Rockbox Technical Forums

Support and General Use => Audio Playback, Database and Playlists => Topic started by: PinkZeppelin on March 26, 2006, 01:12:07 PM

Title: Constant clicking problem (ipod 5g)
Post by: PinkZeppelin on March 26, 2006, 01:12:07 PM
Is it normal for the DAC to make a moderately loud popping noise when shutting down rockbox?
Title: Re: DAC pops when shutting down
Post by: PinkZeppelin on March 26, 2006, 01:30:08 PM
Also there seems to be a constant low background clicking noise.  Turning the volume up also creates a louder clicking noise that occurs whenever I move around the scroll wheel.

I am using an Apple 5G
Title: Re: DAC pops when shutting down
Post by: PinkZeppelin on March 26, 2006, 02:44:00 PM
Well, the DAC popping on shutdown occurs in the Apple Firmware as well, so I guess it isn't a rockbox thing, so it is really a non-issue.

But the low clicking noises and wheel moving noises do not occur in the apple firmware. 

Does anyone else hear the low constant clicks and wheel movement clicks in rockbox?
Title: Re: DAC pops when shutting down
Post by: linuxstb on March 26, 2006, 03:02:10 PM
Well, the DAC popping on shutdown occurs in the Apple Firmware as well, so I guess it isn't a rockbox thing, so it is really a non-issue.

Just because the Apple firmware also has a certain bug doesn't mean we shouldn't try to fix it in Rockbox...

Quote
But the low clicking noises and wheel moving noises do not occur in the apple firmware. 

Does anyone else hear the low constant clicks and wheel movement clicks in rockbox?

Some people have reported this before - but others (including me) don't experience it.  What iPod do you have, and what kind of music files (format and bitrate) ?  Do you get those clicks with all your files, or just some?
Title: Re: DAC pops when shutting down
Post by: PinkZeppelin on March 26, 2006, 03:35:13 PM
Some people have reported this before - but others (including me) don't experience it.  What iPod do you have, and what kind of music files (format and bitrate) ?  Do you get those clicks with all your files, or just some?

I am using an Ipod Video 5G (black), virtually all my music is in Wavpack, but the clicking starts right after the unit is turned on, regardless of codec. 

The sound is a constant, quiet and rhythmic clicking and seems to only occur on the right side of my cans (Sennheiser 280Pros).  The wheel movement noise is easy to reproduce - pause music,  then turn up the volume.  I start hearing a faint clicking noise (this noise also seems only to be in the right channel of my headphones) while moving the wheel when I turn the volume to -11db.  Increasing the volume further makes the wheel noise much more pronounced, and also increases the rhythmic clicking volume. 
Title: Re: DAC pops when shutting down
Post by: obo on March 26, 2006, 03:44:01 PM
I've put a patch together to stop the pop on shutdown.

http://www.rockbox.org/tracker/task/4819 (http://www.rockbox.org/tracker/task/4819)
Title: Re: DAC pops when shutting down
Post by: PinkZeppelin on March 26, 2006, 07:23:19 PM
Anyone have a solution to (or can confirm) the problem with the constant low clicking noises?  ???
Title: Re: Constant clicking problem
Post by: PinkZeppelin on March 27, 2006, 07:56:29 PM
has anyone investigated?  :-\
Title: Re: Constant clicking problem
Post by: PinkZeppelin on March 28, 2006, 01:42:45 AM
I wrote up a bug report:

http://www.rockbox.org/tracker/task/4937
Title: Re: Constant clicking problem
Post by: PinkZeppelin on March 30, 2006, 01:02:18 AM
No responses?  :(

Using RMAA, I analyzed both the apple firmware and the rockbox firmware on my 5G.

Results:


Original Apple Firmware:

(http://img93.imageshack.us/img93/9042/applefirmwarec6xy.png)

Rockbox Firmware:

(http://img63.imageshack.us/img63/9149/rockboxc3mf.png)

It is easy to see the constant low clicking here in the rockbox firmware.

Same picture (Rockbox Firmware) with the clicks circled:

(http://img148.imageshack.us/img148/2394/rbhighlightc6ky.png)

The pictures are resized above, and may be a bit hard to see.  Unresized links:

Apple Firmware:
http://img93.imageshack.us/img93/9042/applefirmwarec6xy.png

Rockbox Firmware:
http://img63.imageshack.us/img63/9149/rockboxc3mf.png

circled:
http://img148.imageshack.us/img148/2394/rbhighlightc6ky.png

The clicking does only seem to be coming from the right channel, as these pictures show.

