Poor video quality problem (DVD Recorder to PC to TV)

[andybray]

Sorry but don't really know where to look for a solution.

I'm recording using a JVC DVD recorder (TV source from internal tuner or digital TV set top box). Have started to use LP mode on the JVC which records in VR mode to DVD RAM or HD at 480 x 576. Despite what looks like an odd resolution it records and plays fine when I just use the DVD Recorder normally and record and playback on the TV (old 4/3 model).

Problems start when I take the recorded video to a PC. I can extract an MPG of the video and then open this in VirtualDub. First problem is that if I look at frames and any part of the frame where there is movement there is a blurry lined effect at the object edge. So when someone turns their head the edges of their head blur with horizontal lines which extend from the outline of their head.

Second problem is that I get an AVI of the same resolution (480x576). I can play this back on the PC by forcing it to 4x3 resolution in say Divx player but if I player on a standalone Divx player I can't control the playback resolution and so get a 480x576 video (i.e. too narrow on the horizontal and black space to left and right. Now I can resize the video in VirtualDub but that makes the edge blurring even worse (unwatchable).

If I record on the JVC at EP mode (352x288) I don't get the problem but the resulting video is very soft (i.e. lacks sharpness). Or I have to leave the source as an MPEG2 file.

Any pointers. Happy to search the forums but don't know quite what to search for. If the video problem I'm describing isn't clear then I'll see if I can grab a frame where there is movement and post that to show the effect.
Andy

[wolfman]

I am not sure, maybe the blue problem is caused by microvision. any way, post an image will be helpful.

[junkmalle]

I'm recording using a JVC DVD recorder (TV source from internal tuner or digital TV set top box). Have started to use LP mode on the JVC which records in VR mode to DVD RAM or HD at 480 x 576. Despite what looks like an odd resolution it records and plays fine when I just use the DVD Recorder normally and record and playback on the TV (old 4/3 model).

Problems start when I take the recorded video to a PC. I can extract an MPG of the video and then open this in VirtualDub. First problem is that if I look at frames and any part of the frame where there is movement there is a blurry lined effect at the object edge. So when someone turns their head the edges of their head blur with horizontal lines which extend from the outline of their head.

That is normal when viewing interlaced video on a computer. Each frame of the mpeg file contains two pictures (aka fields) woven together. On TV you only see one field at a time. While the first field is being displayed the other is left black, then the second field is displayed and the first one is left black. This is why TV flickers a bit. Computer displays are not interlaced so you see both fields at the same time -- hence the "interlace comb lines".

Second problem is that I get an AVI of the same resolution (480x576). I can play this back on the PC by forcing it to 4x3 resolution in say Divx player but if I player on a standalone Divx player I can't control the playback resolution and so get a 480x576 video (i.e. too narrow on the horizontal and black space to left and right. Now I can resize the video in VirtualDub but that makes the edge blurring even worse (unwatchable).

If you keep the vertical size at 576 you might be able to just stretch the width of the picture to 768 pixels to get the right 4:3 aspect ratio. The problem with this is that you won't find many players that can display interlaced AVI files properly.

You'll probably want to deinterlace for use on a computer or set top Divx player -- even though this is cause some loss of image quality.

VirtualDub has a simple deinterlace filter with several options. The first thing you should try is either Discard Field 1 or Discard Field 2. This will simply throw out one field leaving you with a half high image. Then follow that with a Resize Lanczos3 back to the original height -- or whatever size you want to resize to (say, 640x480 or 512x384).

Another method you can try is one of the adaptive deinterlacing filters. These try to keep detail in the static areas and only deinterlace in the areas where there's motion. You'll have to download these filters and install them in VirtualDub's plugin folder.

I use this Smart Deinterlace filter on occasion:

http://neuron2.net/smart/smart.html

[andybray]

junkmalle
Thanks. It's definitely interlace related. I did try a quick deinterlace filter in VirtualDub but used the blend option. It seems to remove the problem but the image quality drops. But then I have to compare it with a lower resolution recording on the DVD recorder. I'll experiment with different settings and also try the smart deinterlace plug in.

The divx player is a Yamada 6700. Interestingly it can handle the interlaced MPG2 file from which I create the AVI with no problem. It's only when I take it to an AVI. So, it looks like a trade off between file size and video quality but then I guess that's the fundamental of video encoding!

Ideally, I'd like to get the AVIs to be visibly identical to the MPEG2 files that the DVD recorder is creating (just smaller in size)

[edDV]

junkmalle
Thanks. It's definitely interlace related. I did try a quick deinterlace filter in VirtualDub but used the blend option. It seems to remove the problem but the image quality drops. But then I have to compare it with a lower resolution recording on the DVD recorder. I'll experiment with different settings and also try the smart deinterlace plug in.

The divx player is a Yamada 6700. Interestingly it can handle the interlaced MPG2 file from which I create the AVI with no problem. It's only when I take it to an AVI. So, it looks like a trade off between file size and video quality but then I guess that's the fundamental of video encoding!

Ideally, I'd like to get the AVIs to be visibly identical to the MPEG2 files that the DVD recorder is creating (just smaller in size)

Just to understand your goal is to compress these files further than LP mode. Are you planning playback to the computer or TV?

A general rule, better image quality in gets you a higher quality compressed image out. For this reason you should consider SP mode for the first step.

