Repository: flutter
Issue: [video_player] plugin mutes on some portrait camera videos
Labels: platform-ios,p: video_player,package,has reproducible steps,P2,found in release: 2.0,found in release: 2.2,team-ios,triaged-ios

## Steps to Reproduce
I'm using `video_player: ^1.0.1` last recent package before `Null-Safety`

I'm playing some videos from Firebase Storage on a Flutter Application.. I have two types of videos (Landscapes & portraits) both in MP4 format..
All videos play perfect on Android..
However, On iOS, Portrait videos play with NO sound(muted)!
Here's a snippet of my code:

```
VideoPlayerController _controller;
    @override
      void initState() {
       super.initState();
       _controller = VideoPlayerController.network(url)
          ..initialize().then((_) {
            // Ensure the first frame is shown after the video is initialized, even before the play button has been pressed.
            setState(() {});
          });
    
      }
```

Then the body is a Stack widget:

```
Stack(
          children: <Widget>[
            FlatButton(
                padding: EdgeInsets.all(0),
                onPressed: () {
                  setState(() {
                    if (play) {
                      _controller?.pause();
                      play = !play;
                    } else {
                      _controller?.play();
                      play = !play;
                    }
                  });
                },
                child: Container(
                  width: MediaQuery.of(context).size.width,
                  height: MediaQuery.of(context).size.height,
                  alignment: Alignment.center,
                  child: _controller.value.initialized
                      ? AspectRatio(
                          aspectRatio: _controller.value.aspectRatio,
                          child: VideoPlayer(_controller),
                        )
                      : Container(),
                )),
    ...//More widgets in the stack...
    ..
    .
```

Notice:
-I also tried to set the volume of the controller manually by using `..setVolume(1.0)` in the `initState`and portrait videos are still muted. 
-iOS Ringer is not the problem cause Landscape videos play perfect!
-I checked the portrait videos links in the firebase storage, and ensured that they all have sound.
-I tried to change the widget `aspectRatio: 9 / 16` to match the portrait videos aspect ratio and still video muted.
-I tried another package `better_player: ^0.0.61` and unfortunately it seems like all packages are based on the `video_player` plugin and thus they have the same issue.

Any help would be really appreciated!
Thanks,

**Expected results:**
Video should play with its sound!

**Actual results:**
Video plays without any sound.

<details>
  <summary>Logs</summary>

<!--
      Run your application with `flutter run --verbose` and attach all the
      log output below between the lines with the backticks. If there is an
      exception, please see if the error message includes enough information
      to explain how to solve the issue.
-->

```
No error messages at all
```

<!--
     Run `flutter analyze` and attach any output of that command below.
     If there are any analysis errors, try resolving them before filing this issue.
-->

```
Nothing.
```

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[✓] Flutter (Channel stable, 1.22.6, on Mac OS X 10.15.7 19H1011 darwin-x64, locale en)
    • Flutter version 1.22.6 at /Users/devyat/development/flutter
    • Framework revision 9b2d32b605 (3 months ago), 2021-01-22 14:36:39 -0800
    • Engine revision 2f0af37152
    • Dart version 2.10.5

 
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Users/devyat/Library/Android/sdk
    • Platform android-30, build-tools 30.0.3
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 12.4)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[!] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] Connected device (1 available)
    • Eidarous’s iPhone (mobile) • ios • iOS 14.4.2
    ! Error: Eidarous’s iPhone is busy: Copying cache files from device. Xcode will continue when Eidarous’s iPhone is finished. (code -10)

! Doctor found issues in 1 category.
```

</details>