Problem cutting m4v file

flyer201

New member
I have a 720p m4v file that looks quite good and plays smoothly. However, seeking is sluggish and I cannot make frame accurate cuts using VideoReDo TVSuite V5. Normally I have no problem using VideoReDo with h.264 video. AviDemux gives similar issues. It will only cut a certain points which I assume are at GOP boundaries and from the look of things given the way those boundaries jump in AVIDemux the boundaries are far apart. As best I understand VideoReDo should be able to cut at any point by re-encoding frames up to the boundary and then copying without encoding the remainder. This appears to be happening but the resultant file will not play smoothly at all. Sometimes frames are skipped at the beginning or end of cuts.

I don't know what it is about the encoding of this file that is giving this problem. I would like to re-encode this file so that cutting will be accurate. I would be grateful for any setting in VideoReDo.

Thanks!
 

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jmc

Active member
A "Quick Stream Fix" might fix the problem.
It usually fixes the jumpiness with dvds.

Recordings can be another ball of wax. Much more likey to have real errors in the video.

As to the "recoding"... try it and see if it works.
It may just drop the bad areas or just stop/crash.

Good luck,
jmc
 

flyer201

New member
Unfortunately Quick Stream Fix does not solve the problem of seeking. As I previously mentioned, there are no issues with normal playback. The video is very high quality and plays very smoothly. If I cut this video with AviDemux on I frames the cuts play smoothly. If I cut with VRD very often the resultant cut plays in a jerky fashion and may be missing frames either at the cut point or end point.

What I would like to know is if there are settings in VRD so that if I force a re-encode it will change the ability to seek and perform cuts accurately? It does not matter at all if I need to increase the file size drastically to accomplish this. By the way, with VRD I can advance through the video frame by frame. Of course I have not looked at all the frames, but in the cut regions all the surrounding frames look entirely normal. I have tried re-encoding with the usual settings, including increasing the bit rate quite a lot. This doesn't fix the problem but I can see a lot of settings in the advanced parameters that probably would change the GOP structure. Would reducing the GOP size possibly help? Can you please recommend something I might try?

Thanks!
 

jmc

Active member
"GOP" size can make a big difference in smoothness of scrolling.
As I understand it, the whole GOP has to be decoded first. (H264)

So 10 seconds or more GOPs are going to be choppy to scroll though.
(Bigger GOPs shrink file size)
I think dvds require a 15 or 18 frame limit in GOPs. I use a setting of 30 frames.
 
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Dan203

Senior Developer
Staff member
9 reference frames is pretty unusual. That could potentially cause an issue if the file also has IDR frames.
 

flyer201

New member
Dan203, Thanks for your reply. Would you be able to walk me through some settings I could try in advanced options?
 

Dan203

Senior Developer
Staff member
Dan203, Thanks for your reply. Would you be able to walk me through some settings I could try in advanced options?
What are you using to record/encode these files?

If all you want to do is recode in VideoReDo just pick the H.264 MP4 profile and set it to Force Recode. We use 3 reference frames by default, which should edit and navigate just fine.
 
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