB3";
29 const VIDEO_SEQUENCE_ERROR = "\x00\x00\x01\xB4";
30 const VIDEO_EXTENSION_START = "\x00\x00\x01\xB5";
31 const VIDEO_SEQUENCE_END = "\x00\x00\x01\xB7";
32 const VIDEO_GROUP_START = "\x00\x00\x01\xB8";
33 const AUDIO_START = "\x00\x00\x01\xC0";
34
35 /**
36 * @return bool
37 */
38 public function Analyze() {
39 $info = &$this->getid3->info;
40
41 $info['fileformat'] = 'mpeg';
42 $this->fseek($info['avdataoffset']);
43
44 $MPEGstreamData = $this->fread($this->getid3->option_fread_buffer_size);
45 $MPEGstreamBaseOffset = 0; // how far are we from the beginning of the file data ($info['avdataoffset'])
46 $MPEGstreamDataOffset = 0; // how far are we from the beginning of the buffer data (~32kB)
47
48 $StartCodeValue = false;
49 $prevStartCodeValue = false;
50
51 $GOPcounter = -1;
52 $FramesByGOP = array();
53 $ParsedAVchannels = array();
54
55 do {
56 //echo $MPEGstreamDataOffset.' vs '.(strlen($MPEGstreamData) - 1024).'<Br>';
57 if ($MPEGstreamDataOffset > (strlen($MPEGstreamData) - 16384)) {
58 // buffer running low, get more data
59 //echo 'reading more data<br>';
60 $MPEGstreamData .= $this->fread($this->getid3->option_fread_buffer_size);
61 if (strlen($MPEGstreamData) > $this->getid3->option_fread_buffer_size) {
62 $MPEGstreamData = substr($MPEGstreamData, $MPEGstreamDataOffset);
63 $MPEGstreamBaseOffset += $MPEGstreamDataOffset;
64 $MPEGstreamDataOffset = 0;
65 }
66 }
67 if (($StartCodeOffset = strpos($MPEGstreamData, self::START_CODE_BASE, $MPEGstreamDataOffset)) === false) {
68 //echo 'no more start codes found.<br>';
69 break;
70 } else {
71 $MPEGstreamDataOffset = $StartCodeOffset;
72 $prevStartCodeValue = $StartCodeValue;
73 $StartCodeValue = ord(substr($MPEGstreamData, $StartCodeOffset + 3, 1));
74 //echo 'Found "'.strtoupper(dechex($StartCodeValue)).'" at offset '.($MPEGstreamBaseOffset + $StartCodeOffset).' ($MPEGstreamDataOffset = '.$MPEGstreamDataOffset.')<br>';
75 }
76 $MPEGstreamDataOffset += 4;
77 switch ($StartCodeValue) {
78
79 case 0x00: // picture_start_code
80 if (!empty($info['mpeg']['video']['bitrate_mode']) && ($info['mpeg']['video']['bitrate_mode'] == 'vbr')) {
81 $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 4, 4));
82 $bitstreamoffset = 0;
83
84 $PictureHeader = array();
85
86 $PictureHeader['temporal_reference'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 10); // 10-bit unsigned integer associated with each input picture. It is incremented by one, modulo 1024, for each input frame. When a frame is coded as two fields the temporal reference in the picture header of both fields is the same. Following a group start header the temporal reference of the earliest picture (in display order) shall be reset to zero.
87 $PictureHeader['picture_coding_type'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 3); // 3 bits for picture_coding_type
88 $PictureHeader['vbv_delay'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 16); // 16 bits for vbv_delay
89 //... etc
90
91 $FramesByGOP[$GOPcounter][] = $PictureHeader;
92 }
93 break;
94
95 case 0xB3: // sequence_header_code
96 // Note: purposely doing the less-pretty (and probably a bit slower) method of using string of bits rather than bitwise operations.
97 // Mostly because PHP 32-bit doesn't handle unsigned integers well for bitwise operation.
98 // Also the MPEG stream is designed as a bitstream and often doesn't align nicely with byte boundaries.
