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  • Raspberry Pi
    4 min | 99708

    #Raspberry Pi 4: Hardware accelerated video decoding (GPU) in Chromium

    Raspberry Pi | 4 min | 99708


    Two months ago, I wrote a tutorial that explains how to get DRM support on Chromium on the Raspberry Pi. If you follow the steps of that tutorial:

    you can use the Chromium web browser to play videos from Netflix, Hulu, HBO, Disney+, Amazon Prime, Spotify, Pandora, and many others (see Fig. 1 & 2).

    Supported Browser
    Fig. 1: Playing videos on Amazon Prime
    using Chromium on the Raspberry Pi OS.
    Supported Browser
    Fig. 2: Playing music on Spotify
    using Chromium on the Raspberry Pi OS.

    AnthonyD wrote in the comment section:

    That is a great solution to the DRM problem on Raspberry Pi! How is the video playback quality in Chromium? Do you know if it uses hardware acceleration or just the CPU?

    Last week I had some time to run some tests and extended the tutorial to add support for hardware acceleration for the video decoding.

    To answer that question, the video playback quality is good, however, per default Chromium uses Software (CPU) to decode the video. This means, no hardware acceleration.

    Graphics Feature Status - Software Acceleration
    Fig. 3: Graphics Feature Status - Chromium on Raspberry Pi 4.

    But, we will change that on this tutorial!

    You may be also interested in this tutorial: Raspberry Pi 4: booting from an SSD with enabled TRIM

    Hardware and Software

    You will need the following hardware and software for this tutorial:

    DIY: Video Decode using Hardware Acceleration

    You need to install a few libraries, but first, the basic step is to update the system typing the following on a Terminal:

    sudo apt-get update
    sudo apt-get upgrade

    Then, install the libraries typing:

    sudo apt-get install libgles2-mesa libgles2-mesa-dev xorg-dev

    To be able to activate the hardware acceleration, first we need to enable the 3D video driver (so-called Fake KMS), and then set the memory to e.g. 128 MB (this is usually a default value). To do that:

    1. Start the raspi-config configurator, typing in a Terminal:
      sudo raspi-config
    2. Go to Advanced Options > GL Driver
    3. Select the option GL (Fake KMS) OpenGL desktop driver with fake KMS and Click OK
    4. Go to Performance Options > GPU Memory (on old Raspbian/Raspberry Pi OS: Advanced Options > Memory Split)
    5. Type 128 and click OK
    6. Select Finish and Reboot the system.

    Note: if you're new to this configurator, you can navigate the menu using the arrows and the tab key from your keyboard.

    Once your Raspberry reboots, you can check that the 3D drivers are loaded and working:

    cat /proc/device-tree/soc/firmwarekms@7e600000/status
    cat /proc/device-tree/v3dbus/v3d@7ec04000/status
    
    # on Raspberry Pi 3 the v3dbus command should be (provided by Alexis in the comments):
    cat /proc/device-tree/soc/v3d@7ec00000/status

    If both commands return okay, then the hardware acceleration is working and activated.

    Enable hardware acceleration in Chromium

    If open a Chromium and go to chrome://gpu, you will still get Fig. 1. To change that, we need to go to chrome://flags and search for

    • Override software rendering list
    • GPU rasterization
    • Out of process rasterization
    • Hardware-accelerated video decode (only available on the new versions of Raspberry Pi OS)

    and change those settings to Enabled (see Fig. 4a/4b). After restarting the web browser, you can refresh chrome://gpu and you will get Fig. 5.

    Chromium flags - hardware acceleration
    Fig. 4a: Chromium flags - Setting flags to activate the Hardware Acceleration (old Raspbian/Raspberry Pi OS).
    Chromium flags - hardware acceleration
    Fig. 4b: Chromium flags - Setting flags to activate the Hardware Acceleration (new Raspberry Pi OS).
    Graphics Feature Status - Hardware Acceleration activated
    Fig. 5: Graphics Feature Status - Video Decode: Hardware accelerated.

    You can check if a video is decoded using hardware or software checking the chrome://media-internals/ URL while playing it. Fig. 6 shows the software decoder (before the changes). Fig. 7 indicates that the MmalVideoDecoder decoder is being used (after the changes). This is the Broadcom’s library for H.264 hardware acceleration on the Raspberry Pi.

    Video Decoder: DecryptingVideoDecoder
    Fig. 6: Media internals - Software Decoder
    Video Decoder: MmalVideoDecoder
    Fig. 7: Media internals - Hardware Decoder

    Reduce screen tearing (Update 20.08.2020)

    You will still get the occasional "screen tearing". You can find more information about this on the forum topic.

    The solution is to disable the xcompmgr composition manager. To do that, you can move/remove the xcompmgr.desktop file typing:

    sudo mv /etc/xdg/autostart/xcompmgr.desktop /home/pi/backup.xcompmgr.desktop
    sudo reboot

    or you can follow these steps:

    1. Start the raspi-config configurator, typing in a Terminal
      sudo raspi-config
    2. Navigate to Advanced Options > Compositor > xcompmgr composition manager
    3. Choose No
    4. Reboot the Raspberry Pi
      sudo reboot

    That should resolve most issues! I still noticed a bit of screen tearing.

    Possible Issue: Raspberry Pi HD Camera - ENOSPC error

    After activating the GPU acceleration in Chromium, I got the following error while trying to take a photo with the HD camera and playing some Youtube video.

    # raspistill -o /tmp/capture.jpg
    mmal: mmal_vc_component_enable: failed to enable component: ENOSPC
    mmal: camera component couldn't be enabled
    mmal: main: Failed to create camera component
    mmal: Failed to run camera app. Please check for firmware updates

    Increasing the CPU memory from 128 to 144 made the error go away:

    sudo raspi-config
    
    # old Raspbian / Raspberry Pi OS:
    # 7 Advanced Options > A3 Memory Split
    
    # new Raspberry Pi OS:
    # 4 Performance Options > P2 GPU Memory
    Chromium flags - hardware acceleration
    Fig. 8: Extending the CPU Memory using raspi-config
    I described the issue as possible, because I tried to reproduce it and did not get the error again. However, I wrote it here, in case someone needs to deal with it.

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