function DecodeFragment($frag, $fragNum, $opt = array())
{
$debug = $this->debug;
$flv = false;
extract($opt, EXTR_IF_EXISTS);
$flvData = "";
$fragPos = 0;
$packetTS = 0;
$fragLen = strlen($frag);
if (!$this->VerifyFragment($frag)) {
LogInfo("Skipping fragment number {$fragNum}");
return false;
}
while ($fragPos < $fragLen) {
ReadBoxHeader($frag, $fragPos, $boxType, $boxSize);
if ($boxType == "mdat") {
$fragLen = $fragPos + $boxSize;
break;
}
$fragPos += $boxSize;
}
LogDebug(sprintf("\nFragment %d:\n" . $this->format . "%-16s", $fragNum, "Type", "CurrentTS", "PreviousTS", "Size", "Position"), $debug);
while ($fragPos < $fragLen) {
$packetType = ReadByte($frag, $fragPos);
$packetSize = ReadInt24($frag, $fragPos + 1);
$packetTS = ReadInt24($frag, $fragPos + 4);
$packetTS = $packetTS | ReadByte($frag, $fragPos + 7) << 24;
if ($packetTS & 0x80000000) {
$packetTS &= 0x7fffffff;
}
$totalTagLen = $this->tagHeaderLen + $packetSize + $this->prevTagSize;
// Try to fix the odd timestamps and make them zero based
$currentTS = $packetTS;
$lastTS = $this->prevVideoTS >= $this->prevAudioTS ? $this->prevVideoTS : $this->prevAudioTS;
$fixedTS = $lastTS + FRAMEFIX_STEP;
if ($this->baseTS == INVALID_TIMESTAMP and ($packetType == AUDIO or $packetType == VIDEO)) {
$this->baseTS = $packetTS;
}
if ($this->baseTS > 1000 and $packetTS >= $this->baseTS) {
$packetTS -= $this->baseTS;
}
if ($lastTS != INVALID_TIMESTAMP) {
$timeShift = $packetTS - $lastTS;
if ($timeShift > $this->fixWindow) {
LogDebug("Timestamp gap detected: PacketTS=" . $packetTS . " LastTS=" . $lastTS . " Timeshift=" . $timeShift, $debug);
if ($this->baseTS < $packetTS) {
$this->baseTS += $timeShift - FRAMEFIX_STEP;
} else {
$this->baseTS = $timeShift - FRAMEFIX_STEP;
}
$packetTS = $fixedTS;
} else {
$lastTS = $packetType == VIDEO ? $this->prevVideoTS : $this->prevAudioTS;
if ($packetTS < $lastTS - $this->fixWindow) {
if ($this->negTS != INVALID_TIMESTAMP and $packetTS + $this->negTS < $lastTS - $this->fixWindow) {
$this->negTS = INVALID_TIMESTAMP;
}
if ($this->negTS == INVALID_TIMESTAMP) {
$this->negTS = $fixedTS - $packetTS;
LogDebug("Negative timestamp detected: PacketTS=" . $packetTS . " LastTS=" . $lastTS . " NegativeTS=" . $this->negTS, $debug);
$packetTS = $fixedTS;
} else {
if ($packetTS + $this->negTS <= $lastTS + $this->fixWindow) {
$packetTS += $this->negTS;
} else {
$this->negTS = $fixedTS - $packetTS;
LogDebug("Negative timestamp override: PacketTS=" . $packetTS . " LastTS=" . $lastTS . " NegativeTS=" . $this->negTS, $debug);
$packetTS = $fixedTS;
}
}
}
}
}
if ($packetTS != $currentTS) {
WriteFlvTimestamp($frag, $fragPos, $packetTS);
}
switch ($packetType) {
case AUDIO:
if ($packetTS > $this->prevAudioTS - $this->fixWindow) {
$FrameInfo = ReadByte($frag, $fragPos + $this->tagHeaderLen);
$CodecID = ($FrameInfo & 0xf0) >> 4;
if ($CodecID == CODEC_ID_AAC) {
$AAC_PacketType = ReadByte($frag, $fragPos + $this->tagHeaderLen + 1);
if ($AAC_PacketType == AAC_SEQUENCE_HEADER) {
if ($this->AAC_HeaderWritten) {
LogDebug(sprintf("%s\n" . $this->format, "Skipping AAC sequence header", "AUDIO", $packetTS, $this->prevAudioTS, $packetSize), $debug);
break;
} else {
LogDebug("Writing AAC sequence header", $debug);
$this->AAC_HeaderWritten = true;
}
} else {
if (!$this->AAC_HeaderWritten) {
