Converged Media Engineer




  1. Prerequisites

    2. Before configuring anything, make sure you have:

    1. Network: A 1G or 10G IP switch that is PTP-aware (Precision Time Protocol, IEEE 1588) for video/audio sync.
    2. PTP Master Clock: Usually a dedicated PTP grandmaster. That all your Cameras, audio interfaces, and recorders must all support SMPTE 2110.
    3. Multicast (IS-05) planning: Decide multicast addresses for each stream (video, audio, ancillary). (IP Addressing Primer)
    4. Network VLANs (optional): Helps isolate media traffic from management traffic.
    5. Monitoring/management software: Optional but very useful (like NMOS or device dashboards).

  2. Set PTP and Synchronization

    SMPTE ST 2110 is an "essence-based" protocol where video, audio, and data are separate streams. To ensure these elements align perfectly at the destination, every device must be synchronized to a common PTP (Precision Time Protocol) reference.

    1. Enable PTP on all devices (cameras, audio interfaces, recorders, and switch ports if required).
    2. Confirm that one device is the PTP grandmaster.
    3. Check offsets in the device dashboards; aim for sub-microsecond sync. Tip: Audio/video drift happens if PTP isn’t stable. Fix this first.
    4. PTP Topology
      1. The Role of PTP in ST 2110
        In a 2110 environment, PTP (IEEE 1588-2008) replaces traditional "Blackburst" or "Tri-level" analog sync. It provides the nanosecond-level accuracy required for the SMPTE ST 2059-2 profile, which defines how media clocks are derived from PTP.

      2. Key PTP Network Roles
        Grandmaster (GM): The ultimate source of time. In professional setups, this is a dedicated hardware generator locked to GPS (GNSS) to provide an absolute TAI (International Atomic Time) reference.

        Boundary Clock (BC): A PTP-aware switch that terminates the PTP flow from the GM and acts as a local master for downstream devices. This is the preferred architecture for 2110 to reduce "packet delay variation" (jitter).

        Transparent Clock (TC): A switch that passes PTP messages through but modifies the "correction field" in the packet header to account for the time the packet spent inside the switch.

        Follower (formerly Slave): End-node devices (Cameras, Audio Consoles, Recorders) that recover the media clock from the incoming PTP packets.

        In a SMPTE 2110 setup, your cameras, audio mics, and recorders are followers, while a grandmaster provides the timing.

      3. Configuration Steps
        1. Define the PTP Domain: Ensure all devices are set to the same PTP Domain Number (typically 127 for ST 2059-2).
        2. Select the Profile: Set the PTP Profile to SMPTE ST 2059-2. This configures the correct message rates (e.g., 8 Sync messages per second).
        3. Establish Communication Mode: Decide between Multicast, Unicast, or Hybrid (Mixed) mode based on your switch's capabilities and the number of Follower devices.
        4. Monitor Lock Status: Verify that all end-nodes report a "Phase Locked" status.

      4. Verification & Troubleshooting
        1. Lock Threshold: While the standard allows for wider margins, a healthy ST 2110 network should maintain an offset from the GM of less than 500 nanoseconds.
        2. BMCA (Best Master Clock Algorithm): If you have redundant Grandmasters, ensure their Priority 1 and Priority 2 values are set correctly so the network doesn't "flip-flop" between time sources.
        3. VLAN Consistency: Ensure PTP traffic is present on all media VLANs. If using ST 2022-7 redundancy, both the Blue and Red networks must be synchronized to the same GM.

      5. Bandwidth Considerations
        Calculating network load is critical to prevent "packet dropping" and buffer overruns. Unlike compressed streaming (H.264), ST 2110 is typically uncompressed, requiring high-throughput infrastructure.
        1. Video Bandwidth (ST 2110-20)
        2. Bandwidth is determined by resolution, frame rate, and bit depth. Because ST 2110-20 only sends the "Active Video" area (removing the SDI blanking), the bitrates are slightly lower than their SDI counterparts:
          1. HD 1080i 59.94 (10-bit): ≈ 1.3 Gbps
          2. HD 1080p 59.94 (10-bit): ≈ 2.5 Gbps (Note: Often rounded to 3G in legacy terms, but 2.5 Gbps on the wire).
          3. UHD/4K 2160p 59.94 (10-bit): ≈ 10 Gbps (Requires 25G or 100G interfaces).
        3. Audio Bandwidth (ST 2110-30)
          Audio consumes significantly less bandwidth than video, but packet overhead is higher due to small payload sizes.
          1. PCM 48kHz / 24-bit: A single channel consumes roughly 1.2 Mbps (payload only).
          2. Standard 8-Channel Stream: Even with network overhead, a standard 8-channel audio flow usually stays well under 12 Mbps.
          3. Correction: The previous estimate of 10 Mbps for a single mic was incorrect; you can fit hundreds of audio channels into the space of one video stream.
        4. Redundancy & Overhead (ST 2022-7)
          If you are running a redundant network (seamless protection switching):
          1. Double the Bandwidth: You must account for the full bandwidth of every stream on both the Primary (Blue) and Secondary (Red) networks simultaneously.
          2. L2/L3 Overhead: Always add a 10% buffer to your calculations to account for PTP traffic, NMOS discovery, and packet headers.
        5. IV. Best Practices
          1. Non-Blocking Architecture: Ensure your switch backplane can handle the aggregate of all ports at full duplex.
          2. Traffic Shaping: Use Traffic Shaping (compliant with ST 2110-21) to ensure "Narrow" or "Wide" senders don't burst and overwhelm switch buffers.
          3. IGMP Snooping: This is mandatory. Without it, your switches will treat Multicast like Broadcast, flooding every port and crashing non-media devices (like laptops or control surfaces).

