Clipping using Rockbox on Sansa e200

[Gregory]

Originally, all my music was ripped as wma, and for some reason, I never noticed any clipping. 

Then I switched to Ogg Vorbis because it was just flat out better; Gapless playback and smaller filesize were my main reasons for switching.  To create the ogg files, I ripped my music as wav files, and then converted them using oggdropXPd. Worked great. 
But then I started noticing the clipping.

  The clipping I am hearing is not severe, but noticable, and it only occurs during the louder parts of my loudest cds.  I thought it was the ogg vorbis, but a quick test rip to wma vbr at the highest setting produced clipping as well.  I tried the wav files directly from the cd too.  It was still clipping.

I have compared rockbox to the cd in a portable cd player, my computer, and get this, even the original Sansa e200 firmware.  Rockbox was the only variable that was causing the clipping.  A reset of all settings didn't help either.  I uninstalled the bootloader, formatted the e200, reinstalled the bootloader, and started to install the latest e200 Rockbox firmware, but at this time, the e200 zip file is broken (of course).

I have done my best to eliminate variables, but it seems that rockbox is to blame.  Trust me, I don't want to believe it either.

Oh, and here is a link to the the track I was trying during all this: (EDIT: Look at post #11)
(It's hosted on my computer so I can't guarantee that it will always be up and running.)

[cpchan]

I am surprised that you didn't hear any clipping on your other equipment. After listening to it and taking a look at the waveform (attached is a screenshot with the "Find Clipping" and "Show Clipping" options in Audacity), I find a large amount of clippings in the file. The original source is a victim of the  "Loudness War"(http://en.wikipedia.org/wiki/Loudness_war).  I suggest you:

1. Replaygain your files with Vorbisgain: http://www.sjeng.org/vorbisgain.html

2. Turn on "Replaygain" and "Prevent Clipping" in Rockbox ("Settings"-> "General Settings"-> "Playback"-> "Replaygain".

To improve sound quality you might with to switch your encoder to AoTuV: http://wiki.hydrogenaudio.org/index.php?title=AoTuV. A quality level of -q 4 should do.

Charles

[Gregory]

That is not the problem.

Here is a line-in recording of the same file being played in the sansa firmware and then in the rockbox firmware: http://74.167.183.209/docs/sansa_vs_rock.wav
Listen carefully after the begining of the chorus;  that's the worst part.

It was recorded with a Creative Audigy sound card using asio drivers and a program called reaper.  Sound qaulity should not be an issue here.  Besides, the clipping is quite distinct anyway.

Also, here is the wma (vbr highest bitrate) of the song so someone can compare the two firmwares for themselves. http://74.167.183.209/docs/04-Fading%20Away.wma
By the way, I hear something that sounds like clipping at the beggining of the song in both firmwares, so ignore that.

My sister has the same player and Rockbox as well.  I'll see how that goes.

[saratoga]

I decoded it in rockbox and using the decoder in foobar2000:

max(pc-rb)
ans =
         3.0517578125e-005         3.0517578125e-005

On my Sansa, the output is identical to 15 bits for both channels.

If yours is not, then you've probably applied some additional gain in rockbox (via EQ, etc).

[Llorean]

That just means the decoder isn't the problem. We know the Codec in the e200 has been a little problematic to configure properly, and may be to blame still.

[Gregory]

Well, my sister's Sansa e200 does the same thing. 

saratoga:  I reinstalled rockbox completely to eliminate that variable.

Llorean: What do you mean by the codec?  Isn't that short for coder/decoder?  Or do you mean the DAC?  I don't exactly lnow the innards of a media player that well.

[saratoga]

Well, my sister's Sansa e200 does the same thing.  

saratoga:  I reinstalled rockbox completely to eliminate that variable.

Did you delete/rename the .rockbox folder first?

[Febs]

Gregory, could you post the contents of your config.cfg file?

[Gregory]

Saratoga: Would a format of the drive count?

Febs: Why would that matter if I re-installed rockbox and tried listening to the song right after?  But I'll upload it when I get home.

[Febs]

Febs: Why would that matter if I re-installed rockbox and tried listening to the song right after?  But I'll upload it when I get home.

No.  Simply re-installing Rockbox won't change stored settings, although formatting your drive should have reset the settings to default.  Nevertheless, it's worth taking a look at your config.cfg file if only to eliminate potential issues.

[cpchan]

Also, here is the wma (vbr highest bitrate) of the song so someone can compare the two firmwares for themselves.
By the way, I hear something that sounds like clipping at the beggining of the song in both firmwares, so ignore that.

I finally got a chance to listen to your wma file. Almost the whole file sounded clipped to me, so I decoded it to wav and looked at the waveform in Audacity. Like I suspect, this is the case (please refer to the screenshot, anything that is red is clipped). Are you using some sort of EQ setting that makes it sound worst to you in Rockbox? Also, what is your volume setting?

Charles

[Gregory]

I guess its only natural to not trust me, but the song clips in rockbox and nowhere else.  Given, the song is very loud and does probably clip some itself.  Maybe I haven't described what I'm hearing well enough.  It's like a popping or clicking, but what I am hearing only occurs in rockbox.  It's not throught the song either, only in certain places, which are generally the loudest parts.  One thing I notice too is that it mostly happens in the left channel, but it does happen in both.  I'm sure a different song might be the other way around, because of small recording differences in the studio.

Please listen to the commparison to see if you can hear it (dedicated host this time, lol).  http://files.filefront.com/sansa+vs+rockwav/;9529253;/fileinfo.html  What I hear in the comparison is exactly the same as what I hear when I'm listening with headphones.

The volume is ususally somewhere around -30db. The volume doesn't make a difference anyway.

The confg file is attached.

And just as a note, it occurs on other songs and albums as well, but not all of them.

[Gregory]

For now, I've found a pretty good solution and I'm disappointed that I didn't think of it before. 
I just enabled the eq, and set the pre-cut to about -2db.  1db may have been enough, but it looked a little close while watching the oscilloscope demo.  Cleared up the problem perfectly.

This solution should point toward a more permanent one, but I wouldn't know anything.

[Llorean]

Are you sure that the "nowhere else" doesn't just mean that other software intentionally goes out of its way to avoid clipping, while Rockbox just plays the audio as-is unless the user explicitly gives it instructions?