AIFF & AIFC

AIFF — Audio Interchange File Format (AIFF) is an audio file format standard co-developed by Apple Computer in 1988, based on Electronic Arts' Interchange File Format (IFF, widely used on Amiga systems). It is most commonly used on Apple Macintosh computer systems. The audio data in a standard AIFF file is uncompressed pulse-code modulation (PCM). Standard AIFF is a leading format in professional audio and video applications and — unlike the better-known lossy MP3 format — is non-compressed and lossless.

AIFC — AIFC is in fact an AIFF file designed to hold compressed audio data as well as uncompressed data. It is an extension of AIFF and was intended to replace it altogether. When a file is imported or exported from Apple Music or iTunes or QuickTime in "AIFF" format, it is actually AIFC that is being used.

Sample Rate — The number of samples of audio carried per second, measured in Hz or kHz (1000 Hz). 44.1 kHz is the sampling rate of audio CDs and 48.0 kHz is commonly used for professional video. Higher sample rates result in higher quality audio with larger file sizes. Setting this to Auto creates an output file with the same sample rate as the input file. If the output file does not support the sample rate of the input file, Pro Audio Converter uses the greatest sample rate that is supported.

Bit Depth — The number of bits used to represent each sample. Increasing bit depth reduces quantization noise and improves the signal-to-noise ratio by about 6 dB per bit. 24-bit digital audio has a theoretical maximum S/N of 144 dB, compared to 96 dB for 16-bit. Audio CDs use 16 bits; 24-bit is common in professional audio and video.

Endianness — The byte order of each sample. Big Endian stores the most significant byte first; Little Endian stores the least significant byte first. By definition, AIFF and AIFC files are always Big Endian.

Channels — The number of audio channels in the output file. Auto attempts to match the input file's channel count. You can also force Stereo (2 channels) or Mono (1 channel).

Quality — Good is optimized for the fastest encoding. Choose Better or Best (optimal for 24-bit sources) for higher quality. The tradeoff is between encoding speed and audio quality.