User:Halftheisland/EA AS4
From Just Solve the File Format Problem
< User:Halftheisland(Difference between revisions)
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| − | {{FormatInfo
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| − | |formattype=electronic
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| − | |subcat=Audio and Music
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| − | |extensions={{ext|as4}} {{ext|asf}}
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| − | }}
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| − | == Description ==
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| − | AS4 / ASF files are an audio file format used in many video games created by Electronic Arts. Note that extensions other than those listed may be AS4 / ASF files as Electronic Arts often change file extensions for different games.
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| − |
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| − | == Information ==
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| − | The basic structure of AS4 / ASF files is similar to that of [[RIFF]], with each file divided into blocks (although, unlike [[RIFF]], the format does not have a global file header).
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| − | Each block starts with a standard header:
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| − | <pre>
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| − | struct ASFBlockHeader
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| − | {
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| − | char szBlockID[4];
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| − | DWORD dwSize;
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| − | };
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| − | </pre>
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| − |
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| − | Where:
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| − | * ''szBlockID'' gives the string ID for the block
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| − | * ''dwSize'' gives the size of the block (including the header) in bytes.
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| − | Each file then consists of a number of blocks, each of which are described below.
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| − | === Header Block ===
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| − | Block ID:'''1SNh'''
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| − | This is the first block in an ASF / AS4 file, describing the audio stream.
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| − | <pre>
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| − | struct EACSHeader
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| − | {
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| − | char szID[4];
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| − | DWORD dwSampleRate;
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| − | BYTE bBits;
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| − | BYTE bChannels;
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| − | BYTE bCompression;
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| − | BYTE bType;
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| − | DWORD dwNumSamples;
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| − | DWORD dwLoopStart;
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| − | DWORD dwLoopLength;
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| − | DWORD dwDataStart;
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| − | DWORD dwUnknown;
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| − | };
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| − | </pre>
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| − | * ''szID'' - the ID string, should always be "EACS"
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| − | * ''dwSampleRate'' - the sample rate for the file
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| − | * ''bBits'' - the resolution of the decompressed sound data, divided by 8 (i.e. 1 = 8-bit, 2 = 16-bit)
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| − | * ''bChannels'' - the number of channels. There are only two options: 1 for mono, 2 for stereo
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| − | * ''bCompression'' - if this is equal to 0x00, the audio data consists of signed 8 or 16-bit [[PCM]]. If it is equal to 0x02, the audio data consists of compressed [[IMA ADPCM]]
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| − |
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| − | === Sound Data ===
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| − | == Software ==
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| − |
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| − | * http://bim.km.ru/gap/
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| − | == Links ==
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| − | * http://www.extractor.ru/articles/electronic_arts_audio_file_formats_description
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Latest revision as of 12:14, 3 October 2013
