For VHS to Divx, what resolution did you pick?

[catback]

I'm converting several NTSC VHS tapes over to Divx so I can archive them onto a CD for playback on my PC. For others who are doing this as well, what resolution do you make you Divx file?

A lot of people chose 352x240 but I think viewing such a small size on a monitor is not practical. You can stretch it out to a larger size but then it gets blurry. I make my Divx encodes of VHS tapes at 640x480 resolution which is a decent size for viewing. I use a video bit rate of 1500-2000 which give me 60-90 minutes per 700 MB cd.

What resolution do you use?

[hakko504]

Well, first I'm in PAL country, and I usually watches most of my DivX on TV too, and I have found that with my setup it works very well to capture things off my VCR in 352x576, deinterlace them and store them in 448x336. 352x288 also works very well if I want to fit a lot of things onto 1CD.

[catback]

Thanks hakko.

Is a TV-out cable from your PC video card to your TV the only current method of viewing Divx files on a TV? I'm not sure if this area has advanced any since a year ago.

[hakko504]

Yes and no.

Yes, for reliable watching on TV and when we consider DivX3 and DivX4

No, because there is a new DVD player called KISSsomenumber that can play ISO compliant MPEG-4 streams. This means DivX5.02 and probably XviD. I wouldn't push it until it has been tested though. And ISO compliant means AAC sound, but since the player is capable of playing MP3 CD I'd guess that it's OK with MP3 and AC3 sound too. You can find more info about this player in the General forum here. I saw a thread about it approximately a week ago, maybe two.

[^^-+I4004+-^^]

>What resolution do you use?

the bigger the better!
if my cel600 could play 720x576 without glitches
(it can if there's not much hi motion)
i wouldn't resize at all..as resizing destroys the image
(blurs it)
this way it's one of these:
640x480
576x432
512x384

if you use SBC you can use your source resolution (640x480)
at 1500-2000 without big problems!
(if i was in your shoes i wouldn't resize at all,as my cel600 can play
640x480 divx without problems....)




btw. hakko have you corrected NICAM sampling frequency to 32khz?
(it's not 22khz)
(hehe)

cheers

Ivo

[hakko504]

Originally posted by ^^-+I4004+-^^
btw. hakko have you corrected NICAM sampling frequency to 32khz? :confused: :confused: :confused:

I do 99.9% of my captures from VHS tape or digital TV, and always via SCART->CVBS cable to my computer.

[^^-+I4004+-^^]

i was reffering to your answer on NICAM some while
ago.....
here
http://forum.doom9.org/showthread.php?s=&threadid=17003&highlight=nicam

as it's not 22khz,but 32khz.......
nothing more...

[hakko504]

How the :devil: am I supposed to remember such an old thread? :p ;) :D I can hardly remember the posts I did yesterday. ;) And besides, even there I said i wasn't sure about the sampling frequency. :)

[^^-+I4004+-^^]

SO,did you corrected it?
(LOL!)

it was a sidenote,make nothing out of it.....

and khm,khm...if you use bt8x8 device for capturing,resizing
to 352x288 is a bit too blurry from my results....
(and if you use matrox it should be even worse as i and Swan
compared these two,and bt8x8 is a bit sharper than matrox...)
that's why i don't reccomend to catback) such "undersizing".......

[hakko504]

And I do use Matrox G400 Marvel, and I'm not really satisfied with the internal resizing of the chip. That's in fact why I use 352x288! This size, along with 352x576, 704x576 and (MPEG-2 only) 720x576, are not resized before being outputted to TV. On TV 352x288 looks better than 384x288 for instance. This is of course not the case on monitor, but as I almost always watch my DivX on TV, I prefer to use resolutions that looks good on TV.

And if I want sharpness, there is always Lanczos resize.

[^^-+I4004+-^^]

>And I do use Matrox G400 Marvel, and I'm not really satisfied with the internal resizing of the chip. That's in fact why I use 352x288! This size, along with 352x576, 704x576 and (MPEG-2 only) 720x576, are not resized before being outputted to TV. On TV 352x288 looks better than 384x288 for instance. This is of course not the case on monitor, but as I almost always watch my DivX on TV, I prefer to use resolutions that looks good on TV.

heh,yes i know of the matrox quirks,make it 32,make it 16 etc.
(make it matrox and not make it what i wan't..hehe)
let me just clarify a bit what you just said and i find that it might confuse some of readers:
capture chips usually capture (horizontally) at a very high resolution
this usually tends to be over full-pal 768x576 (or should i call it "extended pal resolution" as 720x576 is really mpeg2 raster....but dvd players know how to stretch image from 1,25 (720x576) AR to 1,3 for tv ....etc,etc. )
i could find proper numbers for bt8x8 as i have datasheet,but it doesn't matter much :it matters that card initially samples at very high horizontal frequency and if you change resolution on capturing
then hardware resize kicks-in!

