The Longest Journey ISN - Revision history

imported>Ikskoks at 21:19, 21 January 2021

2021-01-21T21:19:25Z

← Older revision	Revision as of 21:19, 21 January 2021
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imported>Ikskoks at 21:19, 21 January 2021

2021-01-21T21:19:25Z

← Older revision		Revision as of 21:19, 21 January 2021
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			[[Category:File Format]]

imported>DenizOezmen: note regarding new TLJ releases

2006-08-29T18:19:42Z

note regarding new TLJ releases

← Older revision	Revision as of 18:19, 29 August 2006
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imported>DenizOezmen: note regarding new TLJ releases

2006-08-29T18:19:42Z

note regarding new TLJ releases

← Older revision		Revision as of 18:19, 29 August 2006
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	=== Format Specifications ===		=== Format Specifications ===

			Note: This file type can only be found in the original 4 CD-release of The Longest Journey. Newer variants (such as the 2 CD- or 1 DVD-version) use the [[The_Longest_Journey_OVS\|OVS]] type instead.

	An ISN, ISS or SSN file contains sound that can be stored by means of one of several codecs, regardless of the file extension. Its header structure is a bit unusual, as it is a collection of space-delimited (!) strings. It starts with the codec description:<br><br>		An ISN, ISS or SSN file contains sound that can be stored by means of one of several codecs, regardless of the file extension. Its header structure is a bit unusual, as it is a collection of space-delimited (!) strings. It starts with the codec description:<br><br>

imported>DenizOezmen: added format description

2006-08-29T18:11:12Z

added format description

← Older revision	Revision as of 18:11, 29 August 2006
(No difference)

imported>DenizOezmen: added format description

2006-08-29T18:11:12Z

added format description

New page

== ISN/ISS/SSN ==

* ''' Format Type ''': Sound 
* ''' [http://en.wikipedia.org/wiki/Endianness Endian Order] ''': Little Endian 

=== Format Specifications ===

An ISN, ISS or SSN file contains sound that can be stored by means of one of several codecs, regardless of the file extension. Its header structure is a bit unusual, as it is a collection of space-delimited (!) strings. It starts with the codec description: 

<tt>
// ISN/ISS/SSN header 
char {X} - Codec 
</tt> 

The codec value determines the procedure for the rest of the file. After the delimiting space character (<tt>0x20</tt>), the specialized header for the codec follows. Currently, the codec types "Sound" and "IMA_ADPCM_Sound" are known. No others have been observed up to now. 

==== Sound codec ====

The codec-specific header in this case is structured as follows: 

<tt>
// Sound header 
char {X} - Unknown 
char {X} - Data size 
char {X} - Channels 
char {X} - Unknown 
char {X} - Frequency 
char {X} - Unknown 
char {X} - Unknown 
</tt> 

Notes:
* The channel value has to be increased by 1 to get the correct value.
* The frequency value is only saved indirectly. The real frequency in Hertz can be computed by dividing 44100 by the read value.

The actual data that follows is comprised of simple raw 16 bit PCM samples. 

==== IMA_ADPCM_Sound codec ====

The codec-specific header in this case is structured as follows: 

<tt>
// IMA_ADPCM_Sound header 
char {X} - Block size 
char {X} - Unknown 
char {X} - Unknown 
char {X} - Channels 
char {X} - Unknown 
char {X} - Frequency 
char {X} - Unknown 
char {X} - Data size 
</tt> 

As with the Sound codec explained above, the channels and frequency values have to be post-processed.

The following data is stored in 4-bit ADPCM coding, where each byte is expanded to two 16 bit PCM samples. The decompression algorithm is actually identical to the one described here [http://wiki.multimedia.cx/index.php?title=Duck_DK4_IMA_ADPCM]. If you are new to ADPCM coding, you should read this page [http://wiki.multimedia.cx/index.php?title=IMA_ADPCM] first. 

=== MultiEx BMS ===

Not written yet 

=== Supported Programs ===

Unknown