Rank: Newbie
Groups: Registered
Joined: 4/11/2016(UTC)
Posts: 2
Location: Prague
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Hi I tested the Instant Replay feature for video judge (4x HD-SDI cameras connected) and have to say that it works quite well with powerfull machine (Core i7 5820K, 32GB Ram, nVidia 960 and BlackMagic DeckLink Quad 2, 120GB SSD for Windows 10 and 520GB SSD for Instant Replay files), vMix v 16.0.0.115.
I have a question regarding the framerate for playback. It seems that it is possible to step by step replayed video only as a 25 frames/sec so one step is 0,04sec.
I am using 4x 1080/50i inputs from HD-SDI cameras (I played with deinterlacing in project properties without success).
Is there a way to reply video in 50fps?
I believe that it can also deliver more smooth slowmotion for replays when used for sport action.
Thank you very much for any help.
Stan
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Rank: Advanced Member
Groups: Registered
Joined: 5/20/2015(UTC) Posts: 493   Location: Copenhagen, Denmark Thanks: 389 times
Was thanked: 100 time(s) in 79 post(s)
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I'm not sure what you try to accomplish. In vMix it easy to change replay speed by right-clicking on the input of your replay channel and ticking the "Show playback speed bar" box, and a bar right next to the input enables you to change the playback speed to e.g. 50 %.
Playback in VLC also enables you to change playback speed by using the keys + and - (plus and minus).
Otherwise, if what you're looking for is regarding your post-production editing software, it depends on the software, but typically, it is possible to change the playback speed of your clip.
I hope this can help you.
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Rank: Newbie
Groups: Registered
Joined: 4/11/2016(UTC)
Posts: 2
Location: Prague
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Hi and sorry for late reply.
I have probably not described my problem (question) very well.
It is not about the option to replay in slowmotion.
The problem is that the incoming signal is 50i so there are 50 frames per sec (I know not the full "progressive" frames).
But during the replay and also during the frame by frame replay we can achieve only 25frames per sec.
Eeach step is only after 0.04 sec but the source video should allow to play one step 0.02sec, even one frame has to be calculated (from interleased frame using some blend or other method).
Using this method also slowmotion play can be more fluent.
I hope it is now better described.
Sorry for my english - it is not my motherlanguage.
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Rank: Advanced Member
Groups: Registered
Joined: 8/5/2015(UTC) Posts: 49 Location: Germany Thanks: 11 times
Was thanked: 3 time(s) in 3 post(s)
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Hi there,
sorry to say that, but 50i is NOT 50 frames/s. It is 50 FIELDS/s which equates to 25fps. 50p is 50fps.
You can however use fields to interpolate between frames. This is how slowmotion is usually done in NLEs. That's why interlaced video looks better than progressive video in NLEs when slowed down. Try progressive video in an NLE and you will likely get ghosting due to the interpolation (except your are using tools like Twixtor).
vMix (as far as I have seen it during our Amercian Football broadcasts) has no interpolation. It simply reduces the speed, therefore showing less frames per sec. You would need to record 720p50 or even 1080p50 in order to get smooth playback at half the speed (which would be 25fps).
Cheers,
Knut
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