getid3_mp3::getOnlyMPEGaudioInfo

		$info['audio']['dataformat']   = 'mp'.getid3_lib::array_max($Distribution['layer'], true);
		$info['fileformat']            = $info['audio']['dataformat'];

		return true;
	}

	/**
	 * @param int  $avdataoffset
	 * @param bool $BitrateHistogram
	 *
	 * @return bool
	 */
	public function getOnlyMPEGaudioInfo($avdataoffset, $BitrateHistogram=false) {
		// looks for synch, decodes MPEG audio header

		$info = &$this->getid3->info;

		static $MPEGaudioVersionLookup;
		static $MPEGaudioLayerLookup;
		static $MPEGaudioBitrateLookup;
		if (empty($MPEGaudioVersionLookup)) {
			$MPEGaudioVersionLookup = self::MPEGaudioVersionArray();
			$MPEGaudioLayerLookup   = self::MPEGaudioLayerArray();
			$MPEGaudioBitrateLookup = self::MPEGaudioBitrateArray();
		}

		$this->fseek($avdataoffset);
		$sync_seek_buffer_size = min(128 * 1024, $info['avdataend'] - $avdataoffset);
		if ($sync_seek_buffer_size <= 0) {
			$this->error('Invalid $sync_seek_buffer_size at offset '.$avdataoffset);
			return false;
		}
		$header = $this->fread($sync_seek_buffer_size);
		$sync_seek_buffer_size = strlen($header);
		$SynchSeekOffset = 0;
		while ($SynchSeekOffset < $sync_seek_buffer_size) {
			if ((($avdataoffset + $SynchSeekOffset)  < $info['avdataend']) && !feof($this->getid3->fp)) {

				if ($SynchSeekOffset > $sync_seek_buffer_size) {
					// if a synch's not found within the first 128k bytes, then give up
					$this->error('Could not find valid MPEG audio synch within the first '.round($sync_seek_buffer_size / 1024).'kB');
					if (isset($info['audio']['bitrate'])) {
						unset($info['audio']['bitrate']);
					}
					if (isset($info['mpeg']['audio'])) {
						unset($info['mpeg']['audio']);
					}
					if (empty($info['mpeg'])) {
						unset($info['mpeg']);
					}
					return false;

				} elseif (feof($this->getid3->fp)) {

					$this->error('Could not find valid MPEG audio synch before end of file');
					if (isset($info['audio']['bitrate'])) {
						unset($info['audio']['bitrate']);
					}
					if (isset($info['mpeg']['audio'])) {
						unset($info['mpeg']['audio']);
					}
					if (isset($info['mpeg']) && (!is_array($info['mpeg']) || (count($info['mpeg']) == 0))) {
						unset($info['mpeg']);
					}
					return false;
				}
			}

			if (($SynchSeekOffset + 1) >= strlen($header)) {
				$this->error('Could not find valid MPEG synch before end of file');
				return false;
			}

			if (($header[$SynchSeekOffset] == "\xFF") && ($header[($SynchSeekOffset + 1)] > "\xE0")) { // synch detected
				$FirstFrameAVDataOffset = null;
				if (!isset($FirstFrameThisfileInfo) && !isset($info['mpeg']['audio'])) {
					$FirstFrameThisfileInfo = $info;
					$FirstFrameAVDataOffset = $avdataoffset + $SynchSeekOffset;
					if (!$this->decodeMPEGaudioHeader($FirstFrameAVDataOffset, $FirstFrameThisfileInfo, false)) {
						// if this is the first valid MPEG-audio frame, save it in case it's a VBR header frame and there's
						// garbage between this frame and a valid sequence of MPEG-audio frames, to be restored below
						unset($FirstFrameThisfileInfo);
					}
				}

