JERKY VIDEO

[Ling]

I know this issue has been raised before, but I can't find the reason why I am ending up with jerky videos when burning a DVD. I am using a compact camera (a Canon Ixus 960i) as my source. The Canon's video format is .avi as far as I know, and I have set the highest setting (30fps). The preview is smooth however. Just the end product is no good.

My project properties are as follows:
NTSC non-drop frame (30 fps)
Microsoft AVI files
24 bits, 640 x 480, 30 fps
Lower Field First
MJPEG Compressor
PCM, 48.000 kHz, 16 Bit, Stereo

The properties of the individual video clips are as follows


Compression: MJPEG Compressor
Attributes: 24 bits, 640X480
Frame rate: 30 fps
File Format: Microsoft AVI files - Open DML

I'm not much of a bof at this, but am trying to learn the ropes here. I have tried to make sure that "Lower Field First" appears in the individual clips, as well as under the project properties. I should mention that we under the PAL system in our country.

Am using a 2Gb RAM, 2Ghz Intel Core Duo Processor laptop.

Any help here would be very appreciated.

[Ken Berry]

Hi Ling -- welcome to the forums!

I am afraid you have a couple of things going against you. On the positive side, the Motion JPEG (MJPEG) format is a good one from the point of view of quality. It was the predecessor of the high quality DV format used in many digital video cameras. It's files are, however, large for video captured on a still camera so you will need fairly large SD cards to hold much video from your Ixus.

However, the major problem is that its frame size (640 x 480) is not part of the international DVD standard for either PAL (720 x 576) or NTSC (720 x 480). Thus, regardless of whatever other editing you do, the editing program (Video Studio) has to increase the frame size to the DVD standard, and to do so, it in effect has to invent the extra data from out of thin air. That alone will degrade your end quality.

The other problem could also be the fact that you are using NTSC video on what I presume is a PAL set-up for your Video Studio. Now, you don't tell us what workflow you are following when trying to burn a DVD. But we have a recommended workflow which is to do your editing, then go to Share > Create Video File > DVD. This will convert your MJPEGs to DVD-compatible mpeg-2 format. The problem here, though, is to know whether that conversion process -- or even the burning process which follows -- are converting the NTSC video to PAL format.

If it is indeed doing that, then again it will on the one hand be substracting some frames to reduce the speed of the video from NTSC's 29.97 frames per second (your 30 fps) down to PAL's 25 fps. And on the other, it will be inventing data to pad out the frame size even more if it is going from 640 x 480 to PAL's 720 x 576. The end quality, frankly would be a mess in terms of quality. In that sense, it would probably be better to use NTSC conversion and burning properties since most stand-alone PAL DVD players these days can play NTSC discs without problem.

Note also that under our recommended workflow, after you produce your new mpeg-2, you go to File > New Project. Don't worry about giving your new project a name. The objective is just to clear the timeline of your current project.

Once that is done, you select Share > Create Disc > DVD. The burning module will open. Use the Add Media button at the top to insert your new mpeg-2 in the burning timeline. Then go to the middle of the three icons in the bottom left of the burning screen. There is a little box beside the words 'Do not convert compliant mpeg files'. Make sure that box is ticked (it usually is by default). That way, your already compliant mpeg file will not be re-encoded. Then build your menus and burn.

Note that if you keep the NTSC format for your DVD, but have VS set up using PAL as the standard, you would need to change the setting to NTSC in the first of the three icons in the burning module (selecting Disc Template Manager).

But are you sure your Ixus does not allow you to select PAL as the video format? I have had several Canon and other brand digital still cameras, and all of them allow this. I currently have a Canon PowerShot SX100IS (marvellous little beast -- 8 MP and 10x optical zoom) and it certainly allows a simple menu change from NTSC to PAL.

[Ling]

Hi Ken,

Thanks very much for the help. Your suggestion worked very well thanks.

Am not sure I understand why, but at least I don't have a jerky video now. It seems that before burning the DVD, the media that is being added must be in MPEG-2 form I see.

Thanks a million,
Glenn

[sjj1805]

I know this issue has been raised before, but I can't find the reason why I am ending up with jerky videos when burning a DVD. I am using a compact camera (a Canon Ixus 960i) as my source. The Canon's video format is .avi as far as I know, and I have set the highest setting (30fps). ......

The problem you had was this.
30fps means there are 30 frames per second. If you cast your mind back to your school days they probably got you to make a flick book or cartoon where you drew images in a small book and then flicked the pages so that they appeared to make a cartoon like movie.

You are using PAL equipment which has a frame rate of 25 frames per second. What you ended up doing was asking the software to insert an extra 5 frames every second - it most probably did this by duplicating frames so you ended up with things appearing jerky.

Quality is determined by "Bit Rate" not "Frame Rate" - a Higher bit rate means higher quality but it also means larger file sizes and so you get less on your DVD. Top Quality standard definition video is roughly 8000 kbps
and you can expect to get 1 hour of video on a standard single layer DVD disc. If you lower the quality to lets say 2500 kbps you would get 2 hours on a standard single layer DVD disc.

