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Topic: Hunting (for infromation about) a preset... (Read 3104 times) previous topic - next topic
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Hunting (for infromation about) a preset...

Hi!

Thanks to the great tool LameTag i have noticed
that i have some files encoded like this:

- VBR-mrth
- Gspycho
- ATH 4
- Noise Shaping 1
- no safe joint-stero mode

MP3s encoded with Lame 3.93 have a lowpass-filter of 20600Hz
and a quality flag value of 98. When they are encoded with Lame 3.90.3
the LPF is at 19400Hz and the quality value is 78.

As i remeber all of these MP3s are ripped with Audiograbber.


Is this a pre-defined Lame preset? - ... and is it good?
And what about the 'insecure' joint-stero mode used here?


Thanks for help,
384kbps

Hunting (for infromation about) a preset...

Reply #1
Quote
Is this a pre-defined Lame preset?

Surely not --alt-preset, since --alt-presets use secure safe joint (nssafejoint) and nspsytune, not gpsycho.

Hunting (for infromation about) a preset...

Reply #2
Doesn't look like a known preset as far as I can tell. I've mapped all the presets in pre-3.93 (or recent 3.90.3) LAME versions that don't store an actual presetID:
Code: [Select]
[vbr_quality][vbr_method][noise_shaping][stereo_mode][ath_type][lowpass]

$KnownEncoderValues[78][4][2][3][4][19000] = '--alt-preset fast standard';
$KnownEncoderValues[78][3][1][3][4][19000] = '--alt-preset standard'; // LAME 3.90.3a (May 2003)
$KnownEncoderValues[78][3][2][3][4][19000] = '--alt-preset standard'; // all other LAMEs
$KnownEncoderValues[78][4][2][3][2][19500] = '--alt-preset fast extreme';
$KnownEncoderValues[78][3][2][3][2][19500] = '--alt-preset extreme';
$KnownEncoderValues[58][1][1][3][2][20500] = '--alt-preset insane';
$KnownEncoderValues[88][1][1][1][2][0]     = '--preset cd';
$KnownEncoderValues[67][1][1][3][2][15000] = '--preset fm/radio';
$KnownEncoderValues[78][1][1][3][2][18000] = '--preset hifi';
$KnownEncoderValues[67][1][1][3][2][18000] = '--preset tape';
$KnownEncoderValues[99][1][1][1][2][0]     = '--preset studio';

$KnownEncoderValues[88][4][1][3][3][19500] = '--r3mix'; // LAME 3.92, 3.93
$KnownEncoderValues[88][4][1][3][3][19600] = '--r3mix'; // LAME 3.90, 3.91

$KnownEncoderValues[65][1][1][0][2][7600]  = '--preset mw-us';
To read the above, you'll need to know that LAME's stereo mode IDs are:
Code: [Select]
$LAMEstereoMode[0] = 'mono';
$LAMEstereoMode[1] = 'stereo';
$LAMEstereoMode[2] = 'dual mono';
$LAMEstereoMode[3] = 'joint stereo';
$LAMEstereoMode[4] = 'forced stereo';
$LAMEstereoMode[5] = 'auto';
$LAMEstereoMode[6] = 'intensity stereo';
$LAMEstereoMode[7] = 'other';
and VBR methods are:
Code: [Select]
$LAMEvbrMethod[0x00] = 'unknown';
$LAMEvbrMethod[0x01] = 'cbr';
$LAMEvbrMethod[0x02] = 'abr';
$LAMEvbrMethod[0x03] = 'vbr-old / vbr-rh';
$LAMEvbrMethod[0x04] = 'vbr-mtrh';
$LAMEvbrMethod[0x05] = 'vbr-new / vbr-mt';
The file you describe doesn't fit a known preset. The quality value would indicate that the file is encoded with VBR parameters equivalent to:
98 = -V0 -q2
78 = -V2 -q2

As I alluded to above - LAME 3.93+ and the latest 3.90.3 (but not earlier compiles of 3.90.3) store a preset ID number in the LAME header tag, and mp3tag would display the name of the preset if one was used with these files. mp3tag doesn't extrapolate presets from previous LAME versions that don't store that information (but getID3() does  )

Hunting (for infromation about) a preset...

Reply #3
A simple command line like  -V 2 --vbr-new --lowpass 19.5 produces the Lame Tag as mentioned. I won't speculate on quality, if you want to be sure just re-encode from the original with a known preset 

Hunting (for infromation about) a preset...

Reply #4
Thanks for the answers!


Quote
mp3tag would display the name of the preset if one was used with these files. mp3tag doesn't extrapolate presets from previous LAME versions that don't store that information (but getID3() does  )

getID3() ... Nice project by the way! - From times to times i use actually my
own Apache by runnig external DOS tools to see information the nice way


Quote
A simple command line like -V 2 --vbr-new --lowpass 19.5

Indeed...
First i thought it was something like R3mix due to the missing safe-joint-stereo mode,
but r3mix uses the "nspsytune" mode as i have seen now.

"-V 2 --vbr-new --lowpass 19.4 -m j -b 80" seems to be used on the majority
of the 'suspicious' (audiograbbed) MP3s.
I guess something went wrong in any way during the ripping process...


384kbps