Sound quality changing while converting into wav

Discussion in 'Audio' started by trunten, Jul 2, 2003.

  1. trunten

    trunten Member

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    It may be the convertors I'm using (Nero and the wav convertor in Winamp), but every time I convert something the sound gets an obvious change in sound quality.

    I've tried some other convertors recently and it put out the same .wav files, if not worse. Anyone have a solution to this?
     
  2. tigre

    tigre Moderator Staff Member

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    Sound quality shouldn't change noticably using Nero. Probably you use some EQ or other DSP for playback.

    Another convertor you could try is foobar2000's diskwriter (http://foobar2000.hydrogenaudio.org). It uses 64bit floatingpoint resolution internally and dithers output (ATH noiseshaped if selected) and should give best possible results.

    One reason for your problem could be clipping. Use Mp3Gain or foobar2000's built in replaygain feature to prevent clipping during playback/decoding.

    If it's something else you could try this: Encode one of your CDs (ideally using EAC + lame --alt preset standard %s %d or higher) and burn an audio-CD from the encoded mp3s. Listen to both on your HiFi to find out if there's still a difference.
     
  3. trunten

    trunten Member

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    Ah! Foobar helped a lot. The 64-bit and 32-bit floating point conversions, however, didn't go to well. The sound became distorted when certain sounds get too high (e.g. guitars and cymbals), but the regular 32-bit conversion worked nicely. I don't hear any changes.

    Thanks!
     
  4. tigre

    tigre Moderator Staff Member

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    If you want to convert lossy compressed audio (e.g. mp3) to .wav for creating audio CDs you want to convert to use 16bit output resolution as audio CDs use this format and fb2k does a good job on converting to 16bit internally. Compared to 32bit output you save space and get best possible quality.

    Ah! This is a sign that your problem is caused by clipping.

    FYI: In audio CD format sample values are between -32768 and 32767. Today (mainstream) CDs are mastered at (too) high volume. Because of this parts of the waveform that exceed the +/-32767 range are "cut" to +/-32767. This is called clipping, the sound (if audible) is comparable to distorted heavy metal guitar amplifiers. Lossy encoding adds (normally inaudible) noise to the original signal, but if this noise causes additional clipping (on playback/decoding) the sound quality is changed as you noticed.

    Best way to avoid this (and to get best sounding .wavs from .mp3s with fb2k:)
    1. Load songs to playlist and highlight them
    2. Rightclick -> Replaygain -> Scan ... (depends on what you need)
    3. Rightclick -> Convert -> Settings
    ---> Output format: Wav (PCM 16bit dithered)
    ---> Processing: [x] use Replaygain, other options (DSP ...) as needed
    4. Rightclick -> Convert -> Run Conversion
     

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