NPR Labs Eyes Streaming Technology asks: What is the best digital audio codec, and what is the optimum bitrate for Internet streaming? That was the question posed by NPR Digital Media, which funded an extensive study by NPR Labs to answer these questions impartially.

While the study was conducted for public radio, the premise and conclusions may be helpful to commercial broadcasters that stream audio as well.

The search for answers was more involved than one might expect, and led to other related investigations, such as the reliability of mobile wireless media, the availability of decoders in consumer equipment and the consistency of loudness from stream to stream. (This last consideration will be the focus on a subsequent article here.)

Internet streaming and related media, such as host websites, mobile applications, digital car products, social tools and API distribution, are the fastest-growing outlets for public radio. At any given moment, there are more than 37,000 average active sessions that are listening to streams from public radio stations and NPR; and that’s up 14 percent over last year.

Until recently, stations — and even NPR itself — used a variety of codecs for streams and podcasts: MP3, LAME, AAC, Ogg, etc., and even more choices of bitrates, ranging from 24 kilobits per second to 160 kbps. Finding a common codec would provide a more uniform quality for listeners and help ensure that the services are uniformly available to listeners on a range of playback equipment, such as smartphones, tablets, WiFi “radios” and personal computers.


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