Levelling info

Any ideas about how to improve MediaMonkey? Let us know!

Moderator: Gurus

ariel
Posts: 78
Joined: Mon Dec 19, 2005 4:12 am

Levelling info

Post by ariel »

As can be seen in the "bugs" forum, I had a lot of levelling issues with the 2.5 betas. Now I found MP3Gain, and I can finally check things with more than my ears.

http://mp3gain.sourceforge.net/

The problem with MP3Gain is that I can't be sure that the values it gives correspond to those calculated by MM's algorithm. Specifically, the clipping value, which, as I understand it, should be the "CD players 100% norm".

MP3Gain shows that clipping occurs in some MM-leveled tracks, even though all my levellings were done with clipping prevention. In some cases the clipping may already be there from the original Audio CD, but I get these "clipped" tracks in about 15% of the tracks I checked, which seems high. Another possibility is that MP3Gain uses a clipping value that is slightly lower than the one used in MM.

And I did a test with a Deutsche Grammophon CD, which shouldn't have clipped tracks on it. I ripped it to MP3 CBR 128, with leveling on, and with clipping prevention checked (on) in the leveling options. I then checked the tracks with MP3Gain - 4 of the 25 tracks were marked as having clipping. Again, I have no idea if it's from the CD, MM or MP3Gain, but in this case I'm inclined to rule out the CD.

So what is needed is for MM itself to tell us what it thinks the volume and clipping will be for a specific track without doing a leveling - the values as computed by MM, not by a 3rd party utility. [Normally I'd call that an analysis of the track, but "analyze" is already used for a leveling mode]

[And, besides the critical replay-gain volume and clipping info like in MP3gain, it would be very nice to have track min/max volume too, to get an idea about a track's dynamic range when coming to deal with unusual tracks]

I think this should be high priority for MM (or MMG). I bought MMG as a power tool, and while it provides the mass leveling I was after, I end up losing more time on fixing specific tracks then I used to with the unspeakable W**, because I have to second guess what MM is doing using my old, watt-worn ears, or an external utility which may, or may not, give results that are compatible with MM.

TIA, Ariel.
Exaxxion
Posts: 53
Joined: Sun Oct 16, 2005 5:47 pm

Post by Exaxxion »

From what I understand, you want to determine what the levelling will be before you actually level a track. If this is the case, then there is actually a way to do this.

First, open MM and go to Tools>Options. Click on "Volume leveling" under "Player".

Next, select the number of decibels that you want to burn your CDs at. Place this value under all of the fields to ensure correct measurement. Personally, I use 80dB so I don't lose my hearing because I listen to music all the time (the minimum measurement I found was 85dB for 8 hours = permanent hearing loss, and 160dB is the human threshold for pain, meaning anything higher won't be felt and will instantly cause permanent hearing loss).

Once done, check the box for "Clipping Prevention" and hit OK. Do a search, select a directory, or grab individual songs you want to test with CTRL+Click.

Press CTRL+Shift+W or go to Tools > "Analyze Volume". This will begin scanning all selected files and once completed will report the proposed changes in +/- dB under the "Leveling" column.

And.... You're done. Congratulations!

Hope this helps :)
ariel
Posts: 78
Joined: Mon Dec 19, 2005 4:12 am

Post by ariel »

From what I understand, you want to determine what the levelling will be before you actually level a track.


No - I want to determine the current volume situation of a track, be it before or after a leveling.

Two things are critical:

1. The MM replay-gain calculation for that track.

2. Is there clipping in the track.

In addition, max & min dB info will be very helpful.

If this is the case, then there is actually a way to do this.
There isn't. When you analyze a track (menu level-analyze) you get a display of a delta dB that is to be applied on the track. You can't tell if that number is:

1. The delta dB needed to bring the (replay-gain) volume to the level specified in "level playback volume" in the options

2. The highest delta dB that will not cause clipping (assuming clipping prevention is on), even if the volume will be lower than the one specified in "level playback volume". And the volume can be significantly lower the one in "level playback volume" - with the relatively few tracks I checked so far with MP3Gain I've already found one that is 7.5 dB below the target value.

