Analog type banding on compressed video

Hi everyone,

I am hoping I can get some help with a puzzling issue. I produced some short video clips that are to be used on an LCD menu system. They have been compressed using various Quicktime codecs but the problem seems to stay.

When I view the video on any of my Macs in Quicktime player the video works great but when my client views it on their PC systems there is an analog style roll on the video (especially on dissolves) almost like the tracking is off (if there was such a thing for digital files).

Any suggestions or help is greatly appreciated.

Julian

More information please

Quicktime CODECs and all information on the data rate, pixel size, etc.

Also need:

Clents PC spec

PC OS eg: Windows 95, 98, ME, 2000, NT et al

Software used eg: Real Player, WMP, Quicktime

Also are they running it off CD-ROM, Web, DVD?


Just to hazard a quick guess...

...its sounds like a low graphics power (or badly in need of a system clean) PC thats having problems with the decompression and the frames are "shearing" trying to refresh the video.

A similar problem can be seen when low power GFX cards try to render games graphics or also when frame rates mis-match CRT Refresh rates. I see your final output will be by LCD but is the client viewing on CRT?

These are of course just guesses. Please could you supply as much information (especially technical) about any problems you are having or else we have problems pin pointing the precise cause.

Cheers


Ben



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

Hi Ben,

Thanks for your help. From what I can tell the issue occurs no matter what CODEC I use. I have tried various sizes (HD is the goal) as well as Sorenson 3, H264 and others just for fun - still the same result. The clients PC is a 2.8GHZ PC with 1GB of RAM - new coputers that should have little issue processing this video. I was just at a friends house checking on his laptop and had the same problem. I tried stepping through the frames and the issue seems to be with playback - not the individual frames.

You may be right about the shearing but why only on PC's? My G4 is far older than the PC's tested on.

The software is Quicktime and although the client is using a custom setup that uses Quicktime the same issue happens directly through the player.

My next step is to try recompressing as a WMV file and see if the issue remains.

I have tried simply compressing the raw video without effects but still have the same problem. Perhaps I should capture something totally different and see if the issue occurs then.

Not quite sure what process to follow.

Anyway - any help from anybody is greatly appreciated.

Cheers,

Julian

Hmm that is really odd

What is the source footage and what are your settings for output?

Ben



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

The original footage was shot on a Sony Z1 in HDV. First try was captured as HDV then converted in Sorenson. Once the problem was noticed I tried everything from downconverting from the camera to converting in Quicktime player and FCP.

Everything was captured via Firewire directly into FCP. The odd part for me is that the problem is only visible on a PC - not a Mac (and I am afraid the client won't switch just for me

Damn them PC users (give most of them a Mac for a few days and they all switch...)

Anyway, HDV 1080i to Sorenson.

Ok but what pixel size, compression settings, Fps, data rate?

Ben



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

PS I'm off to bed now its 1am here and I have the final episode of a BBC1 series to online and grade tomorrow - if you can give me the exact setting you are using for the video output I'll get back to you Monday evening if another mod/expert hasn't replied with a solution.

Regards

Ben



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

OK - so I was able to save as an WMV file and the problem has gone on a windows machine! go figure. It's not the ideal solution but I have sent it to the client to get feedback. I also triad a new service called heywatch.com. I uploaded the master HDV file and the service sent back an AVI in a matter of minutes. Other file types are also available. It's very cool and is mauch faster than my G4

Thanks again for you input - if you ever come across the problem please let me know because I know it will rear its ugly head again...

I'm still intrigued as to what size you are outputting the compressed video - it would help me determine if there is an issue there.

Plus I could test the settings myself and see if its a universal issue we can workaround or specific to your system.

Can you let us know what the compression settings are please? Both the good and the bad ones.

Ben



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

I've attached a few screen shots from QT PLayer. If it will help I can also upload the outputted files so you can see what the issue is first hand.

Julian


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Firstly I think you've got an anamorphic file rather than a square pixels file - for computer playback in CODECs like Sorenson and MPEG 4 I'd recommend making a square pixels version rather than anamorphic.

Also I've not tried anamorphic playback for sorenson 3 or H.264 this so could be an issue.

Try exporting a version that is true 834x480 pixels rather than 720x480 stretched.

Would you mind uploading the two files above - it would be good to test this out and find a solution, not least for my own peace of mind and yours but also for anyone else having similar problems.

Cheers

Ben



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

I've archived 3 versions that have been tested and all came up with the same issue. I started to go a bit crazy with sizes and codecs just to see if I could figure it out.

They are at

[www.yousendit.com]

Let me know if you have any success and thanks for the support Ben.

Ok so now I'm really confuzzled - I've tested the sorenson file on 2 different PCs in Quicktime and they play fine.

I also recompressed an MPEG-4 from it that plays without issue on WMP & VLC.

I still think there must be an issue with the client end.

Either they don't have Quicktime installed correctly or they have an old version or their PCs have low power graphics adaptors.

Essentially you are making a 480 HD Quicktime have a look at the machine specs required for this:

[www.apple.com]

I think if WMV works for this job then you have to go with that, horses for courses.

Are you locked into using 834x480? Could you use a smaller pixel dimension? Say 640x360.

Anyway will test on a couple of my friends PCs later this week to see if any of them cause the issues you describe.

Sorry I can't be any more help at present - without being able to personally check the problem on a machine that replicates it, its difficult to pin point.

I would try exporting an MPEG-4 at 4000kbps to 6000kbps from Quicktime Pro using your Quicktime original and see if that plays back well on the client side. This should play in QT, WMP, Real & VLC on a PC.

Regards

Ben

PS please stay in touch and let me know how it goes.



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

This is why I try to avoid web video and compressors (although I never can). I also triad the video on a buddies laptop and had the same issue.

The client PC's are fairly hefty new machines and seem to fit the specs. It is very odd.

The dimensions need to fit a 42" LCD TV 1360X768 at full screen. So ideally the native dimensions of the video are of less importance than the ability to maintain quality at that size. I have tried various dimension to get the files as small as possible for better playback but it didn't seem to do squat.

As you said - if WMV works atleast it works but it sure would be nice to know what is going wrong in the process for future projects.

I will be doing more tests on my end.

Cheers.

Julian

Absolutely - I'm intrigued as to why you should experience this problem and yet I don't seem to get it...

If I can incapacitate my friend and send you his PC I'll send it over to your client

Seriously though its really bugging me now as to what this could be.

Is this happening on the 42" LCD TV as well?

Ben



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

Initially I thought it might be the client presentation software on the LCD (yes it did show up on the TV) but they then played it on another PC and the same issue occured - it is far more visible at larger screen sizes - what size did you view it at?

On the Mac it looks great!

Ah was the problem appearing only when stretching to full screen? I played it at native 834x480 in the various players with no issue.

I'll have to go back and test it fullscreen, I'll also try it on some other PCs.

What is the presentation software they are using?

You could encode in 16:9 Full Height Anamorphic MPEG-2...


Ben



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

It did show up at native rez but was "more" evident at full screen. I did try Mpeg 2 but they didn't have the MPEG 2 decoder for Quicktime and weren't willing to buy it.

I am not sure of the name of the software it is a proprietary piece from a company in Toronto here in Canada. They use it at airports I was told. I did ask them what worked best but they were of no help at all.