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I am getting slightly (not bad but noticeable none the less) distorted audio on playback. At first I thought it might be simply the small speakers on this laptop but ...
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  1. #1
    oxf
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    Distorted audio from media players


    I am getting slightly (not bad but noticeable none the less) distorted audio on playback. At first I thought it might be simply the small speakers on this laptop but its present using good quality headphones as well so its obviously the audio output itself. I'm using Ubuntu 9.04 and this happens with both Rhythmbox and Banshee.

    OK I know you cant tell me what's wrong based on the brief info above. But how do I start to to track problem down? Is there anything I should check, enter code into terminal to get more info? Or check installed libs etc. So where do I start?

    Thanks
    Mike

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    oxf
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    What's frustrating about this little problem is two things. First the distortion isn't that bad but it is definately there. Its sounds more like a slight "gravely" edge to the audio.

    But the other thing is at one time I had perfect quality even on the little speakers in this lap top. I got thinking about this last night trying to remember if there was a point when it suddenly occurred. I can think of anything ...except.. I did install 9.04 Jaunty (previous Hardy) in late June. I cant say for sure theres a direct correlation as I wasnt using media at that time much but the timing does seem about right. I wonder if there are any audio quality issues in 9.04 vs 8.10/8.04? Of more concern to me right now how do I start worling on this?

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    oxf
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    Well I fixed the problem...I think! Poking around I right clicked on the speaker icon and opened volume control. I got a range of sllders for volume input/ouput etc. I noticed that the PCM one was right up at maximum and when I backed it off to about 70% it took care of the distortion. Obviouslly something was being over driven, makes sense.

    But what exactly is PCM? and how does it relate to my distortion problem? Just curious so if someone woould kindly fill me in
    Thanks..
    Mike

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    Linux Guru reed9's Avatar
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    PCM = Pulse Code Modulation.

    I don't know much about it, but to quote this site
    Quote Originally Posted by Richard Ragon
    Pulse-code modulation (PCM) is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code.
    Basically the PCM device is how digital audio is represented in your system.

  6. #5
    oxf
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    Quote Originally Posted by reed9 View Post
    PCM = Pulse Code Modulation.

    I don't know much about it, but to quote this site

    Basically the PCM device is how digital audio is represented in your system.
    OK thanks! I assume from that then that the PCM sampling is at the input and I was simply overdriving the input by having it up at max.

    Mike

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