PDA

View Full Version : Replaygain: Strange mp3 tag behaviour



Aztek
2009-10-10, 14:09
Hi - I have something weird happening in my mp3 tag info with regards to Replaygain that I need some help on. Basically, I'm getting some inconsistent information appearing between Foobar 2000 and how Squeezecenter is displaying the tag info on my Squeezebox. I suspect that there is hidden file tag info that I can't see on Foobar that is being read by Squeezecenter. Here's my examples:

Ultravox - track - The Voice
Foobar info
bitrate = 192
codec = MP3
channels = 2
samplerate = 44100
mp3_stereo_mode = joint stereo
replaygain_track_gain = -7.51 dB
replaygain_track_peak = 1.030118

However, when I look at the tag info via the Squeezebox - it tells me that the Volume Adjustment is -14.47

Next example
Uncanny X-men - track - Work
Foobar info
bitrate = 192
codec = MP3
channels = 2
samplerate = 44100
mp3_stereo_mode = joint stereo

Via the Squeezebox - Volume Adjustment is -4.57dB - even though Foobar says there is no Replay Gain info

Finally,
Urban Verbs - track Subways
Foobar infobitrate = 320
codec = MP3
channels = 2
samplerate = 44100
mp3_stereo_mode = joint stereo
replaygain_track_gain = -3.45 dB
replaygain_track_peak = 1.019146
replaygain_album_gain = -8.20 dB
replaygain_album_peak = 2.744117

Via Squeezebox - the same - 3.45 dB

Can anyone please advise if it is possible for my mp3 tags to contain Replaygain data that may not be read by Foobar 2000 or why it is being displayed differently?

Many thanks

chitunes
2009-10-10, 14:48
Hi - I have something weird happening in my mp3 tag info with regards to Replaygain that I need some help on. Basically, I'm getting some inconsistent information appearing between Foobar 2000 and how Squeezecenter is displaying the tag info on my Squeezebox. I suspect that there is hidden file tag info that I can't see on Foobar that is being read by Squeezecenter. Here's my examples:
~~~~~~~~~

Can anyone please advise if it is possible for my mp3 tags to contain Replaygain data that may not be read by Foobar 2000 or why it is being displayed differently?

Many thanks

I've always had the same problem with the Duet's and Squeezecenter's volume adjustment readings. In addition, with any of the ReplayGain settings turned on, the volume is adjusted down in excess IMO. Turning up the volume on the controller helps somewhat.

I've posted this question before, but unfortunately, the problem seems to be a baffler.

I'm with Aztek - any ideas, workarounds would be appreciated.

Aztek
2009-10-10, 16:25
I've had some success with fixing the problem but still don't understand it. After doing quite a bit of Googling - I found that there is probably some correlation between Ape V2 tags and Lame header information. While I can't display what I was seeing in Foobar - I found by removing all Tag information with Mp3tag, then adding new ID3 tags and then applying replaygain with Foobar - I got the correct settings displayed on my Squeezebox.

I tried the above on the Ultravox track in my example and now it is showing -7.51dB in Squeezebox instead of the -14.47dB that was there earlier. Once I had made the changes I rescanned my music and voila - it is all fixed.

I don't intend to do this across my entire collection but as tracks come up that sound much lower in volume than the rest - then I will use the above method and tool to get it sorted.

chitunes
2009-10-11, 12:20
I've had some success with fixing the problem but still don't understand it. After doing quite a bit of Googling - I found that there is probably some correlation between Ape V2 tags and Lame header information. While I can't display what I was seeing in Foobar - I found by removing all Tag information with Mp3tag, then adding new ID3 tags and then applying replaygain with Foobar - I got the correct settings displayed on my Squeezebox.

I tried the above on the Ultravox track in my example and now it is showing -7.51dB in Squeezebox instead of the -14.47dB that was there earlier. Once I had made the changes I rescanned my music and voila - it is all fixed.

I don't intend to do this across my entire collection but as tracks come up that sound much lower in volume than the rest - then I will use the above method and tool to get it sorted.

I use only mp3gain and aacgain. As you pointed out, there seems to be a bug in the reading of tags. Some posts from earlier this year suggested that mp3gain tags aren't properly read, so SC applies it a second time, which could account for the doubling of the dB adjustment. Non-tagged tracks seem to adjust properly. Just an observation.

My workaround is to continue using mp3 and aacgain and just disable the volume adjustment on the controller.

bobkoure
2009-10-12, 05:23
If you have APE and MP3 tags with the same name, how do you read them - in the sense of which one overrides the other?
Every tag reading/writing app (including squeezebox) seems to have a different order.
So, you get mysterious tag values.
If you use mp3tag, there's a way to convert all APE tags (or, I think all MP3 tags) in favor of the other. Look in the wiki for a how-to.
Note that, once you've setup mp3tag to do this, the operation is as simple as open folder / select all / save. So it's pretty quick and painless

andyg
2009-10-12, 05:48
If you still have a file that gives you the wrong value, please file a bug and attach the file.

There is one case where gain values can be added together, and that is if you have iTunes SoundCheck data and an RVAD or RVA2 tag.

The basics are that if you have a REPLAYGAIN_TRACK_GAIN tag (in either ID3v2 or APE) it will be used as-is. If not, we look for RVAD or RVA2 and take that value. Then we look for iTunes SoundCheck data in a comment tag, if found this is added to the value from RVAD/RVA2 if any (we do this because that's what iTunes does). LAME tag data is not used.

So for best results, you simply need to run your files through Foobar or another app that writes a set of 4 REPLAYGAIN gain and peak tags.

MrSinatra
2009-10-12, 19:44
i use mostly mp3s and i remove all tags EXCEPT id3v2.3 tags

however, mp3s have a "lame header" and lame will calculate a value for RG that it puts in the header. however, as far as i know, this header, or at least the RG value in it, is completely ignored by SBS.

i don't let itunes touch my files. i use winamp to apply the 4 related RG tags to my files that andy is talking about.

so far i haven't noticed any SBS issues doing it this way, but i will now spot check it here and there. however, i'd guess the answer is in your files, not SBS.