Membrane Video Transcode

Hardware-aware video decoding, encoding, and transcoding elements for the Membrane Framework.

This package owns codec work only. It does not open displays, perform DRM/KMS modesetting, or present frames. Connect canonical output to membrane_video_interop when decoded frames need to be rendered.

Current elements

• Membrane.H265.Decoder decodes H.265 access units with VAAPI, V4L2 Request, V4L2 M2M, or software FFmpeg backends.
• output: :dmabuf emits empty Membrane buffers containing a canonical %VideoInterop.Frame{} under the reserved :video_interop metadata key.
• output: :raw emits copied %Membrane.RawVideo{} frames.
• Runtime instrumentation remains available through Membrane.Instrumentation.

Encoding and composed decode/encode transcoding elements belong in this package as they are added. Presentation sinks and legacy DRM Prime descriptors intentionally do not.

Installation

def deps do
  [
    {:membrane_video_transcode,
     git: "https://github.com/colibri-cam/membrane_video_transcode.git"}
  ]
end

The package currently uses sibling path dependencies for the unpublished interoperability stack:

/workspace/video_interop
/workspace/membrane_video_interop
/workspace/colibri/membrane_video_transcode

Canonical decoded output

child(:decoder, %Membrane.H265.Decoder{
  output: :dmabuf,
  decoder: :auto,
  max_in_flight: 16
})
|> child(:display, %Membrane.VideoInterop.Sink{consumer: consumer})

Canonical native resources use bounded leases, idempotent native retirement, and authenticated abandonment guards. DMA-BUF descriptors and file descriptors remain local to one OS process.

Cross-compiling for Nerves

When NERVES_SDK_SYSROOT is set, mix.exs maps the Nerves C compiler prefix to the matching Rust target and passes the target linker and FFmpeg paths to Rustler. The current mapping includes the standard ARMv6, ARMv7, AArch64, and x86_64 Nerves targets.

The target sysroot must provide FFmpeg with the hardware decoder support selected at runtime.