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Audio playback with SX & EEPROM

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  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-03-04 05:14
    Silly question, is the constant tone high pitched? ...Anywhere near 8kHz?

    If so, you might need a simple RC filter that rolls-off right at or near 8kHz.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • BeanBean Posts: 8,129
    edited 2006-03-04 13:17
    Beau,
    No, it's like a "motor boating" type sound. I'm attempting to use a "homemade" R2R ladder using only 4-bits. I'm I kidding myself into thinking that would produce anywhere near half-decent sound ?

    Bean.

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    "SX-Video·Module" Now available from Parallax for only $28.95

    http://www.parallax.com/detail.asp?product_id=30012

    "SX-Video OSD module" Now available from Parallax for only·$49.95
    http://www.parallax.com/detail.asp?product_id=30015

    Product web site: www.sxvm.com

    "Wise men know when they're right. The wisest also·know when they're wrong."
    ·
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-03-04 15:41
    Bean said...

    8-bit 8000 samples per second

    Another thought.... Is it Stereo or Mono? If not , you should convert it to Mono.

    Bean said...

    When I just put the data onto a DAC I can hear the sound

    Does the playback "rate" seem to be correct or is it about half the speed that you would expect?
    This could be another indication the audio clip is Stereo vs. Mono.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • BeanBean Posts: 8,129
    edited 2006-03-04 15:47
    Beau,
    It is mono and the playback rate seems to be okay. I saw in the .WAV spec that there are "chunks". Are most sound files just 1 big chunk ? Or do they break the file into a series of smaller "chunks" ?
    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "SX-Video·Module" Now available from Parallax for only $28.95

    http://www.parallax.com/detail.asp?product_id=30012

    "SX-Video OSD module" Now available from Parallax for only·$49.95
    http://www.parallax.com/detail.asp?product_id=30015

    Product web site: www.sxvm.com

    "Wise men know when they're right. The wisest also·know when they're wrong."
    ·
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-03-04 16:09
    Bean,

    For 8-Bit Mono, unless things have changed, once you get past the 44 byte header,
    the remaining data is RAW audio with 127 equal to the audio "null".

    Reference:
    www.technology.niagarac.on.ca/courses/ctec1631/WavFileFormat.html

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • BeanBean Posts: 8,129
    edited 2006-03-04 16:54
    Beau,
    Thanks for the info. After convincing myself that it wasn't "in-the-data" I found a program bug. So....
    IT WORKS!!! And the 4-bit DAC isn't that bad. I'm cheating and not even using an audio amp, just low values for the R2R (100 & 200 ohm resistors). I have a 64KB eeprom, so if I store the samples as nibbles @ 8KHz I can store and playback 16 seconds of sound. Pretty cool. I'll have to post this in the project section when I get it further along...

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "SX-Video·Module" Now available from Parallax for only $28.95

    http://www.parallax.com/detail.asp?product_id=30012

    "SX-Video OSD module" Now available from Parallax for only·$49.95
    http://www.parallax.com/detail.asp?product_id=30015

    Product web site: www.sxvm.com

    "Wise men know when they're right. The wisest also·know when they're wrong."
    ·
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