				$dummy = $info; // only overwrite real data if valid header found
				if ($this->decodeMPEGaudioHeader($avdataoffset + $SynchSeekOffset, $dummy, true)) {
					$info = $dummy;
					$info['avdataoffset'] = $avdataoffset + $SynchSeekOffset;
					switch (isset($info['fileformat']) ? $info['fileformat'] : '') {
						case '':
						case 'id3':
						case 'ape':
						case 'mp3':
							$info['fileformat']          = 'mp3';
							$info['audio']['dataformat'] = 'mp3';
							break;
					}
					if (isset($FirstFrameThisfileInfo) && isset($FirstFrameThisfileInfo['mpeg']['audio']['bitrate_mode']) && ($FirstFrameThisfileInfo['mpeg']['audio']['bitrate_mode'] == 'vbr')) {
						if (!(abs($info['audio']['bitrate'] - $FirstFrameThisfileInfo['audio']['bitrate']) <= 1)) {
							// If there is garbage data between a valid VBR header frame and a sequence
							// of valid MPEG-audio frames the VBR data is no longer discarded.
							$info = $FirstFrameThisfileInfo;
							$info['avdataoffset']        = $FirstFrameAVDataOffset;
							$info['fileformat']          = 'mp3';
							$info['audio']['dataformat'] = 'mp3';
							$dummy                       = $info;
							unset($dummy['mpeg']['audio']);
							$GarbageOffsetStart = $FirstFrameAVDataOffset + $FirstFrameThisfileInfo['mpeg']['audio']['framelength'];
							$GarbageOffsetEnd   = $avdataoffset + $SynchSeekOffset;
							if ($this->decodeMPEGaudioHeader($GarbageOffsetEnd, $dummy, true, true)) {
								$info = $dummy;
								$info['avdataoffset'] = $GarbageOffsetEnd;
								$this->warning('apparently-valid VBR header not used because could not find '.GETID3_MP3_VALID_CHECK_FRAMES.' consecutive MPEG-audio frames immediately after VBR header (garbage data for '.($GarbageOffsetEnd - $GarbageOffsetStart).' bytes between '.$GarbageOffsetStart.' and '.$GarbageOffsetEnd.'), but did find valid CBR stream starting at '.$GarbageOffsetEnd);
							} else {
								$this->warning('using data from VBR header even though could not find '.GETID3_MP3_VALID_CHECK_FRAMES.' consecutive MPEG-audio frames immediately after VBR header (garbage data for '.($GarbageOffsetEnd - $GarbageOffsetStart).' bytes between '.$GarbageOffsetStart.' and '.$GarbageOffsetEnd.')');
							}
						}
					}
					if (isset($info['mpeg']['audio']['bitrate_mode']) && ($info['mpeg']['audio']['bitrate_mode'] == 'vbr') && !isset($info['mpeg']['audio']['VBR_method'])) {
						// VBR file with no VBR header
						$BitrateHistogram = true;
					}

					if ($BitrateHistogram) {

						$info['mpeg']['audio']['stereo_distribution']  = array('stereo'=>0, 'joint stereo'=>0, 'dual channel'=>0, 'mono'=>0);
						$info['mpeg']['audio']['version_distribution'] = array('1'=>0, '2'=>0, '2.5'=>0);

