Dynamic Media Facility / Timing
Time inside a DMF workload
Follow the same timestamp through different processing delays.
At the mixer read point
Next read: ITS = x / CPU 8 ms
| Input | ITS | Delay to mixer | At read point | Timing margin |
|---|---|---|---|---|
| Video 1 | x | 9 ms | Waiting | +11 ms |
| Video 2 | x | 2 ms | Waiting | +18 ms |
| Video 3 | x | 10 ms | Waiting | +10 ms |
The table follows the latest mixer read. A non-negative margin means the matching grain is available by its deadline.
Timing terms and ingress conformance
- Grain
- An indexable media unit: a video frame, or one audio sample per channel.
- Source and Flow
- A Source identifies editorial content. A Flow is its technical representation. Mixing creates a new Source and Flow.
- ITS
- The Indexing Time Stamp identifies a grain's intended time in the workload. Here, x is a symbolic ITS; actual values use nanoseconds from the SMPTE epoch.
- Ingress
- External Signals are conformed into usable Flows. Ingress uses frequency and timestamp provenance to assign or adjust ITS, preserving required timing relationships. Frame synchronisation or sample rate conversion is needed when the incoming frequency is not coherent with the workload.
The workload clock provides a shared time domain. Internal Media Functions process asynchronously; matching timestamps allow alignment at the mixer.
Sources and example assumptions
- Media Function Timing Data.pptx, slide 1: the input routes and 20 ms / 31 ms timing example.
- AMWA IN-002: Time and Identity, revision
ab75023. - AMWA IN-005: External Signal Ingress, revision
e845540. - EBU DMF Reference Architecture, version 2.0, April 2026.
This original illustration adds CPU variation after Video 3's 2 ms MF, and a 5 ms example. Repeatable CPU samples are 8, 2, 6, 3, 7, 4 and 5 ms, capped by the selected ceiling. Mixer processing is inferred as 31 - 20 = 11 ms. These delays and the no-output behaviour for a missed read point are illustrative choices, not AMWA requirements. Egress synchronisation is outside this diagram.
IN-002 and IN-005 are evolving AMWA Increments. HK Grotesk and Fira Code are reused unchanged from this repository's deck assets at revision 4e3cddc, under the HK Grotesk licence and Fira Code licence.