it's a good question HOW GOOD THIS HARDWARE RESIZE REALLY IS?
let me tell you ( in brief or not so brief ) what i have seen:
bt8x8 has the lousiest hardware resize there is!( and only ati cards might match the results that bad or even go a bit further with fuzziness than bt8x8! )
capturing with asus cards on lores will give you fuzzy image too....
(judging on the samples i saw..)but i can't be precise, as i haven't tested that myself....
i don't know how good(or bad) matrox gets on 352x288 but i doubt it gives acceptable quality.....(as even on hi-res it's not that sharp)

till this date i have experienced only one device that does really
smashing hardware resize and the image quality on 352x288
is really awesome when compared to others.....
it's Erazor3 card....
and i still use it for lo-res capturing as it can't be beaten!
(i can capture 720x576 (with bt8x8) and resize that with prec.bicubic or lanczos (btw. i didn't saw MUCH difference between these two....) to 352x288
and it looks like sh*t afterwards!beter than direct 352x288 capture but still lousy.....
BUT when i capture with Erazor3 at 352x288 (or 384x288) and leave it that way the result is 10x sharper final divx than the one i could get with bt8x8 on direct lores capture OR resizing afterwards!
i think Erazor3 does clever vertical resizing ie. not throwing fields away but instead doing some form of vertical (2:1) reduction in hi-quality regime.......the image quality nad my tests prove this....)

(i guess i don't have to describe how lousy bt8x8 gets on direct 352x288 capturing....OR even 352x576+vertical reduction 2:1 on-the-fly...)

and hakko,
"This size, along with 352x576, 704x576 and (MPEG-2 only) 720x576, are not resized before being outputted to TV. "

here you should clearly state that it is the stuff of matrox playback
and for different resolutions divx g400 is needed....
so it's not real concern for other cards owners.....
also,we talked about final divx resolutions and not "hardware-specific
resolutions on tv-out for use on particular devices"(hehe).....

so i gather that u use 352x288 as resized afterwards,and not direct
352x288 capture,as that is really wrong resolution to go for on capturing (unless you have Erazor3 offcourse)

also vertical resizing (in hardware) is practically throwing fields away
( NOT good idea if you're capturing moto-races! )

and those are the reasons i don't recommend capturing at lo-res with bt devices and resizing to very small resolution likewise!

>And if I want sharpness, there is always Lanczos resize.

any (and every) resizer blurs,as it must ( lo-res obviously can't carry all of the hi-res info ) and i didn't found lanc. resize to be that much better than VD (or avs') precise bicubic (i tend to agree with avery lee who saw lil or no improvement there,as he include l. resize in new VDub...)
i tend to use sharpening filters if i wan't real sharp image....
(as no resizer will sharpen image really.....resizer can only blur..some types of resizers more some less...)

also
>and I have found that with my setup it works very well to capture things off my VCR in 352x576, deinterlace them and store them in 448x336.

is the horizontal resolution really preserved there?
first your card does lousy resize to 352,and then you blow that to 448?
wouldn't it be better to capture at higher res(closer to the cards intern h. sampling clock ) and downsize that with quality resizer ?
( or are there some hardware and/or hdd freespace problems? )

[ this discussion is almost for capturing forum if it wasn't for the
first post...hehehe ]

cheers

Ivo

[hakko504]

First of all my previous posts only applied to my settings with the matrox card.

Then, I'm not quite sure, but all my tests have indicated that G400 does not resize to 352 wide, but actually halves the sampling frequency in order to acheive this resolution. I've had a few (LQ) videotapes that I wasn't able to make captures from unless I used full resolution. For some reason it also seems like the matrox card does not use the full 8-bit samples if you capture with full resolution (704x576). At least I get the same filesize when capturing 704x576 and when capturing 352x576, both when using Huffy and (matrox)MJPEG.
And you're right it is very questionable what happens to horizontal resolution when I upscale it. In theory it is possible to transform 352x576 to 448x336 with no quality loss as long as you reduce the final number of pixels, but in practice it is very hard to acheive this. Now, I haven't made that many captures since Lanczos resize was introduced, but it is definitely a step in the right direction when you upscale in one direction, and downscale in the other.

