getid3_mpeg Class Reference
Collaboration diagram for getid3_mpeg:
Public Member Functions | |
| getid3_mpeg (&$fd, &$ThisFileInfo) | |
| MPEGsystemNonOverheadPercentage ($VideoBitrate, $AudioBitrate) | |
| MPEGvideoFramerateLookup ($rawframerate) | |
| MPEGvideoAspectRatioLookup ($rawaspectratio) | |
| MPEGvideoAspectRatioTextLookup ($rawaspectratio) | |
Detailed Description
Definition at line 28 of file module.audio-video.mpeg.php.
Member Function Documentation
◆ getid3_mpeg()
| getid3_mpeg::getid3_mpeg | ( | & | $fd, |
| & | $ThisFileInfo | ||
| ) |
Definition at line 31 of file module.audio-video.mpeg.php.
31 {
32 if ($ThisFileInfo['avdataend'] <= $ThisFileInfo['avdataoffset']) {
33 $ThisFileInfo['error'][] = '"avdataend" ('.$ThisFileInfo['avdataend'].') is unexpectedly less-than-or-equal-to "avdataoffset" ('.$ThisFileInfo['avdataoffset'].')';
34 return false;
35 }
36 $ThisFileInfo['fileformat'] = 'mpeg';
37 fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
38 $MPEGstreamData = fread($fd, min(100000, $ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']));
39 $MPEGstreamDataLength = strlen($MPEGstreamData);
40
41 $foundVideo = true;
42 $VideoChunkOffset = 0;
44 if ($VideoChunkOffset >= $MPEGstreamDataLength) {
45 $foundVideo = false;
46 break;
47 }
48 }
49 if ($foundVideo) {
50
51 // Start code 32 bits
52 // horizontal frame size 12 bits
53 // vertical frame size 12 bits
54 // pixel aspect ratio 4 bits
55 // frame rate 4 bits
56 // bitrate 18 bits
57 // marker bit 1 bit
58 // VBV buffer size 10 bits
59 // constrained parameter flag 1 bit
60 // intra quant. matrix flag 1 bit
61 // intra quant. matrix values 512 bits (present if matrix flag == 1)
62 // non-intra quant. matrix flag 1 bit
63 // non-intra quant. matrix values 512 bits (present if matrix flag == 1)
64
65 $ThisFileInfo['video']['dataformat'] = 'mpeg';
66
67 $VideoChunkOffset += (strlen(GETID3_MPEG_VIDEO_SEQUENCE_HEADER) - 1);
68
69 $FrameSizeDWORD = getid3_lib::BigEndian2Int(substr($MPEGstreamData, $VideoChunkOffset, 3));
70 $VideoChunkOffset += 3;
71
72 $AspectRatioFrameRateDWORD = getid3_lib::BigEndian2Int(substr($MPEGstreamData, $VideoChunkOffset, 1));
73 $VideoChunkOffset += 1;
74
75 $assortedinformation = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $VideoChunkOffset, 4));
76 $VideoChunkOffset += 4;
77
78 $ThisFileInfo['mpeg']['video']['raw']['framesize_horizontal'] = ($FrameSizeDWORD & 0xFFF000) >> 12; // 12 bits for horizontal frame size
79 $ThisFileInfo['mpeg']['video']['raw']['framesize_vertical'] = ($FrameSizeDWORD & 0x000FFF); // 12 bits for vertical frame size
80 $ThisFileInfo['mpeg']['video']['raw']['pixel_aspect_ratio'] = ($AspectRatioFrameRateDWORD & 0xF0) >> 4;
81 $ThisFileInfo['mpeg']['video']['raw']['frame_rate'] = ($AspectRatioFrameRateDWORD & 0x0F);
82
83 $ThisFileInfo['mpeg']['video']['framesize_horizontal'] = $ThisFileInfo['mpeg']['video']['raw']['framesize_horizontal'];
84 $ThisFileInfo['mpeg']['video']['framesize_vertical'] = $ThisFileInfo['mpeg']['video']['raw']['framesize_vertical'];
85
86 $ThisFileInfo['mpeg']['video']['pixel_aspect_ratio'] = $this->MPEGvideoAspectRatioLookup($ThisFileInfo['mpeg']['video']['raw']['pixel_aspect_ratio']);
87 $ThisFileInfo['mpeg']['video']['pixel_aspect_ratio_text'] = $this->MPEGvideoAspectRatioTextLookup($ThisFileInfo['mpeg']['video']['raw']['pixel_aspect_ratio']);
