Wrong length for MPEG-2 Layer 3

[Woodgnome]

Rename the attached test.txt to test.mp3 (Github doesn't allow MP3 attachment).

The MP3 is detected as MPEG-2 Layer 3:

falahati\PHPMP3\MpegAudioFrameHeader Object
(
    [bitRate:falahati\PHPMP3\MpegAudioFrameHeader:private] => 48000
    [sampleRate:falahati\PHPMP3\MpegAudioFrameHeader:private] => 11025
    [version:falahati\PHPMP3\MpegAudioFrameHeader:private] => 2
    [profile:falahati\PHPMP3\MpegAudioFrameHeader:private] => 3
    [duration:falahati\PHPMP3\MpegAudioFrameHeader:private] => 0.1045
    [offset:falahati\PHPMP3\MpegAudioFrameHeader:private] => 3336
    [length:falahati\PHPMP3\MpegAudioFrameHeader:private] => 627
    [padding:falahati\PHPMP3\MpegAudioFrameHeader:private] => 1
    [errorProtection:falahati\PHPMP3\MpegAudioFrameHeader:private] => 1
    [privateBit:falahati\PHPMP3\MpegAudioFrameHeader:private] =>
    [copyrighted:falahati\PHPMP3\MpegAudioFrameHeader:private] => 1
    [original:falahati\PHPMP3\MpegAudioFrameHeader:private] => 1
    [mode:falahati\PHPMP3\MpegAudioFrameHeader:private] => 3
    [middleSideStereoJoining:falahati\PHPMP3\MpegAudioFrameHeader:private] =>
    [intensityStereoMode:falahati\PHPMP3\MpegAudioFrameHeader:private] => 0
)

The current length calculation in MpegAudioFrameHeader::tryParse() is:

if ($frame->profile == self::Profile_1) {
	$frame->length = (((12 * $frame->bitRate) / $frame->sampleRate) + $frame->padding) * 4;
} else if ($frame->profile == self::Profile_2 || $frame->profile == self::Profile_3) {
	$frame->length = ((144 * $frame->bitRate) / $frame->sampleRate) + $frame->padding;
}

I cannot find a mention of this in the ISO, but I've seen several sources claim that MPEG-2 Layer 3 samples per frame is acutally 576 / 8 = 72 instead of 1152 / 8 = 144, for example, https://stackoverflow.com/questions/62536328/mpeg-2-and-2-5-problems-calculating-frame-sizes-in-bytes.

Also, claims that padding should be part of the denominator (144 * bitRate / (sampleRate + padding) instead of 144 * bitRate / sampleRate + padding), for example, https://stackoverflow.com/questions/57103676/formula-from-mp3-frame-length.

When I try to append the test MP3 to another MP3 it fails because of this check in MpegAudio::read():

if ($this->memoryPointer >= $this->memoryLength) {
	return false;
}

Updating the frame length calculation to $frame->length = 72 * $frame->bitRate / ($frame->sampleRate + $frame->padding); fixes this issue.