Once again the band began tinkering. “We have a song and we’ve got lots of different ways we can try it, but we don’t know what’s going to work, and that’s why it still sort of feels a bit weirdly amateur,” Mr. Greenwood said. “You’d think by now we’d know what’s going to work, and what’s still frustrating, or kind of encouraging in a way, is that we don’t know whether it’s going to work on a laptop or whether it has to be a piano or. ...”

He half-smiled. “It’s got so twisted,” he added. “What we’ve learned is that you can’t repeat a method that you’ve already used for a song when it did work.”

The sound of “In Rainbows” often seems straightforward, almost like a live band; it is Radiohead’s most gracefully melodic album in a decade. But Radiohead arrived at the music circuitously, and there’s often more tucked into a track than is apparent at first. “Videotape,” with lyrics about recording a happy moment in a tape to be viewed posthumously, has a tolling piano and a beat so elusive that “we spent about a year in rehearsal on that song actually all trying to agree on where the one was,” Mr. Selway said. “Each of us, over the course of a year, we’d all lose it.”

The “Reckoner” that was part of the band’s live sets sounds nothing like the “Reckoner” on the album, which includes the lyrics “in rainbows.” When the band returned from touring, it decided the song needed a second part, and then a third one; eventually it discarded the original. For “All I Need,” Mr. Greenwood said, he wanted to recapture the white noise generated by a band playing loudly in a room, when “all this chaos kicks up.” That sound never materializes in the more analytical confines of a studio. His solution was to have a string section, and his own overdubbed violas, sustaining every note of the scale, blanketing the frequencies.

Mr. Yorke worked on many of the songs in the Rose and Crown. “I sit there, on the way in, because it’s a really nice little table,” he said, pointing. “And then I get out my scraps of paper and I line them up. I need to put them into my book because they’re just scraps of paper, and I’m going to lose them unless I do it. So am I writing here? Probably. I don’t know yet. I’m just collating information. This is a nice, relaxing thing to do, and it also keeps your mind tuned in to the whole thing. And you see things you didn’t know.”

The band and its managers are not releasing the download’s sales figures or average price, and may never do so. “It’s our linen,” Mr. Hufford said. “We don’t want to wash it in public.” A statement from the band rejected estimates by the online survey company ComScore that during October about three-fifths of worldwide downloaders took the album free, while the rest paid an average of $6.