AHI Device - Revision history

Costel Mincea: Text replacement - "" to ""

2025-01-26T19:05:59Z

Text replacement - "<syntaxhighlight>" to "<syntaxhighlight lang="C" line>"

← Older revision		Revision as of 19:05, 26 January 2025
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	AHI device commands use an extended I/O request block named '''AHIRequest''' to send commands to the AHI device. This is the standard '''IOStdReq''' block with some extra fields added at the end.		AHI device commands use an extended I/O request block named '''AHIRequest''' to send commands to the AHI device. This is the standard '''IOStdReq''' block with some extra fields added at the end.
	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	struct AHIRequest		struct AHIRequest
	{		{
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	* Specify which version of the device you need. The lowest supported version is 4.		* Specify which version of the device you need. The lowest supported version is 4.
	* Open '''ahi.device''' unit '''AHI_DEFAULT_UNIT''' or any other unit the user has specified, for example through UNIT tooltype.		* Open '''ahi.device''' unit '''AHI_DEFAULT_UNIT''' or any other unit the user has specified, for example through UNIT tooltype.
	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	struct MsgPort *AHImp;		struct MsgPort *AHImp;
	struct AHIRequest *AHIio;		struct AHIRequest *AHIio;
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	=== Reading from the AHI Device ===		=== Reading from the AHI Device ===
	You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.		You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.
	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	#define FREQUENCY 8000		#define FREQUENCY 8000
	#define TYPE AHIST_M8S		#define TYPE AHIST_M8S
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	=== Closing the AHI Device ===		=== Closing the AHI Device ===
	An '''OpenDevice()''' must eventually be matched by a call to '''CloseDevice()'''. All I/O requests must be complete before '''CloseDevice()'''. If any requests are still pending, abort them with '''AbortIO()''':		An '''OpenDevice()''' must eventually be matched by a call to '''CloseDevice()'''. All I/O requests must be complete before '''CloseDevice()'''. If any requests are still pending, abort them with '''AbortIO()''':
	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	IExec->AbortIO((struct IORequest )AHIio); / Abort any pending requests */		IExec->AbortIO((struct IORequest )AHIio); / Abort any pending requests */
	IExec->WaitPort(AHImp); /* Wait for abort message */		IExec->WaitPort(AHImp); /* Wait for abort message */
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	== Examples ==		== Examples ==
	=== Playback Example ===		=== Playback Example ===
	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	/*		/*
	** This program uses the device interface to play a sampled sound.		** This program uses the device interface to play a sampled sound.
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	=== Double Buffered Sound Example ===		=== Double Buffered Sound Example ===
	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	/* Simple sample player for AHI using the low-level API		/* Simple sample player for AHI using the low-level API
	with double buffered AHIST_DYNAMICSAMPLE sounds.		with double buffered AHIST_DYNAMICSAMPLE sounds.
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	=== Recording Example ===		=== Recording Example ===
	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	/*		/*
	** This program uses the device interface to sample sound data.		** This program uses the device interface to sample sound data.

Janne Peräaho: /* Reading from the AHI Device */

2017-03-20T04:04:50Z

Reading from the AHI Device

← Older revision		Revision as of 04:04, 20 March 2017
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	You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.		You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.
	<syntaxhighlight>		<syntaxhighlight>
			#define FREQUENCY 8000
			#define TYPE AHIST_M8S
			#define BUFFERSIZE 20000

			BYTE buffer[BUFFERSIZE];

	AHIio->ahir_Std.io_Command = CMD_READ;		AHIio->ahir_Std.io_Command = CMD_READ;
	AHIio->ahir_Std.io_Length = BUFFERSIZE;		AHIio->ahir_Std.io_Length = BUFFERSIZE;
	AHIio->ahir_Std.io_Data = &buffer;		AHIio->ahir_Std.io_Data = buffer;
	AHIio->ahir_Type = TYPE;		AHIio->ahir_Type = TYPE;
	AHIio->ahir_Frequency = FREQUENCY;		AHIio->ahir_Frequency = FREQUENCY;

Janne Peräaho: /* Reading from the AHI Device */

2017-03-20T04:01:04Z

Reading from the AHI Device

← Older revision		Revision as of 04:01, 20 March 2017
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	AHIio->ahir_Std.io_Command = CMD_READ;		AHIio->ahir_Std.io_Command = CMD_READ;
	AHIio->ahir_Std.io_Length = BUFFERSIZE;		AHIio->ahir_Std.io_Length = BUFFERSIZE;
	AHIio->ahir_Std.io_Data = &~~buffer1~~;		AHIio->ahir_Std.io_Data = &buffer;
	AHIio->ahir_Type = TYPE;		AHIio->ahir_Type = TYPE;
	AHIio->ahir_Frequency = FREQUENCY;		AHIio->ahir_Frequency = FREQUENCY;