[^^-+I4004+-^^]

>Then, I'm not quite sure, but all my tests have indicated that G400 does not resize to 352 wide, but actually halves the sampling frequency in order to acheive this resolution.

doesn't that mean that it employs 2 separate ADC's (1 for higher sampling and other for lower)?
and in fact 4 as usually 1 is for luma and other for chroma
(ie. every (recently made) capture card has at least 2....)
so it needs 2x2 ADC's....?
i doubt that this is the case....
i've found data for bt8x8:
[from datasheet]

The Bt879 requires an 8*Fsc (28.63636 MHz for NTSC and 35.46895 MHz for
PAL) reference time source. The 8*Fsc clock signal, or CLKx2, is divided down to
CLKx1 internally (14.31818 MHz for NTSC and 17.73 MHz for PAL). CLKx2
and CLKx1 are internal signals and are not made available to the system.
UltraLock™ operates at CLKx1 although the input waveform is sampled at
CLKx2 then low pass filtered and decimated to CLKx1 sample rate.
At a 4*Fsc (CLKx1) sample rate there are 910 pixels for NTSC and 1,135 pixels
for PAL/SECAM within a nominal line time interval (63.5 ms for NTSC and 64 ms
for PAL/SECAM). For square pixel NTSC and PAL/SECAM formats, there
should only be 780 and 944 pixels per video line, respectively. This is because the
square pixel clock rates are slower than a 4*Fsc clock rate; i.e., 12.27 MHz for
NTSC and 14.75 MHz for PAL.

[this means that input video is sampled at 8xFsc(!)-->35,4MHz(!)
but then lo-pass filtered and decimated to 17,73....so it seems there are two decimations in any case when capturing with bt :

35,4Mhz->17,73(ie.1,135pixels)->768(or xxx size)...... ]

the less decimations the better!
(i don't know matrox hardware specs,but again i doubt that it uses
2 separate sampling frequencies....on what basis you mean it does?)

>I've had a few (LQ) videotapes that I wasn't able to make captures from unless I used full resolution


same here and with bt8x8 device....

in the light of stuff i said above,for lores (bigger decimation) more processing is needed (more CPU power.bt8x8 has internal RISC engine that you might call it's CPU) : and as there's more noise,it's harder to do this,and also i presume "UltraLock" is suffering too-->
how will it lock line if there comes noise spike instead of H.sync signal?
therefore more frame drops on lo-res (heavy decimation,interpolation or whatever) and on hi-res still some dropping because noise upsets "UltraLock"
so bt8x8 doesn't know what hapened to the line...so it throws away line&frame alltogether,as how will it output 572lines frame,then 571lines frame etc.

another excerpt:
"NOTE: With stable inputs, UltraLock™ guarantees the time between the falling
edges of HRESET only to within one pixel. UltraLock™ does, however,
guarantee the number of active pixels in a line as long as the above rela-tionship
holds."

[ these are more or less all my thoeries and anyone that comes with better explanation why noise upsets bt8x8 capturing is welcomed ! ]

i think that matrox shares same operational principles as bt8x8,and other capture devices...

>For some reason it also seems like the matrox card does not use the full 8-bit samples if you capture with full resolution (704x576). At least I get the same filesize when capturing 704x576 and when capturing 352x576, both when using Huffy and (matrox)MJPEG.


are you saying it uses 6bits then? wouldn't that compromise image quality?
you get same bitrate capturing to 704x576 and 352x576 huff?
perhaps huff compresses 704 better than 352?
(have you watched "compression ratio" on VD while capturing?that should tell it...)
also if you have same filesize,then why capture to 352 at all
it's better to resize afterwards.(you can't say that cards resizer will be better than VD's or avs'..and i think that card's resizing is to blame for poor 352 performance....)


> In theory it is possible to transform 352x576 to 448x336 with no quality loss as long as you reduce the final number of pixels

aha,you mean there are same number of pixels in both resolutions so it should be the same...but wait,they don't have same amount of pels...352x576 has more than 448x336 so i wonder what reasoning is behind that?
also:for interlaced materal (needs deinterlacing for 336) this is BAD thing->deinterlacing+downsizing means even more blur...
(although downsizing has the "denoise" effect too because it blurs)
i myself wouldn't decimate 576 so much!
[Swan tells me that on matrox interlaced divx works OK when outputted to tv-out..i wish i could say that for my system ( tnt2+bt tv-out )
as it gets interlacing fine every other time.....]

and on the upsizing,it's practically blowing up the image,so there can't be any gain in the BEST case image will be the same after upsizing but i don't think such resizer exist anyhow....
so it's some amount of quality loss....
but if that resizer does it beter than player's then i guess it's justified,but as i see you upsize to some intermediate dimension (
448x336 is nor tv-out res,not monitor res ) and player still has to
upsize it (for display on tv-out or monitor),i wonder what you gain?

cheers

Ivo

[hakko504]

Yes, quite frankly I wonder that too...

first, reduce means lowering number of pixels, so going from 352x576 to 448x336 is valid. Seconly, I must admit I haven't tried interlaced DivX. Maybe it's time to do that.

