What did Confucius revise by sorting out the Book of Songs, Shangshu and other ancient books?

In the revision of The Book of Songs, 305 poems were selected from more than 3,000 poems since the Zhou Dynasty, and each poem was accompanied by music, but Hu Shi thought that Confucius did not delete the poems. At present, too many books think that Confucius deleted some of them, but not too many, about 4500. As for Confucius' revision of Shangshu, 100 was selected. At the same time, Confucius also compiled the Book of Changes and compiled the Spring and Autumn Annals.