Janne Peräaho: /* Reading from the AHI Device */

2017-03-20T04:00:11Z

Reading from the AHI Device

← Older revision		Revision as of 04:00, 20 March 2017
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	You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.		You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.
	<syntaxhighlight>		<syntaxhighlight>
	AHIio->ahir_Std.io_Command = CMD_READ;		AHIio->ahir_Std.io_Command = CMD_READ;
	AHIio->ahir_Std.io_Length = BUFFERSIZE;		AHIio->ahir_Std.io_Length = BUFFERSIZE;
	AHIio->ahir_Std.io_Data = &buffer1;		AHIio->ahir_Std.io_Data = &buffer1;
	AHIio->ahir_Type = TYPE;		AHIio->ahir_Type = TYPE;
	AHIio->ahir_Frequency = FREQUENCY;		AHIio->ahir_Frequency = FREQUENCY;
	AHIio->ahir_Std.io_Offset = 0;		AHIio->ahir_Std.io_Offset = 0;

	IExec->SendIO((struct IORequest *) AHIio);		IExec->SendIO((struct IORequest *) AHIio);

Janne Peräaho: /* Reading from the AHI Device */

2017-03-20T03:59:20Z

Reading from the AHI Device

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 === Reading from the AHI Device ===
 You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.
 ==== Double Buffering ====
 To do double buffering you need two buffers: ''buffer1'' and ''buffer2''. Then do as follows:

Janne Peräaho: /* Multiple Sounds at the Same Time */

2017-03-20T03:43:13Z

Multiple Sounds at the Same Time

← Older revision		Revision as of 03:43, 20 March 2017
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	==== Multiple Sounds at the Same Time ====		==== Multiple Sounds at the Same Time ====
	If you want to play several sounds at the same time, just make a new copy of the IO request you used in '''OpenDevice()''' and '''CMD_WRITE''' it.		If you want to play several sounds at the same time, just make a new copy of the I/O request you used in '''OpenDevice()''' and '''CMD_WRITE''' it.

	The number of available channels is set in the '''AHI Preferences editor''' by the user. If too many requests are sent to the device, the one with the lowest precedence will be muted. When a request is finished, the muted request with the highest precedence will be played.		The number of available channels is set in the '''AHI Preferences editor''' by the user. If too many requests are sent to the device, the one with the lowest precedence will be muted. When a request is finished, the muted request with the highest precedence will be played.

Janne Peräaho: /* Double Buffering */

2017-03-20T03:42:37Z

Double Buffering

← Older revision		Revision as of 03:42, 20 March 2017
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	You write to the device by passing '''AHIRequest''' to the device with '''CMD_WRITE''' set in '''io_Command''', the precedence in '''io_Message.mn_Node.ln_Pri''', the number of bytes to be written in '''io_Length''', the address of the writer buffer set in '''io_Data''', the sample format set in '''ahir_Type''', the desired sample frequency set in '''ahir_Frequency''', the desired volume set in '''ahir_Volume''', and the desired stereo position set in '''ahir_Position'''. Unless you are doing double buffering, '''ahir_Link''' should be set to '''NULL'''. '''io_Length''' must be even multiple of the sample frame size.		You write to the device by passing '''AHIRequest''' to the device with '''CMD_WRITE''' set in '''io_Command''', the precedence in '''io_Message.mn_Node.ln_Pri''', the number of bytes to be written in '''io_Length''', the address of the writer buffer set in '''io_Data''', the sample format set in '''ahir_Type''', the desired sample frequency set in '''ahir_Frequency''', the desired volume set in '''ahir_Volume''', and the desired stereo position set in '''ahir_Position'''. Unless you are doing double buffering, '''ahir_Link''' should be set to '''NULL'''. '''io_Length''' must be even multiple of the sample frame size.
	==== Double Buffering ====		==== Double Buffering ====
	To do double buffering, you need two IO requests: ''AHIio'' and ''AHIio2''. Create the second one by making a copy of the request you used in '''OpenDevice()'''. Then do as follows:		To do double buffering, you need two I/O requests: ''AHIio'' and ''AHIio2''. Create the second one by making a copy of the request you used in '''OpenDevice()'''. Then do as follows:

	* Start the first request (''AHIio'') with '''SendIO()'''.		* Start the first request (''AHIio'') with '''SendIO()'''.
	* Set '''ahir_Link''' in the second request (''AHIio2'') to the address of the first request (''AHIio'') and '''SendIO()''' it.		* Set '''ahir_Link''' in the second request (''AHIio2'') to the address of the first request (''AHIio'') and '''SendIO()''' it.
	* Wait for the first request (''AHIio'') to finish.		* Wait for the first request (''AHIio'') to finish.
	* When finished, fill the first buffer again and repeat, but this time with '''ahir_Link''' of the first request (''AHIio'') set to the address of the second IO request (''AHIio2'').		* When finished, fill the first buffer again and repeat, but this time with '''ahir_Link''' of the first request (''AHIio'') set to the address of the second I/O request (''AHIio2'').