The issue of clipping is very important for classical music, but not only - my lastest tests were initiated by problems I had with a Van Der Graaf Generator CD (huge dynamic range).

Look at the Deutsche Grammophon example I gave in the original message. The CD in question was Orff's Carmina Burana - the volume has everything from super bombastic to whisper-like. And I can't hear any sign of clipping when the CD is played in high quality equipment at a vey high volume. So if the clipping is not on the CD itself, it's either falsley detected by MP3Gain or intoduced by the MM leveling during the rip (which would be a serious bug affecting the quality of tracks). The point is that I can't tell where the problem is - MM doesn't give me the info needed to pinpoint the problem.

I use 80dB


If you came to that value using 2.4, you have to change it in 2.5 to 85 dB ... See the level-related changes for 2.5 in

http://www.mediamonkey.com/sw/whatsnew.txt


Ariel.
Exaxxion
Posts: 53
Joined: Sun Oct 16, 2005 5:47 pm

Post by Exaxxion »

Ok, I think I better understand what you want. It is true that MM says nothing about a standing dB range, and nowhere does it specify what the delta dB given in the Leveling column means. Personally, I have always taken it to mean that that is the change from the original dB to the post-leveling value, and that with clipping prevention on, it is the closest dB it can get to the desired level without clipping the range.

I think that those would be interesting and relatively simple features to add, and I'm sure that those who are interested in the more technical aspects of playing music would enjoy it.

Also, thanks for the tip about the leveling being off in 2.4, but since obtaining 2.5 I have rescanned my library. I thought something was different :P. I don't mind it being a bit quieter; I can always turn up the sound on the computer or increase the preamp in the EQ, but I want it to be at true 80dB anyway.
Wolverine4580
Posts: 10
Joined: Sun Jan 22, 2006 1:45 am

Post by Wolverine4580 »

You guys seem pretty knowledgable on the MM volume leveling. I was wondering why when you do a volume level to a file it adds a offset value to the leveling column, but when you convert a file (like from one bitrate to another) and you check the "level volume" option in the file conversion it doesn't. During the file transfer you see the status window say that is is analyzing the volume, then it goes into the file conversion. The newly created file does not have an offset for the volume leveling, even though it sounds like it actually did change the volume level.
Exaxxion
Posts: 53
Joined: Sun Oct 16, 2005 5:47 pm

Post by Exaxxion »

Good question, and I believe I know the answer.

When you convert a file and select the volume leveling option, it analyzes the volume to find the difference between the volume of the original file and the dB specified in the Options menu under "Volume Leveling", which is necessary for the leveling process. It then uses the delta dB during the conversion process and levels the file while changing it to the different format. A possible explanation for the lack of a leveling value is that this process creates a new file; one which has not yet been analyzed. If I am correct about the process, then the new files, once analyzed, should show a leveling value of approximately 0.0, but depending on the quality of variables such as the conversion and the output format used, it would probably be in the range of -0.5 to +0.5 dB.

However, when you level the volume of an existing track, the process does not create a new file but probably stamps the file with a delta dB of 0. This is at least in part due to the process setting the volume equal to the volume specified in the "Volume Leveling" section, but there could be other more technical aspects to it as well, especially if it is not 0 dB, such as an analysis of the volume once the file has been converted. Clipping prevention could potentially be a factor during leveling, as it could prevent excessively loud or soft tracks from being leveled to the exact desired volume in an attempt to prevent range problems.

I hope this answers your question, Wolverine4580. :)
Wolverine4580
Posts: 10
Joined: Sun Jan 22, 2006 1:45 am

Post by Wolverine4580 »

That makes sense. In the case of volume leveling during audio conversion, the level is done to the original file, so when the new file is generated the volume is already at the desired level. The new file is never analyzed or leveled because it is not needed, so therefore the +/- stamp is never added to the new file. Not a big deal, but I use the leveling stamp to keep track of which tracks I've already leveled the volume on. I just convert the file first without leveling, then run the leveler on the new file so that the stamp is there.
Post Reply