						if ($info['mpeg']['audio']['version'] == '1') {
							if ($info['mpeg']['audio']['layer'] == 3) {
								$info['mpeg']['audio']['bitrate_distribution'] = array('free'=>0, 32000=>0, 40000=>0, 48000=>0, 56000=>0, 64000=>0, 80000=>0, 96000=>0, 112000=>0, 128000=>0, 160000=>0, 192000=>0, 224000=>0, 256000=>0, 320000=>0);
							} elseif ($info['mpeg']['audio']['layer'] == 2) {
								$info['mpeg']['audio']['bitrate_distribution'] = array('free'=>0, 32000=>0, 48000=>0, 56000=>0, 64000=>0, 80000=>0, 96000=>0, 112000=>0, 128000=>0, 160000=>0, 192000=>0, 224000=>0, 256000=>0, 320000=>0, 384000=>0);
							} elseif ($info['mpeg']['audio']['layer'] == 1) {
								$info['mpeg']['audio']['bitrate_distribution'] = array('free'=>0, 32000=>0, 64000=>0, 96000=>0, 128000=>0, 160000=>0, 192000=>0, 224000=>0, 256000=>0, 288000=>0, 320000=>0, 352000=>0, 384000=>0, 416000=>0, 448000=>0);
							}
						} elseif ($info['mpeg']['audio']['layer'] == 1) {
							$info['mpeg']['audio']['bitrate_distribution'] = array('free'=>0, 32000=>0, 48000=>0, 56000=>0, 64000=>0, 80000=>0, 96000=>0, 112000=>0, 128000=>0, 144000=>0, 160000=>0, 176000=>0, 192000=>0, 224000=>0, 256000=>0);
						} else {
							$info['mpeg']['audio']['bitrate_distribution'] = array('free'=>0, 8000=>0, 16000=>0, 24000=>0, 32000=>0, 40000=>0, 48000=>0, 56000=>0, 64000=>0, 80000=>0, 96000=>0, 112000=>0, 128000=>0, 144000=>0, 160000=>0);
						}

						$dummy = array('error'=>$info['error'], 'warning'=>$info['warning'], 'avdataend'=>$info['avdataend'], 'avdataoffset'=>$info['avdataoffset']);
						$synchstartoffset = $info['avdataoffset'];
						$this->fseek($info['avdataoffset']);

						// you can play with these numbers:
						$max_frames_scan  = 50000;
						$max_scan_segments = 10;

						// don't play with these numbers:
						$FastMode = false;
						$SynchErrorsFound = 0;
						$frames_scanned   = 0;
						$this_scan_segment = 0;
						$frames_scan_per_segment = ceil($max_frames_scan / $max_scan_segments);
						$pct_data_scanned = 0;
						for ($current_segment = 0; $current_segment < $max_scan_segments; $current_segment++) {
							$frames_scanned_this_segment = 0;
							if ($this->ftell() >= $info['avdataend']) {
								break;
							}
							$scan_start_offset[$current_segment] = max($this->ftell(), $info['avdataoffset'] + round($current_segment * (($info['avdataend'] - $info['avdataoffset']) / $max_scan_segments)));
							if ($current_segment > 0) {
								$this->fseek($scan_start_offset[$current_segment]);
								$buffer_4k = $this->fread(4096);
								for ($j = 0; $j < (strlen($buffer_4k) - 4); $j++) {
									if (($buffer_4k[$j] == "\xFF") && ($buffer_4k[($j + 1)] > "\xE0")) { // synch detected
										if ($this->decodeMPEGaudioHeader($scan_start_offset[$current_segment] + $j, $dummy, false, false, $FastMode)) {
											$calculated_next_offset = $scan_start_offset[$current_segment] + $j + $dummy['mpeg']['audio']['framelength'];
											if ($this->decodeMPEGaudioHeader($calculated_next_offset, $dummy, false, false, $FastMode)) {
												$scan_start_offset[$current_segment] += $j;
												break;
											}
										}
									}
								}
							}
							$synchstartoffset = $scan_start_offset[$current_segment];
							while (($synchstartoffset < $info['avdataend']) && $this->decodeMPEGaudioHeader($synchstartoffset, $dummy, false, false, $FastMode)) {
								$FastMode = true;
								$thisframebitrate = $MPEGaudioBitrateLookup[$MPEGaudioVersionLookup[$dummy['mpeg']['audio']['raw']['version']]][$MPEGaudioLayerLookup[$dummy['mpeg']['audio']['raw']['layer']]][$dummy['mpeg']['audio']['raw']['bitrate']];

