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Sample Format Comparison

Introduction

SynthArk offers sample banks in multiple file formats, since each soft sample player has it’s own feature set and corresponding format. Sampling always requires trade offs between accuracy, flexibility, and file size. If all of the original modulation (envelopes, LFOs) is sampled, accuracy is high, but flexibility and file size suffer. So, modulation that doesn’t significantly color the sound (amp/pitch envelopes, LFO, velocity routing) can be removed before sampling and later replicated in the soft sample player. This optimizes accuracy, file size, and flexibility, since the musician can then tweak the replicated modulation as necessary for various songs. However, different sample formats have different levels of support for replicating the modulation routings implemented on the source (i.e. sampled) synthesizer.

WAV Format

The WAV file format (and it’s AIFF sibling) has been around for a long time and is relatively universally supported. However, it only encodes sound (i.e. a sample) for a single (mono or stereo) waveform, which can be looped. So, to play a multisample (i.e. multiple samples, split over the key range) preset saved as WAV files, the WAV files must first be imported into a sample player (e.g. VSampler, ProteusX) and mapped to the associated key range. Even then, performance parameters (e.g. envelopes, LFO, velocity, dynamic filter) are lost, since they are not supported by the WAV format, so they must be manually reprogrammed into the sample player (if supported by the player).

SF2 Format

The SF2 (SoundFont) format was developed by Emu and Creative Labs in the 1990’s. It is based on RIFF (like WAV and AIFF), but also includes key mapping and modulation settings. The 2.1 spec supports dual envelopes (volume and pitch or filter), dual LFOs (volume and pitch or filter), along with panning and some effects parameters. Most soft samplers can import SF2, although few play it natively. While many of the WAV issues are addressed, the performance parameters are limited, so complex modulation routings are not supported.

Proprietary Formats

Apple Logic’s EXS24 format has similar capabilities to SF2 (dual envelopes, dual LFOs) and adds some modulation routings not covered in SF2. However, it still lacks many of the advanced modulatin features found in other soft sample player platforms, such as Emu’s EmulatorX and ProteusX (EXB), Native Instruments Kontakt (NKI), and MOTU’s MachFive (M5). Unfortunately, proprietary formats do not transfer well to other platforms. Even when one soft sample player has the ability to import other proprietary formats, the modulation parameters translation is usually poor quality, often creating sounds that show little resemblance to the original.

Summary

Full featured formats, such as EXB and NKI add a lot more performance flexibility than WAV, while sacrificing portability. While WAV can be imported by most software samplers, the imported sound will need extensive tweaking to recover the playability of the full featured formats. Similarly, translations from one proprietary format to another do not always retain all the features found in the source format. SF2 offers a compromise between portability and modulation accuracy. For the best accuracy, choose the format of the software that will play the samples. If you use several sample players and accuracy is not critical, choose SF2. If out-of-the-box playability is not important and only a variety of raw samples are needed, choose WAV.