HydrogenAudio

Lossy Audio Compression => MP3 => MP3 - Tech => Topic started by: siaush on 2007-10-29 12:20:14

Title: [dBPoweramp] Quality Presets Reversed?
Post by: siaush on 2007-10-29 12:20:14
I have been using dBPoweramp for quite sometime, I am currently using R12.3 with LAME 3.97. For what I see from the Spectral Frequency view in Adobe Audition, the High preset seems to have much more data loss (higher frequency parts) than the Low preset. Is this normal? or there's something which is not fine.. Below are the screenshots:


dBpowerAMP:
(http://img140.imageshack.us/img140/1395/dbpoweramppz0.th.png) (http://img140.imageshack.us/my.php?image=dbpoweramppz0.png)

Original
(http://img454.imageshack.us/img454/7789/originalew3.th.png) (http://img454.imageshack.us/my.php?image=originalew3.png)

Fast (Low Quality)
(http://img454.imageshack.us/img454/7295/lowxk8.th.png) (http://img454.imageshack.us/my.php?image=lowxk8.png)

Normal
(http://img132.imageshack.us/img132/6969/normalau2.th.png) (http://img132.imageshack.us/my.php?image=normalau2.png)

Slow (High Quality)
(http://img484.imageshack.us/img484/1406/highno5.th.png) (http://img484.imageshack.us/my.php?image=highno5.png)


The High Quality preset did take longer time to complete than the Normal and Low Quality preset. From what I observed from the Spectral Frequency display, Low Quality seems to retained most data.
Title: [dBPoweramp] Quality Presets Reversed?
Post by: ImAlive on 2007-10-29 13:05:44
HF extension does not equal sound quality.

Since we do not hear graphs, do you actually *hear* any difference? At 320k CBR, except for problem samples, anything is with very high probability transparent and indistinguishable from the original in a double blind test.

"High" takes longer to encode, so the encoder "thinks harder" of encoding decisions - maybe this is why it does not use so many bits for HF parts which one cannot hear anyways and uses them to avoid problems (artefacts) in other sonic ranges (so the encoder is being 'smart', while in low quality mode, it just encodes everything). Just a theory though.

If you have the time, do an ABX test with your music!  You might find that 320k is way overkill...
Title: [dBPoweramp] Quality Presets Reversed?
Post by: pdq on 2007-10-29 13:18:26
Doesn't the lame tag tell you exactly which switches were used in encoding?
Title: [dBPoweramp] Quality Presets Reversed?
Post by: siaush on 2007-10-29 13:36:38
Doesn't the lame tag tell you exactly which switches were used in encoding?


I don't see any tags or parameters available..

So for 320k encodings, should I choose High, Normal or Low for the preset?
Title: [dBPoweramp] Quality Presets Reversed?
Post by: Alex B on 2007-10-29 14:12:29
I don't see any tags or parameters available..

Try the LameTagGUI tool: http://phwip.wordpress.com/home/audio/ (http://phwip.wordpress.com/home/audio/)

Quote
So for 320k encodings, should I choose High, Normal or Low for the preset?

The recommended switch is plain -b 320. (http://wiki.hydrogenaudio.org/index.php?title=LAME (http://wiki.hydrogenaudio.org/index.php?title=LAME))

If dbPoweramp uses it for "normal" quality then it should be fine.
Title: [dBPoweramp] Quality Presets Reversed?
Post by: spoon on 2007-10-29 15:09:07
Those values go into:

lame_set_quality(lgf, EncodingQuality);

Where Normal = 5
Fast = 7
Slow = 2

From lame docs (in one place):

  internal algorithm selection.  True quality is determined by the bitrate
  but this variable will effect quality by selecting expensive or cheap algorithms.
  quality=0..9.  0=best (very slow).  9=worst.
  recommended: 

2    near-best quality, not too slow
5    good quality, fast
7    ok quality, really fast

In another place:

/*
* Internal algorithm selection.
* True quality is determined by the bitrate but this variable will effect
* quality by selecting expensive or cheap algorithms.
* quality=0..9.  0=best (very slow).  9=worst. 
* recommended:  3    near-best quality, not too slow
*              5    good quality, fast
*              7    ok quality, really fast
*/

Lame.exe defaults to 3 as far as I can tell. For R13 I will also switch to 3.
Title: [dBPoweramp] Quality Presets Reversed?
Post by: siaush on 2007-10-29 15:22:28
Do you mean you will switch normal to 3 in R13?

Also, is there anyway to change the quality values in R12?

Another also XD, is it really that the higher quality it goes, it will encode less high frequency to minimize artifacts? It doesn't seems quite right to me... When I compared it with the full quality wav file, shouldn't the quality/data loss be looked for?

Thanks.
Title: [dBPoweramp] Quality Presets Reversed?
Post by: spoon on 2007-10-29 15:25:57
>Do you mean you will switch normal to 3 in R13?

Yes

>Also, is there anyway to change the quality values in R12?

Only between 2, 5, 7

If you want the best recommended mode select Encoding = Slow