Audio Quality Requirements

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Over the last many years since digital portable audio became widely available, convenience has pushed quality to the back burner. Many listeners today have no idea how good music used to sound on vinyl records and CDs. FM radio has the bandwidth to almost perfectly render this level of sound in the car or home equipped with a decent receiver and speakers. While MP3 has a place in your pocket or through earbuds, it disappoints in a professional broadcast operation. Material put on KMKR-LP should be as lossless as possible which means WAV or AIFF and in some cases FLAC when it is created at its maximum resolution settings. Yes, it is true that satellite radio and streaming services do use MP3 type compression but we should be better than that.

The most important number is total bitrate which is a little arithmetic problem: sampling frequency times bit resoluion equals bitrate. On a CD WAV file, that works out to 44 thousand Hz times sixteen bits which is around 700,000 Hz. But that is for one stereo channel at a time so for both channels of stereo in real time, the minimum total bitrate for CD quality is in fact 1411 kb per second. The very best MP3 can do is more like 320 which is about one fourth as good. Some MP3 is 160 and some is 96. These might be OK as background on a a bluetooth poolside rock speaker but it should only be put on the radio when higher fidelity is unobtainable.

48 khz rate is KMKR's old standard for our very first digital recordings but this has been superseded at least for home use by the CD rate of 44.1 khz. Khz is only half the equation; the other part being the depth of resolution. A total bitrate of 48 kbs is way too low and not a realistic number for anything but a garbled telephone line connection. There is another realm in which 48 khz is once again relevant and that is when used with floating or variable bit depth. The most common application is in DVD and home theater multi channel material which is not ever transmitted on the radio in two channel stereo. Its multiple of 96khz is often used for high resolution archiving of legacy analog material but this has no relevance for stereo FM broadcasters either.

To summarize: material from a CD burned on a computer with full resolution WAV files is perfect for KMKR. A flash drive with WAV files is equally good. A flash drive with AIFF files or FLAC files is most likely OK but will be reviewed for technical quality before going on the air. No MP3 file of any resolution or size is achieving our audio quality standard and should not be loaded into our station's RadioDJ library. Volunteer DJs may play MP3s on occasion when a song is highly desired but unavailable in sufficient quality, but this should not be their normal method. Today's modern recording software can be controlled by the user to achieve these quality benchmarks. Old material stored improperly can never be upgraded or repaired. It must be re-captured in high resolution.