![]() In all other cases - e.g., between 44.1 and 96kHz - it is called arbitrary sample-rate conversion (ASRC). Special instances of these conversions are oversampling and undersampling, wherein the input and output sample rates are related by an integer factor - e.g., 44.1 and 88.2kHz. The two-step process of filtering and downsampling is called decimation. Before a signal can be downsampled, it must be low-pass filtered in order to avoid aliasing. In downsampling, the output sample rate is lower than the input sample rate. In upsampling, the output sample rate is higher than the input sample rate. Some manufacturers and consumers also believe that there are benefits to changing the sample rate of a recording on playback - a matter I address below.Īt the highest level, there are only two types of sample-rate conversion. On the playback side, not all equipment or transfer protocols support all sample rates. Often, however, the distribution medium is incapable of carrying that format - e.g., the CD’s limit of 44.1kHz precludes higher sampling rates - or someone makes a business decision to release the recording in a sample rate other than the native one. The best state of affairs is for you to obtain an exact copy of that master. ![]() However a piece of music was recorded, or the various twists and turns it may have taken along its path, there is ultimately a studio master at some particular sample rate. This article focuses on conversions that take place at the distribution and playback end of the chain - explaining what the terms mean, what some of the consequences of conversion are, and the implications for a computer-based audio system. There are different types of sample-rate conversion, and different ways of going about the process. In both the recording and playback of music, it is often necessary or convenient to switch between sample rates. Sample rates of 88.2kHz and above are considered high-resolution. (For an explanation of sample rates, read "Understanding Digital Music - What Bit Depth and Sample Rate Really Mean: Part Two.) The principal sample rates used today are 44.1, 48kHz and their multiples ( i.e., 88.2, 96, 176.4, 192, and so on). Most people interested in digital audio know that music is recorded and played back at more than one sample rate.
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