fix nil pointer on read error using copy frame buffer

mediadevices.go

@@ -2,6 +2,7 @@ package mediadevices
 
 import (
 	"fmt"
+	"log"
 	"math"
 	"strings"
 
@@ -157,6 +158,7 @@ func selectBestDriver(filter driver.FilterFn, constraints MediaTrackConstraints)
 	constraints.selectedMedia = prop.Media{}
 	constraints.selectedMedia.MergeConstraints(constraints.MediaConstraints)
 	constraints.selectedMedia.Merge(bestProp)
+	log.Println("selected media:", constraints.selectedMedia)
 	return bestDriver, constraints, nil
 }
 

pkg/avfoundation/AVFoundationBind/AVFoundationBind.m

@@ -345,7 +345,7 @@ STATUS AVBindSessionProperties(PAVBindSession pSession, PAVBindMediaProperty *pp
         if ([refFormat.mediaType isEqual:AVMediaTypeVideo]) {
             fourCC = CMFormatDescriptionGetMediaSubType(refFormat.formatDescription);
             if (frameFormatFromFourCC(fourCC, &pProperty->frameFormat) != STATUS_OK) {
-                NSLog(@"[WARNING] skipping %@ %dx%d since it's not supported", FourCCString(fourCC), videoDimensions.width, videoDimensions.height);
+                NSLog(@"[WARNING] skipping %@(%d) %dx%d since it's not supported", FourCCString(fourCC), fourCC, videoDimensions.width, videoDimensions.height);
                 continue;
             }
 

pkg/io/broadcast.go

@@ -141,7 +141,9 @@ func (broadcaster *Broadcaster) NewReader(copyFn func(interface{}) interface{})
 			data, err, currentCount = ringData.data, ringData.err, ringData.count
 		}
 
-		data = copyFn(data)
+		if err != nil {
+			data = copyFn(data)
+		}
 		return
 	})
 }