This gist demonstrates how to create an animated pause/resume media playback button for Android. It uses animated vector drawables and state transitions to orchestrate the effect. Some background: https://plus.google.com/u/0/+MoritzPost/posts/3EFF8uC7jXv

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="action_pause">#FF8F00</color>
    <color name="action_resume">#43A047</color>
</resources>

drawable_pause_to_resume_background.xml

<?xml version="1.0" encoding="utf-8"?>
<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
                android:duration="@android:integer/config_longAnimTime"
                android:propertyName="fillColor"
                android:valueFrom="@color/action_pause"
                android:valueTo="@color/action_resume" />

drawable_pause_to_resume_group.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <objectAnimator
        android:duration="@android:integer/config_longAnimTime"
        android:propertyName="rotation"
        android:valueFrom="0"
        android:valueTo="90" />
    <objectAnimator
        android:duration="@android:integer/config_longAnimTime"
        android:propertyName="translateX"
        android:valueFrom="0"
        android:valueTo="8" />
</set>

drawable_pause_to_resume_left.xml

<?xml version="1.0" encoding="utf-8"?>
<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
                android:duration="@android:integer/config_longAnimTime"
                android:propertyName="pathData"
                android:valueFrom="@string/drawable_vector_pause_left"
                android:valueTo="@string/drawable_vector_resume_left"
                android:valueType="pathType" />

drawable_pause_to_resume_right.xml

<?xml version="1.0" encoding="utf-8"?>
<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
                android:duration="@android:integer/config_longAnimTime"
                android:propertyName="pathData"
                android:valueFrom="@string/drawable_vector_pause_right"
                android:valueTo="@string/drawable_vector_resume_right"
                android:valueType="pathType" />

drawable_resume_to_pause_background.xml

<?xml version="1.0" encoding="utf-8"?>
<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
                android:duration="@android:integer/config_longAnimTime"
                android:propertyName="fillColor"
                android:valueFrom="@color/action_resume"
                android:valueTo="@color/action_pause" />

drawable_resume_to_pause_group.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <objectAnimator
        android:duration="@android:integer/config_longAnimTime"
        android:propertyName="rotation"
        android:valueFrom="90"
        android:valueTo="180" />
    <objectAnimator
        android:duration="@android:integer/config_longAnimTime"
        android:propertyName="translateX"
        android:valueFrom="8"
        android:valueTo="0" />
</set>

drawable_resume_to_pause_left.xml

<?xml version="1.0" encoding="utf-8"?>
<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
                android:duration="@android:integer/config_longAnimTime"
                android:propertyName="pathData"
                android:valueFrom="@string/drawable_vector_resume_left"
                android:valueTo="@string/drawable_vector_pause_left"
                android:valueType="pathType" />

drawable_resume_to_pause_right.xml

<?xml version="1.0" encoding="utf-8"?>
<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
                android:duration="@android:integer/config_longAnimTime"
                android:propertyName="pathData"
                android:valueFrom="@string/drawable_vector_resume_right"
                android:valueTo="@string/drawable_vector_pause_right"
                android:valueType="pathType" />

ic_pause.xml

<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
        android:width="192dp"
        android:height="192dp"
        android:viewportWidth="192"
        android:viewportHeight="192">
    <path
        android:name="background"
        android:fillColor="@color/action_pause"
        android:pathData="l192,0 0,192 -192,0 z" />
    <group
        android:name="rotationGroup"
        android:pivotX="96"
        android:pivotY="96">
        <path
            android:name="left"
            android:fillColor="@android:color/white"
            android:pathData="@string/drawable_vector_pause_left" />
        <path
            android:name="right"
            android:fillColor="@android:color/white"
            android:pathData="@string/drawable_vector_pause_right" />
    </group>
</vector>

ic_pause_resume.xml

<?xml version="1.0" encoding="utf-8"?>
<animated-selector xmlns:android="http://schemas.android.com/apk/res/android"
                   android:constantSize="true">

    <item
        android:id="@+id/pressed_selected"
        android:state_selected="true"
        android:state_pressed="true"
        android:drawable="@drawable/ic_resume" />

    <item
        android:id="@+id/action_resume_state"
        android:drawable="@drawable/ic_resume"
        android:state_selected="true" />

    <item
        android:id="@+id/action_pause_state"
        android:drawable="@drawable/ic_pause" />

    <transition
        android:fromId="@id/pressed_selected"
        android:toId="@id/action_resume_state"
        android:drawable="@drawable/ic_pause_to_ic_resume" />

    <transition
        android:fromId="@id/pressed_selected"
        android:toId="@id/action_pause_state"
        android:drawable="@drawable/ic_resume_to_ic_pause" />

</animated-selector>

ic_pause_to_ic_resume.xml

<?xml version="1.0" encoding="utf-8"?>
<animated-vector xmlns:android="http://schemas.android.com/apk/res/android"
                 android:drawable="@drawable/ic_pause">
    <target
        android:name="background"
        android:animation="@anim/drawable_pause_to_resume_background" />
    <target
        android:name="rotationGroup"
        android:animation="@anim/drawable_pause_to_resume_group" />
    <target
        android:name="left"
        android:animation="@anim/drawable_pause_to_resume_left" />
    <target
        android:name="right"
        android:animation="@anim/drawable_pause_to_resume_right" />
</animated-vector>

ic_resume.xml

<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
        android:width="192dp"
        android:height="192dp"
        android:viewportWidth="192"
        android:viewportHeight="192">
    <path
        android:name="background"
        android:fillColor="@color/action_resume"
        android:pathData="l192,0 0,192 -192,0 z" />
    <group
        android:name="rotationGroup"
        android:pivotX="96"
        android:pivotY="96"
        android:translateX="8"
        android:rotation="90">
        <path
            android:name="left"
            android:fillColor="@android:color/white"
            android:pathData="@string/drawable_vector_resume_left" />
        <path
            android:name="right"
            android:fillColor="@android:color/white"
            android:pathData="@string/drawable_vector_resume_right" />
    </group>
</vector>

ic_resume_to_ic_pause.xml

<?xml version="1.0" encoding="utf-8"?>
<animated-vector xmlns:android="http://schemas.android.com/apk/res/android"
                 android:drawable="@drawable/ic_resume">
    <target
        android:name="background"
        android:animation="@anim/drawable_resume_to_pause_background" />
    <target
        android:name="rotationGroup"
        android:animation="@anim/drawable_resume_to_pause_group" />
    <target
        android:name="left"
        android:animation="@anim/drawable_resume_to_pause_left" />
    <target
        android:name="right"
        android:animation="@anim/drawable_resume_to_pause_right" />
</animated-vector>

strings_constants.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="drawable_vector_pause_left">M72,64 l16,0 0,64 -16,0 z</string>
    <string name="drawable_vector_pause_right">M104,64 l16,0 0,64 -16,0 z</string>
    <string name="drawable_vector_resume_left">M96,64 l0,0 0,64 -40,0 z</string>
    <string name="drawable_vector_resume_right">M96,64 l0,0 40,64 -40,0 z</string>
</resources>