mbirth/php-mp3info
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Adjust audio duration in case of VBR with present quality

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wapmorgan 2019-12-03 02:55:12 +03:00
parent 9a7559e0d4
commit 9049767016
2 changed files with 41 additions and 17 deletions
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2
bin/mp3scan
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@ -131,7 +131,7 @@ class Mp3InfoConsoleRunner {
try {
$audio = new Mp3Info($filename, true);
} catch (Exception $e) {
var_dump($filename.': '.$e->getMessage());
var_dump("Exception when parsing ".$filename.': '.$e->getMessage());
return null;
}

56
src/Mp3Info.php
View File

@ -19,6 +19,7 @@ use Exception;
* Used sources:
* * {@link http://mpgedit.org/mpgedit/mpeg_format/mpeghdr.htm mpeg header description}
* * {@link http://id3.org/Developer%20Information id3v2 tag specifications}. Specially: {@link http://id3.org/id3v2.3.0 id3v2.3.0}, {@link http://id3.org/id3v2-00 id3v2.2.0}, {@link http://id3.org/id3v2.4.0-changes id3v2.4.0}
* * {@link https://multimedia.cx/mp3extensions.txt Descripion of VBR header "Xing"}
* * {@link http://gabriel.mp3-tech.org/mp3infotag.html Xing, Info and Lame tags specifications}
*/
class Mp3Info {
@ -118,6 +119,12 @@ class Mp3Info {
*/
public $isVbr = false;
/**
* Contains VBR properties
* @var array
*/
public $vbrProperties = [];
/**
* Channel mode (stereo or dual_mono or joint_stereo or mono)
* @var string
@ -130,12 +137,6 @@ class Mp3Info {
*/
public $framesCount = 0;
/**
* Contains extra flags
* @var array
*/
public $extraFlags = [];
/**
* Audio tags ver. 1 (aka id3v1)
* @var array
@ -188,6 +189,12 @@ class Mp3Info {
*/
private $__cbrFrameSize;
/**
* Frame size for Variable Bit Rate
* @var int
*/
private $__vbrFrameSize;
/**
* $mode is self::META, self::TAGS or their combination.
*
@ -259,6 +266,7 @@ class Mp3Info {
* @link https://github.com/wapmorgan/Mp3Info/issues/13#issuecomment-447470813
*/
$framesCount = $this->readMpegFrame($fp);
$this->framesCount = $framesCount !== null
? $framesCount
: ceil($audioSize / $this->__cbrFrameSize);
@ -270,10 +278,13 @@ class Mp3Info {
}
// The faster way to detect audio duration:
$samples_in_second = $this->layerVersion == 1 ? self::LAYER_1_FRAME_SIZE : self::LAYERS_23_FRAME_SIZE;
// for VBR: adjust samples in second according to VBR quality
if ($this->isVbr && isset($this->vbrProperties['quality'])) {
$samples_in_second = floor($samples_in_second * $this->vbrProperties['quality'] / 100);
}
// Calculate total number of audio samples (framesCount * sampleInFrameCount) / samplesInSecondCount
$this->duration = ($this->framesCount - 1)
* ($this->layerVersion == 1 ? self::LAYER_1_FRAME_SIZE : self::LAYERS_23_FRAME_SIZE)
/ $this->sampleRate;
$this->duration = ($this->framesCount - 1) * $samples_in_second / $this->sampleRate;
}
fclose($fp);
@ -284,7 +295,7 @@ class Mp3Info {
/**
* Read first frame information.
* @param resource $fp
* @return int Number of frames (if present if first frame)
* @return int Number of frames (if present if first frame of VBR-file)
* @throws \Exception
*/
private function readMpegFrame($fp) {
@ -332,15 +343,28 @@ class Mp3Info {
case '2mono': $offset = 13; break;
}
// check for VBR
fseek($fp, $pos + $offset);
if (fread($fp, 4) == self::VBR_SYNC) {
$this->isVbr = true;
$flagsBytes = $this->readBytes($fp, 4);
$this->extraFlags['frames'] = (bool)($flagsBytes[3] & 1);
$this->extraFlags['bytes'] = (bool)($flagsBytes[3] & 2);
$this->extraFlags['TOC'] = (bool)($flagsBytes[3] & 4);
$this->extraFlags['VBR'] = (bool)($flagsBytes[3] & 8);
if ($this->extraFlags['frames']) $framesCount = implode(null, unpack('N', fread($fp, 4)));
// VBR frames count presence
if (($flagsBytes[3] & 2)) {
$this->vbrProperties['frames'] = implode(null, unpack('N', fread($fp, 4)));
}
// VBR stream size presence
if ($flagsBytes[3] & 4) {
$this->vbrProperties['bytes'] = implode(null, unpack('N', fread($fp, 4)));
}
// VBR TOC presence
if ($flagsBytes[3] & 1) {
fseek($fp, 100, SEEK_CUR);
}
// VBR quality
if ($flagsBytes[3] & 8) {
$this->vbrProperties['quality'] = implode(null, unpack('N', fread($fp, 4)));
}
}
// go to the end of frame
@ -352,7 +376,7 @@ class Mp3Info {
fseek($fp, $pos + $this->__cbrFrameSize);
return isset($framesCount) ? $framesCount : null;
return isset($this->vbrProperties['frames']) ? $this->vbrProperties['frames'] : null;
}
/**