88 $ThisFileInfo['mpeg']['video']['frame_rate'] = $this->MPEGvideoFramerateLookup($ThisFileInfo['mpeg']['video']['raw']['frame_rate']);
89
90 $ThisFileInfo['mpeg']['video']['raw']['bitrate'] = getid3_lib::Bin2Dec(substr($assortedinformation, 0, 18));
91 $ThisFileInfo['mpeg']['video']['raw']['marker_bit'] = (bool) getid3_lib::Bin2Dec(substr($assortedinformation, 18, 1));
92 $ThisFileInfo['mpeg']['video']['raw']['vbv_buffer_size'] = getid3_lib::Bin2Dec(substr($assortedinformation, 19, 10));
93 $ThisFileInfo['mpeg']['video']['raw']['constrained_param_flag'] = (bool) getid3_lib::Bin2Dec(substr($assortedinformation, 29, 1));
94 $ThisFileInfo['mpeg']['video']['raw']['intra_quant_flag'] = (bool) getid3_lib::Bin2Dec(substr($assortedinformation, 30, 1));
95 if ($ThisFileInfo['mpeg']['video']['raw']['intra_quant_flag']) {
96
97 // read 512 bits
98 $ThisFileInfo['mpeg']['video']['raw']['intra_quant'] = getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $VideoChunkOffset, 64));
99 $VideoChunkOffset += 64;
100
101 $ThisFileInfo['mpeg']['video']['raw']['non_intra_quant_flag'] = (bool) getid3_lib::Bin2Dec(substr($ThisFileInfo['mpeg']['video']['raw']['intra_quant'], 511, 1));
102 $ThisFileInfo['mpeg']['video']['raw']['intra_quant'] = getid3_lib::Bin2Dec(substr($assortedinformation, 31, 1)).substr(getid3_lib::BigEndian2Bin(substr($MPEGstreamData, $VideoChunkOffset, 64)), 0, 511);
103
104 if ($ThisFileInfo['mpeg']['video']['raw']['non_intra_quant_flag']) {
105 $ThisFileInfo['mpeg']['video']['raw']['non_intra_quant'] = substr($MPEGstreamData, $VideoChunkOffset, 64);
106 $VideoChunkOffset += 64;
107 }
108
109 } else {
110
111 $ThisFileInfo['mpeg']['video']['raw']['non_intra_quant_flag'] = (bool) getid3_lib::Bin2Dec(substr($assortedinformation, 31, 1));
112 if ($ThisFileInfo['mpeg']['video']['raw']['non_intra_quant_flag']) {
113 $ThisFileInfo['mpeg']['video']['raw']['non_intra_quant'] = substr($MPEGstreamData, $VideoChunkOffset, 64);
114 $VideoChunkOffset += 64;
115 }
116
117 }
118
119 if ($ThisFileInfo['mpeg']['video']['raw']['bitrate'] == 0x3FFFF) { // 18 set bits
120
121 $ThisFileInfo['warning'][] = 'This version of getID3() ['.GETID3_VERSION.'] cannot determine average bitrate of VBR MPEG video files';
122 $ThisFileInfo['mpeg']['video']['bitrate_mode'] = 'vbr';
123
124 } else {
125
126 $ThisFileInfo['mpeg']['video']['bitrate'] = $ThisFileInfo['mpeg']['video']['raw']['bitrate'] * 400;
127 $ThisFileInfo['mpeg']['video']['bitrate_mode'] = 'cbr';
128 $ThisFileInfo['video']['bitrate'] = $ThisFileInfo['mpeg']['video']['bitrate'];
129
130 }
131
132 $ThisFileInfo['video']['resolution_x'] = $ThisFileInfo['mpeg']['video']['framesize_horizontal'];
133 $ThisFileInfo['video']['resolution_y'] = $ThisFileInfo['mpeg']['video']['framesize_vertical'];
134 $ThisFileInfo['video']['frame_rate'] = $ThisFileInfo['mpeg']['video']['frame_rate'];
135 $ThisFileInfo['video']['bitrate_mode'] = $ThisFileInfo['mpeg']['video']['bitrate_mode'];
136 $ThisFileInfo['video']['pixel_aspect_ratio'] = $ThisFileInfo['mpeg']['video']['pixel_aspect_ratio'];
137 $ThisFileInfo['video']['lossless'] = false;
138 $ThisFileInfo['video']['bits_per_sample'] = 24;
139
140 } else {
141
142 $ThisFileInfo['error'][] = 'Could not find start of video block in the first 100,000 bytes (or before end of file) - this might not be an MPEG-video file?';
143
144 }
145
146 //0x000001B3 begins the sequence_header of every MPEG video stream.
