getid3_mp3::getOnlyMPEGaudioInfo( int $avdataoffset, bool $BitrateHistogram = false ): bool

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$avdataoffsetint

$BitrateHistogrambooloptional

Default: false

Return value

bool

Performance profile

How much work a call to getid3_mp3::getOnlyMPEGaudioInfo() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Light

Touches nothing outside its own arguments.

Scaling

Scales with input

The body loops, so the work grows with what you pass in.

Instructions

61–235

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 682.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

1

1 place in core call this, so the cost is paid more often than your own code shows.

What one call costs · 28 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost getid3_mp3::getOnlyMPEGaudioInfo() can have, taken from its control-flow graph on PHP 8.5.

This body has more branch combinations than are worth enumerating, so the table covers the outcomes found first rather than every one that exists.

Uses · 13

• getid3_mp3::MPEGaudioVersionArray()
• getid3_mp3::MPEGaudioLayerArray()
• getid3_mp3::MPEGaudioBitrateArray()
• getid3_mp3::fseek()
• getid3_mp3::error()
• getid3_mp3::fread()
• getid3_mp3::feof()
• getid3_mp3::decodeMPEGaudioHeader()
• getid3_mp3::warning()
• getid3_mp3::ftell()
• getid3_lib::safe_inc()
• getid3_lib::SafeDiv()Perform a division, guarding against division by zero

Used by · 1

• getid3_mp3::Analyze()

Source code

View on Trac ↗View on GitHub ↗

1454	public function getOnlyMPEGaudioInfo($avdataoffset, $BitrateHistogram=false) {1455		// looks for synch, decodes MPEG audio header1456 1457		$info = &$this->getid3->info;1458 1459		static $MPEGaudioVersionLookup;1460		static $MPEGaudioLayerLookup;1461		static $MPEGaudioBitrateLookup;1462		if (empty($MPEGaudioVersionLookup)) {1463			$MPEGaudioVersionLookup = self::MPEGaudioVersionArray();1464			$MPEGaudioLayerLookup   = self::MPEGaudioLayerArray();1465			$MPEGaudioBitrateLookup = self::MPEGaudioBitrateArray();1466		}1467 1468		$this->fseek($avdataoffset);1469		$sync_seek_buffer_size = min(128 * 1024, $info['avdataend'] - $avdataoffset);1470		if ($sync_seek_buffer_size <= 0) {1471			$this->error('Invalid $sync_seek_buffer_size at offset '.$avdataoffset);1472			return false;1473		}1474		$header = $this->fread($sync_seek_buffer_size);1475		$sync_seek_buffer_size = strlen($header);1476		$SynchSeekOffset = 0;1477		$SyncSeekAttempts = 0;1478		$SyncSeekAttemptsMax = 1000;1479		$FirstFrameThisfileInfo = null;1480		while ($SynchSeekOffset < $sync_seek_buffer_size) {1481			if ((($avdataoffset + $SynchSeekOffset)  < $info['avdataend']) && !$this->feof()) {1482 1483				if ($SynchSeekOffset > $sync_seek_buffer_size) {1484					// if a synch's not found within the first 128k bytes, then give up1485					$this->error('Could not find valid MPEG audio synch within the first '.round($sync_seek_buffer_size / 1024).'kB');1486					if (isset($info['audio']['bitrate'])) {1487						unset($info['audio']['bitrate']);1488					}1489					if (isset($info['mpeg']['audio'])) {1490						unset($info['mpeg']['audio']);1491					}1492					if (empty($info['mpeg'])) {1493						unset($info['mpeg']);1494					}1495					return false;1496				}1497			}1498 1499			if (($SynchSeekOffset + 1) >= strlen($header)) {1500				$this->error('Could not find valid MPEG synch before end of file');1501				return false;1502			}1503 1504			if (($header[$SynchSeekOffset] == "\xFF") && ($header[($SynchSeekOffset + 1)] > "\xE0")) { // possible synch detected1505				if (++$SyncSeekAttempts >= $SyncSeekAttemptsMax) {1506					// https://github.com/JamesHeinrich/getID3/issues/2861507					// corrupt files claiming to be MP3, with a large number of 0xFF bytes near the beginning, can cause this loop to take a very long time1508					// should have escape condition to avoid spending too much time scanning a corrupt file1509					// if a synch's not found within the first 128k bytes, then give up1510					$this->error('Could not find valid MPEG audio synch after scanning '.$SyncSeekAttempts.' candidate offsets');1511					if (isset($info['audio']['bitrate'])) {1512						unset($info['audio']['bitrate']);1513					}1514					if (isset($info['mpeg']['audio'])) {1515						unset($info['mpeg']['audio']);1516					}1517					if (empty($info['mpeg'])) {1518						unset($info['mpeg']);1519					}1520					return false;1521				}1522				$FirstFrameAVDataOffset = null;1523				if (!isset($FirstFrameThisfileInfo) && !isset($info['mpeg']['audio'])) {1524					$FirstFrameThisfileInfo = $info;1525					$FirstFrameAVDataOffset = $avdataoffset + $SynchSeekOffset;1526					if (!$this->decodeMPEGaudioHeader($FirstFrameAVDataOffset, $FirstFrameThisfileInfo, false)) {1527						// if this is the first valid MPEG-audio frame, save it in case it's a VBR header frame and there's1528						// garbage between this frame and a valid sequence of MPEG-audio frames, to be restored below1529						unset($FirstFrameThisfileInfo);1530					}1531				}1532 1533				$dummy = $info; // only overwrite real data if valid header found

Changelog

Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/ID3/module.audio.mp3.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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