DocumentPicker converts to mp4 when necessary

// FREEBIE

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -2483,6 +2483,14 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
     }
 
     [dataSource setSourceFilename:filename];
+
+    // Although we want to be able to send higher quality attachments throught the document picker
+    // it's more imporant that we ensure the sent format is one all clients can accept (e.g. *not* quicktime .mov)
+    if ([SignalAttachment isInvalidVideoWithDataSource:dataSource dataUTI:type]) {
+        [self sendQualityAdjustedAttachmentForVideo:url filename:filename skipApprovalDialog:NO];
+        return;
+    }
+
     // "Document picker" attachments _SHOULD NOT_ be resized, if possible.
     SignalAttachment *attachment =
         [SignalAttachment attachmentWithDataSource:dataSource dataUTI:type imageQuality:TSImageQualityOriginal];

SignalMessaging/attachments/SignalAttachment.swift

@@ -789,9 +789,6 @@ public class SignalAttachment: NSObject {
         }
 
         if !isInputVideoValidOutputVideo(dataSource: dataSource, dataUTI: dataUTI) {
-            // Most people won't hit this because we convert video when picked from the media picker
-            // But the current API allows sending videos that some Signal clients will not
-            // be able to view. (e.g. when picked from document picker)
             owsFail("building video with invalid output, migrate to async API using compressVideoAsMp4")
         }