[Funky-kun]

I've been using foobar2000 for a couple of years now, and something has caught my attention.
 
I generally play my music shuffled. Sometimes, apparently randomly, within 1 second of the start of a track the volume level seems to change. I think it only decreases. Even if I play the previous track and switch to the same track again, the same thing does not occur twice in a row. Because of this it has been really hard to analyze what's happening.
 
This phenomenon happens on 2 different systems - my old rig with Asus Xonar Essence STX + ASIO output, and also on my laptop with WASAPI event output to Behringer UCA202 / ODAC.
 
All my tracks are scanned for RG, I use track as source and have set it to prevent clipping according to peak for the mp3s in my library, and occasionally apply gain.
 
My DSP chain looks like this:
 
HDCD Decoder
Convert 5.1 to stereo
Convert mono to stereo
Resampler (SoX) mod
VST bridge (for SPAN spectrum analyzer)
George Yohng's VST Wrapper (currently don't use any VST through it, but do so from time to time)
 
I use 1000 ms of buffer for stability's sake. Related in any way?
 
I use the latest version of DarkOne skin and have set automatic download of album and artist art. Could this affect playback in any way? I doubt it, both systems were beefy (Q9550 /w 4 gb ram, i7 2630 /w 6 gb ram)
 
Has anyone else noticed something like this? If not, any ideas what can cause this? Could it be that RG is applied with some delay in playback?

 

[NA Blur]

The first thing to try is another player even if it is winamp or media player.  This will tell you if it is Foobar2000 or something else.
 
Also take note what file it happens on and how compressed if any it is.  I have had issues using Foobar2000 with my m903 with wav files.
 
I do think either the buffer or other delays related to memory usage may be the cause here excluding any equipment issues.  Perhaps change the buffer to 500ms, bit depth to 16-bit, and play an audio CD through your CD player on your PC.
 
Report back with your findings.

 

[Funky-kun]

It happens only with foobar2000. Currently with latest version.
 
It certainly has happened with flac files, not too sure about mp3s, as they are a small part of my library, and it happens randomly. It also only occurs when a track ends and another one starts at random, and never when I manually change tracks.
 
I think this doesn't occur with replay gain set to apply gain. However, I can't really understand why the volume would be attenuated on a flac file. AFAIK mp3s can clip because of the compression, but can the same happen in a flac file?
 
A big part of the problem is that it occurs randomly and relatively rarely. I listened for this effect in the past 2 days, and it didn't occur once. 
 

 

[Funky-kun]

Managed to isolate an occurrence of this, at last!
 
Replaygain mode: prevent clipping according to peak
Source: track
Output: WASAPI (event): ODAC
Buffer: 1000 ms
Same DSP chain as in first post.
 
Playback order: random
When "KMFDM - Megalomanic.flac" ended, the next track was "The Prodigy - Mindfields.flac". Within 1 second of the start of the song, volume was lowered. 
 
 
 
More info on tracks:
 
KMFDM - Megalomanic.flac
 
 
Duration : 6:07.640 (16 212 924 samples)
Sample rate : 44100 Hz
Channels : 2
Bits per sample : 16
Bitrate : 1018 kbps
Codec : FLAC
Encoding : lossless
Tool : reference libFLAC 1.1.2 20050205
Embedded cuesheet : no
Audio MD5 : 736FDEE72E479A707DDC4FBC7275F854
 
Track gain : -8.21 dB
Track peak : 0.980072
 
 
 
 
The Prodigy - Mindfields.flac
 
Duration : 5:39.893 (14 989 296 samples)
Sample rate : 44100 Hz
Channels : 2
Bits per sample : 16
Bitrate : 986 kbps
Codec : FLAC
Encoding : lossless
Tool : reference libFLAC 1.1.3 20061120
Embedded cuesheet : no
Audio MD5 : 7C398E78A5C24ADAA218B38D76324DF4


 
Track gain : -7.86 dB
Track peak : 1.000000
Album gain : -9.64 dB
Album peak : 1.000000
 
EDIT: Mindfields just started on random playback again, and no volume change at all.