1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<HTML> 3<HEAD> 4<META http-equiv="Content-Type" content="text/html; charset=windows-1252"> 5<META name="GENERATOR" content="IBM WebSphere Studio Homepage Builder Version 7.0.0.0 for Windows"> 6<META http-equiv="Content-Style-Type" content="text/css"> 7<TITLE>TWL Extended Sound Features: Overview </TITLE> 8<LINK rel="stylesheet" href="../../../css/nitro.css" type="text/css"> 9</HEAD> 10<BODY> 11<H1 align="left">TWL Extended Sound Features: Overview <IMG src="../../../image/TWL.gif"></H1> 12<P>On TWL, in addition to the NITRO-SDK's SND library, you can use the <A href="../../list_snd.html#Extra">SNDEX library</A>. This library provides several extended features to supplement the features in the NITRO-SDK's SND library.</P> 13 <H2>CODEC Mode</H2> 14<P>The TWL console has built-in hardware known as "CODEC" to control microphone input, speaker output, and Touch Screen input. By using this CODEC, TWL provides the following two modes for NITRO compatibility. See the <I>Programming Manual</I> for details on the CODEC hardware.</P> 15 <TABLE> 16 <TR> 17<TD width="25%">CODEC-DS</TD> 18<TD width="75%">This environment is identical to the sound circuit on the NITRO console.<BR>NTR ROMs boot up in this mode when they are running on the TWL console.</TD> 19 </TR> 20 <TR> 21<TD width="25%">CODEC-TWL</TD> 22<TD width="75%">This environment uses a sound circuit specific to the TWL system. A TWL ROM usually boots up in this mode. You can specify which CODEC mode to use for a ROM in the ROM specification file.</TD> 23 </TR> 24 </TABLE> 25<P><FONT color="red">You cannot change the CODEC mode at run time.</FONT></P> 26<P>When you use the TWL camera feature, you must play a specific audio sample either when taking a still photo or when starting and stopping video recording. Note that the forced audio output feature can be used only when the CODEC is operating in CODEC-TWL mode. <FONT color="red">Therefore, the <A href="../../../camera/about_camera.html">Camera Operations library</A> can be used only when the CODEC is in CODEC-TWL mode.</FONT></P> 27 28<H2>Extended Features</H2> 29<P>The following sound-related features have been added on the TWL console. See each function's description for more details.</P> 30 <UL> 31<LI>Getting the headphone connection state 32<LI>Getting and setting the mute setting 33<LI>Getting and changing the I2S frequency 34<LI>Getting and changing the rate for mixing DSP audio output 35<LI>Getting and changing the speaker volume 36<LI>Setting IIR filters for microphone input data and speaker output data 37<LI>Setting callbacks invoked when the volume button is pressed on the TWL console 38 </UL> 39 40<H2>Note</H2> 41<P>Mutexes are used by processing related to each extended sound feature, so these features cannot be used simultaneously. A SNDEX function returns <CODE>SNDEX_RESULT_EXCLUSIVE</CODE> and quit if another SNDEX function is still running.</P> 42<P>When you execute the <A href="../../../dsp/common/DSP_PlayShutterSound.html"><CODE>DSP_PlayShutterSound</CODE></A> shutter sound playback function, internally the function makes use of extended sound functionality automatically. For this reason, until the playback of shutter sound has ended, SNDEX functions returns <CODE>SNDEX_RESULT_EXCLUSIVE</CODE> and quits without doing anything.<BR>The exception is the <A href="../SNDEX_SetVolumeSwitchCallback.html"><CODE>SNDEX_SetVolumeSwitchCallback</CODE></A> function, which succeeds because all it does is configure function settings. Use the <A href="../../../dsp/common/DSP_IsShutterSoundPlaying.html"><CODE>DSP_IsShutterSoundPlaying</CODE></A> function to determine the end of the shutter sound playback process.</P> 43<P>The SNDEX functions internally continue to block if PXI receive interrupts are prohibited because they use a PXI receive interrupt to detect that their processing completed. In asynchronous versions of these functions, callbacks do not return.</P> 44 45<H2>See Also</H2> 46<P><A href="../../list_snd.html#Extra">SNDEX Function List</A></P> 47 48<H2>Revision History</H2> 49<P> 502009/01/22 Deleted the text about the Changing the Voice Forced Output Settings feature because it is not related to application development.<BR> 2008/11/07 Added mention of mutexes during shutter sound playback to <B>Note</B>.<BR> 2008/10/27 Added mention of the restrictions on the Changing the Voice Forced Output Settings feature.<BR> 2008/09/30 Added mention of restrictions on use of camera in different CODEC modes.<BR> 2008/09/12 Initial version.</P> 51<hr><p>CONFIDENTIAL</p></body> 52</HTML> 53 54 55<!-- <A href="../SNDEX_SetIirFilter.html">SNDEX_SetIirFilter[Async]()</A> --> 56 57
