Add some timings clarifications based on NAB learnings.#544
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Signed-off-by: Vincent Trussart <vincent.trussart@grassvalley.com>
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Jun 5, 2026
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| Grains are organized as ring buffers. The grain count is a function of the flow grain_rate and desired history length. For example if a flow grain_rate is 50/1, each grain will be worth 20'000'000 ns (1/50 \* 1'000'000) of data. A ring buffer with 100ms of history will have 5 grains (5 \* 20ms/grain = 100ms). Time starts at the SMPTE 2059-1 epoch and is expressed a nanoseconds since that epoch. | ||
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| Ring buffer indices encode timing information — **the ring buffer cannot be treated as a simple queue of grains.** A writer media function must carefully compute the grain index at which it writes based on the frequency domain of the incoming grains. If the writer cannot guarantee that the external source shares a common frequency domain with the MXL host, it must implement a re-synchronization strategy (grain drop, grain repeat, dynamic audio resampling, etc.) to maintain alignment with the host's timing. |
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| Ring buffer indices encode timing information — **the ring buffer cannot be treated as a simple queue of grains.** A writer media function must carefully compute the grain index at which it writes based on the frequency domain of the incoming grains. If the writer cannot guarantee that the external source shares a common frequency domain with the MXL host, it must implement a re-synchronization strategy (grain drop, grain repeat, dynamic audio resampling, etc.) to maintain alignment with the host's timing. | |
| Ring buffer indices encode timing information — **the ring buffer cannot be treated as a simple queue of grains.** A writer media function must carefully compute the grain index at which it writes based on the frequency domain of the incoming grains. If the writer cannot guarantee that the external source shares a common clock frequency with the MXL host, it must implement a re-synchronization strategy (grain drop, grain repeat, dynamic audio resampling, etc.) to maintain alignment with the host's timing. |
Nitpick on wording.
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The terminology is chosen to be similar to what is used in the DMF Sync workgroup (common frequency domains)
Signed-off-by: Vincent Trussart <vincent.trussart@grassvalley.com>
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Details
Add some clarifications related to timing based on NAB learnings.
Backport requirements
yes