147 //But in MPEG-2, this header must immediately be followed by an
148 //extension_start_code (0x000001B5) with a sequence_extension ID (1).
149 //(This extension contains all the additional MPEG-2 stuff.)
150 //MPEG-1 doesn't have this extension, so that's a sure way to tell the
151 //difference between MPEG-1 and MPEG-2 video streams.
152
154 $ThisFileInfo['video']['codec'] = 'MPEG-2';
155 } else {
156 $ThisFileInfo['video']['codec'] = 'MPEG-1';
157 }
158
159
160 $AudioChunkOffset = 0;
161 while (true) {
163 if ($AudioChunkOffset >= $MPEGstreamDataLength) {
164 break 2;
165 }
166 }
167
168 for ($i = 0; $i <= 7; $i++) {
169 // 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
170 // I have no idea why or what the difference is, so this is a stupid hack.
171 // If anybody has any better idea of what's going on, please let me know - info@getid3.org
172
173 $dummy = $ThisFileInfo;
175 $ThisFileInfo = $dummy;
176 $ThisFileInfo['audio']['bitrate_mode'] = 'cbr';
177 $ThisFileInfo['audio']['lossless'] = false;
178 break 2;
179
180 }
181 }
182 }
183
184 // Temporary hack to account for interleaving overhead:
185 if (!empty($ThisFileInfo['video']['bitrate']) && !empty($ThisFileInfo['audio']['bitrate'])) {
186 $ThisFileInfo['playtime_seconds'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / ($ThisFileInfo['video']['bitrate'] + $ThisFileInfo['audio']['bitrate']);
187
188 // Interleaved MPEG audio/video files have a certain amount of overhead that varies
189 // by both video and audio bitrates, and not in any sensible, linear/logarithmic patter
190 // Use interpolated lookup tables to approximately guess how much is overhead, because
191 // playtime is calculated as filesize / total-bitrate
192 $ThisFileInfo['playtime_seconds'] *= $this->MPEGsystemNonOverheadPercentage($ThisFileInfo['video']['bitrate'], $ThisFileInfo['audio']['bitrate']);
193
194 //switch ($ThisFileInfo['video']['bitrate']) {
195 // case('5000000'):
196 // $multiplier = 0.93292642112380355828048824319889;
197 // break;
198 // case('5500000'):
199 // $multiplier = 0.93582895375200989965359777343219;
200 // break;
201 // case('6000000'):
202 // $multiplier = 0.93796247714820932532911373859139;
203 // break;
204 // case('7000000'):
205 // $multiplier = 0.9413264083635103463010117778776;
206 // break;
207 // default:
208 // $multiplier = 1;
209 // break;
210 //}
211 //$ThisFileInfo['playtime_seconds'] *= $multiplier;
212 //$ThisFileInfo['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.';
213 if ($ThisFileInfo['video']['bitrate'] < 50000) {
214 $ThisFileInfo['warning'][] = 'Interleaved MPEG audio/video playtime may be slightly inaccurate for video bitrates below 100kbps. Except in extreme low-bitrate situations, error should be less than 1%. Report to info@getid3.org if greater than this.';
215 }
216 }
217
218 return true;
219 }
BigEndian2Int($byteword, $synchsafe=false, $signed=false)
Definition: getid3.lib.php:234
decodeMPEGaudioHeader($fd, $offset, &$ThisFileInfo, $recursivesearch=true, $ScanAsCBR=false, $FastMPEGheaderScan=false)
Definition: module.audio.mp3.php:401
MPEGvideoAspectRatioLookup($rawaspectratio)
