Rockbox Ports are now being developed for various digital audio players!
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...
This is one of the principles used in MP3 encodeing. Its really not surprising that many people didn't notice the sample rate problem.
Quote from: saratoga on March 31, 2006, 06:13:33 PMThis 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.
Amoung those that can hear them, sensitivity to them is generally very low. This is one of the principles used in MP3 encodeing.
Either people listen to music at ridiculously low bitrates, or have no clue on how to properly encode mp3s.
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.
Anyway, MP3 lowpass is configurable, but the spec clearly intends you to use no higher then ~15-16KHz, not 18KHz.
Its perfectly reasonable that many people using Rockbox would never notice a 22Khz sample rate, even listening to lossless audio.
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.
Quote from: saratogaAnyway, 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.
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).
Quote from: saratogaIts 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.
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.
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