to top

OEM Dependencies for Media Resource Manager

In this document

This document is intended to help original equipment manufacturers (OEMs) properly implement support for Android media resource manager and related APIs.

1. Max concurrent codec instances

The CodecCapabilities.getMaxSupportedInstances interface returns the maximum number of supported concurrent codec instances.

The CTS test testGetMaxSupportedInstances(android.media.cts.MediaCodecCapabilitiesTest) is used to enforce the proper maximum is set in /etc/media_codecs.xml.

Here is an example:

...
<MediaCodecs>
    ...
    <Encoders>
        <MediaCodec name="OMX.<vendor>.video.encoder.avc" type="video/avc" >
           ...
            <Limit name="concurrent-instances" max="13" />
        </MediaCodec>
        ...
    </Encoders>
    ...
</MediaCodecs>

OEMs can use this test to generate the concurrent limits that pass the test. To do this:

  1. Run the test first using cts-tradefed.
  2. Evaluate the resulting failure message. Here is an example:
    There was 1 failure:
    1) testGetMaxSupportedInstances(android.media.cts.MediaCodecCapabilitiesTest)
    junit.framework.AssertionFailedError: In order to pass the test, please publish
    following codecs' concurrent instances limit in /etc/media_codecs.xml:
    <MediaCodec name="OMX.<vendor>.video.encoder.mpeg4" type="video/mp4v-es" >
        <Limit name="concurrent-instances" max="13" />
    </MediaCodec>
    <MediaCodec name="OMX.<vendor>.video.encoder.h263" type="video/3gpp" >
        <Limit name="concurrent-instances" max="13" />
    </MediaCodec>
    <MediaCodec name="OMX.<vendor>.video.encoder.avc" type="video/avc" >
        <Limit name="concurrent-instances" max="13" />
    </MediaCodec>
    <MediaCodec name="OMX.<vendor>.video.encoder.vp8" type="video/x-vnd.on2.vp8" >
        <Limit name="concurrent-instances" max="13" />
    </MediaCodec>
    <MediaCodec name="OMX.<vendor>.video.decoder.avc" type="video/avc" >
        <Limit name="concurrent-instances" max="13" />
    </MediaCodec>
    <MediaCodec name="OMX.<vendor>.video.decoder.avc.secure" type="video/avc" >
        <Limit name="concurrent-instances" max="4" />
    </MediaCodec>
    <MediaCodec name="OMX.<vendor>.video.decoder.mpeg4" type="video/mp4v-es" >
        <Limit name="concurrent-instances" max="12" />
    </MediaCodec>
    <MediaCodec name="OMX.<vendor>.video.decoder.h263" type="video/3gpp" >
        <Limit name="concurrent-instances" max="12" />
    </MediaCodec>
    <MediaCodec name="OMX.<vendor>.video.decoder.vp8" type="video/x-vnd.on2.vp8" >
        <Limit name="concurrent-instances" max="12" />
    </MediaCodec>
    
  3. Add the concurrent-instances lines suggested in the test failure message to the /etc/media_codecs.xml file.
  4. Re-run the test to verify its success.

2. Achievable frame rates for video codecs

The VideoCapabilities.getAchievableFrameRatesFor interface returns the range of achievable video frame rates for a video size. This information must be provided by the OEM for each device via an XML file placed at /etc/media_codecs_performance.xml. These settings are tested by the com.android.cts.videoperf.VideoEncoderDecoderTest and android.media.cts.VideoDecoderPerfTest CTS tests.

OEMs can use the CTS tests to generate the XML files that pass the tests. To do this:

  1. Run the tests first using cts-tradefed. Given the variability of Android performance, it is recommended the tests are run multiple times to get more accurate minimum and maximum values.
  2. Use the provided get_achievable_rates.py script to generate the XML file.
  3. Place the XML file at: /etc/media_codecs_performance.xml
    This is usually done by placing the XML file in the device project (device/<vendor>/<product>) and adding a PRODUCT_COPY_FILES line to device.mk like so:
    PRODUCT_COPY_FILES += \
    ...
       device/moto/shamu/media_codecs.xml:system/etc/media_codecs.xml \
    +    device/moto/shamu/media_codecs_performance.xml:system/etc/media_codecs_performance.xml
    
  4. Re-run the performance tests to verify their success.

3. Co-exist of secure codec and non-secure codec

  • supports-secure-with-non-secure-codec — If the instance of secure codec and the instance of non-secure codec can’t co-exist at the same time, that should be indicated as global setting in the media_codecs.xml file.
    <MediaCodecs>
        <Settings>
            <Setting name="supports-secure-with-non-secure-codec" value="false" />
        </Settings>
        <Encoders>
    …
    
  • supports-multiple-secure-codecs — If co-exist of multiple secure codec instances is not supported, that should be indicated as a global setting in the media_codecs.xml file.
    <MediaCodecs>
        <Settings>
            <Setting name="supports-multiple-secure-codecs" value="false" />
        </Settings>
        <Encoders>
    …
    
  • Note that the both settings are true by default, meaning if they are supported, there’s no need to add the setting line to the media_codecs.xml.
  • The ResourceManagerTest CTS tests may fail if these two settings were not set properly.