On 26/05/2020 08:31, dikshita@xxxxxxxxxxxxxx wrote: > Hi, > > A gentle reminder for the review. It's on my TODO list. I hope to get to it this week or next week at the latest. Regards, Hans > > On 2020-05-08 11:51, Dikshita Agarwal wrote: >> There are many commercialized video use cases which needs metadata info >> to be circulated between v4l2 client and v4l2 driver. >> >> METADATA has following requirements associated: >> •Metadata is an optional info available for a buffer. It is not >> mandatorily for every buffer. >> For ex. consider metadata ROI (Region Of Interest). ROI is specified >> by clients to indicate >> the region where enhanced quality is desired. This metadata is given >> as an input information >> to encoder output plane. Client may or may not specify the ROI for a >> frame during encode as >> an input metadata. Also if the client has not provided ROI metadata >> for a given frame, >> it would be incorrect to take the metadata from previous frame. If the >> data and >> metadata is asynchronous, it would be difficult for hardware to decide >> if it >> needs to wait for metadata buffer or not before processing the input >> frame for encoding. >> •Synchronize the buffer requirement across both the video node/session >> (incase metadata is being processed as a separate v4l2 video >> node/session). >> This is to avoid buffer starvation. >> •Associate the metadata buffer with the data buffer without adding any >> pipeline delay >> in waiting for each other. This is applicable both at the hardware >> side (the processing end) >> and client side (the receiving end). >> •Low latency usecases like WFD/split rendering/game streaming/IMS have >> sub-50ms e2e latency >> requirements, and it is not practical to stall the pipeline due to >> inherent framework latencies. >> High performance usecase like high-frame rate playback/record can >> lead to frame loss during any pipeline latency. >> >> To address all above requirements, we used v4l2 Request API as >> interlace. >> >> As an experiment, We have introduced new control >> V4L2_CID_MPEG_VIDEO_VENUS_METADATA >> to contain the METADATA info. Exact controls can be finalized once the >> interface is discussed. >> >> For setting metadata from userspace to kernel, let say on encode output >> plane, >> following code sequence was followed >> 1. Video driver is registering for media device and creating a media >> node in /dev >> 2. Request fd is allocated by calling MEDIA_IOC_REQUEST_ALLOC IOCTL on >> media fd. >> 3. METADATA configuration is being applied on request fd using >> VIDIOC_S_EXT_CTRLS IOCTL >> and the same request fd is added to buf structure structure before >> calling VIDIOC_QBUF on video fd. >> 4. The same request is queued through MEDIA_REQUEST_IOC_QUEUE IOCTL to >> driver then, as a result >> to which METADATA control will be applied to buffer through S_CTRL. >> 5. Once control is applied and request is completed, >> MEDIA_REQUEST_IOC_REINIT IOCTL is called >> to re-initialize the request. >> >> We could achieve the same on capture plane as well by removing few >> checks present currently >> in v4l2 core which restrict the implementation to only output plane. >> >> We profiled below data with this implementation : >> 1. Total time taken ( round trip ) for setting up control data on video >> driver >> with VIDIOC_S_EXT_CTRLS, QBUF and Queue Request: 737us >> 2. Time taken for first QBUF on Output plane to reach driver with >> REQUEST API enabled (One way): 723us >> 3. Time taken for first QBUF on Output plane to reach driver without >> REQUEST API (One way) : 250us >> 4. Time taken by each IOCTL to complete ( round trip ) with REQUEST >> API enabled : >> a. VIDIOC_S_EXT_CTRLS : 201us >> b. VIDIOC_QBUF : 92us >> c. MEDIA_REQUEST_IOC_QUEUE: 386us >> >> Kindly share your feedback/comments on the design/call sequence. >> Also as we experimented and enabled the metadata on capture plane as >> well, please comment if any issue in >> allowing the metadata exchange on capture plane as well. >> >> Reference for client side implementation can be found at [1]. >> >> Thanks, >> Dikshita >> >> [1] >> https://git.linaro.org/people/stanimir.varbanov/v4l2-encode.git/log/?h=dikshita/request-api >> >> Dikshita Agarwal (3): >> Register for media device >> - Initialize and register for media device >> - define venus_m2m_media_ops >> - Implement APIs to register/unregister media controller. >> Enable Request API for output buffers >> - Add dependency on MEDIA_CONTROLLER_REQUEST_API in Kconfig. >> - Initialize vb2 ops buf_out_validate and buf_request_complete. >> - Add support for custom Metadata control >> V4L2_CID_MPEG_VIDEO_VENUS_METADATA >> - Implemeted/Integrated APIs for Request setup/complete. >> Enable Request API for Capture Buffers >> >> drivers/media/common/videobuf2/videobuf2-v4l2.c | 4 +- >> drivers/media/platform/Kconfig | 2 +- >> drivers/media/platform/qcom/venus/core.h | 36 ++++ >> drivers/media/platform/qcom/venus/helpers.c | 247 >> +++++++++++++++++++++++- >> drivers/media/platform/qcom/venus/helpers.h | 15 ++ >> drivers/media/platform/qcom/venus/venc.c | 63 +++++- >> drivers/media/platform/qcom/venus/venc_ctrls.c | 61 +++++- >> drivers/media/v4l2-core/v4l2-ctrls.c | 10 + >> drivers/media/v4l2-core/v4l2-mem2mem.c | 17 +- >> include/media/v4l2-ctrls.h | 1 + >> include/media/venus-ctrls.h | 22 +++ >> 11 files changed, 465 insertions(+), 13 deletions(-) >> create mode 100644 include/media/venus-ctrls.h
