[OpenAL] Status of OpenAL 1.1 on OS X

[Jim Wrenholt]

I tried implementing the following code but discovered a small  
problem.  Sometimes the lengths of totalAudioFrames and  
tFSCatalogInfo.dataLogicalSize are not the same.  (I was loading 8- 
bit mono WAV files).  The result is some noise at the end of each  
buffer.

>         // allocate a buffer to read it into
>         tABL.mBuffers[0].mData = calloc( totalAudioFrames, sizeof 
> ( char ) );

>         // load the file's data into our OpenAL buffer
>         ALsizei size = tFSCatalogInfo.dataLogicalSize;

I changed that last line to
	ALsizei size = totalAudioFrames;

and now the noise is gone.  Again, I am using 8-bit mono WAV files,  
so whether this works as a general solution is not clear to me.

Jim


On Aug 21, 2006, at 4:52 PM, George Warner wrote:

> On Mon, 21 Aug 2006 10:47:22 +0200, "Sven Panne" <Sven.Panne at BenQ.com>
> wrote:
>>> Several Mac OS X OpenAL developers have requested a
>>> replacement for alutLoadWAVFile (and I needed it for a few of
>>> my projects ;-) so... [...]
>>
>> http://www.openal.org/openal_webstf/specs/alut.html#Loading :-)The
>> corresponding LGPL'd code is available e.g. via Subversion at
>> http://opensource.creative.com/repos/openal/trunk/alut/src/ 
>> alutLoader.c.
>
> The problem with that routine is that it only loads WAV files. The  
> alut 1.1
> replacement API ( alutCreateBufferFromFile ) is source file  
> agnostic (which
> is why I chose to implement it instead of the depreciated API).
>
> BTW: In my testing I determined that I wasn't handling all file  
> formats
> correctly. Our Core Audio guru set me strait; This (newer) version  
> of the
> code worked for all sound file formats I could find to test it  
> with. ;-)
>
> // 
> ********************************************************************** 
> ***
> //
> //    alutCreateBufferFromFile (  inFilename )
> //
> //    Purpose:    Create OpenAL buffer from contents of a file
> //
> //    Inputs:     inFilename - address of complete file name ( path )
> //
> //  Returns:    On success, a handle to an OpenAL buffer containing  
> the
> loaded sound.
> //                It returns AL_NONE on failure.
> //
> ALuint alutCreateBufferFromFile ( const char * inFilename )
> {
>     ALuint result = AL_NONE;    // assume failure
>     ExtAudioFileRef tExtAudioFileRef = NULL;
>     AudioBufferList tABL;
>
>     tABL.mNumberBuffers = 1;
>     tABL.mBuffers[0].mNumberChannels = 0;
>     tABL.mBuffers[0].mDataByteSize = 0;
>     tABL.mBuffers[0].mData = nil;
>
>     do {
>         FSRef tFSRef;    // convert the path into an FSRef
>         OSStatus status = FSPathMakeRef( ( const UInt8 * )inFilename,
> &tFSRef, FALSE );
>         if ( noErr != status ) break;
>
>         FSCatalogInfo tFSCatalogInfo;    // determine the size of  
> the file
>         status = FSGetCatalogInfo( &tFSRef, kFSCatInfoDataSizes,
> &tFSCatalogInfo, NULL, NULL, NULL );
>         if ( noErr != status ) break;
>
>         // Open the input file
>         status = ExtAudioFileOpen( &tFSRef, &tExtAudioFileRef );
>         if ( noErr != status ) break;
>
>         AudioStreamBasicDescription tASBD;    // get the  
> description ( ASDB
> ) of the audio file on disk
>         UInt32 asbd_size = sizeof( AudioStreamBasicDescription );
>         status = ExtAudioFileGetProperty( tExtAudioFileRef,
> kExtAudioFileProperty_FileDataFormat, &asbd_size, &tASBD );
>         if ( noErr != status ) break;
>
>         // OpenAL doesn't need 16-bit or stereo sounds so...
>         ALenum  format = AL_FORMAT_MONO8;
>         if ( !format ) break;
>
>         // configure the output ASBD
>         //tASBD.mSampleRate = tASBD.mSampleRate;    // don't change  
> the
> sample rate
>         tASBD.mFormatID = kAudioFormatLinearPCM;
>         tASBD.mFormatFlags = kAudioFormatFlagIsPacked;
>         tASBD.mBytesPerPacket = 1;
>         tASBD.mFramesPerPacket = 1;
>         tASBD.mBytesPerFrame = 1;
>         tASBD.mChannelsPerFrame = 1;
>         tASBD.mBitsPerChannel = 8;
>         tASBD.mReserved = 0;
>
>         // now set the output ASDB
>         status = ExtAudioFileSetProperty( tExtAudioFileRef,
> kExtAudioFileProperty_ClientDataFormat, asbd_size, &tASBD );
>         if ( noErr != status ) break;
>
>         tABL.mBuffers[0].mNumberChannels = tASBD.mChannelsPerFrame;
>         tABL.mBuffers[0].mDataByteSize =  
> tFSCatalogInfo.dataLogicalSize;
>
>         SInt64 totalAudioFrames;    // determine the number of  
> frames in the
> file
>         UInt32 ioPropertyDataSize = sizeof( totalAudioFrames );
>         status = ExtAudioFileGetProperty( tExtAudioFileRef,
> kExtAudioFileProperty_FileLengthFrames, &ioPropertyDataSize,
> &totalAudioFrames );
>         if ( noErr != status ) break;
>
>         UInt32 numberOfFrames = totalAudioFrames;
>
>         // allocate a buffer to read it into
>         tABL.mBuffers[0].mData = calloc( totalAudioFrames, sizeof 
> ( char ) );
>         if ( !tABL.mBuffers[0].mData ) {
>             status = memFullErr;
>             break;
>         }
>
>         // read all the frames into the buffer
>         status = ExtAudioFileRead( tExtAudioFileRef,  
> &numberOfFrames, &tABL
> );
>         if ( noErr != status ) break;
>
>         // generate a new OpenAL buffer
>         alGenBuffers( 1, &result );
>         status = alGetError( );
>         if ( AL_NO_ERROR != status ) break;
>
>         // load the file's data into our OpenAL buffer
>         ALsizei size = tFSCatalogInfo.dataLogicalSize;
>         ALsizei freq = tASBD.mSampleRate;
>         alBufferData( result, format, tABL.mBuffers[0].mData, size,  
> freq );
>         status = alGetError( );
>         if ( AL_NO_ERROR != status ) break;
>     } while ( FALSE );
>
>     if ( tExtAudioFileRef ) {    // close the audio file
>         ExtAudioFileDispose( tExtAudioFileRef );
>     }
>
>     if ( tABL.mBuffers[0].mData ) {    // dispose of the data buffer
>         free( tABL.mBuffers[0].mData );
>     }
>
>     return result;
> }
>
> -- 
> Enjoy,
> George Warner,
> Schizophrenic Optimization Scientist
> Apple Developer Technical Support (DTS)
>
>
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