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PiSP Convert GStreamer Element

pispconvert is a GStreamer element that provides hardware-accelerated image scaling and format conversion using the Raspberry Pi's PiSP Backend.

Properties

Property Type Default Description
output-buffer-count uint 4 Number of backend buffers to allocate (1-32)
crop string "0,0,0,0" Crop region for all outputs as "x,y,width,height"
crop0 string "0,0,0,0" Crop region for output 0 as "x,y,width,height"
crop1 string "0,0,0,0" Crop region for output 1 as "x,y,width,height"

Crop Parameters

Crop values of 0,0,0,0 (default) means no cropping - the full input is used. If width or height is 0, it defaults to the full input dimension. Values are automatically clipped to fit within the input.

  • crop - Sets the same crop region for both outputs
  • crop0 - Sets crop region for output 0 only
  • crop1 - Sets crop region for output 1 only

Supported Formats

GStreamer Formats

RGB, RGBx, BGRx, I420, YV12, Y42B, Y444, YUY2, UYVY, NV12_128C8, NV12_10LE32_128C8

DRM Formats

RG24, XB24, XR24, YU12, YV12, YU16, YU24, YUYV, UYVY, NV12, NV12:0x0700000000000004, P030:0x0700000000000004

Colorimetry

pispconvert uses the colorimetry reported in the input caps to select the correct YCbCr conversion matrix. The supported colour spaces are: jpeg (full-range BT.601), smpte170m (limited-range BT.601), rec709, rec709_full, bt2020, and bt2020_full.

When no output colorimetry is specified, it defaults to matching the input.

Some webcams and V4L2 sources report incorrect colorimetry (e.g. limited-range when the sensor actually produces full-range data), which can result in incorrect colours. You can override the input colorimetry by specifying it explicitly in the caps filter. The colorimetry string format is range:matrix:transfer:primaries.

For example, to force full-range BT.601 (jpeg) on a webcam:

gst-launch-1.0 \
    v4l2src device=/dev/video0 io-mode=dmabuf ! \
    "video/x-raw(memory:DMABuf),format=DMA_DRM,drm-format=YUYV,width=640,height=480,colorimetry=1:4:0:1" ! \
    pispconvert ! \
    "video/x-raw(memory:DMABuf),format=DMA_DRM,drm-format=YUYV,width=800,height=600" ! \
    waylandsink

You can check the actual colorimetry of your camera with:

v4l2-ctl -d /dev/video0 --get-fmt-video

Examples

Single Output

Basic scaling and format conversion:

gst-launch-1.0 filesrc location=input.yuv ! \
    rawvideoparse width=4056 height=3040 format=i420 framerate=30/1 ! \
    pispconvert ! \
    video/x-raw,format=RGB,width=1920,height=1080 ! \
    filesink location=output.rgb

Dual Output

Simultaneous scaling to two different resolutions/formats:

gst-launch-1.0 filesrc location=input.yuv ! \
    rawvideoparse width=4056 height=3040 format=i420 framerate=30/1 ! \
    pispconvert name=p \
    p.src0 ! queue ! video/x-raw,format=RGB,width=1920,height=1080 ! filesink location=output0.rgb \
    p.src1 ! queue ! video/x-raw,format=I420,width=640,height=480 ! filesink location=output1.yuv

With Cropping

Crop the input before scaling:

gst-launch-1.0 filesrc location=input.yuv ! \
    rawvideoparse width=4056 height=3040 format=i420 framerate=30/1 ! \
    pispconvert crop="500,400,3000,2200" ! \
    video/x-raw,format=RGB,width=1920,height=1080 ! \
    filesink location=output.rgb

Camera with DMABuf

Using a camera source with DMABuf for zero-copy processing:

gst-launch-1.0 \
    v4l2src device=/dev/video16 io-mode=dmabuf num-buffers=100 ! \
    "video/x-raw(memory:DMABuf),format=DMA_DRM,drm-format=YUYV,width=640,height=480" ! \
    pispconvert ! \
    "video/x-raw(memory:DMABuf),format=DMA_DRM,drm-format=YUYV,width=4096,height=1080" ! \
    waylandsink sync=false

Camera with Software Buffers

Using a camera source with standard memory buffers:

gst-launch-1.0 \
    v4l2src device=/dev/video16 num-buffers=100 ! \
    "video/x-raw,width=640,height=480" ! \
    pispconvert ! \
    video/x-raw,format=RGB,width=4096,height=1080 ! \
    waylandsink

Decode H.265 Video and Reformat

Using hardware H.265 decoder with DMABuf passthrough:

gst-launch-1.0 filesrc location=video.mkv ! matroskademux ! h265parse ! v4l2slh265dec ! \
    "video/x-raw(memory:DMABuf),format=DMA_DRM,drm-format=NV12:0x0700000000000004" ! \
    pispconvert ! \
    "video/x-raw(memory:DMABuf),format=DMA_DRM,drm-format=YUYV,width=4096,height=1080" ! \
    waylandsink

Using software buffer input instead of DMABuf:

gst-launch-1.0 filesrc location=video.mkv ! matroskademux ! h265parse ! v4l2slh265dec ! \
    "video/x-raw,format=NV12_128C8" ! \
    pispconvert ! \
    "video/x-raw(memory:DMABuf),format=DMA_DRM,drm-format=YUYV,width=4096,height=1080" ! \
    waylandsink