Fix buffer underrun problems on slow iBooks

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%40773

src/cdrom/macosx/AudioFilePlayer.cpp

@@ -110,8 +110,8 @@ AudioFilePlayer::AudioFilePlayer (const FSRef           *inFileRef)
 
     OpenFile (inFileRef, fileDataSize);
         
-    // we want about a seconds worth of data for the buffer
-    int bytesPerSecond = UInt32 (mFileDescription.mSampleRate * mFileDescription.mBytesPerFrame);
+    // we want about 4 seconds worth of data for the buffer
+    int bytesPerSecond = UInt32 (4 * mFileDescription.mSampleRate * mFileDescription.mBytesPerFrame);
     
 #if DEBUG
     printf("File format:\n");