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BETech  
#1 Posted : Tuesday, July 26, 2016 1:34:18 AM(UTC)
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When using vMix Replay, I have noticed that when changing speed using a variable speed controller, the playback video pauses for a frame or two and then resumes at the selected speed. This is very noticeable on fast sporting events such as today’s ‘Tour de France’. The transition between variable speeds using the controller are not smooth, nor are they when using the in-built slider within the vMix software.

The recording format is 100Mb/s, single channel. Is the MPEG-HD encoder for vMix Replay using GOP or I-Frame to record the transport stream? I-frame is preferable. Does anyone else report a similar issue during slow-mo playback when changing speeds when using the fader/slider/T-bar?

Updated information:

The recordings appear to be GOP, with two I-Frames. Interesting to have two I-Frames in a GOP structure. May have some bearing on the variable speed replay freezing on a frame within the GOP before receiving the next GOP of I-frames. Usually, the I-frames are stand-alone and independent of one another. A necessary requirement for smooth slo-mo replays. Martin, your thoughts on this.
admin  
#2 Posted : Tuesday, July 26, 2016 3:08:23 AM(UTC)
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Can you confirm you are using 17.0.0.105? There was some improvements with the frame buffering to better handle
adjusting the speed when using new MIDI controllers now supported.

As for the GOP, this has no impact on replay internally as vMix will buffer plenty of frames to always have enough available for playback.

Ultimately though, since vMix Replay doesn't have access to dedicated video decoder hardware that can keep perfect audio/video sync
at all playback speeds, a couple of frames here and there during fast speed changes is to be expected on a software system.

Regards,

Martin
vMix
BETech  
#3 Posted : Thursday, July 28, 2016 12:07:53 AM(UTC)
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Version Update 17.0.0.106 provides smooth transitions between various speeds using the in-built speed slider/fader and also for physical control surfaces.

This refinement in the slow-motion video playback is an extraordinary improvement. With thanks to Martin and his team.
Maximus  
#4 Posted : Thursday, July 28, 2016 10:17:09 PM(UTC)
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I have also experienced the slow motion playback and this was of some concern. I will be testing version 106 on tomorrow on a Cricket match, so I will see how it goes and report back.

Maxi
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