View Full Version : "Quality" of Converted MP3

06-06-2008, 02:48 PM
After converting a file from WMA to MP3, I notice that in the ID3 tag produced by Lame it says the quality is "78 (V2 and q2)".

Was wondering what the number means, and how to change it?

This is exactly what it says when I right click on the file using Audio Identifier and click, Display Lame Tag.

Tag revision: 0
Version string: 3.97
Quality: 78 (V2 and q2)
Encoding method: vbr new / vbr mtrh
Lowpass: 18,600Hz
RG track peak: <not stored>
RG track gain: <not stored>
RG album gain: <not stored>
nspsytune: yes
nssafejoint: yes
nogap continued: no
nogap continuation: no
ATH type: 4
Bitrate: minimal (-b) bitrate 32
Encoder delay: 576 samples
Padded at end: 1,332 samples
Noise shaping: 1
Stereo mode: joint
Unwise settings: no
Source sample freq: 44.1kHz
MP3Gain change: <none>
Preset: V2: preset standard (fast mode)
Surround info: none
Music length: 5,121,277 bytes
Actual Music CRC: CCBD
Info tag CRC: 5799
Actual Info Tag CRC: 5799

06-06-2008, 03:25 PM
Which settings did you use in mp3 (Lame)?

Why would you want to change the quality number in from the Lame header?

06-06-2008, 11:25 PM
My settings are from top to bottom, Quality (VBR), -V 2 - vbr new, Encoding set at Slow (High quality), Frequency: As source, and Source: Auto.

And I'm just curious about it, I have a tendency to over obsess and want things to be perfect, and like to know what I'm working with. I like to learn new things and I've been encoding mp3's for my personal use for a while, but I have never noticed that quality bit.

06-07-2008, 03:46 AM
if you used -v 2 then the value is correct in the header (it shows v2)

06-11-2008, 03:52 PM
So then you don't know what the quality tag is, what it's purpose is, or how it affects the mp3 file?

06-11-2008, 04:05 PM
The qaulity tag is an old reminent it is stored in a VBRI header it is a rough estimation of quality - the idea was programs could report the quality back, there is no standard values are 0 to 100, so 98 means nothing. Which ever program you are using takes the v2 part from the lame header. Changing the quality value in the vbr header does nothing.