Others should be able to see, hear, and do these same measurements as well. 

Comments?

Title: Re: Constant clicking problem
Post by: lostlogic on March 30, 2006, 10:15:25 AM
As we discussed on IRC, I believe this to be related to our slow I2C implementation, and occurs when the battery status and/or realtime clock are updated (the battery is read at up-to 2.5hz and the clock at up-to 1hz).  Nothing is going to change with it until someone spends a lot of time analyzing the portalplayer's I2C control registers, or finds a datasheet for the damned thing.
Title: Re: Constant clicking problem
Post by: TREX666 on March 30, 2006, 01:28:10 PM
So rockbox will never run as fast as it should with the current I2C implementation. Unless Portalplayer hands over datasheets
Title: Re: Constant clicking problem
Post by: PinkZeppelin on March 31, 2006, 02:02:41 AM
damn, it looks to be a lot of work to fix the problem.  I dearly hope someone is willing to go through the code or find the datasheet. 

Because of the background clicking problem, I have reverted to using the apple firmware w/ 1 giant, inefficient apple lossless file per album (due to lack of gapless playback). 

Needless to say, it sucks.

I pray someone will be able to fix this...
Title: Re: Constant clicking problem
Post by: lostlogic on March 31, 2006, 04:24:29 PM
Going through the code won't help -- I've been through it... this involves either getting the datasheet, or disassembling the apple firmware, or painstakingly trying bit combinations to control the portalplayer i2c driver.

I for one can't detect the clicking no matter what volume I use on my shure E3 in-ear monitors, so I can also suggest using a lower impedance pair of earphones.
Title: Re: Constant clicking problem
Post by: PinkZeppelin on March 31, 2006, 06:08:01 PM
i was able to detect the constant clicking easily with my EP-630s when turning up to otherwise earsplitting volumes - but, as said before, could hear it at normal listening volumes on my HD280 pros.   

Now, if you arent able to hear it at the highest volumes, maybe it was a problem with my player.  If you record back your ipod in rockbox playing the RMAA file, normalize if needed, then check the spectral graph of the file, then it would answer that question.

Nevertheless, I returned my 5G.  I was bothered by the clicking in the rockbox firmware and the lousy apple firmware.  I still have my H140, but there is deep bass hum whenever the harddisk spins in the rockbox firmware (ill run RMAA tests and make a thread in the appropriate section later). 

Because of the sound noise problems I have found in both flavors of rockbox (both on my H140 and the Ipod 5G), and the fact that even some people (including at least 1 rockbox developer) seemed to think the X5 sounded fine when it was playing back with a 10khz lowpass filter make me a bit skeptical about rockbox audio quality claims...
Title: Re: Constant clicking problem
Post by: saratoga on March 31, 2006, 06:13:33 PM

Because of the sound noise problems I have found in both flavors of rockbox (both on my H140 and the Ipod 5G), and the fact that even some people (including at least 1 rockbox developer) seemed to think the X5 sounded fine when it was playing back with a 10khz lowpass filter make me a bit skeptical about rockbox audio quality claims...


Many people cannot hear high frequencies well or at all, and do not use good headphones.  Amoung those that can hear them, sensitivity to them is generally very low.  This is one of the principles used in MP3 encodeing. 

Its really not surprising that many people didn't notice the sample rate problem.
Title: Re: Constant clicking problem
Post by: PinkZeppelin on March 31, 2006, 06:23:13 PM
This is one of the principles used in MP3 encodeing. 

Its really not surprising that many people didn't notice the sample rate problem.

Mp3 encoding is supposed to have a lowpass around 18khz, not 10khz.  Either people listen to music at ridiculously low bitrates, or have no clue on how to properly encode mp3s. 

Title: Re: Constant clicking problem
Post by: lostlogic on March 31, 2006, 10:53:48 PM
The only claim I know of that rockbox makes about audio quality is that unlike many stock firmwares, we do not futz with the audio output of the codec, we simply play it back to the hardware as is (unless you turn on the various 'enhancement' options available).

As for the H140 buzz, that occurs with stock and rockbox firmwares as far as I know (at least it did on my H340), so don't try to pin that on rockbox, it's a problem with isolation on the iRiver players.

