Why Moov head in the tail of the MP4 can quickly play, drag

User feedback with Chrome direct broadcast MP4, you can quickly play and drag, and the use of Flash Player to wait a long time to play.

The analysis:

First, about Chrome's quick play and drag

1. Chrome uses H5 's video tag to play

2, Chrome is very smart, if read MP4 file, found that Moov box is not in front of the file, will directly read the MP4 file tail, loading Moov box

3. When dragging, Chrome uses a range request to request the byte offset of the keyframe from the Moov box

Second, about Flash

1, Flash if read MP4 file, found Moov box is not in the front of the file, will not directly read the MP4 file tail to find Moov box, so flash to wait for all the files to download, take to the end of the file Moov head, can play normally.

PS: Our streaming media server, even if the moov at the end of the file will first send Moov head out to the CDN or the user, the equivalent of CDN back to the source, or the user back to the source of the request to the MP4, is already moov head in the file head, although this time the source station is Moov head in the file tail MP4.