99 $info['video']['codec'] = 'MPEG-1'; // will be updated if extension_start_code found
100
101 $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 4, 8));
102 $bitstreamoffset = 0;
103
104 $info['mpeg']['video']['raw']['horizontal_size_value'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 12); // 12 bits for horizontal frame size. Note: horizontal_size_extension, if present, will add 2 most-significant bits to this value
105 $info['mpeg']['video']['raw']['vertical_size_value'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 12); // 12 bits for vertical frame size. Note: vertical_size_extension, if present, will add 2 most-significant bits to this value
106 $info['mpeg']['video']['raw']['aspect_ratio_information'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 4); // 4 bits for aspect_ratio_information
107 $info['mpeg']['video']['raw']['frame_rate_code'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 4); // 4 bits for Frame Rate id code
108 $info['mpeg']['video']['raw']['bitrate'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 18); // 18 bits for bit_rate_value (18 set bits = VBR, otherwise bitrate = this value * 400)
109 $marker_bit = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
110 $info['mpeg']['video']['raw']['vbv_buffer_size'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 10); // 10 bits vbv_buffer_size_value
111 $info['mpeg']['video']['raw']['constrained_param_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: constrained_param_flag
112 $info['mpeg']['video']['raw']['load_intra_quantiser_matrix'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: load_intra_quantiser_matrix
113
114 if ($info['mpeg']['video']['raw']['load_intra_quantiser_matrix']) {
115 $bitstream .= getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 12, 64));
116 for ($i = 0; $i < 64; $i++) {
117 $info['mpeg']['video']['raw']['intra_quantiser_matrix'][$i] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8);
118 }
119 }
120 $info['mpeg']['video']['raw']['load_non_intra_quantiser_matrix'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1);
121
122 if ($info['mpeg']['video']['raw']['load_non_intra_quantiser_matrix']) {
123 $bitstream .= getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 12 + ($info['mpeg']['video']['raw']['load_intra_quantiser_matrix'] ? 64 : 0), 64));
124 for ($i = 0; $i < 64; $i++) {
125 $info['mpeg']['video']['raw']['non_intra_quantiser_matrix'][$i] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8);
126 }
127 }
128
129 $info['mpeg']['video']['pixel_aspect_ratio'] = self::videoAspectRatioLookup($info['mpeg']['video']['raw']['aspect_ratio_information']); // may be overridden later if file turns out to be MPEG-2
130 $info['mpeg']['video']['pixel_aspect_ratio_text'] = self::videoAspectRatioTextLookup($info['mpeg']['video']['raw']['aspect_ratio_information']); // may be overridden later if file turns out to be MPEG-2
131 $info['mpeg']['video']['frame_rate'] = self::videoFramerateLookup($info['mpeg']['video']['raw']['frame_rate_code']);
132 if ($info['mpeg']['video']['raw']['bitrate'] == 0x3FFFF) { // 18 set bits = VBR
133 //$this->warning('This version of getID3() ['.$this->getid3->version().'] cannot determine average bitrate of VBR MPEG video files');
134 $info['mpeg']['video']['bitrate_mode'] = 'vbr';
135 } else {
136 $info['mpeg']['video']['bitrate'] = $info['mpeg']['video']['raw']['bitrate'] * 400;
137 $info['mpeg']['video']['bitrate_mode'] = 'cbr';
138 $info['video']['bitrate'] = $info['mpeg']['video']['bitrate'];
139 }
140 $info['video']['resolution_x'] = $info['mpeg']['video']['raw']['horizontal_size_value'];
141 $info['video']['resolution_y'] = $info['mpeg']['video']['raw']['vertical_size_value'];
142 $info['video']['frame_rate'] = $info['mpeg']['video']['frame_rate'];
143 $info['video']['bitrate_mode'] = $info['mpeg']['video']['bitrate_mode'];
144 $info['video']['pixel_aspect_ratio'] = $info['mpeg']['video']['pixel_aspect_ratio'];
145 $info['video']['lossless'] = false;
146 $info['video']['bits_per_sample'] = 24;
147 break;
148
149 case 0xB5: // extension_start_code
150 $info['video']['codec'] = 'MPEG-2';
151
152 $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 4, 8)); // 48 bits for Sequence Extension ID; 61 bits for Sequence Display Extension ID; 59 bits for Sequence Scalable Extension ID
153 $bitstreamoffset = 0;
154
155 $info['mpeg']['video']['raw']['extension_start_code_identifier'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 4); // 4 bits for extension_start_code_identifier
156 //echo $info['mpeg']['video']['raw']['extension_start_code_identifier'].'<br>';
157 switch ($info['mpeg']['video']['raw']['extension_start_code_identifier']) {
158 case 1: // 0001 Sequence Extension ID
159 $info['mpeg']['video']['raw']['profile_and_level_indication'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8); // 8 bits for profile_and_level_indication
160 $info['mpeg']['video']['raw']['progressive_sequence'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: progressive_sequence
161 $info['mpeg']['video']['raw']['chroma_format'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for chroma_format
162 $info['mpeg']['video']['raw']['horizontal_size_extension'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for horizontal_size_extension
163 $info['mpeg']['video']['raw']['vertical_size_extension'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for vertical_size_extension
164 $info['mpeg']['video']['raw']['bit_rate_extension'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 12); // 12 bits for bit_rate_extension
165 $marker_bit = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
166 $info['mpeg']['video']['raw']['vbv_buffer_size_extension'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8); // 8 bits for vbv_buffer_size_extension
167 $info['mpeg']['video']['raw']['low_delay'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: low_delay
168 $info['mpeg']['video']['raw']['frame_rate_extension_n'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for frame_rate_extension_n
169 $info['mpeg']['video']['raw']['frame_rate_extension_d'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 5); // 5 bits for frame_rate_extension_d
170
171 $info['video']['resolution_x'] = ($info['mpeg']['video']['raw']['horizontal_size_extension'] << 12) | $info['mpeg']['video']['raw']['horizontal_size_value'];
172 $info['video']['resolution_y'] = ($info['mpeg']['video']['raw']['vertical_size_extension'] << 12) | $info['mpeg']['video']['raw']['vertical_size_value'];
173 $info['video']['interlaced'] = !$info['mpeg']['video']['raw']['progressive_sequence'];
174 $info['mpeg']['video']['interlaced'] = !$info['mpeg']['video']['raw']['progressive_sequence'];
175 $info['mpeg']['video']['chroma_format'] = self::chromaFormatTextLookup($info['mpeg']['video']['raw']['chroma_format']);
176
177 if (isset($info['mpeg']['video']['raw']['aspect_ratio_information'])) {
178 // MPEG-2 defines the aspect ratio flag differently from MPEG-1, but the MPEG-2 extension start code may occur after we've already looked up the aspect ratio assuming it was MPEG-1, so re-lookup assuming MPEG-2
179 // This must be done after the extended size is known, so the display aspect ratios can be converted to pixel aspect ratios.