Finally, I do not doubt that the clicking problem occurs, as I said, we have a known issue with our I2C driver which could cause such a problem.  When using Rockbox, you need to realize that it is a _free software_ project.  It is developed for fun.  If you have a problem with it, fine, but don't act _entitled_ to a fix or  change to rockbox behavior.  You are more than welcome to develop your own solution, as the source is there for your modification.

I (unfortunately) do not have the software, hardware, nor knowledge to do RMAA analysis of my player, but I would be interested in other datapoints on the clicking issue.
Title: Re: Constant clicking problem
Post by: Llorean on March 31, 2006, 10:56:47 PM
Also, keep in mind that Rockbox has not been RELEASED yet. On ANY of the software codec targets. While it's at version 2.5 for the Archoses, the overall 3.0 will be version 1 for the iRivers, and 3.1 will be the first release for the iPods. Until then, you shouldn't *expect* anything to work a specific way, or even at all. So while bug reports are welcome, you are using a prerelease software, and should keep that in mind at all points in time.
Title: Re: Constant clicking problem
Post by: saratoga on March 31, 2006, 11:28:16 PM
This is one of the principles used in MP3 encodeing. 

Its really not surprising that many people didn't notice the sample rate problem.

Mp3 encoding is supposed to have a lowpass around 18khz, not 10khz.  


Please don't misquote me.  What I said was:

Quote
Amoung those that can hear them, sensitivity to them is generally very low.  This is one of the principles used in MP3 encodeing. 

Note that I said people had low sensitivity, not that they were lowpassing all high frequency sounds.  Theres a very big difference between the two. 

Anyway, MP3 lowpass is configurable, but the spec clearly intends you to use no higher then ~15-16KHz, not 18KHz.  Even if you force the lowpass higher, very little high frequency content is encoded (or rather very little bitrate is allocated due to the sfb21 issue in the MP3 format).  For this reason, when you FFT MP3 encoded audio, even with LAME, much of the energy above 16KHz is actually noise.

Quote
Either people listen to music at ridiculously low bitrates, or have no clue on how to properly encode mp3s. 

Or, as I already suggested, they're insensitive to higher frequency sound.

You may be interested in looking at the equal loudness curves here:

http://en.wikipedia.org/wiki/Absolute_Threshold_of_Hearing

or the information here:

http://en.wikipedia.org/wiki/Psychoacoustics

Note that high frequency sensitivity drops off VERY quickly with age.  You're already well past your prime by the time you're 20.  By age 40, the average male has already lost 10 fold as much high frequency sensitivity as they've lost at low frequencies. 

Its perfectly reasonable that many people using Rockbox would never notice a 22Khz sample rate, even listening to lossless audio.
Title: Re: Constant clicking problem
Post by: PinkZeppelin on April 01, 2006, 04:08:10 PM
Quote from: lostlogic
The only claim I know of that rockbox makes about audio quality is that unlike many stock firmwares, we do not futz with the audio output of the codec, we simply play it back to the hardware as is (unless you turn on the various 'enhancement' options available).

As for the H140 buzz, that occurs with stock and rockbox firmwares as far as I know (at least it did on my H340), so don't try to pin that on rockbox, it's a problem with isolation on the iRiver players.

Finally, I do not doubt that the clicking problem occurs, as I said, we have a known issue with our I2C driver which could cause such a problem.  When using Rockbox, you need to realize that it is a _free software_ project.  It is developed for fun.  If you have a problem with it, fine, but don't act _entitled_ to a fix or  change to rockbox behavior.  You are more than welcome to develop your own solution, as the source is there for your modification.

I (unfortunately) do not have the software, hardware, nor knowledge to do RMAA analysis of my player, but I would be interested in other datapoints on the clicking issue.

I just ran some tests on my H140 and the bass hum does indeed to effect both original and rockbox firmware, so I did erraneously pin that on rockbox. 

I am not upset at rockbox development, I am just upset when people claim that the audio sounds fine when it is not true, or when I make threads like this and don't get answers until I actually measure the problem.  It would have been nice to know that the H140s had a buzzing problem before I purchased it last year (but that is not really anyones fault).

Quote from: saratoga
Anyway, MP3 lowpass is configurable, but the spec clearly intends you to use no higher then ~15-16KHz, not 18KHz.

I don't think that is quite right.  Using the standard (and recommended) Lame 3.97b encoding setting, the resulting mp3s have a lowpass around 19khz.

Quote from: saratoga
Its perfectly reasonable that many people using Rockbox would never notice a 22Khz sample rate, even listening to lossless audio.

