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Does MmalVideoDecoder use FFmpeg?

Wed Sep 11, 2019 2:05 pm

I'm looking at using Chromium to play video content on the RPi4, so am looking at how Chromium accelerates playback. I know that Chromium uses FFmpeg for software decoding, and the MMAL patch applied to Chromium on the RPi allows it to use the MMAL API to access the GPU for decoding certain content, but wondered how it does this.

With the MMAL patch applied, are videos still decoded using FFmpeg, but with additional access to the GPU, or is FFmpeg bypassed entirely and the MMAL API accessed through some other means?

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Raspberry Pi Engineer & Forum Moderator
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Re: Does MmalVideoDecoder use FFmpeg?

Wed Sep 11, 2019 4:16 pm

MMAL is used directly using the normal MMAL API from https://github.com/raspberrypi/userland ... rface/mmal

There are a few performance tweaks in there.
If using the older framebuffer based X rendering then it uses the ISP hardware to resize and format convert to RGBA of exactly the right size to fit the window. Composition is then a memcpy.
If using the GL driver, the It is using some of the latest updates to MMAL and vcsm to allow exporting dmabufs for zero copy import into GL.
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