180 $info['mpeg']['video']['pixel_aspect_ratio'] = self::videoAspectRatioLookup($info['mpeg']['video']['raw']['aspect_ratio_information'], 2, $info['video']['resolution_x'], $info['video']['resolution_y']);
181 $info['mpeg']['video']['pixel_aspect_ratio_text'] = self::videoAspectRatioTextLookup($info['mpeg']['video']['raw']['aspect_ratio_information'], 2);
182 $info['video']['pixel_aspect_ratio'] = $info['mpeg']['video']['pixel_aspect_ratio'];
183 $info['video']['pixel_aspect_ratio_text'] = $info['mpeg']['video']['pixel_aspect_ratio_text'];
184 }
185
186 break;
187
188 case 2: // 0010 Sequence Display Extension ID
189 $info['mpeg']['video']['raw']['video_format'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 3); // 3 bits for video_format
190 $info['mpeg']['video']['raw']['colour_description'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: colour_description
191 if ($info['mpeg']['video']['raw']['colour_description']) {
192 $info['mpeg']['video']['raw']['colour_primaries'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8); // 8 bits for colour_primaries
193 $info['mpeg']['video']['raw']['transfer_characteristics'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8); // 8 bits for transfer_characteristics
194 $info['mpeg']['video']['raw']['matrix_coefficients'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8); // 8 bits for matrix_coefficients
195 }
196 $info['mpeg']['video']['raw']['display_horizontal_size'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 14); // 14 bits for display_horizontal_size
197 $marker_bit = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
198 $info['mpeg']['video']['raw']['display_vertical_size'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 14); // 14 bits for display_vertical_size
199
200 $info['mpeg']['video']['video_format'] = self::videoFormatTextLookup($info['mpeg']['video']['raw']['video_format']);
201 break;
202
203 case 3: // 0011 Quant Matrix Extension ID
204 break;
205
206 case 5: // 0101 Sequence Scalable Extension ID
207 $info['mpeg']['video']['raw']['scalable_mode'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for scalable_mode
208 $info['mpeg']['video']['raw']['layer_id'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 4); // 4 bits for layer_id
209 if ($info['mpeg']['video']['raw']['scalable_mode'] == 1) { // "spatial scalability"
210 $info['mpeg']['video']['raw']['lower_layer_prediction_horizontal_size'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 14); // 14 bits for lower_layer_prediction_horizontal_size
211 $marker_bit = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
212 $info['mpeg']['video']['raw']['lower_layer_prediction_vertical_size'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 14); // 14 bits for lower_layer_prediction_vertical_size
213 $info['mpeg']['video']['raw']['horizontal_subsampling_factor_m'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 5); // 5 bits for horizontal_subsampling_factor_m
214 $info['mpeg']['video']['raw']['horizontal_subsampling_factor_n'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 5); // 5 bits for horizontal_subsampling_factor_n
215 $info['mpeg']['video']['raw']['vertical_subsampling_factor_m'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 5); // 5 bits for vertical_subsampling_factor_m
216 $info['mpeg']['video']['raw']['vertical_subsampling_factor_n'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 5); // 5 bits for vertical_subsampling_factor_n
217 } elseif ($info['mpeg']['video']['raw']['scalable_mode'] == 3) { // "temporal scalability"
218 $info['mpeg']['video']['raw']['picture_mux_enable'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: picture_mux_enable
219 if ($info['mpeg']['video']['raw']['picture_mux_enable']) {
220 $info['mpeg']['video']['raw']['mux_to_progressive_sequence'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: mux_to_progressive_sequence
221 }
222 $info['mpeg']['video']['raw']['picture_mux_order'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 3); // 3 bits for picture_mux_order
223 $info['mpeg']['video']['raw']['picture_mux_factor'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 3); // 3 bits for picture_mux_factor
224 }
225
226 $info['mpeg']['video']['scalable_mode'] = self::scalableModeTextLookup($info['mpeg']['video']['raw']['scalable_mode']);
227 break;
228
229 case 7: // 0111 Picture Display Extension ID
230 break;
231
232 case 8: // 1000 Picture Coding Extension ID
233 $info['mpeg']['video']['raw']['f_code_00'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 4); // 4 bits for f_code[0][0] (forward horizontal)
234 $info['mpeg']['video']['raw']['f_code_01'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 4); // 4 bits for f_code[0][1] (forward vertical)
235 $info['mpeg']['video']['raw']['f_code_10'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 4); // 4 bits for f_code[1][0] (backward horizontal)
236 $info['mpeg']['video']['raw']['f_code_11'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 4); // 4 bits for f_code[1][1] (backward vertical)
237 $info['mpeg']['video']['raw']['intra_dc_precision'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for intra_dc_precision
238 $info['mpeg']['video']['raw']['picture_structure'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for picture_structure
