Looking at the concept of bit-perfect, it's arguablyimpossible to have bit perfect playback in a real-time system because there areno bits. Because audiois real time, there is no error correction that can be done to this squarewave, any resulting wave form IS your music. That new version ofthe square wave is also created from power in the power supply. Basedon the input voltages, logic switches create a new version, a duplicate, of thesquare wave (either theoretically identical or altered). A computer is made up ofbillions of transistors, all switching very quickly to changes in logic(mathematical algorithms created by the operating system and software). The timing, or duty cycle, along with the amplitudedetermine the frequency response of that square wave. This PWM signal has both amplitude characteristicsand timing characteristics. This pulse width modulation is an analogrepresentation of what we conceptualize as a digital signal and is created byvoltage in the power supply. Real time processes in a computer take the form of a square wave,specifically a pulse width modulation. Even if an application loads data into memory forprocessing, everything before and the whole operation after is a real timeoperation. Let's all start by agreeing that audio is areal-time process. This was important when storage was expensive, but now storage is plentiful and cheap.įinally the third camp, my camp, gets two paragraphs because it's my camp and I'm writing this. To get the highest quality, you will want to avoid lossy formats like MP3 (Moving Picture Experts Group Layer-3), AAC (Advanced Audio Coding), and OGG (Ogg Vorbis, the name Ogg derives from the jargon word ogging) that sacrifice audio quality for file size. DSD is the Philips/Sony system used to create the SACD (Super Audio Compact Disk) format, while MQA is a very clever codec that compresses the relatively little energy in the higher frequency bands to make the files smaller while retaining a hi-res result (it's also a good format for streaming services). Hi-res files may be offered in the FLAC (Free Lossless Audio Codec) or AIFF (Audio Interchange File Format) format, as well as DSD (Direct Stream Digital) and MQA (Master Quality Authenticated). We all know that your system is only as good as its weakest link, so I started with either 24/192 or 24/96 FLAC files. Opinions will vary on what constitutes hi-res audio, but I set my sights on resolutions equal to or better than 24-bit/96-kHz.
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