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  1. #1

    noise after digitalizing into ADPCM from DVD player

    Dear all,

    I have a problem of audio noise, please give me some advice.

    I put the recorded file at http://cad.csie.ncku.edu.tw/~hsusc/noise.rar

    This file is from a device which digitalized the audio into MS ADPCM (44.1) from DVD player through RCA connectors. I recodered it with my NB. At begining, I thought the noise is distortion. But I lower down the vol., there are still noises in the noise.wav. The sound from DVD directly is much louder but almost have no noise.

    What is the cause of the noise? I tried to analysed the wav forms, and just found the it is not so smooth like DVD player's. Any suggestions about the audio quality are also welcome!

    Thanks!

  2. #2
    Administrator Dave's Avatar
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    Sorry, I can't open your file. Plus it is a whopping 12MB which will put a lot of people off from even trying. Are you able to take a small section of the audio and provide it in a wav or mp3 format?

    The noise could still be distortion even if it doesn't sound loud. Distortion can happen in a number of ways. Make sure there is no part of your audio chain which could be overdriving the signal.
    Dave Owen
    MediaCollege.com

  3. #3
    Hi! Dove,

    Thanks for your suggestion!
    I've reduced the file szie and updated the file links.
    the distortion one: <a href="http://cad.csie.ncku.edu.tw/~hsusc/noise.wav">
    http://cad.csie.ncku.edu.tw/~hsusc/noise.wav</a>
    the original DVD: <a href="http://cad.csie.ncku.edu.tw/~hsusc/DVD.wav"> http://cad.csie.ncku.edu.tw/~hsusc/DVD.wav</a>

  4. #4
    Senior Member SC358's Avatar
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    I just heard your recording. It sounds like your overdriving.... somewhere. Either your output is too high or your input is very low. It could also be an impedence mismatch from a balance line to unbalance line. Try re-recording at a lower level. If that doesn't make an improvement, then what type of cable and connectors are you using?
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  5. #5
    Hi! Dave,

    I'm so sorry that I made wrong typing.



    Hi! SC358,
    I'm not so familiar with audio, and I have several simple questions.

    What do the input and output mean? The input and output of my device, or of my PC? I've tried to lower done the input/output level of the device, but it doesn't work. noise.wav was recorded after I lower done the input level to -3db, and the output is 0db.

    And what are the balance line & unbalance line? Is it related to RCA line?
    The cable and connectors I used is RCA lines (or said AV cables), connect the device and DVD player directly.

    Thanks!

  6. #6
    Senior Member SC358's Avatar
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    Sorry for creating more confusion with my explanation, FranceHsu. I didn't mean to complicate things any further than necessary. The questions may be simple but the answer can be a bit more complicated.

    Quote
    Quote: FranceHsu
    What do the input and output mean? The input and output of my device, or of my PC?
    Output is in reference to the Source, while Input refers to the Target. Or Output = player and Input = recorder, if this makes sense. Somewhere your original audio is clean - your source. When you listened to the playback of your recording (input to the machine that made the recording) it got noisey. I try to remember & use the Source/Target method for many things.... gotta keep it simple!

    Quote
    Quote: FranceHsu
    I've tried to lower done the input/output level of the device, but it doesn't work. noise.wav was recorded after I lower done the input level to -3db, and the output is 0db.
    At this point, I'd recommend re-recording since the recording is unuseable - if you have a VU meter to watch your output levels, go by that and peak no higher than 0 VU. If that's not good enough, lower it till it sounds acceptable to you. The VU is an added visual monitoring device to give you a better sense of reference than your ear.

    Quote
    Quote: FranceHsu
    And what are the balance line & unbalance line? Is it related to RCA line? The cable and connectors I used is RCA lines (or said AV cables), connect the device and DVD player directly.
    Balance and unbalance lines have to do more with the grade of equipment, broadcast vs. industrial vs. consumer. With that in mind, that determines the type of cables and connectors. Your RCA cables are actually phono (plugs for males, jacks for females). RCA is an old brand name, just as Xerox is to photocopy machine. As long as your equipment source and target are both RCA (in your case), then we can eliminate an impedence mismatch.

    So give that a whirl and let us know how it goes.
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  7. #7
    Administrator Dave's Avatar
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    For some reason I am still having trouble with the files. I can open them but they won't play properly. Anyway, I'm a bit tied up with another project today so I can't hang around - I just thought it might be worth mentioning the following page if you haven't seen it already. It provides a general overview of distortion:

    http://www.mediacollege.com/audio/howto/distortion.html
    Dave Owen
    MediaCollege.com

  8. #8
    Senior Member SC358's Avatar
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    That's a great overview Dave. My advice at times (or most ) may be too... mysterious or perplexing to others because I'm use to conversing with other collegues and co-workers in the industry. Many explanations are not as simple as the questions since, one concept affects another, which affects another, etc.

    In any case, I'll try not to let it get out of hand - just hit me with a brick if I do!
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

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