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Diffstat (limited to 'mc-v4l2-api.rst')
| -rw-r--r-- | mc-v4l2-api.rst | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/mc-v4l2-api.rst b/mc-v4l2-api.rst index 5ac0c01..1f91336 100644 --- a/mc-v4l2-api.rst +++ b/mc-v4l2-api.rst @@ -66,8 +66,11 @@ display it in either plain text (``--print-topology`` or ``-p``) or `DOT format $ media-ctl -d /dev/media0 --print-dot | dot -Tsvg > omap3isp.svg -The following graph represents the TI OMAP3 ISP, with entities corresponding to -subdevices in green and entities corresponding to video devices in yellow. +:numref:`media-graph-ti-omap3-isp` represents the TI OMAP3 ISP, with entities +corresponding to subdevices in green and entities corresponding to video +devices in yellow. + +.. _media-graph-ti-omap3-isp: .. graphviz:: omap3isp.dot :caption: Media graph of the TI OMAP3 ISP @@ -115,7 +118,9 @@ of subdevice-specific options to access subdevices from the command line (see ``v4l2-ctl --help-subdev`` for a detailed list). The rest of this document will use the NXP i.MX8MP ISP as an example. Its media -graph is as follows: +graph is shown in :numref:`media-graph-nxp-imx8mp`. + +.. _media-graph-nxp-imx8mp: .. graphviz:: imx8mp-isp.dot :caption: Media graph of the NXP i.MX8MP @@ -189,8 +194,11 @@ Where video devices expose only the format of the frames being captured to memory, subdevices allow fine-grained configuration of formats on every pad in the pipeline. This enables setting up pipelines with different internal configurations to match precise use cases. To understand why this is needed, -let's consider the following simplified example, where a 12MP camera sensor -(IMX477) is connected to an SoC that includes an ISP and a scaler. +let's consider the simplified example in :numref:`scaling-pipeline`, where a +12MP camera sensor (IMX477) is connected to an SoC that includes an ISP and a +scaler. + +.. _scaling-pipeline: .. graphviz:: scaler.dot :caption: Scaling pipeline @@ -210,14 +218,18 @@ ways through the pipeline. Let's assume that, in all cases, we want to capture important than quality, the sensor will typically subsample the image to comply with the bandwidth limitations of the ISP. As the subsampling factor is restricted to powers of two, the scaler is further used to achieve the exact -desired size. +desired size (:numref:`scaling-pipeline-fast`). + +.. _scaling-pipeline-fast: .. graphviz:: scaler-fast.dot :caption: Fast scaling On the other hand, when capturing still images, the full image should be processed through the pipeline and resized at the very end using the higher -quality scaler. +quality scaler (:numref:`scaling-pipeline-hq`). + +.. _scaling-pipeline-hq: .. graphviz:: scaler-hq.dot :caption: High quality scaling |