LogDebug(sprintf("%s\n" . $this->format, "Discarding audio packet received before AAC sequence header", "AUDIO", $packetTS, $this->prevAudioTS, $packetSize), $debug);
break;
}
}
}
if ($packetSize > 0) {
// Check for packets with non-monotonic audio timestamps and fix them
if (!($CodecID == CODEC_ID_AAC and ($AAC_PacketType == AAC_SEQUENCE_HEADER or $this->prevAAC_Header))) {
if ($this->prevAudioTS != INVALID_TIMESTAMP and $packetTS <= $this->prevAudioTS) {
LogDebug(sprintf("%s\n" . $this->format, "Fixing audio timestamp", "AUDIO", $packetTS, $this->prevAudioTS, $packetSize), $debug);
$packetTS += FRAMEFIX_STEP / 5 + ($this->prevAudioTS - $packetTS);
WriteFlvTimestamp($frag, $fragPos, $packetTS);
}
}
if (is_resource($flv)) {
$this->pAudioTagPos = ftell($flv);
$status = fwrite($flv, substr($frag, $fragPos, $totalTagLen), $totalTagLen);
if (!$status) {
LogError("Failed to write flv data to file");
}
if ($debug) {
LogDebug(sprintf($this->format . "%-16s", "AUDIO", $packetTS, $this->prevAudioTS, $packetSize, $this->pAudioTagPos));
}
} else {
$flvData .= substr($frag, $fragPos, $totalTagLen);
if ($debug) {
LogDebug(sprintf($this->format, "AUDIO", $packetTS, $this->prevAudioTS, $packetSize));
}
}
if ($CodecID == CODEC_ID_AAC and $AAC_PacketType == AAC_SEQUENCE_HEADER) {
$this->prevAAC_Header = true;
} else {
$this->prevAAC_Header = false;
}
$this->prevAudioTS = $packetTS;
$this->pAudioTagLen = $totalTagLen;
} else {
LogDebug(sprintf("%s\n" . $this->format, "Skipping small sized audio packet", "AUDIO", $packetTS, $this->prevAudioTS, $packetSize), $debug);
}
} else {
LogDebug(sprintf("%s\n" . $this->format, "Skipping audio packet in fragment {$fragNum}", "AUDIO", $packetTS, $this->prevAudioTS, $packetSize), $debug);
}
if (!$this->audio) {
$this->audio = true;
}
break;
case VIDEO:
if ($packetTS > $this->prevVideoTS - $this->fixWindow) {
$FrameInfo = ReadByte($frag, $fragPos + $this->tagHeaderLen);
$FrameType = ($FrameInfo & 0xf0) >> 4;
$CodecID = $FrameInfo & 0xf;
if ($FrameType == FRAME_TYPE_INFO) {
LogDebug(sprintf("%s\n" . $this->format, "Skipping video info frame", "VIDEO", $packetTS, $this->prevVideoTS, $packetSize), $debug);
break;
}
if ($CodecID == CODEC_ID_AVC) {
$AVC_PacketType = ReadByte($frag, $fragPos + $this->tagHeaderLen + 1);
if ($AVC_PacketType == AVC_SEQUENCE_HEADER) {
if ($this->AVC_HeaderWritten) {
LogDebug(sprintf("%s\n" . $this->format, "Skipping AVC sequence header", "VIDEO", $packetTS, $this->prevVideoTS, $packetSize), $debug);
break;
} else {
LogDebug("Writing AVC sequence header", $debug);
$this->AVC_HeaderWritten = true;
}
} else {
if (!$this->AVC_HeaderWritten) {
LogDebug(sprintf("%s\n" . $this->format, "Discarding video packet received before AVC sequence header", "VIDEO", $packetTS, $this->prevVideoTS, $packetSize), $debug);
break;
}
}
}
if ($packetSize > 0) {
$pts = $packetTS;
if ($CodecID == CODEC_ID_AVC and $AVC_PacketType == AVC_NALU) {
$cts = ReadInt24($frag, $fragPos + $this->tagHeaderLen + 2);
$cts = $cts + 0xff800000 ^ 0xff800000;
$pts = $packetTS + $cts;
if ($cts != 0) {
LogDebug("DTS: {$packetTS} CTS: {$cts} PTS: {$pts}", $debug);
}
}
// Check for packets with non-monotonic video timestamps and fix them
if (!($CodecID == CODEC_ID_AVC and ($AVC_PacketType == AVC_SEQUENCE_HEADER or $AVC_PacketType == AVC_SEQUENCE_END or $this->prevAVC_Header))) {
