#583 LAME MP3 Encoding Results Incorrect

[Fred]

Using the newest x64 version of MediaInfo and the newest version of LAME MP3 (3.98.4), MediaInfo incorrectly recognizes the encoder settings for CBR files. While it does detect that they're constant bitrate and detects the correct bitrate, the encoder settings generally list the files as -V 4, which is completely incorrect. It should identify the option as -b <CBR bitrate>. Tested with two different encoder frontends at both 256kbps and 320kbps.

[Jerome Martinez]

Please provide a sample file I can check the Lame header.

[Fred]

Picture of output

[Fred]

I've had a discussion on a forum about this, apparently it's because the MP3 encoder detection algorithm uses some sort of internal "quality" notation in the header, which by default is set to match that of a V4 file for CBR LAME encodes. Simplest way around this would probably be to differ the algorithm if the bitrate is detected as constant, and simply set the encoder settings to be "-b <detected CBR bitrate>" rather than guessing in that manner.

For some reason it wouldn't allow me to directly upload an MP3 (probably too large of a file or a network timeout), so here's a link. I've also uploaded a picture of the output and highlighted the correct/incorrect bits.
http://fileape.com/dl/qQ5w3CoA2KsvQUIg

[Propheticus]

Heads-up, this problem still exists.

BitRate_Mode/String : Constant
BitRate/String : 320 Kbps
Channel(s)/String : 2 channels
SamplingRate/String : 44.1 KHz
Compression_Mode/String : Lossy
Encoded_Library/String : LAME3.99r
Encoded_Library_Settings : -m j -V 4 -q 3 -lowpass 20.5

This is CBR 320Kbps. Same result from 2 different frontends (foobar2000 and TAudioConverter)