DVB Capture...and now?

[Merlink]

Hello, I use a Nexus-S DVB Capture card to acquire Star Trek Episodes from an italian paytv. I noticed some strangeness:

1) When i watch it on DVBExtreme, the image is almost perfect, when i frameserve it trought AviSynth, i get 16 black pixels on the top of it with some strange white moving bars...btw i crop them...but...what are them?

2) Actually I trasform these files into VCD episodes (well...uh...i started just now...so this is what i WANT to do... eheh) can i simply crop the black bars and resize to 352x288 or do i have to deinterlace it too?

I use pvastrumento to demux+fix, then DVD2Avi to create the .d2v and then avisynth (2.5.1) to frameserve it...

Tnx A Lot

See Ya

[FreQi]

1) The moving white lines and black space is pretty normal for most broadcast television. As I understand it, it's "header noise" that VCR's inject into the image when they play the video from tape. When your tv gets the image, it doesn't show 10 or so of the pixels on any of the 4 edges so you wouldn't see the black or the noise normally, and it actually hides a small portion of the video too. Although HDTV's show everything, so DTV broadcasts make an effort not to have these pixels wasted (or "damaged"). You just need to crop them off then resize the image to whatever your target is.

2) I don't know anything about "DVB", but I know with analog captures, anything that has more than 240 horizontal lines, you will have interlacing effects. Now, if you're getting a progressive scan feed, then you obviously won't need to deinterlace anything. If you're not sure, you can usually tell by opening the video in virtualdub and going frame-by-frame through it, and look for horizontal lines during on screen movement, or scene changes. Now that I think about it, I think DVD2AVI tells you if it's interlaced or progressive... don't hold me to that statement however.

[symonjfox]

Originally posted by Merlink
[B]1) When i watch it on DVBExtreme, the image is almost perfect, when i frameserve it trought AviSynth, i get 16 black pixels on the top of it with some strange white moving bars...btw i crop them...but...what are them?

Sometimes I get them too. AFAIK it should be the teletext informations (because teletext is decrypted by the Television, not by the decoder). They simply are cropped by the TV and so you won't see them.

2) Actually I trasform these files into VCD episodes (well...uh...i started just now...so this is what i WANT to do... eheh) can i simply crop the black bars and resize to 352x288 or do i have to deinterlace it too?

This is a procedure for SVCD or CVD (CVD is better since many DVB programs are broadcasted at 352x576, so you don't need to resize or deinterlace).

first check if the capture is really interlaced (i mean that some DVB transmissions are interlaced, but the images they broadcast are progressive. This isn't a problem, because television ALWAYS show you interlaced fields). If you find that the capture is Progressive, just crop & resize.
If it's really interlaced (and if you are sure you want to deinterlace), you must put a DEINTERLACE filter (I use smartdeinterlace or Tomsnocomp) before everything else.

For CVD, my opinion is to keep them INTERLACED (on standalone DVD players you will get better quality).

Example:

Loadplugin("D:\programmi\avisynth 2.5\plugins\mpeg2dec3.dll")
LoadPlugin("D:\Programmi\avisynth 2.5\plugins\tomsmocomp.dll")
LoadPlugin("D:\Programmi\avisynth 2.5\plugins\mpasource.dll")
V=mpeg2source("E:\video01.d2v",ipp=True,CPU=4) #ipp=True if interlaced, False if doesn't
V=TomsMoComp(V,0,10,0) #Just if needed to deinterlace
V=Bilinearresize(V,352,576)
V=Letterbox(V,8,8,8,8) #you can letterbox 8 pixel from the image because these are never shown on your TV, so you can gain some video quality
A=mpasource("E:\audio01.mpa", Normalize=True) #this is a new filter that allows to directly import MP1 2 3 files, so you can just encode everything in your favourite MPEG 2 encoder).
AudioDub(V,A)
Trim(123,1234)



I believe that CVD give MUCH MORE quality over VCD, and also interlaced frames makes the moviments more realistics.
If you still think that VCD is your choice, so it's quite easy:


Loadplugin("D:\programmi\avisynth 2.5\plugins\mpeg2dec3.dll")
LoadPlugin("D:\Programmi\avisynth 2.5\plugins\mpasource.dll")
V=mpeg2source("E:\video01.d2v")
V=Bilinearresize(V,352,288)
V=Letterbox(V,8,8,8,8)
A=mpasource("E:\Audio.mpa", Normalize=True)
AudioDub(V,A)
Trim(123,1234)


The explanation is easy: VCD has a vertical res of 288, so it's half of 576 (full PAL res). Interlaced frames, divided by 2 means automatic deinterlace. If you want to do VCDs, just letterbox 8 pixel for side, to hide some imperfections (such these white blocks on black screen)

Good work :cool: