For the past 14 years, producer Andy Zax has been digging into the music and sounds of Woodstock, that culture-shifting music festival that unfolded in August of 1969. Now, 50 years later, all 32 performances — the audio announcements, the entirety of this three-day festival in upstate New York — is about to be released by Rhino Records in a 38-disc box titled Woodstock - Back To The Garden: The Definitive 50th Anniversary Archive. There's also a 10-CD collection, a book by Woodstock promoter Michael Lang, a Blu-ray disc and more. Andy Zax came to the NPR studios to play some of that previously unheard or released music and talk about the history of this culture-altering festival.