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	FC-AV Overview: FC Levels, Containers, and Headers This section provides a more detailed look at FC-AV and is intended for technical managers and engineers. Many of the graphics in this section come from a presentation made by Steve Wilson at Boeing titled "Fibre Channel - Audio Video Profile" presented at the AS-1A2 High Speed 1760 Task Group in July 2004. The Fibre Channel standard comprises 5 “levels” of implementation, starting with Level 0 - the physical layer (transmitters and receivers), and moves to the higher level protocol layers, 1 – 4. Level 1 is the Transmission Protocol, and includes 8B/10B Encoding. Level 2 is the signaling protocol, and includes the definition of FC Frames, and a container system used to encapsulate Video Frames. Layer 3 isn’t used in FC-AV applications, and the Frame Header Control Protocol of Level 4 is used as a way to transport FC-AV containers. FC-AV uses components of the first three levels (0-2), plus the Frame Header Control Protocol from Layer 4 of the FC-AV specification. The diagram below shows a simple overview of the levels and their broad categories. In most implementations, Level 3, FC-Management is not used, but FHCP from Level 4 is used. FHCP is a low-overhead way to send FC-AV containers, which lends itself to low-latency, efficient data transmission. The diagram below provides visualization of the how the FC-AV Levels work to transmit video information. An important aspect of Level 1 is that the signals are 8B/10B encoded. This encoding provides for a balanced DC behavior allowing for long transport distances. The implication of 8B/10B encoding is that for every 8 bits (every byte) of information to be sent, the physical link transmits 10Bits, which add 20% overhead on the physical link (sending 10 bits but only getting 8 bits of real data or sending 40 bits but only getting 32). For example, to transmit 32 bits (4 bytes), the 8B/10B encoding will physically transmit 40 bits over the link. The 4 bytes will be stripped back down to 32 bits after it has been received. One of the things that happens in the 8B/10B process is that bytes are designated as data or special characters, such a Start of Frame (SOF), End of Frame (EOF), IDLE characters, or others special characters. The other implication is that when data is not being transmitted over the physical link IDLE characters will be inserted so that a continuous transmission is maintained. FC-AV Clause 5 defines a container system to transmit an entire Video Frame, a container is made up of a container header, and objects, otherwise known as the payload . The Simple Parametric Digital Video profile in Clause 5 uses 4 Objects for encapsulating the ancillary data, audio data, and video data. The diagram below shows a sequence of FC Frames that each contain payload . The payload from the whole sequence of FC Frames, is a container . A container is assembled from the payload of many FC Frames. For example, to transmit a 480x480, 8-bit monochrome image, it would take 120 FC Frames, where the payload in each FC Frame has 4 lines of video data. Since the container includes more information than just the video frame, it will take more FC Frames to transmit the entire container. In this case, the payload of the first FC Frame transmitted would contain Object 0, or the container header – which includes ancillary data. The payload of the next FC Frame would contain the first lines of video data, in Object 2. Payload typically only contains Object 0 and Object 2, since Object 1 is for audio that isn’t used, and Object 3 is used for video data for interlaced video frames. In total, 121 FC frames are needed to transmit the 480x480, 8-bit mono image. The payload from these 121 frames make up the container. The Container Header, which is included with ancillary date in Object 0, is defined in the table below. The Container header is 88 bytes long (22 long words). Moving to Level 4 of the FC-AV protocol, we come to the Frame Header Control Protocol (FHCP). In the diagram below, the first things to note are the PAYLOAD in the FC Frame that has a “piece” of the FC-AV container, and the HEADER. The frame header is used as a means to communicate information that is needed to reconstruct the video image that is encapsulated in the container.

FC-AV Overview: FC Levels, Containers, and Headers
This section provides a more detailed look at FC-AV and is intended for technical managers and engineers. Many of the graphics in this section come from a presentation made by Steve Wilson at Boeing titled "Fibre Channel - Audio Video Profile" presented at the AS-1A2 High Speed 1760 Task Group in July 2004.

The Fibre Channel standard comprises 5 “levels” of implementation, starting with Level 0 - the physical layer (transmitters and receivers), and moves to the higher level protocol layers, 1 – 4. Level 1 is the Transmission Protocol, and includes 8B/10B Encoding. Level 2 is the signaling protocol, and includes the definition of FC Frames, and a container system used to encapsulate Video Frames. Layer 3 isn’t used in FC-AV applications, and the Frame Header Control Protocol of Level 4 is used as a way to transport FC-AV containers. FC-AV uses components of the first three levels (0-2), plus the Frame Header Control Protocol from Layer 4 of the FC-AV specification. The diagram below shows a simple overview of the levels and their broad categories. In most implementations, Level 3, FC-Management is not used, but FHCP from Level 4 is used. FHCP is a low-overhead way to send FC-AV containers, which lends itself to low-latency, efficient data transmission.

The diagram below provides visualization of the how the FC-AV Levels work to transmit video information.

An important aspect of Level 1 is that the signals are 8B/10B encoded. This encoding provides for a balanced DC behavior allowing for long transport distances. The implication of 8B/10B encoding is that for every 8 bits (every byte) of information to be sent, the physical link transmits 10Bits, which add 20% overhead on the physical link (sending 10 bits but only getting 8 bits of real data or sending 40 bits but only getting 32). For example, to transmit 32 bits (4 bytes), the 8B/10B encoding will physically transmit 40 bits over the link. The 4 bytes will be stripped back down to 32 bits after it has been received. One of the things that happens in the 8B/10B process is that bytes are designated as data or special characters, such a Start of Frame (SOF), End of Frame (EOF), IDLE characters, or others special characters. The other implication is that when data is not being transmitted over the physical link IDLE characters will be inserted so that a continuous transmission is maintained.

FC-AV Clause 5 defines a container system to transmit an entire Video Frame, a container is made up of a container header, and objects, otherwise known as the payload . The Simple Parametric Digital Video profile in Clause 5 uses 4 Objects for encapsulating the ancillary data, audio data, and video data. The diagram below shows a sequence of FC Frames that each contain payload . The payload from the whole sequence of FC Frames, is a container . A container is assembled from the payload of many FC Frames. For example, to transmit a 480x480, 8-bit monochrome image, it would take 120 FC Frames, where the payload in each FC Frame has 4 lines of video data. Since the container includes more information than just the video frame, it will take more FC Frames to transmit the entire container. In this case, the payload of the first FC Frame transmitted would contain Object 0, or the container header – which includes ancillary data. The payload of the next FC Frame would contain the first lines of video data, in Object 2. Payload typically only contains Object 0 and Object 2, since Object 1 is for audio that isn’t used, and Object 3 is used for video data for interlaced video frames. In total, 121 FC frames are needed to transmit the 480x480, 8-bit mono image. The payload from these 121 frames make up the container.

The Container Header, which is included with ancillary date in Object 0, is defined in the table below. The Container header is 88 bytes long (22 long words).

Moving to Level 4 of the FC-AV protocol, we come to the Frame Header Control Protocol (FHCP). In the diagram below, the first things to note are the PAYLOAD in the FC Frame that has a “piece” of the FC-AV container, and the HEADER. The frame header is used as a means to communicate information that is needed to reconstruct the video image that is encapsulated in the container.