Definition: module.audio-video.mpeg.php:279
MPEGsystemNonOverheadPercentage($VideoBitrate, $AudioBitrate)
Definition: module.audio-video.mpeg.php:222
MPEGvideoAspectRatioTextLookup($rawaspectratio)
Definition: module.audio-video.mpeg.php:284
MPEGvideoFramerateLookup($rawframerate)
Definition: module.audio-video.mpeg.php:274
const GETID3_MPEG_VIDEO_EXTENSION_START
Definition: module.audio-video.mpeg.php:22
const GETID3_MPEG_VIDEO_SEQUENCE_HEADER
Definition: module.audio-video.mpeg.php:20
References getid3_lib\BigEndian2Bin(), getid3_lib\BigEndian2Int(), getid3_lib\Bin2Dec(), getid3_mp3\decodeMPEGaudioHeader(), GETID3_MPEG_AUDIO_START, GETID3_MPEG_VIDEO_EXTENSION_START, GETID3_MPEG_VIDEO_SEQUENCE_HEADER, MPEGsystemNonOverheadPercentage(), MPEGvideoAspectRatioLookup(), MPEGvideoAspectRatioTextLookup(), and MPEGvideoFramerateLookup().
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◆ MPEGsystemNonOverheadPercentage()
| getid3_mpeg::MPEGsystemNonOverheadPercentage | ( | $VideoBitrate, | |
| $AudioBitrate | |||
| ) |
Definition at line 222 of file module.audio-video.mpeg.php.
222 {
223 $OverheadPercentage = 0;
224
225 $AudioBitrate = max(min($AudioBitrate / 1000, 384), 32); // limit to range of 32kbps - 384kbps (should be only legal bitrates, but maybe VBR?)
226 $VideoBitrate = max(min($VideoBitrate / 1000, 10000), 10); // limit to range of 10kbps - 10Mbps (beyond that curves flatten anyways, no big loss)
227
228
229 //OMBB[audiobitrate] = array(video-10kbps, video-100kbps, video-1000kbps, video-10000kbps)
230 $OverheadMultiplierByBitrate[32] = array(0, 0.9676287944368530, 0.9802276264360310, 0.9844916183244460, 0.9852821845179940);
231 $OverheadMultiplierByBitrate[48] = array(0, 0.9779100089209830, 0.9787770035359320, 0.9846738664076130, 0.9852683013799960);
232 $OverheadMultiplierByBitrate[56] = array(0, 0.9731249855367600, 0.9776624308938040, 0.9832606361852130, 0.9843922606633340);
233 $OverheadMultiplierByBitrate[64] = array(0, 0.9755642683275760, 0.9795256705493390, 0.9836573009193170, 0.9851122539404470);
234 $OverheadMultiplierByBitrate[96] = array(0, 0.9788025247497290, 0.9798553314148700, 0.9822956869792560, 0.9834815119124690);
235 $OverheadMultiplierByBitrate[128] = array(0, 0.9816940050925480, 0.9821675936072120, 0.9829756927470870, 0.9839763420152050);
236 $OverheadMultiplierByBitrate[160] = array(0, 0.9825894094561180, 0.9820913399073960, 0.9823907143253970, 0.9832821783651570);
237 $OverheadMultiplierByBitrate[192] = array(0, 0.9832038474336260, 0.9825731694317960, 0.9821028622712400, 0.9828262076447620);
238 $OverheadMultiplierByBitrate[224] = array(0, 0.9836516298538770, 0.9824718601823890, 0.9818302180625380, 0.9823735101626480);
239 $OverheadMultiplierByBitrate[256] = array(0, 0.9845863022094920, 0.9837229411967540, 0.9824521662210830, 0.9828645172100790);
240 $OverheadMultiplierByBitrate[320] = array(0, 0.9849565280263180, 0.9837683142805110, 0.9822885275960400, 0.9824424382727190);
241 $OverheadMultiplierByBitrate[384] = array(0, 0.9856094774357600, 0.9844573394432720, 0.9825970399837330, 0.9824673808303890);
242
243 $BitrateToUseMin = 32;
244 $BitrateToUseMax = 32;
