How to use saveVideoSnapshotAt api to take snapshot.

[2019801]

use ./buildMobileVLCKit.sh -s build MobileVLCKit.

I add a button in SimplePalyback project to do snapshot.

code:
- (IBAction)takeSnapshot:(UIButton *)sender {
NSString* path = NSHomeDirectory();
NSString* snapshotFile = [path stringByAppendingString:@"/1.png"];
NSLog(path);
[_mediaplayer saveVideoSnapshotAt:snapshotFile withWidth:0 andHeight:0];
[_mediaplayer saveVideoSnapshotAt:path withWidth:0 andHeight:0];

}

When I click the button then get error:
[0c2de874] core video output error: Encoding support not compiled-in!
[0c2de874] core video output error: Failed to convert image for snapshot
[0c2de874] core video output error: Encoding support not compiled-in!
[0c2de874] core video output error: Failed to convert image for snapshot

How to compiled-in, and how to use saveVideoSnapshotAt api to take snapshot?
And I also want record media, I can’t find the api, which api can do record?

Thanks,
Farrell