        Summary Table for Planning:
        Stream Type Format Bitrate (Approx)
        Video (2110-20) 1080p 59.94, 10-bit 2.5 Gbps
        Audio (2110-30) 8-Ch, 48kHz, 1ms packet 12 Mbps
        Ancillary (2110-40) Closed Captions / HDR Metadata < 5 Mbps

      6. Setting up a Grandmaster
        1. Physically connect the GM to the media network (ideally core switch) → Accurate. Best practice in ST 2110 deployments is to connect the GM to a high-quality core/spine switch (often via redundant ports) for low-latency distribution.
        2. Clock source: GPS or internal oscillator → GPS (or GNSS) is the gold standard for traceable time in broadcast. Internal oscillator is a fallback (holdover mode), but for production, GPS is strongly recommended to avoid drift.
        3. PTP profile: SMPTE 2110 typically uses ST 2059-2, a specialized PTP profile for broadcast.
           ST 2059-2 uses IEEE 1588-2008 (PTPv2) as the underlying protocol.
           PTP distributes clock information across a network.
           ST 2059-2 sets the rules for using PTP in a media production context,
          including:
            1.Synchronizing video frames
            2.Aligning audio samples
            3.Coordinating multi-camera shoots

    5. Time Representation
      1. Uses International Atomic Time (TAI) as the base.
      2. Adds PTP epoch offsets for network distribution. PTP timestamps are relative to the PTP epoch (January 1, 1970, 00:00:00 TAI). ST 2059-2 defines the SMPTE Epoch (also January 1, 1970, 00:00:00 TAI) for aligning media signals (phase of video/audio at that instant). The "offsets" refer to deterministic phase calculations from the epoch, not arbitrary additions.
      3. Avoids errors that would accumulate if devices used independent clocks.

    6. Synchronization Accuracy
      1. ST 2059-2 ensures sub-microsecond synchronization across devices. The profile targets ±500 ns (1 µs total) across the network.
      2. Typical target: <1 μs for audio/video alignment, which is critical for lip sync and multi-camera consistency.

        Priority and domain: PTP allows multiple domains; ensure all devices use the same one.

    7. Enable Announce and Sync messages:
      The GM will broadcast its time.
      1. Announce Messages
        Purpose:
        1. Let devices know who the Grandmaster Clock is.
        2. Used to determine the best clock in the network.
        3. Details:
          1. Sent periodically by Grandmaster Clocks (or by other clocks if they are competing).
          2. Contain clock quality information:
            1. Clock class
            2. Clock accuracy
            3. Priority (for tie-breaking)
            4. Current offset from other clocks
        4. Function in the network:
          1. Devices use Announce messages to run the Best Master Clock Algorithm (BMCA).
          2. This ensures that the network agrees on a single Grandmaster.
          3. If the current Grandmaster fails, a new one is selected automatically.
        5. Analogy:
          Think of it as a "Who's the boss clock?". ST 2059-2 allows announce interval -3 to +1 log2 seconds (125 ms to 2 s), but recommended/default is often 1 s (log2 0) in many deployments. Every device listens and decides which clock to follow.

      2. Sync Messages
        Purpose:
        1. Tell devices the current time of the Grandmaster.
        2. Allow all devices to align their local clocks with the Grandmaster.
        3. Details:
          1. Sent frequently. ST 2059-2 recommends sync interval -8 to -1 log2 seconds (3.906 ms to 500 ms), but common broadcast practice (per vendors like Arista, Cisco, Evertz) is -3 (125 ms) or -4 (62.5 ms) for sync; not 1 ms. 1 ms is too aggressive and can overload networks.
          2. Can be either:
            1. Sync-only (with timestamp in a separate Follow_Up message)
            2. Two-step (Sync message + Follow_Up message) for precise timing. ST 2059-2 supports both; two-step is more common in broadcast due to easier hardware implementation.
            3. Devices measure network delay using Delay_Req/Delay_Resp messages, and adjust their clocks accordingly.
        4. Function in the network:
          1. Ensures all cameras, recorders, and audio devices timestamp data consistently.
          2. Critical for frame-accurate video switching and lip-sync audio
        5. Analogy:
          If Announce messages say "This clock is the boss," Sync messages say "Here's the exact time you should follow."

