Anyone seeing repeated frames in rendered video?

[John Rofrano]

Are you rendering to a frame rate that is different from the source and if so, have you disabled resample on any of your video events. That might cause duplicate frames.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Anthony Atkielski]

Nope, source and rendered frame rates are the same, both interlaced 1920x1080x50i. Unfortunately, it is extremely hard to pin down the conditions that correspond to repeated frames, but they are perceptible and irritating. I don’t think this was happening in the past because I probably would have noticed it. It’s only a few frames out of a long video, but I’m still not happy about it. The repeated frames are not seen when you slowly step through the video frame-by-frame on the timeline; they only appear in the rendered output.

I’ve been racking my brain trying to figure out what I could have changed to cause this, but I haven’t come up with anything. I upgraded to Platinum HD Version 11 about two weeks ago, and then applied the lastest Build 256 update, and my impression is that it might have started with Build 256 (since I don’t recall noticing it prior to that).

[John Rofrano]

Yea, it could be a bug in the latest build. It doesn’t sound like anything you are doing. I would report it to Sony.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Jean-pierre Taran]

I have noted similar artefacts with your parameters, namely interlaced 1920x1080x50i if:
1 – the video clips are not positioned flush against one another, or slightly overlap and, at the same time,
2 – I render long videos, e.g. 20-40 min with hundreds of clips.

Then on render I get a characteristic toggle between the first frame of the mismatched clip and the current frame till end of the clip and instabilities propagate to the end of the video.

My remedy: mark last frame of prior clip and first frame of clip concerned and erase that. The clips will then sit flush against each other. Also it helps to reduce the data rate from the nominal 16 MB/s to 15 or less. I use 14.6 for hour-long films.

Hope that helps.

[Anthony Atkielski]

Hmm, I’m not sure I understand your suggestion.

Right now I have a video of about 15 minutes that has perhaps 60 clips or so in it. Most of the transitions are crossfades, so practically all the clips overlap. How would I carry out your suggestion in this case?

It has occurred to me that it might be something related to a particular frame being in a particular position between clips, but I haven’t been able to isolate it.

Either way, it seems like a bug, so I’ll have to report it, but if I had a solid reproduction scenario that would help a lot. And a useful workaround would help as well.

I’m wondering if maybe positioning clips so that their lengths, start/end points, and overlap durations are some special multiple of frames (?). Like maybe if everything aligns on n-frame boundaries, it might work. But I don’t know what n would be, even assuming that this method makes any sense at all.

[Jean-pierre Taran]

Right now I have a video of about 15 minutes that has perhaps 60 clips or so in it. Most of the transitions are crossfades, so practically all the clips overlap. How would I carry out your suggestion in this case?

I do have crossfades as well, and they don’t seem to pose any problem. I actually had in mind what you describe in your last paragraph. You should have an integer number of frames (including zero) for spacing between successive clips, whether you position them flush, or overlapped for your crossfade.

It has occurred to me that it might be something related to a particular frame being in a particular position between clips, but I haven’t been able to isolate it.

Sometimes, a funny problem shows up as a result of sliding clips usideways along the time line, such as you will do when you adjust your crossfade: a duplicate of the video is generated exactly superimposed or shifted by a frame or two. I guess this might result, in my case, from a malfunction of the mouse’s left button. To check if this happens to you, open a video track above, mark the suspected videos, drag and drop them up into the new track. If a video clip is left behind, that’s a duplicate and you want to erase it; then drag back everything else into place.

I’m wondering if maybe positioning clips so that their lengths, start/end points, and overlap durations are some special multiple of frames (?). Like maybe if everything aligns on n-frame boundaries, it might work. But I don’t know what n would be, even assuming that this method makes any sense at all.

That problem might appear if you shoot at 29.9 fps (NTSC) and render at 25.

To try and speed up the investigation, have you tried rendering, e.g., the second half of your stream only?
If the problem vanishes, then I see two possible causes, which are not mutually exclusive:
– either you had an orphan image carried over from the first half as discussed up above;
– or you are trying to use too fast a baud rate; you might improve the situation by setting the binary flow rate at 15 or even 14 Mbits/s. I personally had to settle down for 14.6 for my longest films. For me, the default 16 generate instabilities beyond a couple of minutes.

I hope this helps, and that my jargon is intelligible (sorry, English isn’t my mother tongue)

[John Rofrano]

Do you have Quantize to Frames disabled by any chance? That could cause all sorts of rame based problems.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Anthony Atkielski]

Quantize to Frames is turned on.

I think something was broken in going from Platinum HD 10.0 to 11.0. The previous video didn’t have any problems like this (that I noticed), and it was edited with 10.0.