239 $info['mpeg']['video']['raw']['top_field_first'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: top_field_first
240 $info['mpeg']['video']['raw']['frame_pred_frame_dct'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: frame_pred_frame_dct
241 $info['mpeg']['video']['raw']['concealment_motion_vectors'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: concealment_motion_vectors
242 $info['mpeg']['video']['raw']['q_scale_type'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: q_scale_type
243 $info['mpeg']['video']['raw']['intra_vlc_format'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: intra_vlc_format
244 $info['mpeg']['video']['raw']['alternate_scan'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: alternate_scan
245 $info['mpeg']['video']['raw']['repeat_first_field'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: repeat_first_field
246 $info['mpeg']['video']['raw']['chroma_420_type'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: chroma_420_type
247 $info['mpeg']['video']['raw']['progressive_frame'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: progressive_frame
248 $info['mpeg']['video']['raw']['composite_display_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: composite_display_flag
249 if ($info['mpeg']['video']['raw']['composite_display_flag']) {
250 $info['mpeg']['video']['raw']['v_axis'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: v_axis
251 $info['mpeg']['video']['raw']['field_sequence'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 3); // 3 bits for field_sequence
252 $info['mpeg']['video']['raw']['sub_carrier'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: sub_carrier
253 $info['mpeg']['video']['raw']['burst_amplitude'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 7); // 7 bits for burst_amplitude
254 $info['mpeg']['video']['raw']['sub_carrier_phase'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8); // 8 bits for sub_carrier_phase
255 }
256
257 $info['mpeg']['video']['intra_dc_precision_bits'] = $info['mpeg']['video']['raw']['intra_dc_precision'] + 8;
258 $info['mpeg']['video']['picture_structure'] = self::pictureStructureTextLookup($info['mpeg']['video']['raw']['picture_structure']);
259 break;
260
261 case 9: // 1001 Picture Spatial Scalable Extension ID
262 break;
263 case 10: // 1010 Picture Temporal Scalable Extension ID
264 break;
265
266 default:
267 $this->warning('Unexpected $info[mpeg][video][raw][extension_start_code_identifier] value of '.$info['mpeg']['video']['raw']['extension_start_code_identifier']);
268 break;
269 }
270 break;
271
272
273 case 0xB8: // group_of_pictures_header
274 $GOPcounter++;
275 if (!empty($info['mpeg']['video']['bitrate_mode']) && ($info['mpeg']['video']['bitrate_mode'] == 'vbr')) {
276 $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 4, 4)); // 27 bits needed for group_of_pictures_header
277 $bitstreamoffset = 0;
278
279 $GOPheader = array();
280
281 $GOPheader['byte_offset'] = $MPEGstreamBaseOffset + $StartCodeOffset;
282 $GOPheader['drop_frame_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: drop_frame_flag
283 $GOPheader['time_code_hours'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 5); // 5 bits for time_code_hours
284 $GOPheader['time_code_minutes'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 6); // 6 bits for time_code_minutes
285 $marker_bit = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // The term "marker_bit" indicates a one bit field in which the value zero is forbidden. These marker bits are introduced at several points in the syntax to avoid start code emulation.
286 $GOPheader['time_code_seconds'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 6); // 6 bits for time_code_seconds
287 $GOPheader['time_code_pictures'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 6); // 6 bits for time_code_pictures
288 $GOPheader['closed_gop'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: closed_gop
289 $GOPheader['broken_link'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: broken_link
290
291 $time_code_separator = ($GOPheader['drop_frame_flag'] ? ';' : ':'); // While non-drop time code is displayed with colons separating the digit pairs "HH:MM:SS:FF" drop frame is usually represented with a semi-colon (;) or period (.) as the divider between all the digit pairs "HH;MM;SS;FF", "HH.MM.SS.FF"
292 $GOPheader['time_code'] = sprintf('%02d'.$time_code_separator.'%02d'.$time_code_separator.'%02d'.$time_code_separator.'%02d', $GOPheader['time_code_hours'], $GOPheader['time_code_minutes'], $GOPheader['time_code_seconds'], $GOPheader['time_code_pictures']);
293
294 $info['mpeg']['group_of_pictures'][] = $GOPheader;
295 }
296 break;
297
298 case 0xC0: // audio stream
299 case 0xC1: // audio stream
300 case 0xC2: // audio stream
301 case 0xC3: // audio stream
302 case 0xC4: // audio stream
303 case 0xC5: // audio stream
304 case 0xC6: // audio stream
305 case 0xC7: // audio stream
306 case 0xC8: // audio stream
307 case 0xC9: // audio stream
308 case 0xCA: // audio stream
309 case 0xCB: // audio stream
310 case 0xCC: // audio stream
311 case 0xCD: // audio stream
312 case 0xCE: // audio stream
313 case 0xCF: // audio stream
314 case 0xD0: // audio stream
315 case 0xD1: // audio stream
316 case 0xD2: // audio stream
317 case 0xD3: // audio stream
318 case 0xD4: // audio stream