	==== Distortion ====		==== Distortion ====

Janne Peräaho: /* Double Buffering */

2017-03-20T03:41:27Z

Double Buffering

← Older revision		Revision as of 03:41, 20 March 2017
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	To do double buffering you need two buffers: ''buffer1'' and ''buffer2''. Then do as follows:		To do double buffering you need two buffers: ''buffer1'' and ''buffer2''. Then do as follows:
	* Fill the first buffer (''buffer1'') with '''DoIO()''' and '''io_Offset''' set to 0.		* Fill the first buffer (''buffer1'') with '''DoIO()''' and '''io_Offset''' set to 0.
	* Start filling the second buffer (''buffer2'') with '''SendIO()''' using the same IO request, but '''do not''' clear '''io_Offset'''.		* Start filling the second buffer (''buffer2'') with '''SendIO()''' using the same I/O request, but '''do not''' clear '''io_Offset'''.
	* Process the first buffer and wait until the IO request is finished.		* Process the first buffer and wait until the I/O request is finished.
	* Start over with '''SendIO()''' on the first buffer.		* Start over with '''SendIO()''' on the first buffer.

Janne Peräaho: /* Double Buffering */

2017-03-19T23:55:23Z

Double Buffering

← Older revision		Revision as of 23:55, 19 March 2017
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	You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.		You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.
	==== Double Buffering ====		==== Double Buffering ====
	To do double buffering:		To do double buffering you need two buffers: ''buffer1'' and ''buffer2''. Then do as follows:
	* Fill the first buffer with '''DoIO()''' and '''io_Offset''' set to 0.		* Fill the first buffer (''buffer1'') with '''DoIO()''' and '''io_Offset''' set to 0.
	* Start filling the second buffer with '''SendIO()''' using the same IO request, but '''do not''' clear '''io_Offset'''.		* Start filling the second buffer (''buffer2'') with '''SendIO()''' using the same IO request, but '''do not''' clear '''io_Offset'''.
	* Process the first buffer and wait until the IO request is finished.		* Process the first buffer and wait until the IO request is finished.
	* Start over with '''SendIO()''' on the first buffer.		* Start over with '''SendIO()''' on the first buffer.

	==== Distortion ====		==== Distortion ====
	The samples will automatically be converted to the sample format set in '''ahir_Type''' and to the sample frequency set in '''ahir_Frequency'''. Because it is quite unlikely that you ask for same sample frequency the user has chosen in the '''AHI Preferences Editor''', chances that the quality is lower than expected are pretty high. The worst problem is probably the anti-aliasing filter before the A/D converter. If the user has selected a higher sampling/mixing frequency than you request, the signal will be distorted according to the Nyquist sampling theorem. If, on the other hand, the user has selected a lower sampling/mixing frequency than you request, the signal will not be distorted but rather bandlimited more than necessary.		The samples will automatically be converted to the sample format set in '''ahir_Type''' and to the sample frequency set in '''ahir_Frequency'''. Because it is quite unlikely that you ask for same sample frequency the user has chosen in the '''AHI Preferences Editor''', chances that the quality is lower than expected are pretty high. The worst problem is probably the anti-aliasing filter before the A/D converter. If the user has selected a higher sampling/mixing frequency than you request, the signal will be distorted according to the Nyquist sampling theorem. If, on the other hand, the user has selected a lower sampling/mixing frequency than you request, the signal will not be distorted but rather bandlimited more than necessary.

Janne Peräaho: /* Reading from the AHI Device */

2017-03-19T23:52:58Z

Reading from the AHI Device

← Older revision		Revision as of 23:52, 19 March 2017
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	=== Reading from the AHI Device ===		=== Reading from the AHI Device ===
			You read from the AHI device by passing an '''AHIRequest''' to the device with '''CMD_READ''' set in the '''io_Command''', the number of bytes to be read set in '''io_Length''', the address of the read buffer set in '''io_Data''', the desired sample format set in '''ahir_Type''', and the desired sample frequency set in '''ahir_Frequency'''. The first read command in a sequence should also have '''io_Offset''' set to 0. '''io_Length''' must be an even multiple of the sample frame size.
	==== Double Buffering ====		==== Double Buffering ====
			To do double buffering:
			* Fill the first buffer with '''DoIO()''' and '''io_Offset''' set to 0.
			* Start filling the second buffer with '''SendIO()''' using the same IO request, but '''do not''' clear '''io_Offset'''.
			* Process the first buffer and wait until the IO request is finished.
			* Start over with '''SendIO()''' on the first buffer.
	==== Distortion ====		==== Distortion ====
			The samples will automatically be converted to the sample format set in '''ahir_Type''' and to the sample frequency set in '''ahir_Frequency'''. Because it is quite unlikely that you ask for same sample frequency the user has chosen in the '''AHI Preferences Editor''', chances that the quality is lower than expected are pretty high. The worst problem is probably the anti-aliasing filter before the A/D converter. If the user has selected a higher sampling/mixing frequency than you request, the signal will be distorted according to the Nyquist sampling theorem. If, on the other hand, the user has selected a lower sampling/mixing frequency than you request, the signal will not be distorted but rather bandlimited more than necessary.

	=== Writing to the AHI Device ===		=== Writing to the AHI Device ===