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OBD:SNDD: Difference between revisions
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:''For metadata instances used to group sounds together, randomize them, adjust their volume or frequency, etc, see [[OSBD]] and its subtypes: [[OSAm]], [[OSIm]] and [[OSGr]].'' | :''For metadata instances used to group sounds together, randomize them, adjust their volume or frequency, etc, see [[OSBD]] and its subtypes: [[OSAm]], [[OSIm]] and [[OSGr]].'' | ||
SNDD instances is where Oni stores sound data. In Vanilla Oni game data, sounds are either mono or stereo waveforms (with sampling frequencies of either 22.05 kHz or 44.1 kHz), compressed to save on storage space. Both the PC and Mac versions use a form of [[wp: | SNDD instances is where Oni stores sound data. In Vanilla Oni game data, sounds are either mono or stereo waveforms (with sampling frequencies of either 22.05 kHz or 44.1 kHz), compressed to save on storage space. Both the PC and Mac versions use a form of [[wp:Adaptive differential pulse-code modulation|ADPCM]] compression (Adaptive Differential Pulse-Code Modulation), where 16-bit sound samples are encoded as 4-bit "nibbles" (resulting roughly in a 4:1 compression ratio as compared to uncompressed 16-bit [[wp:Pulse-code modulation|PCM]]). | ||
*On PC (both retail and demo), sounds are encoded using Microsoft's ADPCM codec (implemented in [[wp:FFmpeg|FFmpeg]] as '''adpcm_ms'''). See [https://wiki.multimedia.cx/index.php/Microsoft_ADPCM HERE] for a quick description. | *On PC (both retail and demo), sounds are encoded using Microsoft's ADPCM codec (implemented in [[wp:FFmpeg|FFmpeg]] as '''adpcm_ms'''). See [https://wiki.multimedia.cx/index.php/Microsoft_ADPCM HERE] for a quick description. | ||
*On Mac, sounds are encoded using QuickTime's IMA4 codec (implemented in | *On Mac, sounds are encoded using QuickTime's IMA4 codec (implemented in FFmpeg as '''adpcm_ima_qt'''). See [https://wiki.multimedia.cx/index.php/Apple_QuickTime_IMA_ADPCM HERE] for a quick description. | ||
As a unique feature of Oni game data, SNDD files have a significantly different structure depending on the engine version. For PC retail (.dat/.raw storage, no .sep files), the SNDD files are larger and include a 50-byte chunk of data that is equivalent to the "fmt " chunk of a WAVE file. For the other two versions (PC demo and Mac, .dat/.raw/.sep storage), this 50-byte block is missing. It turns out that the extra format data allows the PC retail to support both MS ADPCM and IMA4, as well as uncompressed PCM, whereas PC demo and Mac engines only support MS ADPCM and IMA4, respectively. (It has not been confirmed whether the PC retail engine supports other WAVE formats beyond PCM and MS ADPCM, such as Mu-Law or A-Law PCM, IEEE float PCM, etc.) | As a unique feature of Oni game data, SNDD files have a significantly different structure depending on the engine version. For PC retail (.dat/.raw storage, no .sep files), the SNDD files are larger and include a 50-byte chunk of data that is equivalent to the "fmt " chunk of a WAVE file. For the other two versions (PC demo and Mac, .dat/.raw/.sep storage), this 50-byte block is missing. It turns out that the extra format data allows the PC retail to support both MS ADPCM and IMA4, as well as uncompressed PCM, whereas PC demo and Mac engines only support MS ADPCM and IMA4, respectively. (It has not been confirmed whether the PC retail engine supports other WAVE formats beyond PCM and MS ADPCM, such as Mu-Law or A-Law PCM, IEEE float PCM, etc.) | ||
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===IMA4 ADPCM .raw data (Mac)=== | ===IMA4 ADPCM .raw data (Mac)=== | ||
''For an overview of the IMA ADPCM algorithm and IMA4 header (if interested), see [https://wiki.multimedia.cx/index.php/Apple_QuickTime_IMA_ADPCM HERE]. For an actual implementation example, see | ''For an overview of the IMA ADPCM algorithm and IMA4 header (if interested), see [https://wiki.multimedia.cx/index.php/Apple_QuickTime_IMA_ADPCM HERE]. For an actual implementation example, see FFmpeg.'' | ||
:The IMA4 ADPCM stream data (stored in the .raw file) consists of 34-byte blocks (in the case of stereo, there is an even number of such blocks, with Left and Right blocks interleaved). | :The IMA4 ADPCM stream data (stored in the .raw file) consists of 34-byte blocks (in the case of stereo, there is an even number of such blocks, with Left and Right blocks interleaved). | ||
:The first two bytes of each block form a header that sets the initial predictor (upper 9 bits) and step (lower 7 bits) for decoding the block's samples. Typically they are used only for the first block, or for sudden changes of the waveform's value range. | :The first two bytes of each block form a header that sets the initial predictor (upper 9 bits) and step (lower 7 bits) for decoding the block's samples. Typically they are used only for the first block, or for sudden changes of the waveform's value range. | ||
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===MS ADPCM .raw data (PC demo)=== | ===MS ADPCM .raw data (PC demo)=== | ||
''For a detailed overview of the ADPCM algorithm (if interested), see [https://wiki.multimedia.cx/index.php/Microsoft_ADPCM HERE]. For an actual implementation example, see | ''For a detailed overview of the ADPCM algorithm (if interested), see [https://wiki.multimedia.cx/index.php/Microsoft_ADPCM HERE]. For an actual implementation example, see FFmpeg.'' | ||
:The MS ADPCM stream data (stored in .raw) consists of 512- or 1024-byte blocks (512 bytes for 22.05 kHz mono, 1024 bytes for 22.05 kHz stereo) | :The MS ADPCM stream data (stored in .raw) consists of 512- or 1024-byte blocks (512 bytes for 22.05 kHz mono, 1024 bytes for 22.05 kHz stereo) | ||
:Each block starts with a 7- or 14-byte header (7 bytes for mono, 14 bytes for stereo), which includes the 16-bit values of the block's first two samples. | :Each block starts with a 7- or 14-byte header (7 bytes for mono, 14 bytes for stereo), which includes the 16-bit values of the block's first two samples. | ||