if ($this->prevVideoTS != INVALID_TIMESTAMP and $packetTS <= $this->prevVideoTS) {
LogDebug(sprintf("%s\n" . $this->format, "Fixing video timestamp", "VIDEO", $packetTS, $this->prevVideoTS, $packetSize), $debug);
$packetTS += FRAMEFIX_STEP / 5 + ($this->prevVideoTS - $packetTS);
WriteFlvTimestamp($frag, $fragPos, $packetTS);
}
}
if (is_resource($flv)) {
$this->pVideoTagPos = ftell($flv);
$status = fwrite($flv, substr($frag, $fragPos, $totalTagLen), $totalTagLen);
if (!$status) {
LogError("Failed to write flv data to file");
}
if ($debug) {
LogDebug(sprintf($this->format . "%-16s", "VIDEO", $packetTS, $this->prevVideoTS, $packetSize, $this->pVideoTagPos));
}
} else {
$flvData .= substr($frag, $fragPos, $totalTagLen);
if ($debug) {
LogDebug(sprintf($this->format, "VIDEO", $packetTS, $this->prevVideoTS, $packetSize));
}
}
if ($CodecID == CODEC_ID_AVC and $AVC_PacketType == AVC_SEQUENCE_HEADER) {
$this->prevAVC_Header = true;
} else {
$this->prevAVC_Header = false;
}
$this->prevVideoTS = $packetTS;
$this->pVideoTagLen = $totalTagLen;
} else {
LogDebug(sprintf("%s\n" . $this->format, "Skipping small sized video packet", "VIDEO", $packetTS, $this->prevVideoTS, $packetSize), $debug);
}
} else {
LogDebug(sprintf("%s\n" . $this->format, "Skipping video packet in fragment {$fragNum}", "VIDEO", $packetTS, $this->prevVideoTS, $packetSize), $debug);
}
if (!$this->video) {
$this->video = true;
}
break;
case SCRIPT_DATA:
break;
default:
if ($packetType == 10 or $packetType == 11) {
LogError("This stream is encrypted with Akamai DRM. Decryption of such streams isn't currently possible with this script.", 2);
} else {
if ($packetType == 40 or $packetType == 41) {
LogError("This stream is encrypted with FlashAccess DRM. Decryption of such streams isn't currently possible with this script.", 2);
} else {
LogInfo("Unknown packet type " . $packetType . " encountered! Unable to process fragment {$fragNum}");
break 2;
}
}
}
$fragPos += $totalTagLen;
}
$this->duration = round($packetTS / 1000, 0);
if (is_resource($flv)) {
$this->filesize = ftell($flv) / (1024 * 1024);
return true;
} else {
return $flvData;
}
}
break;
} else {
LogDebug("Writing AVC sequence header");
$AVC_HeaderWritten = true;
}
} else {
if (!$AVC_HeaderWritten) {
LogDebug(sprintf("%s\n" . $format, "Discarding video packet received before AVC sequence header", "VIDEO", $packetTS, $prevVideoTS, $packetSize));
break;
}
}
}
if ($packetSize > 0) {
$pts = $packetTS;
if ($CodecID == CODEC_ID_AVC and $AVC_PacketType == AVC_NALU) {
$cts = ReadInt24($flvTag, $tagPos + $tagHeaderLen + 2);
$cts = $cts + 0xff800000 ^ 0xff800000;
$pts = $packetTS + $cts;
if ($cts != 0) {
LogDebug("DTS: {$packetTS} CTS: {$cts} PTS: {$pts}");
}
}
// Check for packets with non-monotonic video timestamps and fix them
if (!($CodecID == CODEC_ID_AVC and ($AVC_PacketType == AVC_SEQUENCE_HEADER or $AVC_PacketType == AVC_SEQUENCE_END or $prevAVC_Header))) {
if ($prevVideoTS != INVALID_TIMESTAMP and $packetTS <= $prevVideoTS) {
LogDebug(sprintf("%s\n" . $format, "Fixing video timestamp", "VIDEO", $packetTS, $prevVideoTS, $packetSize));
$packetTS += FRAMEFIX_STEP / 5 + ($prevVideoTS - $packetTS);
WriteFlvTimestamp($flvTag, $tagPos, $packetTS);
}
}
$pVideoTagPos = ftell($flvOut);