319 case 0xD5: // audio stream
320 case 0xD6: // audio stream
321 case 0xD7: // audio stream
322 case 0xD8: // audio stream
323 case 0xD9: // audio stream
324 case 0xDA: // audio stream
325 case 0xDB: // audio stream
326 case 0xDC: // audio stream
327 case 0xDD: // audio stream
328 case 0xDE: // audio stream
329 case 0xDF: // audio stream
330 //case 0xE0: // video stream
331 //case 0xE1: // video stream
332 //case 0xE2: // video stream
333 //case 0xE3: // video stream
334 //case 0xE4: // video stream
335 //case 0xE5: // video stream
336 //case 0xE6: // video stream
337 //case 0xE7: // video stream
338 //case 0xE8: // video stream
339 //case 0xE9: // video stream
340 //case 0xEA: // video stream
341 //case 0xEB: // video stream
342 //case 0xEC: // video stream
343 //case 0xED: // video stream
344 //case 0xEE: // video stream
345 //case 0xEF: // video stream
346 if (isset($ParsedAVchannels[$StartCodeValue])) {
347 break;
348 }
349 $ParsedAVchannels[$StartCodeValue] = $StartCodeValue;
350 // http://en.wikipedia.org/wiki/Packetized_elementary_stream
351 // http://dvd.sourceforge.net/dvdinfo/pes-hdr.html
352 /*
353 $PackedElementaryStream = array();
354 if ($StartCodeValue >= 0xE0) {
355 $PackedElementaryStream['stream_type'] = 'video';
356 $PackedElementaryStream['stream_id'] = $StartCodeValue - 0xE0;
357 } else {
358 $PackedElementaryStream['stream_type'] = 'audio';
359 $PackedElementaryStream['stream_id'] = $StartCodeValue - 0xC0;
360 }
361 $PackedElementaryStream['packet_length'] = getid3_lib::BigEndian2Int(substr($MPEGstreamData, $StartCodeOffset + 4, 2));
362
363 $bitstream = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 6, 3)); // more may be needed below
364 $bitstreamoffset = 0;
365
366 $PackedElementaryStream['marker_bits'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for marker_bits -- should be "10" = 2
367 echo 'marker_bits = '.$PackedElementaryStream['marker_bits'].'<br>';
368 $PackedElementaryStream['scrambling_control'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 2); // 2 bits for scrambling_control -- 00 implies not scrambled
369 $PackedElementaryStream['priority'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: priority
370 $PackedElementaryStream['data_alignment_indicator'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: data_alignment_indicator -- 1 indicates that the PES packet header is immediately followed by the video start code or audio syncword
371 $PackedElementaryStream['copyright'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: copyright -- 1 implies copyrighted
372 $PackedElementaryStream['original_or_copy'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: original_or_copy -- 1 implies original
373 $PackedElementaryStream['pts_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: pts_flag -- Presentation Time Stamp
374 $PackedElementaryStream['dts_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: dts_flag -- Decode Time Stamp
375 $PackedElementaryStream['escr_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: escr_flag -- Elementary Stream Clock Reference
376 $PackedElementaryStream['es_rate_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: es_rate_flag -- Elementary Stream [data] Rate
377 $PackedElementaryStream['dsm_trick_mode_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: dsm_trick_mode_flag -- DSM trick mode - not used by DVD
378 $PackedElementaryStream['additional_copy_info_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: additional_copy_info_flag
379 $PackedElementaryStream['crc_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: crc_flag
380 $PackedElementaryStream['extension_flag'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 1); // 1 bit flag: extension_flag
381 $PackedElementaryStream['pes_remain_header_length'] = self::readBitsFromStream($bitstream, $bitstreamoffset, 8); // 1 bit flag: priority
382
383 $additional_header_bytes = 0;
384 $additional_header_bytes += ($PackedElementaryStream['pts_flag'] ? 5 : 0);
385 $additional_header_bytes += ($PackedElementaryStream['dts_flag'] ? 5 : 0);
386 $additional_header_bytes += ($PackedElementaryStream['escr_flag'] ? 6 : 0);
387 $additional_header_bytes += ($PackedElementaryStream['es_rate_flag'] ? 3 : 0);
388 $additional_header_bytes += ($PackedElementaryStream['additional_copy_info_flag'] ? 1 : 0);
389 $additional_header_bytes += ($PackedElementaryStream['crc_flag'] ? 2 : 0);
390 $additional_header_bytes += ($PackedElementaryStream['extension_flag'] ? 1 : 0);
391 $PackedElementaryStream['additional_header_bytes'] = $additional_header_bytes;
392 $bitstream .= getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $StartCodeOffset + 9, $additional_header_bytes));
393
394 $info['mpeg']['packed_elementary_streams'][$PackedElementaryStream['stream_type']][$PackedElementaryStream['stream_id']][] = $PackedElementaryStream;
395 */
396 $getid3_temp = new getID3();
397 $getid3_temp->openfile($this->getid3->filename, $this->getid3->info['filesize'], $this->getid3->fp);
398 $getid3_temp->info = $info;
399 $getid3_mp3 = new getid3_mp3($getid3_temp);
400 for ($i = 0; $i <= 7; $i++) {
401 // some files have the MPEG-audio header 8 bytes after the end of the $00 $00 $01 $C0 signature, some have it up to 13 bytes (or more?) after
402 // I have no idea why or what the difference is, so this is a stupid hack.
403 // If anybody has any better idea of what's going on, please let me know - info@getid3.org
404 $getid3_temp->info = $info; // only overwrite real data if valid header found
405 //echo 'audio at? '.($MPEGstreamBaseOffset + $StartCodeOffset + 4 + 8 + $i).'<br>';
406 if ($getid3_mp3->decodeMPEGaudioHeader($MPEGstreamBaseOffset + $StartCodeOffset + 4 + 8 + $i, $getid3_temp->info, false)) {
407 //echo 'yes!<br>';
408 $info = $getid3_temp->info;
409 $info['audio']['bitrate_mode'] = 'cbr';
410 $info['audio']['lossless'] = false;
411 break;
412 }
413 }
414 unset($getid3_temp, $getid3_mp3);
415 break;
416
417 case 0xBC: // Program Stream Map
418 case 0xBD: // Private stream 1 (non MPEG audio, subpictures)
419 case 0xBE: // Padding stream
420 case 0xBF: // Private stream 2 (navigation data)
421 case 0xF0: // ECM stream
422 case 0xF1: // EMM stream
423 case 0xF2: // DSM-CC stream
424 case 0xF3: // ISO/IEC_13522_stream
425 case 0xF4: // ITU-I Rec. H.222.1 type A
426 case 0xF5: // ITU-I Rec. H.222.1 type B
427 case 0xF6: // ITU-I Rec. H.222.1 type C
428 case 0xF7: // ITU-I Rec. H.222.1 type D
429 case 0xF8: // ITU-I Rec. H.222.1 type E
430 case 0xF9: // ancilliary stream
431 case 0xFA: // ISO/IEC 14496-1 SL-packtized stream
432 case 0xFB: // ISO/IEC 14496-1 FlexMux stream
433 case 0xFC: // metadata stream
434 case 0xFD: // extended stream ID
435 case 0xFE: // reserved data stream
436 case 0xFF: // program stream directory
437 // ignore
438 break;
439
440 default:
441 // ignore
442 break;
443 }
444 } while (true);
445
446
447
448 // // Temporary hack to account for interleaving overhead:
449 // if (!empty($info['video']['bitrate']) && !empty($info['audio']['bitrate'])) {
450 // $info['playtime_seconds'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / ($info['video']['bitrate'] + $info['audio']['bitrate']);
451 //
452 // // Interleaved MPEG audio/video files have a certain amount of overhead that varies
453 // // by both video and audio bitrates, and not in any sensible, linear/logarithmic pattern
454 // // Use interpolated lookup tables to approximately guess how much is overhead, because
455 // // playtime is calculated as filesize / total-bitrate
456 // $info['playtime_seconds'] *= self::systemNonOverheadPercentage($info['video']['bitrate'], $info['audio']['bitrate']);
457 //
458 // //switch ($info['video']['bitrate']) {
459 // // case('5000000'):
460 // // $multiplier = 0.93292642112380355828048824319889;
461 // // break;
462 // // case('5500000'):
463 // // $multiplier = 0.93582895375200989965359777343219;
464 // // break;
465 // // case('6000000'):
466 // // $multiplier = 0.93796247714820932532911373859139;
467 // // break;
468 // // case('7000000'):
469 // // $multiplier = 0.9413264083635103463010117778776;
470 // // break;
471 // // default:
472 // // $multiplier = 1;
473 // // break;
474 // //}
475 // //$info['playtime_seconds'] *= $multiplier;
476 // //$this->warning('Interleaved MPEG audio/video playtime may be inaccurate. With current hack should be within a few seconds of accurate. Report to info@getid3.org if off by more than 10 seconds.');
477 // if ($info['video']['bitrate'] < 50000) {
478 // $this->warning('Interleaved MPEG audio/video playtime may be slightly inaccurate for video bitrates below 100kbps. Except in extreme low-bitrate situations, error should be less than 1%. Report to info@getid3.org if greater than this.');
479 // }
480 // }
481 //
482 /*
483 $time_prev = 0;
484 $byte_prev = 0;
485 $vbr_bitrates = array();
486 foreach ($info['mpeg']['group_of_pictures'] as $gopkey => $gopdata) {
487 $time_this = ($gopdata['time_code_hours'] * 3600) + ($gopdata['time_code_minutes'] * 60) + $gopdata['time_code_seconds'] + ($gopdata['time_code_seconds'] / 30);
488 $byte_this = $gopdata['byte_offset'];
489 if ($gopkey > 0) {
490 if ($time_this > $time_prev) {
491 $bytedelta = $byte_this - $byte_prev;
492 $timedelta = $time_this - $time_prev;
493 $this_bitrate = ($bytedelta * 8) / $timedelta;
494 echo $gopkey.': ('.number_format($time_prev, 2).'-'.number_format($time_this, 2).') '.number_format($bytedelta).' bytes over '.number_format($timedelta, 3).' seconds = '.number_format($this_bitrate / 1000, 2).'kbps<br>';
495 $time_prev = $time_this;
496 $byte_prev = $byte_this;
497 $vbr_bitrates[] = $this_bitrate;
498 }
499 }
500 }
