Embedded metadata support for Jetson Nano


While looking for some confirmation about the embedded metadata capture support on Jetson Nano, I found a couple of contradictory entries. Since the referral for the technical documentation of the Nano is typically the TX1, I have attached the corresponding entry asking for the specific case of the Jetson TX1 (which I assume would apply as well for Nano’s VI block).

  1. The developer is asking for a way to disable / bypass metadata support and, as part of the responses from one of the forum moderators, it is stated that:
    Nano VI HW didn’t support the embedded data the VI ignore this package.

  2. On this other entry, the specific concern is about the TX1 embedded metadata support, it is stated that:
    a. Embedded data support for TX1 and TX2 is valid through libargus, NOT for the direct V4L2 path.
    b. V4L2 does not have interface and that needs an extension for embedded data.
    c. For the kernel driver implementation, that should be a massive effort for TX1 since TX1’s VI HW cannot extract metadata with the same tegra channel.

I would like to confirm that:

  1. Is embedded metadata capture possible on Nano’s MIPI CSI2 port? It seems like it should by using Argus.
  2. If supported, would this be just as a header to the frame (beginning of the frame), footer or both?

Diego Chaverri

hello diego.chaverri,

that’s correct, Nano (or, t210 series) cannot support embedded data directly.
you should refer to Technical Reference Manual, see the CSI chapter.
for example,

Currently, VI/ISP cannot differentiate between embedded data or pixel data.

since there are two pixel parsers on Nano. if you’re only have single video source, you can sink pixel data to 1st pixel parser and embedded data to 2nd pixel parser. there’s CSI register, CSI_PP*_EMBEDDED_DATA_OPTIONS, it can specify how to deal the embedded data line.
please also refer to VI chapter, [31.3.5 Embedded Data Formats] for the details of handling embedded metadata.
for example,

The CSI[,1,2] can discard embedded data in the CSI[,1,2], to pass embedded data through one pixel parser with the image data being presented to the other pixel parser, or to combine the embedded data with the frame data when presented to a single pixel parser.

in the currently software implementation, it’s now only support embedded data in the beginning (head) of the frame.
also, this is Argus API, Ext::SensorPrivateMetadata to access sensor embedded metadata.

Thanks for the information @JerryChang, greatly appreciated.

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