ILIAS  release_5-3 Revision v5.3.23-19-g915713cf615
Public Member Functions
getid3_amr Class Reference

getID3() by James Heinrich info@.nosp@m.geti.nosp@m.d3.or.nosp@m.g // More...

+ Inheritance diagram for getid3_amr:
+ Collaboration diagram for getid3_amr:

Public Member Functions

 Analyze ()
 
 amr_mode_bitrate ($key)
 
 amr_mode_bytes_per_frame ($key)
 
- Public Member Functions inherited from getid3_handler
 __construct (getID3 $getid3, $call_module=null)
 
 Analyze ()
 
 AnalyzeString ($string)
 
 setStringMode ($string)
 
 saveAttachment ($name, $offset, $length, $image_mime=null)
 

Additional Inherited Members

- Protected Member Functions inherited from getid3_handler
 ftell ()
 
 fread ($bytes)
 
 fseek ($bytes, $whence=SEEK_SET)
 
 feof ()
 
 isDependencyFor ($module)
 
 error ($text)
 
 warning ($text)
 
 notice ($text)
 
- Protected Attributes inherited from getid3_handler
 $getid3
 
 $data_string_flag = false
 
 $data_string = ''
 
 $data_string_position = 0
 
 $data_string_length = 0
 

Detailed Description

getID3() by James Heinrich info@.nosp@m.geti.nosp@m.d3.or.nosp@m.g //

Definition at line 18 of file module.audio.amr.php.

Member Function Documentation

◆ amr_mode_bitrate()

getid3_amr::amr_mode_bitrate (   $key)

Definition at line 67 of file module.audio.amr.php.

References $key, and array.

67  {
68  static $amr_mode_bitrate = array(
69  0 => 4750,
70  1 => 5150,
71  2 => 5900,
72  3 => 6700,
73  4 => 7400,
74  5 => 7950,
75  6 => 10200,
76  7 => 12200,
77  );
78  return (isset($amr_mode_bitrate[$key]) ? $amr_mode_bitrate[$key] : false);
79  }
array
Create styles array
The data for the language used.
Definition: 40duplicateStyle.php:19
$key
$key
Definition: croninfo.php:18

◆ amr_mode_bytes_per_frame()

getid3_amr::amr_mode_bytes_per_frame (   $key)

Definition at line 81 of file module.audio.amr.php.

References $key, and array.

Referenced by Analyze().

81  {
82  static $amr_mode_bitrate = array(
83  0 => 13, // 1-byte frame header + 95 bits [padded to: 12 bytes] audio data
84  1 => 14, // 1-byte frame header + 103 bits [padded to: 13 bytes] audio data
85  2 => 16, // 1-byte frame header + 118 bits [padded to: 15 bytes] audio data
86  3 => 18, // 1-byte frame header + 134 bits [padded to: 17 bytes] audio data
87  4 => 20, // 1-byte frame header + 148 bits [padded to: 19 bytes] audio data
88  5 => 21, // 1-byte frame header + 159 bits [padded to: 20 bytes] audio data
89  6 => 27, // 1-byte frame header + 204 bits [padded to: 26 bytes] audio data
90  7 => 32, // 1-byte frame header + 244 bits [padded to: 31 bytes] audio data
91  );
92  return (isset($amr_mode_bitrate[$key]) ? $amr_mode_bitrate[$key] : false);
93  }
array
Create styles array
The data for the language used.
Definition: 40duplicateStyle.php:19
$key
$key
Definition: croninfo.php:18
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◆ Analyze()

getid3_amr::Analyze ( )

Definition at line 21 of file module.audio.amr.php.

References $info, amr_mode_bytes_per_frame(), array, getid3_handler\error(), getid3_handler\feof(), getid3_handler\fread(), getid3_handler\fseek(), and getid3_lib\PrintHexBytes().