501 echo 'average_File_bitrate = '.number_format(array_sum($vbr_bitrates) / count($vbr_bitrates), 1).'<br>';
502 */
503 //echo '<pre>'.print_r($FramesByGOP, true).'</pre>';
504 if (!empty($info['mpeg']['video']['bitrate_mode']) && ($info['mpeg']['video']['bitrate_mode'] == 'vbr')) {
505 $last_GOP_id = max(array_keys($FramesByGOP));
506 $frames_in_last_GOP = count($FramesByGOP[$last_GOP_id]);
507 $gopdata = &$info['mpeg']['group_of_pictures'][$last_GOP_id];
508 $info['playtime_seconds'] = ($gopdata['time_code_hours'] * 3600) + ($gopdata['time_code_minutes'] * 60) + $gopdata['time_code_seconds'] + (($gopdata['time_code_pictures'] + $frames_in_last_GOP + 1) / $info['mpeg']['video']['frame_rate']);
509 if (!isset($info['video']['bitrate'])) {
510 $overall_bitrate = ($info['avdataend'] - $info['avdataoffset']) * 8 / $info['playtime_seconds'];
511 $info['video']['bitrate'] = $overall_bitrate - (isset($info['audio']['bitrate']) ? $info['audio']['bitrate'] : 0);
512 }
513 unset($info['mpeg']['group_of_pictures']);
514 }
515
516 return true;
517 }
518
519 /**
520 * @param string $bitstream
521 * @param int $bitstreamoffset
522 * @param int $bits_to_read
523 * @param bool $return_singlebit_as_boolean
524 *
525 * @return bool|int
526 */
527 private function readBitsFromStream(&$bitstream, &$bitstreamoffset, $bits_to_read, $return_singlebit_as_boolean=true) {
528 $return = bindec(substr($bitstream, $bitstreamoffset, $bits_to_read));
529 $bitstreamoffset += $bits_to_read;
530 if (($bits_to_read == 1) && $return_singlebit_as_boolean) {
531 $return = (bool) $return;
532 }
533 return $return;
534 }
535
536 /**
537 * @param int $VideoBitrate
538 * @param int $AudioBitrate
539 *
540 * @return float|int
541 */
542 public static function systemNonOverheadPercentage($VideoBitrate, $AudioBitrate) {
543 $OverheadPercentage = 0;
544
545 $AudioBitrate = max(min($AudioBitrate / 1000, 384), 32); // limit to range of 32kbps - 384kbps (should be only legal bitrates, but maybe VBR?)
546 $VideoBitrate = max(min($VideoBitrate / 1000, 10000), 10); // limit to range of 10kbps - 10Mbps (beyond that curves flatten anyways, no big loss)
547
548
549 //OMBB[audiobitrate] = array(video-10kbps, video-100kbps, video-1000kbps, video-10000kbps)
550 $OverheadMultiplierByBitrate[32] = array(0, 0.9676287944368530, 0.9802276264360310, 0.9844916183244460, 0.9852821845179940);
551 $OverheadMultiplierByBitrate[48] = array(0, 0.9779100089209830, 0.9787770035359320, 0.9846738664076130, 0.9852683013799960);
552 $OverheadMultiplierByBitrate[56] = array(0, 0.9731249855367600, 0.9776624308938040, 0.9832606361852130, 0.9843922606633340);
553 $OverheadMultiplierByBitrate[64] = array(0, 0.9755642683275760, 0.9795256705493390, 0.9836573009193170, 0.9851122539404470);
554 $OverheadMultiplierByBitrate[96] = array(0, 0.9788025247497290, 0.9798553314148700, 0.9822956869792560, 0.9834815119124690);
555 $OverheadMultiplierByBitrate[128] = array(0, 0.9816940050925480, 0.9821675936072120, 0.9829756927470870, 0.9839763420152050);
556 $OverheadMultiplierByBitrate[160] = array(0, 0.9825894094561180, 0.9820913399073960, 0.9823907143253970, 0.9832821783651570);
557 $OverheadMultiplierByBitrate[192] = array(0, 0.9832038474336260, 0.9825731694317960, 0.9821028622712400, 0.9828262076447620);
558 $OverheadMultiplierByBitrate[224] = array(0, 0.9836516298538770, 0.9824718601823890, 0.9818302180625380, 0.9823735101626480);
559 $OverheadMultiplierByBitrate[256] = array(0, 0.9845863022094920, 0.9837229411967540, 0.9824521662210830, 0.9828645172100790);
560 $OverheadMultiplierByBitrate[320] = array(0, 0.9849565280263180, 0.9837683142805110, 0.9822885275960400, 0.9824424382727190);
561 $OverheadMultiplierByBitrate[384] = array(0, 0.9856094774357600, 0.9844573394432720, 0.9825970399837330, 0.9824673808303890);
562
563 $BitrateToUseMin = 32;
564 $BitrateToUseMax = 32;
565 $previousBitrate = 32;
566 foreach ($OverheadMultiplierByBitrate as $key => $value) {
567 if ($AudioBitrate >= $previousBitrate) {
568 $BitrateToUseMin = $previousBitrate;
569 }
570 if ($AudioBitrate < $key) {
571 $BitrateToUseMax = $key;
572 break;
573 }
574 $previousBitrate = $key;
575 }
576 $FactorA = ($BitrateToUseMax - $AudioBitrate) / ($BitrateToUseMax - $BitrateToUseMin);
577
578 $VideoBitrateLog10 = log10($VideoBitrate);
579 $VideoFactorMin1 = $OverheadMultiplierByBitrate[$BitrateToUseMin][floor($VideoBitrateLog10)];
580 $VideoFactorMin2 = $OverheadMultiplierByBitrate[$BitrateToUseMax][floor($VideoBitrateLog10)];
581 $VideoFactorMax1 = $OverheadMultiplierByBitrate[$BitrateToUseMin][ceil($VideoBitrateLog10)];
582 $VideoFactorMax2 = $OverheadMultiplierByBitrate[$BitrateToUseMax][ceil($VideoBitrateLog10)];
583 $FactorV = $VideoBitrateLog10 - floor($VideoBitrateLog10);
584
585 $OverheadPercentage = $VideoFactorMin1 * $FactorA * $FactorV;
586 $OverheadPercentage += $VideoFactorMin2 * (1 - $FactorA) * $FactorV;
587 $OverheadPercentage += $VideoFactorMax1 * $FactorA * (1 - $FactorV);
588 $OverheadPercentage += $VideoFactorMax2 * (1 - $FactorA) * (1 - $FactorV);
589
590 return $OverheadPercentage;
591 }
592
593 /**
594 * @param int $rawframerate
595 *
596 * @return float
597 */
598 public static function videoFramerateLookup($rawframerate) {
599 $lookup = array(0, 23.976, 24, 25, 29.97, 30, 50, 59.94, 60);
600 return (float) (isset($lookup[$rawframerate]) ? $lookup[$rawframerate] : 0);
601 }
602
603 /**
604 * @param int $rawaspectratio
605 * @param int $mpeg_version
606 * @param int $width
607 * @param int $height
608 *
609 * @return float
610 */
611 public static function videoAspectRatioLookup($rawaspectratio, $mpeg_version=1, $width=0, $height=0) {
612 $lookup = array(
613 1 => array(0, 1, 0.6735, 0.7031, 0.7615, 0.8055, 0.8437, 0.8935, 0.9157, 0.9815, 1.0255, 1.0695, 1.0950, 1.1575, 1.2015, 0),
614 2 => array(0, 1, 1.3333, 1.7778, 2.2100, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
615 );
616 $ratio = (float) (isset($lookup[$mpeg_version][$rawaspectratio]) ? $lookup[$mpeg_version][$rawaspectratio] : 0);
617 if ($mpeg_version == 2 && $ratio != 1) {
618 // Calculate pixel aspect ratio from MPEG-2 display aspect ratio
619 $ratio = $ratio * $height / $width;
620 }
621 return $ratio;
622 }
623
624 /**
625 * @param int $rawaspectratio
626 * @param int $mpeg_version
627 *
628 * @return string
629 */
630 public static function videoAspectRatioTextLookup($rawaspectratio, $mpeg_version=1) {
631 $lookup = array(
632 1 => array('forbidden', 'square pixels', '0.6735', '16:9, 625 line, PAL', '0.7615', '0.8055', '16:9, 525 line, NTSC', '0.8935', '4:3, 625 line, PAL, CCIR601', '0.9815', '1.0255', '1.0695', '4:3, 525 line, NTSC, CCIR601', '1.1575', '1.2015', 'reserved'),
633 2 => array('forbidden', 'square pixels', '4:3', '16:9', '2.21:1', 'reserved', 'reserved', 'reserved', 'reserved', 'reserved', 'reserved', 'reserved', 'reserved', 'reserved', 'reserved', 'reserved'), // http://dvd.sourceforge.net/dvdinfo/mpeghdrs.html
634 );
635 return (isset($lookup[$mpeg_version][$rawaspectratio]) ? $lookup[$mpeg_version][$rawaspectratio] : '');
636 }
637
638 /**
639 * @param int $video_format
640 *
641 * @return string
642 */
643 public static function videoFormatTextLookup($video_format) {
644 // ISO/IEC 13818-2, section 6.3.6, Table 6-6. Meaning of video_format
645 $lookup = array('component', 'PAL', 'NTSC', 'SECAM', 'MAC', 'Unspecified video format', 'reserved(6)', 'reserved(7)');
646 return (isset($lookup[$video_format]) ? $lookup[$video_format] : '');
647 }
648
649 /**
650 * @param int $scalable_mode
651 *
652 * @return string
653 */
654 public static function scalableModeTextLookup($scalable_mode) {
655 // ISO/IEC 13818-2, section 6.3.8, Table 6-10. Definition of scalable_mode
656 $lookup = array('data partitioning', 'spatial scalability', 'SNR scalability', 'temporal scalability');
657 return (isset($lookup[$scalable_mode]) ? $lookup[$scalable_mode] : '');
658 }
659
660 /**
661 * @param int $picture_structure
662 *
663 * @return string
664 */
665 public static function pictureStructureTextLookup($picture_structure) {
666 // ISO/IEC 13818-2, section 6.3.11, Table 6-14 Meaning of picture_structure
667 $lookup = array('reserved', 'Top Field', 'Bottom Field', 'Frame picture');
668 return (isset($lookup[$picture_structure]) ? $lookup[$picture_structure] : '');
669 }
670
671 /**
672 * @param int $chroma_format
673 *
674 * @return string
675 */
676 public static function chromaFormatTextLookup($chroma_format) {
677 // ISO/IEC 13818-2, section 6.3.11, Table 6-14 Meaning of picture_structure
678 $lookup = array('reserved', '4:2:0', '4:2:2', '4:4:4');
679 return (isset($lookup[$chroma_format]) ? $lookup[$chroma_format] : '');
680 }
681
682 }
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