Our friends in the U.S.A. and Japan use a different television standard to Europe, they use a standard named NTSC which has 29.97 frames per second. The film industry use 24 frames per second.

[Ling]

sjj1805,

Thanks very much for the info. I'm learning here all the time. I need to spend a lot of time of these forums to increase my knowledge.

3 Questions:

1) I would be happy with 2 hours on a DVD. Do you suggest leavig it on a fixed bit rate of 2 500?

2) Under "Project properties", and then "Microsoft AVI files", should I leave the compression to "None"?

3) It is under "MPEG files", that I should select a constant bit rate of 2500?

Would really appreciate you replies to these questions

Kind regards
Glenn

[Ken Berry]

I think I should jump in here quickly and say I think Steve mis-typed 2500 when I am sure he meant 4500. The latter would give approx. 2 hours of average quality video on a single layer DVD, particularly if using either Dolby or mpeg layer 2 audio. A bitrate of 2500 would probably allow closer to 4 hours of video, but the quality, frankly, would be appalling.

Regarding your questions:

1) You may be happy with 2 hours of video fitting on a single layer disc. But the ultimate question is -- are you interested in squeezing in as much as possible on a single disc, or are you concerned with quality as well. At a bit rate of 4500 kbps, you will get, as I say, average quality -- if your original video is good quality, then that bit rate will give you something that looks like decent VHS quality. 6000 kbps will be noticeably better quality, and you will be able to fit 90 minutes or a little longer of video on a single layer DVD. Top quality is 8000 kbps or higher, but that will allow only about one hour to 70 minutes of video per DVD. It's always a trade-off between final acceptable quality and how much you want to squeeze onto a single disc (which are dirt cheap these days, after all)...

You also talk about a "fixed bit rate". You may not have intended this, but in fact it raises an important point about whether you should should a Constant Bitrate (CBR) or Variable Bitrate. As with everything, there are exponents of both. In terms of final quality, there are many who argue that using a CBR will give the best overall quality. However, the VBR means that when there is less action or less changes in the general scenery in a video, the editing program can detect this and use available information to fill things out. Thus it can drop the bitrate in those parts of the video, and increase them when lots of detailed action is taking place. Hence, for many others, VBR is the most efficient use of video space.

2) If you are talking about DV/AVI files, then yes, you should not change the default compression of 'None'...

3) Yes, in setting up the mpeg properties, change it to 4500 kbps is you are happy with a longer DVD but one which is not optimum quality.

[Ling]

I have just discovered that after rendering the AVI clips into MPEG using the create video file function, when I try to play the MPEG file, there is no sound! Why?

However, when I select "New project", select "Create Disc", and then add the new video file, if I go to "preview", the sound it back. Why is this?

Another hassle, when to post a reply, I have to hit submit numerous times before it will post. I wonder what the problem is?

[Ken Berry]

When you try to play the new mpeg back, are you using Clip mode or Project mode?

As for the submission button, we have been having various problems in recent months with the speed of the Board's workings. Corel does not seem to be able to fix all the problems. So I am afraid you may just have to live with it. I get the same problem, by the way. It is also the cause of why some people seem to post the same answer 2 or even 3 times...

[Ling]

I have been trying to post this damn reply now all mornng. Must have clicked on submit over 30 times by now. It makes posting on this forum a real pain!

If I try and click on the individual MPEG file, once it has been created, and Media Player then opens up, there is no sound.

In Videostudio however, once I add that new video file to a new project and that click on preview, the sound is back!

It's actually not serious, since I have sound at least in the preview mode, just wondered why when clicking on the file in isolation there wasn't any sound.

[lancecarr]

Windows Media Player is notoriously ill suited as a test bed for MPEG files unless you have set it up with an associated MPEG2 codec that Microsoft deem compatible.
Simply ignore any result you are gtting with WMP. If the file is playing with sound from within VS you should be good to go.

[Ling]

I'm probably asking an obvious question here, but I'll ask it anyway.

Thanks for all the replies thus far. It has helped so much!

Would you guys say the quality of the video will be any worse if I use the two stage process of first rendering the avi file to a mpeg file, and then creating a new project and then inserting the video file and and burning the DVD, compared to doing it all in one process?

[Trevor Andrew]

Hi

In theory any of the two options should produce the same quality.

Either option will take the same time and use the same amount of memory.

There have been problems with some users rendering the video in the burner module.

I prefer to Share Create Video File first. Using the resultant file to burn to dvd.
I can play the new file on the pc to check quality, then burn a dvd.

[Black Lab]

I ditto Trevor.

[Ken Berry]

... And there will be no loss of quality in the two stage process if (1) the mpeg-2 created in Stage 1 is fully DVD-compatible and (2) you make sure 'Do not convert compliant mpeg files' is ticked in the second of the three icons in the bottom left of the burning screen...