What happened to the career trajectory of audio and video? For decades, they were members of the same club. But now, when it comes to quality, video is the superstar.

Television shoppers only want the best, so they insist on the highest resolution.

Music, meanwhile, remains stuck in another era, the late 20th century, and the early days of digital music downloads. In those days, agonizingly slow dial-up speeds made downloading a music CD’s uncompressed files impractical. It took hours.

That led to the MP3, created by the Moving Picture Experts Group, or MPEG, an international collection of experts that established standards for audio-video compression and transmission.

The MP3 made sense then.

An MP3 encoded at 128 kilobits per second was a fraction of an uncompressed CD (1,411 kilobits per second), allowing faster downloads. It also took up less hard-drive space. An 8-gigabyte portable music player holds maybe 15 albums of uncompressed music files, but close to 150 using low-bit-rate MP3 encoding.

MP3 files that were sold in stores were encrypted, too. That’s essential to music-industry licensing because it makes them harder to copy illegally. (The CD was unencrypted.)

More than a decade later, high-definition video is available at the iTunes Store or at Netflix, Vudu and other streaming services. Yet CD-quality downloads — never mind higher-def music — is unavailable at iTunes or Amazon.com or any other major music seller.

While video downloads have gone high-def, the most notable advance in music downloads is the iTunes Store’s switch from 128 kbps AAC files to 256 kbps AAC files, which changes the compression ratio to 5.5-1 from 11-1. That’s an improvement, but still a long way from the original music.

Space and speed no longer fit the audio equation.

Hard-drive space is less than $100 for a 1-terrabyte (1,000-gigabyte) external drive. High-speed broadband has replaced dial-up Internet connections. For portable use, iTunes software can automatically convert lossless or uncompressed files to a smaller, compressed format to fit more songs.

No technological, or practical, reason prevents music downloads from matching sound quality available in the home since the 1990s.

Maybe it doesn’t make a difference. People listen to music on iPhones, smartphones, iPads and tablets using headphones on noisy subways, in busy offices or relaxing while scanning the Internet, where quality doesn’t count.

But, as with video, we deserve to have the option of high-quality sound.