Stream Setup

Create Blocks

The ASIL-D or ASIL-B(D) producer and consumers must indicate whether they require CRC validation when creating the blocks by calling NvSciStreamProducerCreate2() with crcValidate set to true. Similarly, the consumer application can call NvSciStreamConsumerCreate2() with crcValidate set to true.

User-defined Endpoint Information

When the producer/consumer provides the endpoint information to the other side, it calls NvSciStreamBlockUserInfoSetWithCrc() to send the endpoint information and calls NvSciStreamBlockUserInfoGetWithCrc() to query the endpoint information.

The producer application must define a unique stream ID for each stream and send it to all consumer applications as part of the endpoint information. The consumers share this stream ID along with the CRC values the producer to validate if the producer process and consumer process are connected to the same stream.

The application must query the user information by different userType in the same order as that set by the application at remote ends. As CRC is generated based on the order of information set or retrieved, the order of setting the user information and retrieving the user information must be same on both ends.

Query Connection Index

Once the consumer receives the NvSciStreamEventType_Connected event, The consumer calls NvSciStreamConsumerIndexGet() to query the connection index. It must share the connection index with the producer along with the NvSciIpc endpoint name in a later validation step. The producer application can tell which indexed consumer is ASIL-D or ASIL-B(D) according to the NvSciIpc channel.

Packet Layout

The application must set up buffer attributes to allocate extra CRC buffers in each packet for each endpoint, because they need to exchange the CRC values and additional validation data in the shared buffer instead of the regular communication channel used for sending and receiving messages. For example, in a stream with two consumers, it needs to allocate three CRC buffers per packet: one for the producer and the remaining two for each consumer.

When the pool sends the final layout, it calls NvSciStreamBlockElementAttrSetWithCrc() to set the reconciled element attributes. All CRC buffer objects are visible to the producer reapplication, but the consumer application should only access the producer’s CRC element and its own CRC element. The pool calls NvSciStreamBlockElementNotVisible() to mark the consumer’s CRC buffer objects only visible to the owner, who has read-write permission.

The produer/consumer applications must call NvSciStreamBlockElementAttrGetWithCrc()to query the reconciled attributes for each element in the same order in which the pool set the attributes, such as from element index 0 to element index (element_count -1).

Buffer Objects

The pool creates new packets one by one. The next new packet is created after receiving the packet acceptance status from producer and consumers, and it calls NvSciStreamPoolPacketInsertBufferWithCrc() to add the buffer objects to the new packet.

The producer/consumer applications call NvSciStreamBlockPacketBufferGetWithCrc() to query the buffer objects from each packet. The producer application must track CRC values for each consumer by providing an array of CRC values to this call. According to the element type and the index of the consumer, the producer can tell if the indexed element is a CRC element for the indexed consumer, and it only updates the CRC value for that consumer.

Synchronization Objects

The producer/consumer calls NvSciStreamBlockElementSignalObjSetWithCrc()/ NvSciStreamBlockElementSignalObjGetWithCrc() to set/query the synchronization objects. The applications must set or get the information in the same order, such as from element index 0 to element index (element_count - 1).

When the producer queries the synchronization objects from each consumer, it should maintain the CRC values for different consumers.

Validation Event

When the consumer application completes the buffer and synchronization setup steps, it must validate whether the buffer and synchronization objects to meet its buffer/ synchronization requirement.

If the above validation is passed, the consumer application writes the validation data into its own CRC element of the first created packet and calls NvSciStreamBlockSetupStatusSet() with NvSciStreamSetup_CrcImport to inform the producer that the initialization-time validation data is ready. The validation data should include the following:

• A user-defined magic ID to indicate it is init-time validation data
• All the CRC init-time values maintained by the consumer
• The stream ID received from the producer as one part of the endpoint information
• A connection index of the consumer
• The NvSciIpc endpoint name used by the consumer process

When the producer application receives the NvSciStreamEventType_Validate event, the producer application must verify the data provided by each ASIL-D or ASIL-B(D) consumer in the consumer’s CRC elements of the first created packet:

• The magic number matches the init-time magic number
• The stream ID is the same as that sent by the producer
• The consumer index is unique and in a valid range
• Determine which indexed consumer is the ASIL-D or ASIL-B(D) consumer according to the NvSciIpc endpoint name provided by the consumer. The Producer application must keep track of the consumer indexes of ASIL-D or ASIL-B(D) consumers and must validate the data only from those consumers
• The CRC values provided by the consumers are the same as those calculated by the producer

The producer application can skip validating the information from non ASIL-D or non ASIL-B(D) consumers, which may provide incorrect information.

The producer application also must validate the buffer and synchronization objects to meet its buffer/ synchronization requirement.

• Retrieve the reconciled attribute list from the buffer/synchronization objects via NvSciBufObjGetAttrList/ NvSciSyncObjGetAttrList
• Validate that the reconciled attribute list meets its own requirements via NvSciBufAttrListValidateReconciledAgainstAttrs/ NvSciSyncAttrListValidateReconciledAgainstAttrs
• Validate the buffer/synchronization objects satisfies the constraints of the the associated reconciled attribute list via NvSciBufObjValidate/ NvSciSyncObjValidate

The producer application must query the max buffer access permission for the lower ASIL consumers on the reconciled attribute list associated with the NvSciBufObj(s) using NvSciBufObjGetMaxPerm.

Only when the validation process is complete, the producer application can inform the stream to start streaming by calling NvSciStreamBlockSetupStatusSet() with NvSciStreamSetup_CrcImport.