XBMC Music Settings
#1
I hope this is the best place to post this in the forums.

I wanted to share my recent experience with audio quality replay problems and the XBMC.

I use XBMC exclusively as a Digital Music Server. I have a 300GB hard drive installed on the Xbox. The Xbox feeds a Sony 1070 A/V receiver via digital audio output out to a high-end Sony speaker system (ok...so, Sony is not known for high end speakers...but, these speakers are designed for SACD and reproduces trebles to 100,000 hz!!). I rip CDs using Exact Audio Copy with a FLAC front end...and take the time to make really good copies. I spent hours on A/B comparisons before I went down this path of fully embracing digital audio. And, was fully convinced that this XBMC set-up was virtually indistinguishable from the sound quality of my Sony 300-cd Mega changer connected via optical audio. As a matter of fact using the digital audio settings and send stereo to all speakers, the sound, although not SACD quality, sounded better than the CD player (and the benefit of having the Sony's cool blue multi-channel surround sound light come on!!).

Then, I bought the new Madeleine Peyroux CD "Careless Love."

The flac files when replayed via the Sony stereo produced unbelievably poor sound and distortion that sounded like a speaker blowing out.

I first thought that I must have introduced some distortion into the media transfer process. I upgraded EAC...upgraded FLAC...checked all ripping settings....reinstalled my disc drive..and re-ripped the CD.

The distortion was still there. I then played the CD directly via the Xbox....distortion still there....although the CD played pretty well via a Bose Lifestyle system in my game room...

Hmmmnn.....mystery?

Then I searched around for problems with the disc and found this CD review by George Graham.

http://georgegraham.com/reviews/peyroux.html

The "excessive volume compression" issue explained the phenomenon. Click on the explanation within the review on excessive volume compression for some interesting background on the subject.

So, I searched on the forum here and read a thread where Mr. Jonathan Marshall suggested turning down the preamp gain.

I made some tweaks to the Music Settings and voila.....the sound is once more incredible!!Nod

I changed the My Music settings as follows.

Replay Gain Mode - Enabled -- to Track Level Option (more on this setting below).

Pre-Amp Level Replay Gained Files - turned down to 80db.

Pre-Amp Level Non-Replay Gained Files - turned down to 80db.

Avoid Clipping on Replay Gained Files - Enabled.

Now....I don't know why the Replay Gain Mode toggle made a difference, as I never introduced "replay gain" into the media transfer process...but, it made a HUGE difference. Perhaps there is some default gain added on particular CDs??

I also noticed a significant improvement on Corrine Bailey Rae's recent CD....especially on the first track when strong bass kicks in.

ClearSong
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#2
You need to enable Replay Gain support for the "Pre-Amp Level Non-Replay Gained Files" to work. This represents the gain level to be used on files which have no Replay Gain tag (which according to your description is your entire digital music collection.) Since you dont have any Replay Gain tags present, it shouldn't matter which selection you pick (Track or Album).
Always read the XBMC online-manual, FAQ and search the forum before posting.
Do not e-mail XBMC-Team members directly asking for support. Read/follow the forum rules.
For troubleshooting and bug reporting please make sure you read this first.
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#3
All the preamp gain for non-replay gain files does is apply gain (positive or negative, depending on the difference from 89dB).

If you have it set on 80dB, then it is effectively reducing all the sound by 9dB. This is identical to dropping the volume control by 9dB.

The only possible source of distortion in the XBMC output process is the resampling to 48kHz. It is conceivable that when resampling a very compressed music source that some of the output may go past the digital maximum, and thus produce a small amount of clipping. As the replay gain is applied prior to resampling, dropping the source range by a few dB means that this possible clipping will not occur.

Cheers,
Jonathan
Always read the XBMC online-manual, FAQ and search the forum before posting.
Do not e-mail XBMC-Team members directly asking for support. Read/follow the forum rules.
For troubleshooting and bug reporting please make sure you read this first.


Image
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#4
Thank you both for your confirming responses.

kraqh3d, that explains the Replay Gain question.

Jonathan, that explains the resoution that I found for CDs suffering from excessive volume compression.

Thanks again for helping to build and maintain an incredible platform for managing, organizing, and playing digital media!

XBMC rocks!!
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#5
the flac frontend has replaygain on by deafult, maybe you encoded your files with it and did not realise? if you would like to use replaygain in the future but batch encode albums then the frontend probably isnt the best way to add the RG tags, foobar2000 would be my reccomendation as its fast and easy to use if you dont like foobar i think jriver's media center/player also does rg tagging but works to the old value of 83db rather than the current standard of 89.
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#6
wayland,

The FLAC front end has an option for replaygain. However, I have never turned it on.

So...excessive CD volume compression appears to be the culprit here.

If you haven't reviewed the article that I referenced above by George Graham.

Found here....

http://georgegraham.com/reviews/peyroux.html

....you'll find some interesting information and insight into other CDs that experience excessive compression. I only ran into this in the last fortnight = of the plus 850 CDs on my harddrive only a handful had this affliction.

ClearSong
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#7
As a recording and mastering engineer I can vent a bit of my frustration on this issue here.

As the years have gone by the pressure to make albums louder and louder has increased. In the end all this really achieves is to ruin any sense of dynamics (the difference between quiet and loud parts). If you listen to rock recordings from the 70s against more current recordings you will certainly notice this. Obviously this applies more to certain styles of music than others but the trend continues to make music have less of an impact when it "kicks in". If you want it louder, turn up your sound system! It is a pretty recent thing with digital players, etc, that people have listened to tracks from different recordings one after another. This makes people think, wow, this track is quiet or this track is loud. The fact is they are just different. Certainly some recordings are just quieter(not less dynamic) than others which is why the replay gain idea came about(but can also throw off dynamics between songs from the same album).

Sometimes I think if I have one more client ask to make their album louder I'll shoot myself.

Ok, I feel better now. Wink
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