getid3_riff::ParseRIFFAMV( int $startoffset, int $maxoffset ): array|false

Compatibility

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

Parameters

$startoffsetint

$maxoffsetint

Return value

array|false

Performance profile

How much work a call to getid3_riff::ParseRIFFAMV() 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

Trivial

Touches nothing outside its own arguments.

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

31–243

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 337.

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 · 4 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost getid3_riff::ParseRIFFAMV() can have, taken from its control-flow graph on PHP 8.5.

Uses · 6

• getid3_riff::fseek()
• getid3_riff::fread()
• Exception::__construct()Create a new exception
• getid3_lib::PrintHexBytes()
• getid3_lib::LittleEndian2Int()
• getid3_riff::warning()

Used by · 1

• getid3_riff::Analyze()

Source code

View on Trac ↗View on GitHub ↗

1477	public function ParseRIFFAMV($startoffset, $maxoffset) {1478		// AMV files are RIFF-AVI files with parts of the spec deliberately broken, such as chunk size fields hardcoded to zero (because players known in hardware that these fields are always a certain size1479 1480		// https://code.google.com/p/amv-codec-tools/wiki/AmvDocumentation1481		//typedef struct _amvmainheader {1482		//FOURCC fcc; // 'amvh'1483		//DWORD cb;1484		//DWORD dwMicroSecPerFrame;1485		//BYTE reserve[28];1486		//DWORD dwWidth;1487		//DWORD dwHeight;1488		//DWORD dwSpeed;1489		//DWORD reserve0;1490		//DWORD reserve1;1491		//BYTE bTimeSec;1492		//BYTE bTimeMin;1493		//WORD wTimeHour;1494		//} AMVMAINHEADER;1495 1496		$info = &$this->getid3->info;1497		$RIFFchunk = false;1498 1499		try {1500 1501			$this->fseek($startoffset);1502			$maxoffset = min($maxoffset, $info['avdataend']);1503			$AMVheader = $this->fread(284);1504			if (substr($AMVheader,   0,  8) != 'hdrlamvh') {1505				throw new Exception('expecting "hdrlamv" at offset '.($startoffset +   0).', found "'.substr($AMVheader,   0, 8).'"');1506			}1507			if (substr($AMVheader,   8,  4) != "\x38\x00\x00\x00") { // "amvh" chunk size, hardcoded to 0x38 = 56 bytes1508				throw new Exception('expecting "0x38000000" at offset '.($startoffset +   8).', found "'.getid3_lib::PrintHexBytes(substr($AMVheader,   8, 4)).'"');1509			}1510			$RIFFchunk = array();1511			$RIFFchunk['amvh']['us_per_frame']   = getid3_lib::LittleEndian2Int(substr($AMVheader,  12,  4));1512			$RIFFchunk['amvh']['reserved28']     =                              substr($AMVheader,  16, 28);  // null? reserved?1513			$RIFFchunk['amvh']['resolution_x']   = getid3_lib::LittleEndian2Int(substr($AMVheader,  44,  4));1514			$RIFFchunk['amvh']['resolution_y']   = getid3_lib::LittleEndian2Int(substr($AMVheader,  48,  4));1515			$RIFFchunk['amvh']['frame_rate_int'] = getid3_lib::LittleEndian2Int(substr($AMVheader,  52,  4));1516			$RIFFchunk['amvh']['reserved0']      = getid3_lib::LittleEndian2Int(substr($AMVheader,  56,  4)); // 1? reserved?1517			$RIFFchunk['amvh']['reserved1']      = getid3_lib::LittleEndian2Int(substr($AMVheader,  60,  4)); // 0? reserved?1518			$RIFFchunk['amvh']['runtime_sec']    = getid3_lib::LittleEndian2Int(substr($AMVheader,  64,  1));1519			$RIFFchunk['amvh']['runtime_min']    = getid3_lib::LittleEndian2Int(substr($AMVheader,  65,  1));1520			$RIFFchunk['amvh']['runtime_hrs']    = getid3_lib::LittleEndian2Int(substr($AMVheader,  66,  2));1521 1522			$info['video']['frame_rate']   = 1000000 / $RIFFchunk['amvh']['us_per_frame'];1523			$info['video']['resolution_x'] = $RIFFchunk['amvh']['resolution_x'];1524			$info['video']['resolution_y'] = $RIFFchunk['amvh']['resolution_y'];1525			$info['playtime_seconds']      = ($RIFFchunk['amvh']['runtime_hrs'] * 3600) + ($RIFFchunk['amvh']['runtime_min'] * 60) + $RIFFchunk['amvh']['runtime_sec'];1526 1527			// the rest is all hardcoded(?) and does not appear to be useful until you get to audio info at offset 256, even then everything is probably hardcoded1528 1529			if (substr($AMVheader,  68, 20) != 'LIST'."\x00\x00\x00\x00".'strlstrh'."\x38\x00\x00\x00") {1530				throw new Exception('expecting "LIST<0x00000000>strlstrh<0x38000000>" at offset '.($startoffset +  68).', found "'.getid3_lib::PrintHexBytes(substr($AMVheader,  68, 20)).'"');1531			}1532			// followed by 56 bytes of null: substr($AMVheader,  88, 56) -> 1441533			if (substr($AMVheader, 144,  8) != 'strf'."\x24\x00\x00\x00") {1534				throw new Exception('expecting "strf<0x24000000>" at offset '.($startoffset + 144).', found "'.getid3_lib::PrintHexBytes(substr($AMVheader, 144,  8)).'"');1535			}1536			// followed by 36 bytes of null: substr($AMVheader, 144, 36) -> 1801537 1538			if (substr($AMVheader, 188, 20) != 'LIST'."\x00\x00\x00\x00".'strlstrh'."\x30\x00\x00\x00") {1539				throw new Exception('expecting "LIST<0x00000000>strlstrh<0x30000000>" at offset '.($startoffset + 188).', found "'.getid3_lib::PrintHexBytes(substr($AMVheader, 188, 20)).'"');1540			}1541			// followed by 48 bytes of null: substr($AMVheader, 208, 48) -> 2561542			if (substr($AMVheader, 256,  8) != 'strf'."\x14\x00\x00\x00") {1543				throw new Exception('expecting "strf<0x14000000>" at offset '.($startoffset + 256).', found "'.getid3_lib::PrintHexBytes(substr($AMVheader, 256,  8)).'"');1544			}1545			// followed by 20 bytes of a modified WAVEFORMATEX:1546			// typedef struct {1547			// WORD wFormatTag;       //(Fixme: this is equal to PCM's 0x01 format code)1548			// WORD nChannels;        //(Fixme: this is always 1)1549			// DWORD nSamplesPerSec;  //(Fixme: for all known sample files this is equal to 22050)1550			// DWORD nAvgBytesPerSec; //(Fixme: for all known sample files this is equal to 44100)1551			// WORD nBlockAlign;      //(Fixme: this seems to be 2 in AMV files, is this correct ?)1552			// WORD wBitsPerSample;   //(Fixme: this seems to be 16 in AMV files instead of the expected 4)1553			// WORD cbSize;           //(Fixme: this seems to be 0 in AMV files)1554			// WORD reserved;1555			// } WAVEFORMATEX;1556			$RIFFchunk['strf']['wformattag']      = getid3_lib::LittleEndian2Int(substr($AMVheader,  264,  2));

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-video.riff.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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