223 $OverheadPercentage = 0;
225 $AudioBitrate = max(min($AudioBitrate / 1000, 384), 32);
226 $VideoBitrate = max(min($VideoBitrate / 1000, 10000), 10);
230 $OverheadMultiplierByBitrate[32] = array(0, 0.9676287944368530, 0.9802276264360310, 0.9844916183244460, 0.9852821845179940);
231 $OverheadMultiplierByBitrate[48] = array(0, 0.9779100089209830, 0.9787770035359320, 0.9846738664076130, 0.9852683013799960);
232 $OverheadMultiplierByBitrate[56] = array(0, 0.9731249855367600, 0.9776624308938040, 0.9832606361852130, 0.9843922606633340);
233 $OverheadMultiplierByBitrate[64] = array(0, 0.9755642683275760, 0.9795256705493390, 0.9836573009193170, 0.9851122539404470);
234 $OverheadMultiplierByBitrate[96] = array(0, 0.9788025247497290, 0.9798553314148700, 0.9822956869792560, 0.9834815119124690);
235 $OverheadMultiplierByBitrate[128] = array(0, 0.9816940050925480, 0.9821675936072120, 0.9829756927470870, 0.9839763420152050);
236 $OverheadMultiplierByBitrate[160] = array(0, 0.9825894094561180, 0.9820913399073960, 0.9823907143253970, 0.9832821783651570);
237 $OverheadMultiplierByBitrate[192] = array(0, 0.9832038474336260, 0.9825731694317960, 0.9821028622712400, 0.9828262076447620);
238 $OverheadMultiplierByBitrate[224] = array(0, 0.9836516298538770, 0.9824718601823890, 0.9818302180625380, 0.9823735101626480);
239 $OverheadMultiplierByBitrate[256] = array(0, 0.9845863022094920, 0.9837229411967540, 0.9824521662210830, 0.9828645172100790);
240 $OverheadMultiplierByBitrate[320] = array(0, 0.9849565280263180, 0.9837683142805110, 0.9822885275960400, 0.9824424382727190);
241 $OverheadMultiplierByBitrate[384] = array(0, 0.9856094774357600, 0.9844573394432720, 0.9825970399837330, 0.9824673808303890);
243 $BitrateToUseMin = 32;
244 $BitrateToUseMax = 32;
245 $previousBitrate = 32;
246 foreach ($OverheadMultiplierByBitrate as $key => $value) {
247 if ($AudioBitrate >= $previousBitrate) {
248 $BitrateToUseMin = $previousBitrate;
250 if ($AudioBitrate < $key) {
251 $BitrateToUseMax = $key;
254 $previousBitrate = $key;
256 $FactorA = ($BitrateToUseMax - $AudioBitrate) / ($BitrateToUseMax - $BitrateToUseMin);
258 $VideoBitrateLog10 = log10($VideoBitrate);
259 $VideoFactorMin1 = $OverheadMultiplierByBitrate[$BitrateToUseMin][floor($VideoBitrateLog10)];
260 $VideoFactorMin2 = $OverheadMultiplierByBitrate[$BitrateToUseMax][floor($VideoBitrateLog10)];
261 $VideoFactorMax1 = $OverheadMultiplierByBitrate[$BitrateToUseMin][ceil($VideoBitrateLog10)];
262 $VideoFactorMax2 = $OverheadMultiplierByBitrate[$BitrateToUseMax][ceil($VideoBitrateLog10)];
263 $FactorV = $VideoBitrateLog10 - floor($VideoBitrateLog10);
265 $OverheadPercentage = $VideoFactorMin1 * $FactorA * $FactorV;
266 $OverheadPercentage += $VideoFactorMin2 * (1 - $FactorA) * $FactorV;
267 $OverheadPercentage += $VideoFactorMax1 * $FactorA * (1 - $FactorV);
268 $OverheadPercentage += $VideoFactorMax2 * (1 - $FactorA) * (1 - $FactorV);
270 return $OverheadPercentage;