21 {
22
23 fseek($fd, $ThisFileInfo[
'avdataoffset'], SEEK_SET);
24 $LPACheader =
fread($fd, 14);
25 if (substr($LPACheader, 0, 4) != 'LPAC') {
26 $ThisFileInfo['error'][] = 'Expected "LPAC" at offset '.$ThisFileInfo['avdataoffset'].', found "'.$StreamMarker.'"';
27 return false;
28 }
29 $ThisFileInfo['avdataoffset'] += 14;
30
31 $ThisFileInfo['fileformat'] = 'lpac';
32 $ThisFileInfo['audio']['dataformat'] = 'lpac';
33 $ThisFileInfo['audio']['lossless'] = true;
34 $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
35
40
41 $ThisFileInfo['lpac']['flags']['is_wave'] = (bool) ($flags['audio_type'] & 0x40);
42 $ThisFileInfo['lpac']['flags']['stereo'] = (bool) ($flags['audio_type'] & 0x04);
43 $ThisFileInfo['lpac']['flags']['24_bit'] = (bool) ($flags['audio_type'] & 0x02);
44 $ThisFileInfo['lpac']['flags']['16_bit'] = (bool) ($flags['audio_type'] & 0x01);
45
46 if ($ThisFileInfo['lpac']['flags']['24_bit'] && $ThisFileInfo['lpac']['flags']['16_bit']) {
47 $ThisFileInfo['warning'][] = '24-bit and 16-bit flags cannot both be set';
48 }
49
50 $ThisFileInfo['lpac']['flags']['fast_compress'] = (bool) ($flags['parameters'] & 0x40000000);
51 $ThisFileInfo['lpac']['flags']['random_access'] = (bool) ($flags['parameters'] & 0x08000000);
52 $ThisFileInfo['lpac']['block_length'] = pow(2, (($flags['parameters'] & 0x07000000) >> 24)) * 256;
53 $ThisFileInfo['lpac']['flags']['adaptive_prediction_order'] = (bool) ($flags['parameters'] & 0x00800000);
54 $ThisFileInfo['lpac']['flags']['adaptive_quantization'] = (bool) ($flags['parameters'] & 0x00400000);
55 $ThisFileInfo['lpac']['flags']['joint_stereo'] = (bool) ($flags['parameters'] & 0x00040000);
56 $ThisFileInfo['lpac']['quantization'] = ($flags['parameters'] & 0x00001F00) >> 8;
57 $ThisFileInfo['lpac']['max_prediction_order'] = ($flags['parameters'] & 0x0000003F);
58
59 if ($ThisFileInfo['lpac']['flags']['fast_compress'] && ($ThisFileInfo['lpac']['max_prediction_order'] != 3)) {
60 $ThisFileInfo['warning'][] = 'max_prediction_order expected to be "3" if fast_compress is true, actual value is "'.$ThisFileInfo['lpac']['max_prediction_order'].'"';
61 }
62 switch ($ThisFileInfo['lpac']['file_version']) {
63 case 6:
64 if ($ThisFileInfo['lpac']['flags']['adaptive_quantization']) {
65 $ThisFileInfo['warning'][] = 'adaptive_quantization expected to be false in LPAC file stucture v6, actually true';
66 }
67 if ($ThisFileInfo['lpac']['quantization'] != 20) {
68 $ThisFileInfo['warning'][] = 'Quantization expected to be 20 in LPAC file stucture v6, actually '.$ThisFileInfo['lpac']['flags']['Q'];
69 }
70 break;
71
72 default:
73
74 break;
75 }
76
77 $dummy = $ThisFileInfo;
79 $ThisFileInfo['avdataoffset'] = $dummy['avdataoffset'];
80 $ThisFileInfo['riff'] = $dummy['riff'];
81 $ThisFileInfo['error'] = $dummy['error'];
82 $ThisFileInfo['warning'] = $dummy['warning'];
83 $ThisFileInfo['lpac']['comments']['comment'] = $dummy['comments'];
84 $ThisFileInfo['audio']['sample_rate'] = $dummy['audio']['sample_rate'];
85
86 $ThisFileInfo['audio']['channels'] = ($ThisFileInfo['lpac']['flags']['stereo'] ? 2 : 1);
87
88 if ($ThisFileInfo['lpac']['flags']['24_bit']) {
89 $ThisFileInfo['audio']['bits_per_sample'] = $ThisFileInfo['riff']['audio'][0]['bits_per_sample'];
90 } elseif ($ThisFileInfo['lpac']['flags']['16_bit']) {
91 $ThisFileInfo['audio']['bits_per_sample'] = 16;
92 } else {
93 $ThisFileInfo['audio']['bits_per_sample'] = 8;
94 }
95
96 if ($ThisFileInfo['lpac']['flags']['fast_compress']) {
97
98 $ThisFileInfo['audio']['encoder_options'] = '-1';
99 } else {
100 switch ($ThisFileInfo['lpac']['max_prediction_order']) {
101 case 20:
102 $ThisFileInfo['audio']['encoder_options'] = '-2';
103 break;
104 case 30:
105 $ThisFileInfo['audio']['encoder_options'] = '-3';
106 break;
107 case 40:
108 $ThisFileInfo['audio']['encoder_options'] = '-4';
109 break;
110 case 60:
111 $ThisFileInfo['audio']['encoder_options'] = '-5';
112 break;
113 }
114 }
115
116 $ThisFileInfo['playtime_seconds'] = $ThisFileInfo['lpac']['total_samples'] / $ThisFileInfo['audio']['sample_rate'];
117 $ThisFileInfo['audio']['bitrate'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['playtime_seconds'];
118
119 return true;
120 }