fix issue for screen sharing.

Author: cloudwebrtc

sdk/objc/native/src/objc_video_track_source.mm

@@ -37,7 +37,7 @@ - (void)capturer:(RTC_OBJC_TYPE(RTCVideoCapturer) *)capturer
 ObjCVideoTrackSource::ObjCVideoTrackSource() : ObjCVideoTrackSource(false) {}
 
 ObjCVideoTrackSource::ObjCVideoTrackSource(bool is_screencast)
- : AdaptedVideoTrackSource(/* required resolution alignment */ 2),
+ : AdaptedVideoTrackSource(/* required resolution alignment */ is_screencast? 16 : 2),
  is_screencast_(is_screencast) {}
 
 ObjCVideoTrackSource::ObjCVideoTrackSource(RTCObjCVideoSourceAdapter *adapter) : adapter_(adapter) {