Wowza Community

Variable Frame Rate recordings

Despite sending constant frame rates from our encoder, and zero dropped frames being reported, the Wowza Live stream recordings come back as VFR 100% of the time. Any idea what would cause this? The dips in frame rates are usually very slight as well.
Typical min/max rates:

Encoder settings:

@Rose Power-Wowza Community Manager This is regarding Frame Rate, not bit rate. Even with that selected frame rate remains unaffected.

Oh, my sincere apologies for misreading that! Let me look into this for you right away.

@Bryce Seifert the engineers would like to know if you’re recording source stream or transcoder output?

So, this is very peculiar behavior and the engineers would like to ask you to submit a support ticket in order to take a closer look at this. We have an idea of what may be causing it on our end, but will require the ticket to replicate and test. Thanks so much.

Got it. Submitted under ticket 354939

Thanks! I’ll keep an eye on it.

No worries! It is a source stream recording.

Hello, Exist a Fix for this issue ? We have the same. Our Encoder send 50FPS (CONSTANT) and the recording is Variable between 45 and 55 Frames.

Frame rate mode                          : Variable
Frame rate                               : 50.000 FPS
Minimum frame rate                       : 45.455 FPS
Maximum frame rate                       : 55.556 FPS


can you please post the result from this ticket. We have the same issue.

@Christian Siegert

I suspect the problem stems from how we handle the internal timing of frames. Internally we keep track of frames on a millisecond precision timescale and unfortunately most video solutions natively run on a 90KHz time scale which introduces inherent rounding issues when translating to round milliseconds.

If we look at the reported frame rate max and min, you can see how this manifests:
1/29.412 = 0.339 (aka 34ms)
1/30.303 = 0.330 (aka 33ms)

We have to have an occasional 34ms frame, because we can’t have a 33.33333333333333333 ms frame as we would want to.