[BUG] Screen is flipped vertically when streaming from Android device

[burakkaraceylan]

Stream broadcasted from an Android device is shown vertically flipped on the web applicaton.
To Reproduce
Steps to reproduce the behavior:

1. Build and run broadcast sample on Android device
2. Go to receiver sample on the web app
3. Click play
4. See error

Expected behavior
Stream should be shown exactly as it is on the android application

Screenshots

Environment (please complete the following information):

• OS: Android 11
• Browser: Chrome
• Unity Version: 2020.3.21f1
• Package version [e.g. 3.1.0-exp2]

[karasusan]

@burakkaraceylan
Thanks for the feedback.
There is a workaround that change graphics API to Vulkan.

[burakkaraceylan]

Is that possible? As far as I know you can't compile AR core when vulkan is enabled.

[karasusan]

memo: WRS-166

[karasusan]

@burakkaraceylan
Unfortunately, AR core is needed to build GLES graphic API.

There is a workaround that customizing ScreenStreamSender using another constructor of VideoStreamTrack.
https://github.com/Unity-Technologies/com.unity.webrtc/blob/develop/Runtime/Scripts/VideoStreamTrack.cs#L113-L119

[burakkaraceylan]

For now I am handling it like this. Can it be done better or faster?

       IEnumerator RecordFrame()
        {
            yield return new WaitForEndOfFrame();

            ScreenCapture.CaptureScreenshotIntoRenderTexture(_flippedTexture);
            Graphics.Blit(_flippedTexture, m_sendTexture, new Vector2(1.0f, -1.0f), new Vector2(0.0f, 1.0f));
        }

[karasusan]

@burakkaraceylan
Nice. We have a plan fixing this issue that adding a flag to flip texture to VideoStreamTrack.

[yinhew]

For now I am handling it like this. Can it be done better or faster?

       IEnumerator RecordFrame()
        {
            yield return new WaitForEndOfFrame();

            ScreenCapture.CaptureScreenshotIntoRenderTexture(_flippedTexture);
            Graphics.Blit(_flippedTexture, m_sendTexture, new Vector2(1.0f, -1.0f), new Vector2(0.0f, 1.0f));
        }

@burakkaraceylan How did you apply this work around?
This code is part of the package.
How did you edit the code after you installed the package?

I installed the WebRTC package following https://github.com/Unity-Technologies/com.unity.webrtc/blob/develop/Documentation~/install.md#case-of-unity-20203
Did you do the same?

[burakkaraceylan]

@yinhew I cloned the git repo and installed from disk to get the latest version. But, you should still be able to edit the scripts anyway. It's an open source package and screen stream sender is just a C# script. However, what I did was I cloned the screen stream sender script and made my own version where I fiddle with it and use it in the stream list.

[yinhew]

Got it, thanks a lot! @burakkaraceylan

[karasusan]

This issue is fixed #630.
The new version will be released in this month.