Choppy result - for some time - on Bluray

[Gary Nattrass]

It seemed to be better if I edited it native codec but then exported a master from FCP as pro res 422. I did still seem to get some problems when uploading for IPTV at 1.5mbs but the only way to stabilise it all together was to transcode to flash for upload but this took a long time and the quality was not as good.

That is why I went onto P2 as it has a higher original bit rate and just seems to be more stable once it has gone through all the compression processes.

OK most of this was all tested with HDV not Xdcam but it seemed to be related to re-compressing long gop material, as I said it doesnt seem to happen now I am on P2.

Sorry didnt see your post in the blu-ray section as I dont tend to use that format very much, most of my delivery is H264 mpeg4 to computers and clients find it just as easy to have their material on a laptop in HD or DVD for SD, the quality from P2 is very good on both.

[Luc De Wandel]

Thanks, Gary. I'm also editing in native XDCAM 35 mbit vb - 25p, and then exporting to QT in ProRes422. The QT-movie doesn't have the problem, so it must be happening in the transcoding to Bluray. And as I'm a complete newbie in Bluray authoring, I have no idea how to influence that last transcoding process. There's even no choice of different codecs for Bluray in Toast 10, as far as I can see.

That's why I hoped someone with a lot of Bluray experience would read my post in the Bluray section. But no luck so far...

[Anton Strauss]

Originally Posted by Luc De Wandel

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 don't see this problem at all, I shoot, edit and encode interlaced

here is another thing that could cause your problem

the menu settings must match the movie settings

if the movie is progressive, the menu needs to be rendered progressive

if the menu is rendered interlaced and you push a button to start play, the video will stutter for a second or two while the changeover from interlace to progressive takes place

I use DVDit Pro HD for Blu-ray authoring and I can set my menu to match the movie, the frame rate must also match or you get the same stutter
http://www.videoproductions.com.au/e...-framerate.avi

or does your stutter happen while just watching the movie and a pan or zoom starts in the video, in that case I have no clue because I don't get these problems using interlaced

do you see these stutters when watching hollywood blu-ray releases that are progressive

also, are you watching on a true progressive display? Plasma? LCD?

is the display native 1920x1080?

[Luc De Wandel]

Hi Anton,
Yep, that's the problem: the stutter happens only while watching the movie and a pan or zoom starts in the video - or an object starts moving fast. Only a second or so, then it goes on smoothly. That's what makes it so awkward.

It's on a full-HD LCD tv from Loewe, native 1920 x 1080 and true progressive.

Someone suggested it might be the bluray player that cannot keep up with the sudden peak in bitrate when an important (datawise) movement starts. I'm going to try and find another player to compare.

[Anton Strauss]

can you shoot and upload a clip around 5 sec long with a pan in it

I will then use my software to make a Progressive BD-R and test and I will upload the BDMV and Certificate folder so you can burn and test, if it still stutters, then the problem must be the player

[Luc De Wandel]

OK, thanks for the help Anton. I tried to upload the clip in QT, Prores422, 25p., which is exactly 47 MB big, but I got this error message from DVInfo: "Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 46976178 bytes) in /export/sites/dvinfo.net/docs/forum/includes/class_core.php on line 1930".

Don't know what happened, I'll try again later.

[Luc De Wandel]

Second try, got this message again: "Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 46976178 bytes) in /export/sites/dvinfo.net/docs/forum/includes/class_core.php on line 1930". Looks like there are some MB's in the allocation site already. No idea how these got there.

I guess I won't be able to send it this way. I can try via e-mail and Yousendit if that's OK for you. Let me know.

[Anton Strauss]

can you upload to some file sharing site or your own hosting provider may have an option?

[Luc De Wandel]

Sent you the file by FTP, Anton. Thanks.
My provider doesn't offer this possibility, but perhaps you could send it back using Yousendit?

[Anton Strauss]

I had a look at your clip

it was shot progressive at 25fps and as a result, what you are seeing is normal, your zoom and pan are way too fast for progressive shooting

if I shoot the same interlaced, it will be much smoother because there are 50 images per second instead of only 25

however, I believe you can improve things by finding a suitable shutter speed in your camera, I have not tested this but others may be able to advice you on the best shutter setting

[Luc De Wandel]

Hi Anton,

thanks for the comment. I did some tests with fast pans in interlaced yesterday and there everything stays perfectly smooth, as you point out. The pan-speed is indeed too fast for progressive. But I keep finding it strange that, once burnt to Bluray, the resulting video only stutters the very first second and then continues in the same smooth way as if it were interlaced. That's what confused me.

[Anton Strauss]

try various shutter speeds with progressive

I may try that later myself

btw, I did not even need to burn it, it already acts as you describe while playing in Edius with HD monitor connected

[Luc De Wandel]

I carefully compared the QT movie to the burnt sequence on Bluray, and the stutter that you see throughout the whole QT clip is gone in the Bluray, except for the first second. So there must be some correction in the encoding to Bluray that stabilises the image, after missing the start.

That's what makes it disturbing, because it doesn't look natural. It stutters and then takes off to a normal, smooth pan. In QT it stutters all the time, which is less disturbing IMHO. Anyway, after doing the test with both, I like interlaced better. Just wonder if there are any disadvantages in using interlaced, as I see so many people sticking to progressive only. Or is it just a matter of taste: filmic look against video-ENG look?

[Anton Strauss]

if you plan to shoot in order to output to film, I would use progressive

for all TV work, I use interlaced, until someone can prove me wrong :)

also, if you go to the cinema and you see a pan that is too fast, you will get an instant headache and it looks like what you are seeing on blu-ray

[Luc De Wandel]

Thanks for the advice, Anton. As I'm only a hobbyist in video, I'll probably stick to showing my movies at home and in the video club. In the first case I watch them on a full-HD LCD-screen and in the second a HD-beamer does the (marvellous) job. So it's going to be interlaced most of the time, I suppose.