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Article #2147

recording from DSP problems

#2147
From: Lo Shih
Date: Sat, 19 Dec 1992 04:10
78 lines
2550 bytes
We are building a Sound App and we're having problems recording
from the DSP. We're using a MetaResearch Digital Ears to sample
our sound into the Next standard Sound structure. 

We know that the Digital Ears works because we can issue a "sndrecord -d"
command from the terminal with success.

We're setting the data format of our Sound to SND_FORMAT_DSP_DATA_16 
when recording and changing the data format to SND_FORMAT_LINEAR_16
when playing (which is recommended by the GeneralRef/AppKit docs).
We know that we've filled the Sound struct with some data. We get a 
logical value for duration sampleCount and dataSize. 

However, when we send the sound a play message, nothing is played
and an error code "18" is returned. We put some of our code at the
end of this article.

Please help us if you can. 
                                    - Lo Shih
                                    - Chris Miller






our code:

- record:sender
{ 
  /*
   *  If ready, initialize the sound struct and record
   */
  if ([theSound status] == NX_SoundStopped) {
    [self setSoundSize];
        
    sndError = [theSound record];
    [self printError];
  }
  
  return self;
}

- setSoundSize
{
  /*
   *  if the NXRadio is on MIC then record from microphone
   *  otherwise record from the DSP
   */
  if ([micRadio state]) {
    [theSound setDataSize:(int)9000000
      dataFormat:(int)SND_FORMAT_MULAW_8
      samplingRate:(int)SND_RATE_CODEC
      channelCount:(int)1
      infoSize:(int)4];
  }
  else {
    [theSound setDataSize:(int)9000000
      dataFormat:(int)SND_FORMAT_DSP_DATA_16
      samplingRate:(int)SND_RATE_HIGH
      channelCount:(int)2
      infoSize:(int)4];
  }
}

- play:sender
{
  if (([theSound status] == NX_SoundStopped) || 
          ([theSound status] == NX_SoundPlayingPaused)) {
    if (![theSound isPlayable]) {
        [theSound convertToFormat:(int)SND_FORMAT_LINEAR_16];
    }
    sndError = [theSound play];
    [self printError];
  }
    
  return self;    
}
Technical Details
Message-ID: <SbV=wG=@engin.umich.edu>
Path: arc1-ca.pugleaf.net!sparky!uunet!caen!dmno

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Newsgroups: comp.sys.next.programmer
Path: arc1-ca.pugleaf.net!sparky!uunet!caen!dmno
From: dmno@math.lsa.umich.edu (Lo Shih)
Subject: recording from DSP problems
Message-ID: <SbV=wG=@engin.umich.edu>
Date: Fri, 18 Dec 92 23:10:27 EST
Organization: University of Michigan, Mathematics Department, Ann Arbor
Sender: Lo Shih and Chris Miller, {lfo}{ff}
Distribution: comp.sys.next.programmer
Keywords: DSP, Sound, record, IB, AppKit
Nntp-Posting-Host: winterpark.math.lsa.umich.edu
Lines: 79