[junkmalle]

It's definitely interlace related. I did try a quick deinterlace filter in VirtualDub but used the blend option. It seems to remove the problem but the image quality drops.

Although the selection is labeled "Blend fields together (best)" it's usually not the best! Blending tends to look like motion blur when motions are small which is fine, but when motions get large it starts looking like a double exposure. Which it is really -- it's taking two separate pictures and blending them into one. If you want to use blend I recommend following up with a little sharpening with the Sharpen filter. Set Sharpen to somewhere between 15 and 30.

This isn't a problem for you since your dealing with PAL sources, but blend deinterlace can look really bad with NTSC telecined film sources.

[andybray]

edDV - for the quality of the source then LP quality recording on the DVD recorder seemed fine and I could just leave it that. But I typically edit out the ads on a PC rather than on the DVD recorder (which for some bizarre reason won't edit out scenes on the HDD but only on a DVD-RAM or DVD-RW and so I have to dub it to DVD). While on the PC I have tried to encode as an AVI to get the file size down below that of an LP MPEG2 but without degrading the quality. I might view the AVI on a PC but it must play OK on a standalone DVD/DIVX player when transferred to a DVDR. I have also a Pinnacle Media server which could stream the AVI from the PC directly but I have tended to use the DVD/DIVX player as I don't have to worry about network performance (WLAN).

junkmalle - Thanks for the tips. Is it my imagination or can the effect of the interlace vary depending on the source? I'm in the UK and have recorded analog source using the TV tuner in the DVD recorder but also digital source (digital broadcast - Freeview) coming on from a set top box via SCART to the DVD recorder. The problem seems much more noticeable on the digital source. I can't see any settings on the STB or the DVD recorder that would make any difference.

andy[/quote]

[lordsmurf]

- Stop de-interlacing on the PC.
- Stop using VR mode, use DVD-Video mode
- Stop using DVD-RAM, use DVD-RW or DVD-R
- Use Womble MPEG-VCR to edit commercials.
- Do not use anything beyond 4-hour (LP mode)

If you do all of these things, you'll have high quality video and zero problems.

[junkmalle]

Is it my imagination or can the effect of the interlace vary depending on the source?

Yes, it will vary depending on the source.

Live video feeds (soccer games, news, etc.) are usually fully interlaced. The video camera takes a "snapshot" every 50th of a second and sends that field over the air/cable. When a computer or DVR captures it joins pairs of fields together to make a full frame. If nothing is moving you get a "clear" picture, but when things are moving you see interlace comb lines.

Movies shot on film will normally not appear interlaced in recordings. Literally the PAL video signal is interlaced, but when the computer/DVR captures it each pair of fields come from the same film frame so there are no comb lines.

If you're only editing out commercials on the computer and plan on burning the video onto DVDs don't deinterlace. When a DVD player plays the interlaced video it will send one field at a time to the TV -- just like it was originally broadcast.

If you want to watch the interlaced video on a computer try using a player that deinterlaces on-the-fly. Most DVD player software will do this. That way your interlaced video remains intact, there is no loss due to deinterlacing (which always reduces the video quality).

Only in the case where you want to make video only for the computer should you consider deinterlacing.

[andybray]

Junkmalle,
If I leave everything as MPEG2 then I can't see the interlace effect on the TV whether I playback using the original JVC DVD recorder or my DVD Player. The problem is solely with AVIs played back on a TV. My Yamada 6700 Divx player doesn't seem to do anything like you describe to compensate for the interlace in an AVI and so it is very visible when I play back. So, to playback an AVI on theTV then I currently need to deinterlace.
Andy

[junkmalle]

If I leave everything as MPEG2 then I can't see the interlace effect on the TV whether I playback using the original JVC DVD recorder or my DVD Player.

Yes, your TV is an interlaced device. Each frame of the MPEG video contains two pictures. The PVR/DVD player knows how to pry the two fields apart and send them to the TV one at a time, then moves onto the next pair. You see 50 different half (every other scanline) pictures per second, not 25 frames. On the computer you see both fields at the same time unless you are using a player that knows how to deinterlace.

The problem is solely with AVIs played back on a TV. My Yamada 6700 Divx player doesn't seem to do anything like you describe to compensate for the interlace in an AVI and so it is very visible when I play back. So, to playback an AVI on the TV then I currently need to deinterlace.
Andy

Yes, my Liteon 2002 can't properly play interlaced AVI files either. I don't know of any that do. That's another case where you want to deinterlace. But with writable DVD media as cheap as it is now I just use MPEG2 for interlaced material. You probably don't even have to bother mastering -- your player will probably play MPEG2 files off ISO DVDs.

[andybray]

Thanks. I'm beginning to think it would be simpler to leave interlaced material as MPEG2 as suggested. My Yamada 6700 does indeed play back ISO DVDs with .MPG files on quite happily and handles the screen resolution and interlace. As my JVC DVD Recorder does not seem to do scene edits for HDD recordings (but it does for DVD-RAM) then I may still need to edit out ads on the PC. Otherwise I could even do some basic edits on the JVC HDD and then dub to DVD-R. Copying from DVD to HDD is very slow and much quicker on a PC.

As an aside....to cap it all I started to get audio sync problems on playing back the AVIs on the Yamada (after doing a FF). Now I've FFed other AVIs before and I believe I have the firmware that fixed that problem but just another indication that getting the TV content to AVIs may be more trouble than it's worth.
Andy