getid3_mp3::RecursiveFrameScanning( int $offset, int $nextframetestoffset, bool $ScanAsCBR ): bool
- Source
wp-includes/ID3/module.audio.mp3.php:1166
Compatibility
- WordPress
- core
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.
Parameters
$offsetint$nextframetestoffsetint$ScanAsCBRbool
Return value
bool
Performance profile
How much work a call to getid3_mp3::RecursiveFrameScanning() 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
- Scaling
- Scales with input
- Instructions
- 26–84
- Plugin surface
- None
- Called by
- 1
Touches nothing outside its own arguments.
The body loops, so the work grows with what you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 114.
Nothing here hands control to plugin code.
1 place in core call this, so the cost is paid more often than your own code shows.
What one call costs · 5 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost getid3_mp3::RecursiveFrameScanning() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 26–30 | ->decodeMPEGaudioHeader() |
$i && !->decodeMPEGaudioHeader() && !empty($value) | 54 | ->decodeMPEGaudioHeader(), ->decodeMPEGaudioHeader() |
$i && !->decodeMPEGaudioHeader() | 54–61 | ->decodeMPEGaudioHeader(), ->decodeMPEGaudioHeader(), ->warning() |
$i && ->decodeMPEGaudioHeader() | 58–70 | ->decodeMPEGaudioHeader(), ->decodeMPEGaudioHeader(), ::getid3_lib() |
$i && ->decodeMPEGaudioHeader() | 63–84 | ->decodeMPEGaudioHeader(), ->decodeMPEGaudioHeader(), ::getid3_lib(), ->error() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 114 instructions, 26–84 executed per call, 11 branches. The work does not change between versions.
An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.
Uses · 4
- getid3_mp3::decodeMPEGaudioHeader()
- getid3_lib::safe_inc()
- getid3_mp3::error()
- getid3_mp3::warning()
Used by · 1
Source code
public function RecursiveFrameScanning(&$offset, &$nextframetestoffset, $ScanAsCBR) { $info = &$this->getid3->info; $firstframetestarray = array('error' => array(), 'warning'=> array(), 'avdataend' => $info['avdataend'], 'avdataoffset' => $info['avdataoffset']); $this->decodeMPEGaudioHeader($offset, $firstframetestarray, false); $info['mp3_validity_check_bitrates'] = array(); for ($i = 0; $i < $this->mp3_valid_check_frames; $i++) { // check next (default: 50) frames for validity, to make sure we haven't run across a false synch if (($nextframetestoffset + 4) >= $info['avdataend']) { // end of file return true; } $nextframetestarray = array('error' => array(), 'warning' => array(), 'avdataend' => $info['avdataend'], 'avdataoffset'=>$info['avdataoffset']); if ($this->decodeMPEGaudioHeader($nextframetestoffset, $nextframetestarray, false)) { getid3_lib::safe_inc($info['mp3_validity_check_bitrates'][intval($nextframetestarray['mpeg']['audio']['bitrate'])]); if ($ScanAsCBR) { // force CBR mode, used for trying to pick out invalid audio streams with valid(?) VBR headers, or VBR streams with no VBR header if (!isset($nextframetestarray['mpeg']['audio']['bitrate']) || !isset($firstframetestarray['mpeg']['audio']['bitrate']) || ($nextframetestarray['mpeg']['audio']['bitrate'] != $firstframetestarray['mpeg']['audio']['bitrate'])) { return false; } } // next frame is OK, get ready to check the one after that if (isset($nextframetestarray['mpeg']['audio']['framelength']) && ($nextframetestarray['mpeg']['audio']['framelength'] > 0)) { $nextframetestoffset += (int) $nextframetestarray['mpeg']['audio']['framelength']; } else { $this->error('Frame at offset ('.$offset.') is has an invalid frame length.'); return false; } } elseif (!empty($firstframetestarray['mpeg']['audio']['framelength']) && (($nextframetestoffset + $firstframetestarray['mpeg']['audio']['framelength']) > $info['avdataend'])) { // it's not the end of the file, but there's not enough data left for another frame, so assume it's garbage/padding and return OK return true; } else { // next frame is not valid, note the error and fail, so scanning can contiue for a valid frame sequence $this->warning('Frame at offset ('.$offset.') is valid, but the next one at ('.$nextframetestoffset.') is not.'); return false; } } return true; }Changelog
Unchanged from 6.7.7 through 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
- Something wrong on this page? Report it and it gets fixed in the next regeneration.