[Bug]: Transformer Demo video is initially clipped after export

[calren]

[Bug]: Transformer Demo video is initially clipped after export

[calren]

After more investigating, this seems to be a Compose-related issue. When the sample was isolated to only use Views (https://github.com/calren/ViewsTransformerExoPlayerDemo), the issue was no longer present.

The Compose issue is being tracked here: androidx/media#1237 . Using the 1.4.0-rc01 version of PlayerView should resolve this issue. Once Media3 1.4.0-rc01 is released, I will update the Media3 dependency and test again.

In the mean time, I don't think we need to merge the fix that involves using AspectRatioFrameLayout, so I will close #173

[calren]

@droid-girl Any idea why this might be happening? Feels like the code might be missing something in between setting the mediaItem on the exoplayer and preparing exoplayer for playback (https://github.com/android/platform-samples/blob/main/samples/media/video/src/main/java/com/example/platform/media/video/TransformerVideoComposition.kt#L261-L272), but I can't figure out what's missing. Hoping someone on the ExoPlayer team can help debug.

[calren]

From Kristina: Maybe we should try AspectRatioLayout, ie: https://github.com/androidx/media/blob/d833d59124d795afc146322fe488b2c0d4b9af6a/demos/transformer/src/main/res/layout/transformer_activity.xml#L88

I will give this a try and see if the issue persists.

[calren]

I got the issue resolved by:

1. Putting PlayerView inside AspectRatioFrameLayout

    <androidx.media3.ui.AspectRatioFrameLayout
        android:id="@+id/input_debug_aspect_ratio_frame_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <androidx.media3.ui.PlayerView
            android:id="@+id/media_player"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

    </androidx.media3.ui.AspectRatioFrameLayout>

2. Explicitly setting aspect ratio in the Activity / Fragment
   binding.inputDebugAspectRatioFrameLayout.setAspectRatio(16f/9f)

Will submit a PR for this fix.

This doesn't seem very intuitive, so I will explore ways we can make this easier for the developer.