Several versions ago, we spotted Google Duo prepping a feature that would allow users to send video and audio messages to contacts. Version 21 of the video conferencing app is now rolling out and better details the upcoming functionality.

About APK Teardowns: In this ‘APK teardown,’ we’ve decompiled the latest version of an application that was uploaded to the Play Store. When an app (or an APK, to be specific, in the case of Android apps) is decompiled, we’re able to see various lines of code within that hint at possible future features. Keep in mind that Google may or may not ever ship these features, and our interpretation of what they are may be imperfect. With that in mind, read on.

Start/stop buttons for recording

As we spotted in our last teardown of Duo, one way the messaging feature could be accessed will be through the dialing screen. While waiting for a recipient to answer a call, users could tap a send button to launch an interface to record their message. Version 21 adds two new icons for this interface that show the start and stop recording buttons.

Message notifications

Several strings in this version describe the notification that recipients will receive, noting whether it is a video or voice message and who it’s from. Depending on the type, a Listen or Watch button will also be displayed with that notification.

<string name=”notification_body_for_message”>From %s</string>

<string name=”notification_cta_audio_message”>LISTEN</string>

<string name=”notification_cta_video_message”>WATCH</string>

Video expiration

Another string suggests that video message can expire if not watched during a certain time range. It’s unclear at this time whether users will have any control over the duration or whether there’s a default length.

<string name=”video_clip_count_text”>+ %s</string>

<string name=”video_clip_expire_alert_message”>Expires in %s</string>

Saving messages?

Other strings refer to saving videos, though it’s unclear whether this is an ability for either senders or recipients to save messages or whether it’s a reference to the recording and sending process of a message.

<string name=”save_video_fail_message”>Failed to save the video</string>

<string name=”save_video_success_message”>Successfully saved the video</string>

Camera effects

As of version 17, Google Duo began working on camera effects. The debug menu now lists controls for brightness, contrast, and saturation that might one day be accessible to users.

<string name=”pref_camerabrightness_default”>0.0</string>

<string name=”pref_camerabrightness_dlg”>Enter camera brightness ([-1.0, 1.0]) after enabling video processing</string>

<string name=”pref_camerabrightness_key”>camera_brightness_preference</string>

<string name=”pref_camerabrightness_title”>Camera brightness</string>


<string name=”pref_cameracontrast_default”>1.0</string>

<string name=”pref_cameracontrast_dlg”>Enter camera contrast (>=0.0) after enabling video processing</string>

<string name=”pref_cameracontrast_key”>camera_contrast_preference</string>

<string name=”pref_cameracontrast_title”>Camera contrast</string>


<string name=”pref_camerasaturation_default”>1.0</string>

<string name=”pref_camerasaturation_dlg”>Enter camera saturation (>=0.0) after enabling video processing</string>

<string name=”pref_camerasaturation_key”>camera_saturation_preference</string>

<string name=”pref_camerasaturation_title”>Camera saturation</string>


Dylan contributed to this article

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Abner Li

Editor-in-chief. Interested in the minutiae of Google and Alphabet. Tips/talk: abner@9to5g.com