mpeg2 playback problem

[mike20021969]

when i capture video from my freeview box (UK) in mpeg2 format (using a terratec grabster av400 or adstech DVDXpressDX2) everythings seems fine - the live monitored video on the computer screen as it is recording is flawless.
but when i playback the mpeg2 files (in windows media player,real player or divx player) there is a problem that has started appearing on the bottom of the video - there is like a white "data" line a few pixels high on the bottom of the video.

is there a setting i can adjust to remove this line?

i've attatched a couple of images to show what i'm suddenly getting.
on the video file it looks like it is vibrating when the video is played back.
thanks.







this problem only exists on video that is captured.MPEG files off my camcorder when dragged to the computer do not show any errors at the bottom of the video.
i have tried different usb and video leads for the capture devices to see if it helped but nothing (i didn't think this would help as the monitored live video showed no problems but thought it was worth a try).

[Nelson37]

Overscan problem. These lines are not meant to be displayed on a regular TV. May be cropped off when played to your TV.

I believe what you are seeing is actually the CC data, you may be able to turn this off at the source but would still have a blank black line. Some cards/software can crop while capturing, some using different resolution or AR can remove this.

It's not really an error, more like the capture is actually Too complete.

This may or may not help but I found on my Sat service that when set to 1080i, the CC data was stripped out even over the SD S-video output and the extra line was just plain black. Not perfect, but less distracting.

[mike20021969]

thanks for the reply.
on friday i did a live recording of the beijing olympics onto my computer and there was no lines at the bottom (the scart from the freeview box goes in my daewoo harddrive/dvd recorder.then the output from the daewoo goes into the grabster via s-video and l/r phono lead.a usb lead from the grabster goes in computer.that's how it's always connected even when the problem was not there ie over the past couple of years until friday just gone).
the problem only started yesterday (saturday) for no reason - i haven't altered any settings in the meantime for this to suddenly happen.
you say turn off the cc data at the source,yet i didn't turn it on.i assume cc data is closed captioning.
my freeview and daewoo players don't have closed captioning data capabilities.
also i have one of those media hard drive players (for playing music/video/photo's) directly onto the tv without the need for a pc (it's an emtec movie cube).i get the white data lines from that too.

i don't understand why it's happening from various video sources all of a sudden.
and why it doesn't appear on the live monitoring - just the recording?
thanks.

(note: recording from a camcorder into either video capture device and the playback is perfect).

[jagabo]

i don't understand why it's happening from various video sources all of a sudden.
and why it doesn't appear on the live monitoring - just the recording?

The junk at the bottom of the frame is probably part of the broadcast. You don't see it when live monitoring because the device/software is overscanning the image. You just don't see the outer few percent of the frame. On a non-overscanning device you'll sometimes see junk at the other edges of the frame too. Broadcasters "know" you can't see the edges of the frame so they don't care about leaving junk out there.

[mike20021969]

The junk at the bottom of the frame is probably part of the broadcast. You don't see it when live monitoring because the device/software is overscanning the image. You just don't see the outer few percent of the frame. On a non-overscanning device you'll sometimes see junk at the other edges of the frame too. Broadcasters "know" you can't see the edges of the frame so they don't care about leaving junk out there.

thanks for the reply.
like i said over the past couple of years the problem was not there.
it only started happening since saturday *confused*
plus a test recording i did using the emtec movie cube to play into the capture device shows this data line too (nothing to do with a broadcast signal).
it's got me beat - i'm gonna try recording something (via freeview and grabster) to another computer to see if the data line is there just to rule out a fault on this laptop for some reason.

note: regarding tv recordings,the error is only from widescreen (16x9) signal source,it doesn't show on 14x9 recordings (a semi widescreen picture for viewing on a 4x3 screen in the uk).

[jagabo]

It would help a bit if you posted full frame caps, not cropped or resized bits. Even a small MPEG sample that shows the error. VirtualDubMod is good for saving frames.

Have you installed any MPEG2 codecs or file splitters lately? Any video editing software (which might have done the above)? Some MPEG codecs do different things at the edges when the frame size is not Mod16. That could be an issue.

[mike20021969]

It would help a bit if you posted full frame caps, not cropped or resized bits. Even a small MPEG sample that shows the error. VirtualDubMod is good for saving frames.

Have you installed any MPEG2 codecs or file splitters lately? Any video editing software (which might have done the above)? Some MPEG codecs do different things at the edges when the frame size is not Mod16. That could be an issue.

the top picture is full frame uncropped (the crops were just for close up purposes).all i have done is converted to widescreen.
i have had k-lite codec pack installed but that has been there for well over a year.
i did try uninstalling seeing if i could locate why this problem is occuring but it didn't help.

all the mpeg2 encoding is done on the fly within the grabster or ads tech capture device units.
here is a raw mpeg file straight from the grabster (15 seconds/12.2MB):

http://www.4shared.com/file/60509708/b1c4cb7c/TEST2.html?dirPwdVerified=e2bbdeec

this is how it looks before it even goes near video editing software (i convert it to widescreen [720x400] later as my devices only support 720x576.so this file is compressed widescreen.NB this problem only started saturday just gone).
it'll now be interesting to see if you get the problem when playing it back.
here is some 14x9 that i recorded which is error free:

http://www.4shared.com/file/60512184/9e47df5c/TEST3.html?dirPwdVerified=e2bbdeec

if you don't see it,the problem must then be my pc and some playback codec.

NOTE (12.30pm):
i've just been monitoring the live preview using the ads tech capture device and the error is showing before i'm even recording,but it doesn't show on the terratec live preview.

to summarise when live monitoring using ads tech capture:
freeview 16x9=error,
emtec movie cube (media playback unit)=error
14x9=no error
16x9 dvd=no error
16x9 camcorder=no error

this is a bit of a mystery.

[jagabo]

Regarding the ads tech vs terratec live previews, I'm pretty sure you'll find that terratec is cropping the frame. View something where you can detect if the frame is cropped (a program guide, test pattern, etc.) to verify this.

I see the noise at the bottom of the frame in TEST2.MPG too (no noise in TEST3.MPG). It's definitely in the file. Given that the noise isn't random I believe Nelson37 is right -- this is closed caption or some other data being transmitted with the video.

[mike20021969]

It's definitely in the file. Given that the noise isn't random I believe Nelson37 is right -- this is closed caption or some other data being transmitted with the video.

as it is showing in the live preview,then that explains why it is being recorded in the mpg file.
with my laptop,ads tech and terratec, i'm gonna try a second freeview box hopefully this week to rule out a fault on the one i'm currently using.
if the fault is still there,then i'm gonna try with a second laptop.
i'm at a loss as to why everything was ok friday then not on saturday.

watch this space....