I think virtually nobody could discern anything above even 18khz, which is why many lossy encoders aim at transparency by using a lowpass around those frequencies.   


Nevertheless,

Thank you lostlogic for explaining the clicking problem.  I'm now looking into a purchase of an X5, just need to have someone post a spectral view like I did to confirm that there are no audio anomalies.
Title: Re: Constant clicking problem
Post by: saratoga on April 01, 2006, 07:44:34 PM


I am not upset at rockbox development, I am just upset when people claim that the audio sounds fine when it is not true, or when I make threads like this and don't get answers until I actually measure the problem. 


Then you're welcome to hire someone to document your bug reports for you. 

Quote
Quote from: saratoga
Anyway, MP3 lowpass is configurable, but the spec clearly intends you to use no higher then ~15-16KHz, not 18KHz.

I don't think that is quite right.  Using the standard (and recommended) Lame 3.97b encoding setting, the resulting mp3s have a lowpass around 19khz.

Not to be an ass, but read the whole paragraph.  The very next sentence literally explains why you're misunderstanding the issue:

Quote
Even if you force the lowpass higher, very little high frequency content is encoded (or rather very little bitrate is allocated due to the sfb21 issue in the MP3 format). 

As I said, you can set the lowpass in LAME to whatever you want.  That doesn't mean you're getting much but noise above ~15-16k.  If you're still confused, google sfb21.  Its a well documented flaw in the MP3 format, and there are plenty of people who have explained it better then I.

Quote
Quote from: saratoga
Its perfectly reasonable that many people using Rockbox would never notice a 22Khz sample rate, even listening to lossless audio.

I think virtually nobody could discern anything above even 18khz, which is why many lossy encoders aim at transparency by using a lowpass around those frequencies.   

I don't disagree, but I don't think you understood my post.  I was talking about sample rate, not low pass (sample rate must be > 2x lowpass).
Title: Re: Constant clicking problem
Post by: Llorean on April 01, 2006, 08:05:23 PM
Zep: A lot of time when you complain about audio quality, it's something you can only here with high impedence phones or other situations where not everyone notices it. Also, a lot of the developers use their Archoses, or other older players, as their primary listening, possibly even while in the process of testing things on-target for newer devices. So, sound related issues that are faint (and the ticking is something I don't hear, though I have heard the volume clicks) don't get noticed.

Then there's the fact that unless it's something very noticeable to *everyone* it's almost impossible to pin down what causes it. If and when you put up full documentation like the graph you did, it is *incredibly* helpful for finding out what's wrong. In any project it's always asked that you provide as much information about a bug, and a means of reproducing it. So, yeah, you didn't get a response until you measured the problem. But many MANY people have complained about the sound in Rockbox, and then when asked to measure it in the past, have come back with results that show it was identical. So, you'll have to forgive the developers here for taking complaints about sound quality with a grain of salt, but when you're used to people telling you Rockbox sounds like a "bag of shit" you start to want some evidence as to what *exactly* is wrong with the audio, so that not only you have proof it is wrong (if it doesn't show up in your phones) but also so you know where to begin looking for the problem.
Title: Re: Constant clicking problem
Post by: lostlogic on April 02, 2006, 12:02:14 PM
Patience is of the essence here... the I2C driver problem that I believe to cause the clicking on ipod is something that needs fixing for many reasons (all of which are better than a -100dB clicking that is only audible with 100ohm earphones), I'm sure that I or someone will be working on the issue, but it could be a year before it changes.

It would probably make sense to use a headphone amp with your ipod in the meantime as the low impedence of the amp would eliminate the click.
Title: Re: Constant clicking problem
Post by: travishayes89 on April 02, 2006, 11:46:58 PM
all i know about the clicking is that if you turn the appropriate option off in the stock firmware you should get no clicking in it, and i never heard a clicking in Rockbox even with a pair of Sony "studio monitors" (i didn't feel like looking for the number).
Title: Re: Constant clicking problem
Post by: PinkZeppelin on July 18, 2006, 11:56:49 AM
Patience is of the essence here... the I2C driver problem that I believe to cause the clicking on ipod is something that needs fixing for many reasons (all of which are better than a -100dB clicking that is only audible with 100ohm earphones), I'm sure that I or someone will be working on the issue, but it could be a year before it changes.

haven't been here in a while, just checking to see if any progress has been made so far?