        6. Verify network delays: If using transparent clocks, the switches will automatically adjust timing messages.


          1. Grandmaster → All devices: Announce (master identity, priority, clock quality)
          2. Grandmaster → All devices: Sync (timestamp t1 at send)
          3. Grandmaster → All devices: Follow_Up (precise t1 timestamp if not included in Sync)
          4. Slave → Grandmaster: Delay_Req (time t2 when sent)
          5. Grandmaster → Slave: Delay_Resp (time t3 when Delay_Req received by master)
          6. Transparent clocks modify timestamps in-flight to account for their own delay.
            *Boundary clocks generate a new Sync/Follow_Up for downstream devices.



        7. Setting up Slave Devices (Cameras, Recorders)
          1. Choose PTP as clock source in the device menu.
          2. Ensure the same PTP domain as the GM.
          3. Verify device shows “Locked to GM” or similar.
        8. Verification
          1. On your GM, you can see slave device list with offset from GM.
          2. Look for offsets typically <1 µs in a properly configured broadcast network.
          3. Any devices showing "unlocked" indicate network or configuration issues.
        9. Common Gotchas
          1. Mixed vendor devices: Not all PTP implementations behave the same; always test for interop.
          2. Network latency: High jitter can desync slaves.
          3. Redundant GMs: If failover isn’t configured, devices may temporarily lose sync.
     
  3. Configure Video Streams for your 3 cameras:
    1. Assign unique multicast addresses for each camera:
       Example: 239.0.1.1, 239.0.1.2, 239.0.1.3
    2. Assign video formats (SMPTE 2110-20):
       Resolution, frame rate, and bit depth (e.g., 1080p59.94, 10-bit)
    3. Enable ancillary data (SMPTE 2110-40) if needed (e.g., camera tally, captions).
    4. Set flow IDs and stream names (for NMOS or device discovery).
     
  4. Configure Audio Streams
     For 6 microphones, you have two common options:
    1. Option A ‐ 6 audio streams, each 1 mic
      Each mic gets its own SMPTE 2110-30 stream (uncompressed PCM)
      . Assign unique multicast addresses, e.g.:
      239.0.2.1 → Mic 1    239.0.2.2 → Mic 2 … and so on.
    2. Option B ‐ 2 audio devices with 3 channels each
      Bundle 3 mics into 1 stream per audio interface (3 channels per stream).
      More efficient, fewer streams.
      Multicast addresses:
      239.0.2.1 → Audio interface 1 (mics 1–3)    239.0.2.2 → Audio interface 2 (mics 4–6)
    3. Set sample rate (48 kHz typical for video production).
    4. Align audio clock to PTP to ensure sync with video.
    5. Label each channel correctly in dashboards for recording or mixing.

  5. Configure Recorders / Destinations
    For 3 recording channels, you might:
    1. Map camera feeds to recording channels (1 recorder per camera, or 3 camera angles into 1 recorder with tracks).
    2. Map audio feeds to recorder tracks:
       Decide if you record all 6 mics separately, or mix them down.
    3. Use NMOS / SDI emulation if your recorder supports 2110 discovery.
    4. Confirm clock source: Recorder should follow PTP.
     
  6. Network Considerations
    1. Ensure multicast traffic flows correctly:
       IGMP Snooping/Proxy on switches.
       Avoid flooding non-media ports.
    2. Check bandwidth per stream:
       1080p59.94 10-bit ≈ 3 Gbps per camera.
       PCM 48 kHz 24-bit 6 channels ≈ 8–10 Mbps per mic.
    3. Prioritize streams if needed with QoS.

  7. Verification
    1. Check video output on each recording device.
    2. Monitor audio channels:
       Ensure no drift relative to video.
       Confirm levels and labeling.
    3. Use a monitoring tool (e.g., Ember+ or NMOS dashboard) to verify all streams:
       Active sources
       PTP offsets
       Multicast addresses
     
  8. Optional Enhancements:
    1. Redundancy: SMPTE ST2022-7 for dual-path streams.
    2. Tally & control: SMPTE 2110-40 or GPIO over IP.
    3. Mixing & switching: Use a 2110-enabled router or switcher for live switching.
     
  9. Conclusion Summary Flow (High Level)
    1. Network + PTP master clock
    2. Camera streams → 2110-20 + ancillary
    3. Mic streams → 2110-30 → sync with video
    4. Map video + audio to recorders
    5. Verify multicast, bandwidth, QoS
    6. Monitor & test streams

 



 

UPDATED
03/15/26
V260315-1.0