And why would you need 2 ADCs just to be able to use two sampling rates? :confused:

I'm afraid it's been a while since I did a capture, so I don't remember the exact numbers, but as far as I recall, the picture looked better when captured at 352x576 and resized to 448x336 than if I capture at 704x576 and resize to 448x336.

Oh, there is one thing about 448x336, it is just enough size to have in a window on the desktop while doing other things at the same time.

I'll see if I can find anything about the chip in the matrox card. I'm quite sure though that matrox and bt seems to work in different ways.

[rmatei]

Why on earth would you want to encode at such high resolutions? Especially with the noise and jitter from VHS captures, it's murderous to codecs. The higher resolution you capture at, the better; I can do 720x480 in huffyuv for NTSC. This ensures you first have max detail to work with. However, if you filter and deinterlace well, you can safely downsize to 384x288 without losing detail. It'll be more compressible, and you'll squish out the noise. Remember, this is VHS; it has very little detail to start with. If you have space to spare, 512x384 is the highest I'd go.

[^^-+I4004+-^^]

>you can safely downsize to 384x288 without losing detail

you're kidding,right?
it's not that canon "VHS is lores system" again,is it?
if it is,go here :
http://forum.doom9.org/showthread.php?s=&threadid=34122&highlight=vhs+resolution+is

if it isn't then check your eyesight first-> although ntsc downsize
to 384 (480->384) is not as drastic as pal's would be (576->384)

downsizing blurs,deinterlace blurs,so what are you talking about?
let me just say that i'm only resizing porn that much...
sometimes i leave it at 720x576 and that way i get sharpest image quality (as sharpness is what i aim for )

>Remember, this is VHS; it has very little detail to start with


well for sure it's not broadcast quality,and it DOES jitter,
but that's a reason more NOT to destroy any detail that's left
with aggressive downsizing and therefore blurring.......

[let me just point out that i'm mostly doing natural video (ie. no cartoons etc.) and usually go for 2cd rips.....and sometime even 2xcd
rips...(normally i use 650MB cdr's...therefore 738MB in xcd mode )]

noise?well divx3 swallows anything really on that high bitrate
(1500-1800kbit/s )
and i even do some sharpening sometimes....
there's no saving if you wan't quality!
(1cd rips of this materials would look plain ugly.....and if i would
cut resolution in half.......well, then image is too blurred , as
bt8x8 device doesn't have that sharpness to start with....)

[VJWitness]

Hi,

I think you shouldn´t use DivX for storing VHS-data. The resolution on a tape is only slightly higher than the VCD-resolution.
My tip:
capture in the NTSC-match of PAL 480x360 at a bitrate of 3000 kbps in DivX and then use TMPEG to convert it into VCD.
If you insist on DivX reencode the 3000 kbps file with the bitrate of your choice and use the temporal-smoother-filter on a setting between 3 and 6. This depends on the quality of the source video. If you got a crystal-clear tape (like an original movie) the results should be pretty good. But, please, don´t expect a miracle!

Bye,
VJWITNESS

[hakko504]

@VJ

Sorry, but DivX will beat the hell out of VCD any day. VCD can never compete: it uses a fixed resolution(352x288/240), fixed bitrate (which is way too high), and is nowhere near the quality you can achieve with DivX (or XviD).

Don't make the mistake of confusing effective resolution with actual resolution.
Effective resolution of a VHS tape is very close to what you find on VCD, yes. But actual resolution is somewhere in the area of full D1 (720x576/480) where every pixel actually has very little information, thus making the effective resolution much lower. Our discussion here has been how to extract as much information as possible from a VHS tape, remove the noise and store it in the best way possible.

[VJWitness]

Hi hakko,

I know about the poor qualities of the VCD (fixed resolution and high fixed bitrate), but the resulting picture-quality will be quite the same (true, if you encode a DivX in that resolution it will outsize the VCD). I use this method to achieve compatibility to set-top-boxes.

If you want DivX, try the suggested settings, I only forgot to mention the deinterlacer. The results I got were quite satisfying (the intermediate file before I converted to VCD).

Bye,
VJWITNESS