								if (empty($dummy['mpeg']['audio']['framelength'])) {
									$SynchErrorsFound++;
									$synchstartoffset++;
								} else {
									getid3_lib::safe_inc($info['mpeg']['audio']['bitrate_distribution'][$thisframebitrate]);
									getid3_lib::safe_inc($info['mpeg']['audio']['stereo_distribution'][$dummy['mpeg']['audio']['channelmode']]);
									getid3_lib::safe_inc($info['mpeg']['audio']['version_distribution'][$dummy['mpeg']['audio']['version']]);
									$synchstartoffset += $dummy['mpeg']['audio']['framelength'];
								}
								$frames_scanned++;
								if ($frames_scan_per_segment && (++$frames_scanned_this_segment >= $frames_scan_per_segment)) {
									$this_pct_scanned = ($this->ftell() - $scan_start_offset[$current_segment]) / ($info['avdataend'] - $info['avdataoffset']);
									if (($current_segment == 0) && (($this_pct_scanned * $max_scan_segments) >= 1)) {
										// file likely contains < $max_frames_scan, just scan as one segment
										$max_scan_segments = 1;
										$frames_scan_per_segment = $max_frames_scan;
									} else {
										$pct_data_scanned += $this_pct_scanned;
										break;
									}
								}
							}
						}
						if ($pct_data_scanned > 0) {
							$this->warning('too many MPEG audio frames to scan, only scanned '.$frames_scanned.' frames in '.$max_scan_segments.' segments ('.number_format($pct_data_scanned * 100, 1).'% of file) and extrapolated distribution, playtime and bitrate may be incorrect.');
							foreach ($info['mpeg']['audio'] as $key1 => $value1) {
								if (!preg_match('#_distribution$#i', $key1)) {
									continue;
								}
								foreach ($value1 as $key2 => $value2) {
									$info['mpeg']['audio'][$key1][$key2] = round($value2 / $pct_data_scanned);
								}
							}
						}

						if ($SynchErrorsFound > 0) {
							$this->warning('Found '.$SynchErrorsFound.' synch errors in histogram analysis');
							//return false;
						}

						$bittotal     = 0;
						$framecounter = 0;
						foreach ($info['mpeg']['audio']['bitrate_distribution'] as $bitratevalue => $bitratecount) {
							$framecounter += $bitratecount;
							if ($bitratevalue != 'free') {
								$bittotal += ($bitratevalue * $bitratecount);
							}
						}
						if ($framecounter == 0) {
							$this->error('Corrupt MP3 file: framecounter == zero');
							return false;
						}
						$info['mpeg']['audio']['frame_count'] = getid3_lib::CastAsInt($framecounter);
						$info['mpeg']['audio']['bitrate']     = ($bittotal / $framecounter);

						$info['audio']['bitrate'] = $info['mpeg']['audio']['bitrate'];


						// Definitively set VBR vs CBR, even if the Xing/LAME/VBRI header says differently
						$distinct_bitrates = 0;
						foreach ($info['mpeg']['audio']['bitrate_distribution'] as $bitrate_value => $bitrate_count) {
							if ($bitrate_count > 0) {
								$distinct_bitrates++;
							}
						}
						if ($distinct_bitrates > 1) {
							$info['mpeg']['audio']['bitrate_mode'] = 'vbr';
						} else {
							$info['mpeg']['audio']['bitrate_mode'] = 'cbr';
						}
						$info['audio']['bitrate_mode'] = $info['mpeg']['audio']['bitrate_mode'];

					}

					break; // exit while()
				}
			}

			$SynchSeekOffset++;
			if (($avdataoffset + $SynchSeekOffset) >= $info['avdataend']) {
				// end of file/data

				if (empty($info['mpeg']['audio'])) {

					$this->error('could not find valid MPEG synch before end of file');
					if (isset($info['audio']['bitrate'])) {
						unset($info['audio']['bitrate']);
					}
					if (isset($info['mpeg']['audio'])) {
						unset($info['mpeg']['audio']);
					}
					if (isset($info['mpeg']) && (!is_array($info['mpeg']) || empty($info['mpeg']))) {
						unset($info['mpeg']);
					}