Choppy result - for some time - on Bluray
 

I experienced something very awkward when burning edited movies from my XDCAM-HD (PDW-F350) to Bluray disk: whenever there's a panning or other motion, the first few seconds the image stutters, but after that everything moves smoothly. So there a a few seconds of choppy video, followed by perfect footage.

How is this possible? Is it a Bluray encoding artefact? (Shot in HD, 25p, edited in FCP, exported to QT in ProRes 422 and encoded that QT-movie to Bluray).

what output setting do you have in the Blu-ray player setup menu?

mine can be set to 1080p or 1080i or 720p

Bitrate may be too high?
 

Just a thought but if your encoding for the bluray was using too high a bitrate that might have this effect - you didn't say what SW you are using to do the encoding?

FCP7?
Something else?

Dave

Bluray was burnt with 1080, movie was inported in Toast bluray burner in Quicktime (ProRes422). Editing was done in FCP 6 - starting from original clips in XDCAM-HD, 25 p. The Quicktime movie does not suffer from this effect, only the Bluray result.

did you output mpeg or H264 for the blu-ray

what max bitrate did you use for video and audio

when I use mpeg, I usually set fixed bitrate to 24000 (max at 35000 if using variable) for video and 384 for ac3 audio

Anton, in Toast 10, there's very little I can choose as far as bitrate and burning speed are concerned. The 'burning speed' box is not even lighted up, so I cannot choose any of this. I'm using XDCAM 25 p variable bitrate to make the Quicktime movie, is that any help?

but what are you putting on the blu-ray, it can only be mpeg or h264 or some other vc1 format that nobody uses

MPEG, I suppose, there's no choice as far as I can see. Even in the 'recorder settings' there's no menu that offers format alternatives.

sorry, but after doing lots of Blu-ray, I can assure you that there is no room for "I suppose"

a cheap encoding and authoring tool can be found at TMPGEnc - We Make Digital Video Easy!

I just bought Roxio's Toast 10 + HD-Plug in for 250,- euros. Will the software you mention give me better quality and more control of the burning process on a Mac? Authoring is not so important for me, top quality image is.

ouch, don't think there is a Mac version

Dont know if its relevant but in all my IPTV tests I have had a lot of problems using long gop material for transcoding to web and DVD, dont know about blu ray but for a lot of my tests I had to transcode to flash to stabilise the stream.

Now I am on panasonic P2 with intra frame codecs it never happens anymore.

Anton, I talked to somenone yesterday who has some experience with Bluray, and he told me that this is a typical bluray problem. The very first frames of any new movement (pan, tilt, zoom) are choppy, then the movement smoothens. That's exactly what I'm experiencing. Have you experienced this too? I cannot imagine all bluray-users accepting this as 'normal'.

Any other suggestions?

Gary, Thanks for the info. The strange thing is that 90% of the movement is OK and smooth. It only stutters just in the very beginning. I know the problem you describe, but that represents itself al along the movie when there's a pan or a tilt, not just for a few seconds at the start of every fresh movement. Most of the footage looks fantastic, only when panning, zooming or tilting there is this strange 'stutter' that stabilizes immediately afterwards.

I saw that stutter several times when I was on long gop and as you say its at the start, it was almost like some form of encoding buffer was trying to catch up and re-sync the frames.

Making material progressive seemed to improve it but I had lots of hours spent with problems uploading material that had been re-compressed for delivery.

As said I dont have those problems now so whether the 35mbs long gop codecs dont like re-compressing or not I dont know.

That indeed sounds like the same problem, Gary. I'm always using progressive mode, so it's not awful, just a little disturbing (and distracting). Did you eventually find a solution to get rid of it?

I also posted this on the Bluray authoring forum a week ago, but all I got was only 48 readers, no repliers...