21  {
22  $info = &$this->getid3->info;
23 
24  $this->fseek($info['avdataoffset']);
25  $AMRheader = $this->fread(6);
26 
27  $magic = '#!AMR'."\x0A";
28  if (substr($AMRheader, 0, 6) != $magic) {
29  $this->error('Expecting "'.getid3_lib::PrintHexBytes($magic).'" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes(substr($AMRheader, 0, 6)).'"');
30  return false;
31  }
32 
33  // shortcut
34  $info['amr'] = array();
35  $thisfile_amr = &$info['amr'];
36 
37  $info['fileformat'] = 'amr';
38  $info['audio']['dataformat'] = 'amr';
39  $info['audio']['bitrate_mode'] = 'vbr'; // within a small predefined range: 4.75kbps to 12.2kbps
40  $info['audio']['bits_per_sample'] = 13; // http://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec: "Sampling frequency 8 kHz/13-bit (160 samples for 20 ms frames), filtered to 200–3400 Hz"
41  $info['audio']['sample_rate'] = 8000; // http://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec: "Sampling frequency 8 kHz/13-bit (160 samples for 20 ms frames), filtered to 200–3400 Hz"
42  $info['audio']['channels'] = 1;
43  $thisfile_amr['frame_mode_count'] = array(0=>0, 1=>0, 2=>0, 3=>0, 4=>0, 5=>0, 6=>0, 7=>0);
44 
45  $buffer = '';
46  do {
47  if ((strlen($buffer) < $this->getid3->fread_buffer_size()) && !feof($this->getid3->fp)) {
48  $buffer .= $this->fread($this->getid3->fread_buffer_size() * 2);
49  }
50  $AMR_frame_header = ord(substr($buffer, 0, 1));
51  $codec_mode_request = ($AMR_frame_header & 0x78) >> 3; // The 2nd bit through 5th bit (counting the most significant bit as the first bit) comprise the CMR (Codec Mode Request), values 0-7 being valid for AMR. The top bit of the CMR can actually be ignored, though it is used when AMR forms RTP payloads. The lower 3-bits of the header are reserved and are not used. Viewing the header from most significant bit to least significant bit, the encoding is XCCCCXXX, where Xs are reserved (typically 0) and the Cs are the CMR.
52  if ($codec_mode_request > 7) {
53  break;
54  }
55  $thisfile_amr['frame_mode_count'][$codec_mode_request]++;
56  $buffer = substr($buffer, $this->amr_mode_bytes_per_frame($codec_mode_request));
57  } while (strlen($buffer) > 0);
58 
59  $info['playtime_seconds'] = array_sum($thisfile_amr['frame_mode_count']) * 0.020; // each frame contain 160 samples and is 20 milliseconds long
60  $info['audio']['bitrate'] = (8 * ($info['avdataend'] - $info['avdataoffset'])) / $info['playtime_seconds']; // bitrate could be calculated from average bitrate by distributation of frame types. That would give effective audio bitrate, this gives overall file bitrate which will be a little bit higher since every frame will waste 8 bits for header, plus a few bits for octet padding
61  $info['bitrate'] = $info['audio']['bitrate'];
62 
63  return true;
64  }
getid3_handler\error
error($text)
Definition: getid3.php:1752
getid3_lib\PrintHexBytes
static PrintHexBytes($string, $hex=true, $spaces=true, $htmlencoding='UTF-8')
Definition: getid3.lib.php:18
getid3_handler\fread
fread($bytes)
Definition: getid3.php:1683
array
Create styles array
The data for the language used.
Definition: 40duplicateStyle.php:19
getid3_handler\feof
feof()
Definition: getid3.php:1741
getid3_amr\amr_mode_bytes_per_frame
amr_mode_bytes_per_frame($key)
Definition: module.audio.amr.php:81
getid3_handler\fseek
fseek($bytes, $whence=SEEK_SET)
Definition: getid3.php:1711
$info
$info
Definition: index.php:5
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The documentation for this class was generated from the following file: