The world's most popular music channel isn't iTunes, Spotify or Radio 1 – it's YouTube. Three hundred hours of video are uploaded to YouTube every minute, and much of that video is music – but it's music in a format that isn't ideal for listening to on portable devices like smartphones or iPods. That doesn't mean you can't download it or change the format, however.
File formats and quality
YouTube music download apps such as aTube Catcher, which we’ll use in this tutorial, support a wide range of file formats. The most commonly used format for music is MP3, which works on pretty much anything from smartphones to connected car stereos. When you download music using aTube Catcher, your results will be saved as MP3s. It’s not the most cutting edge music format, but it’s by far the most widely supported.
MP3s can be saved at different bitrates, which adjust the sound quality to reduce file size or vice versa. aTube Catcher’s music downloader offers five options, ranging from 320Kbps – the highest quality, which is nearly indistinguishable from CD – down to 64Kbps, which is slightly less pleasant than being jammed into a metal dustbin and pushed off a cliff.
Lossy compression: what it is, and when it's good
MP3 uses something called lossy compression to adjust file sizes, so you can get something that sounds pretty close to CD quality with a file size of about 1/12 of the original.
That’s great but it does involve the computer getting rid of things it thinks your ears won’t miss, and the more aggressively it does that the worse the sound quality becomes – so a 128Kbps MP3 is half the size of a 256Kbps one, but it’s also noticeably poorer quality. Unless you’ve got really atrocious speakers, we’d recommend sticking to 192Kbps or 256Kbps.
Choosing the right bitrate for YouTube music
Watching a black and white film on a colour TV doesn't magically colourise it, and whacking your audio converter's settings up to maximum bitrates won't magically improve the sound quality of a YouTube video if the original isn't up to snuff.
In most cases, the music you'll hear on a YouTube video is an AAC stream of 128 to 192kbps – even though YouTube recommends that video uploaders use a bitrate of 384kbps for stereo audio. That may be for future-proofing, or it may be to get the best results from Google's own music compression, but either way it means there's little point in going beyond 192kbps when you create M4A/AAC files, or around 256kbps for MP3s.
Is downloading music from YouTube legal?
That's a very good question. It's certainly against YouTube's terms of service, which say you can only use its content for streaming, and you could argue that it's unethical too: many artists depend on YouTube's ads for their income, so any ad-free playback you do is depriving them of their wages.
To download music legally, you need permission from the copyright holder. You should be able to contact them through the About section of their profile, or via their YouTube channel.