245 $previousBitrate = 32;
246 foreach ($OverheadMultiplierByBitrate as $key => $value) {
247 if ($AudioBitrate >= $previousBitrate) {
248 $BitrateToUseMin = $previousBitrate;
249 }
250 if ($AudioBitrate < $key) {
251 $BitrateToUseMax = $key;
252 break;
253 }
254 $previousBitrate = $key;
255 }
256 $FactorA = ($BitrateToUseMax - $AudioBitrate) / ($BitrateToUseMax - $BitrateToUseMin);
257
258 $VideoBitrateLog10 = log10($VideoBitrate);
259 $VideoFactorMin1 = $OverheadMultiplierByBitrate[$BitrateToUseMin][floor($VideoBitrateLog10)];
260 $VideoFactorMin2 = $OverheadMultiplierByBitrate[$BitrateToUseMax][floor($VideoBitrateLog10)];
261 $VideoFactorMax1 = $OverheadMultiplierByBitrate[$BitrateToUseMin][ceil($VideoBitrateLog10)];
262 $VideoFactorMax2 = $OverheadMultiplierByBitrate[$BitrateToUseMax][ceil($VideoBitrateLog10)];
263 $FactorV = $VideoBitrateLog10 - floor($VideoBitrateLog10);
264
265 $OverheadPercentage = $VideoFactorMin1 * $FactorA * $FactorV;
266 $OverheadPercentage += $VideoFactorMin2 * (1 - $FactorA) * $FactorV;
267 $OverheadPercentage += $VideoFactorMax1 * $FactorA * (1 - $FactorV);
268 $OverheadPercentage += $VideoFactorMax2 * (1 - $FactorA) * (1 - $FactorV);
269
270 return $OverheadPercentage;
271 }
Referenced by getid3_mpeg().
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◆ MPEGvideoAspectRatioLookup()
| getid3_mpeg::MPEGvideoAspectRatioLookup | ( | $rawaspectratio | ) |
Definition at line 279 of file module.audio-video.mpeg.php.
279 {
280 $MPEGvideoAspectRatioLookup = array(0, 1, 0.6735, 0.7031, 0.7615, 0.8055, 0.8437, 0.8935, 0.9157, 0.9815, 1.0255, 1.0695, 1.0950, 1.1575, 1.2015, 0);
281 return (isset($MPEGvideoAspectRatioLookup[$rawaspectratio]) ? (float) $MPEGvideoAspectRatioLookup[$rawaspectratio] : (float) 0);
282 }
Referenced by getid3_mpeg().
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◆ MPEGvideoAspectRatioTextLookup()
| getid3_mpeg::MPEGvideoAspectRatioTextLookup | ( | $rawaspectratio | ) |
Definition at line 284 of file module.audio-video.mpeg.php.
284 {
285 $MPEGvideoAspectRatioTextLookup = array('forbidden', 'square pixels', '0.6735', '16:9, 625 line, PAL', '0.7615', '0.8055', '16:9, 525 line, NTSC', '0.8935', '4:3, 625 line, PAL, CCIR601', '0.9815', '1.0255', '1.0695', '4:3, 525 line, NTSC, CCIR601', '1.1575', '1.2015', 'reserved');
286 return (isset($MPEGvideoAspectRatioTextLookup[$rawaspectratio]) ? $MPEGvideoAspectRatioTextLookup[$rawaspectratio] : '');
287 }
Referenced by getid3_mpeg().
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◆ MPEGvideoFramerateLookup()
| getid3_mpeg::MPEGvideoFramerateLookup | ( | $rawframerate | ) |
Definition at line 274 of file module.audio-video.mpeg.php.
274 {
275 $MPEGvideoFramerateLookup = array(0, 23.976, 24, 25, 29.97, 30, 50, 59.94, 60);
276 return (isset($MPEGvideoFramerateLookup[$rawframerate]) ? (float) $MPEGvideoFramerateLookup[$rawframerate] : (float) 0);
277 }
Referenced by getid3_mpeg().
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The documentation for this class was generated from the following file:
- Services/MediaObjects/getid3/getid3/module.audio-video.mpeg.php
