Add page for OEMs

oems.md

+---
+layout: default
+title: OEM testing
+weight: 6
+---
+
+<div id="table-of-contents">
+<div id="table-of-contents-header">Contents</div>
+<div markdown="1">
+* TOC
+{:toc}
+</div>
+</div>
+
+ExoPlayer is used by a large number of Android applications. As an OEM, it's
+important to ensure that ExoPlayer works correctly both on new devices, and on
+new platform builds for existing devices. This page describes compatibility
+tests that we recommend running before shipping a device or platform OTA, and
+some of the common failure modes encountered when running them.
+
+## Running the tests ##
+
+To run ExoPlayer's playback tests, first check out the latest release of
+ExoPlayer from [GitHub][]. You can then run the tests from the command line or
+Android Studio.
+
+### Command line ###
+
+From the root directory, build and install the playback tests:
+```
+./gradlew :playbacktests:installDebug
+```
+Next, run the playback tests in the GTS package:
+```
+adb shell am instrument -w -r -e debug false \
+  -e package com.google.android.exoplayer2.playbacktests.gts \
+  com.google.android.exoplayer2.playbacktests.test/android.test.InstrumentationTestRunner
+```
+Test results appear in STDOUT.
+
+### Android Studio ###
+
+Open the ExoPlayer project, navigate to the `playbacktests` module, right click
+on the `gts` folder and run the tests. Test results appear in Android Studio's
+Run window.
+
+## Common failure modes ##
+
+Some of the common failure modes encountered when running ExoPlayer's playback
+tests are described below, together with the likely root cause in each case. We
+will add to this list as further failure modes are discovered.
+
+### Unexpected video buffer presentation timestamp ###
+
+Logcat will contain an error similar to:
+```
+Caused by: java.lang.IllegalStateException: Expected to dequeue video buffer
+with presentation timestamp: 134766000. Instead got: 134733000 (Processed
+buffers since last flush: 2242).
+```
+This failure is most often caused by the video decoder under test incorrectly
+discarding, inserting or re-ordering buffers. In the example above, the test
+expected to dequeue a buffer with presentation timestamp `134766000` from
+`MediaCodec.dequeueOutputBuffer`, but found that it dequeued a buffer with
+presentation timestamp `134733000` instead. We recommend that you check the
+decoder implementation when encountering this failure, in particular that it
+correctly handles adaptive resolution switches without discarding any buffers.
+
+### Too many dropped buffers ###
+
+Logcat will contain an error similar to:
+```
+junit.framework.AssertionFailedError: Codec(DashTest:Video) was late decoding:
+200 buffers. Limit: 25.
+```
+This failure is a performance problem, where the video decoder under test was
+late decoding a large number of buffers. In the example above, ExoPlayer dropped
+200 buffers because they were late by the time they were dequeued, for a test
+that imposes a limit of 25. The most obvious cause is that the video decoder
+is too slow decoding buffers. If the failures only occur for the subset of tests
+that play Widevine protected content, it's likely that the platform operations
+for buffer decryption are too slow. We recommend checking the performance of
+these components, and looking at whether any optimizations can be made to speed
+them up.
+
+### Native window could not be authenticated ###
+
+Logcat will contain an error similar to:
+```
+SurfaceUtils: native window could not be authenticated
+ExoPlayerImplInternal: Internal runtime error.
+ExoPlayerImplInternal: android.media.MediaCodec$CodecException: Error 0xffffffff
+```
+This failure is indicative of the platform failing to correctly set the secure
+bit flag.
+
+### Test timed out ###
+
+Logcat will contain an error similar to:
+```
+AssertionFailedError: Test timed out after 300000 ms.
+```
+This failure is most often caused by poor network connectivity during the test
+run. If the device appears to have good network connectivity then it's possible
+that the test is getting stuck calling into a platform component (e.g.
+`MediaCodec`, `MediaDrm`, `AudioTrack` etc). Inspect the call stacks of the
+threads in the test process to establish whether this is the case.
+
+[GitHub]: https://github.com/google/ExoPlayer