Archiving to CD

[John Wray]

There are similar topics to this already in the forum, but I couldn't find anything definitive, so I'm asking anew.

I'm trying to archive some NTSC videotapes onto CD. I want to store around 50 minutes of video per CD, and I'm trying to pick a codec to use. I've tried MPEG-1 at its VCD settings, and didn't much like the quality (although it was a lot better than I expected, and has the distinct advantage that, if I use the right color CD blanks, and the phase of the moon is just right, I can play it back on my Sony DVD player). I've just tried DivX ;-), and that had different artifacts, which to my eyes were worse than the lower bitrate VCD/MPEG-1, so I'm hoping that I'm just not using the codec properly.

For both MPEG-1 and DivX, I've captured my source video using a Marvel G200 at full-screen, minimum compression, then used VirtualDub to swap fields and de-interlace (and scale in the case of MPEG-1). With DivX, I got VirtualDub to encode as well; with MPEG-1 I re-compressed with MJPEG, then used bbMPEG to encode.

The artifacts that the DivX compression gives me make it look like I'm watching the video through a window blind - it looks like there's a finely-spaced horizontal grid in front of the picture. I'm using the maximum bitrate that'll let me fit my material onto a CD.

So I'm looking for guidance, either to help make DivX work better (maybe I shouldn't be de-interlacing for DivX?), or suggestions as to other codecs to try.

[Dr Mordrid]

IMHO MPEG-1 really is about the best solution for CD archiving. That said VCD's setting of 1150 kbps is a bit low for decent quality.

Have you considered using 80 minute/700 meg CD's and a higher bitrate? I'd start out using TMPGEnc, 2 pass VBR (variable bitrate: saves space) with a max bitrate of 1850kbps, minimum of 300kbps and an average of 1550kbps. I used the highest quality motion search.

This fits about 52 minutes on a 700mb disk using 704x480 MJPeg captures. Adjust the max & average bitrates as necessary as this may change depending on the content of the video.

Dr. Mordrid


[This message has been edited by Dr Mordrid (edited 15 December 2000).]

[Indiana]

Does this give better quality than DivX ;-) Fast Motion set at 3000KBps? With this setting also roughly an hour full PAL fits on one CD.

[Biker]

Doc - I got to ask about you kbps?
I use Avi2Mpg with the following compromise settings -
bitrate 1200 kbits/s
190 kbytes/s

and I reduce the audio to 96kbits/s Joint stereo to save space.

Question - is your suggested 1150kbps the top
figure i have shown reduced, or the bottom one set very high?

I could also do with an explanation of the difference between kbits/s andkbytes/s please.

One more question - motion search magnitude. Do i put a large number in here to reduce artifacts on fast motion, and what sort of number please?

I use Avi2Mpg even though it is slow, because it gives me quite a good picture with more contrast and an effectively sharper picture than the LSX MP2 encoder for the same settings and MUCH smaller files, which i find strange.

Gosh i have asked quite a few things here.
PS. John, the Avi2mpg encoder is also FREE.

[Dr Mordrid]

kbps = kbits/sec
kbits = kbytes*8
kbytes = kbits/8

Don't expect to get the same results with AVI2MPG that I get with TMPGEnc.

Also I didn't recommend 1150 kbps. That is the VideoCD spec and too low for decent archival quality. I recommended, as a starting point, the following which I DID test;

max bitrate: 1850 kbps
avg bitrate: 1550 kbps
min bitrate: 300 kbps

2 pass VBR (variable bitrate) encoding

This resulted in just under 14 megs/minute of MPEG or ~51-52 minutes/700 meg CD-R.

In terms of motion search different programs list it in different ways. Some use verbal terms like TMPGEnc. Others use a numeric scale, most often running from 1 to 20. 20 would indicate a high quality motion search, which would be used for fast motion videos where artifacts are most likely.

bbMPEG has a Motion Estimation/Pel Movement/Horizontal setting that an go stratospheric in its value, but cranking this up too high has the penalty of lenthening the rendering time.

Dr. Mordrid

[Biker]

Doc - just gotta say, thanks for all your answers and info. Its much appreciated.

Warning - I willl be asking more on this soon after a couple of checks with different proggies! - Ta.

I did download the free Avi2mpg2 recently which i think uses the BBmpg codec. But my first tests were not to good (No where near as good as Avi2mpg!). And it appeared complex. So i guess some testing and playing about is in order. It was faster, but probably because it was all on default settings. I am not sure whether it had the latest version of the codec either. It was the official website.


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[John Wray]

Dr. Mordrid wrote:

>Have you considered using 80 minute/700 meg
>CD's and a higher bitrate? I'd start out
>using TMPGEnc, 2 pass VBR (variable
>bitrate: saves space) with a max bitrate
>of 1850kbps, minimum of 300kbps and an
>average of 1550kbps. I used the highest
>quality motion search.

I downloaded TMPG and tried it with those settings. Wow! It's by far the best MPEG-1 I've seen. It's also incredibly slow (seems to take around 10 hours to compress 10 minutes of 704x480 video on my PIII-850), but I can put up with that.

Thanks!

[Dr Mordrid]

You can speed up the rendering a tad by using a slower motion search IF the video isn't too fast moving.

Dr. Mordrid


------------------
Asus P3B-F 6 PCI
PIII/850
Gigabyte GA-6R7+ slotkey
Matrox G400/Flex3D
Matrox RT-2000
256 megs RAM
Promise SuperTrak100 (4 x 60g IBM 75GXP: 240g RAID0)
AWE64 Gold

[This message has been edited by Dr Mordrid (edited 17 December 2000).]

[bongo]

Dr. Mordrid..once you have converted your video to CD for archival purposes, is it possible to use it for future use in vide editing...or do you have to capture the source video all over again? specifically would any software video edit program import the archivedcd video codec...I imagine in your example it is Tmpenc...?

[This message has been edited by bongo (edited 18 December 2000).]

[Walrus]

bongo: It's possible to reedit archived video... though it isn't recommended. MPEG compression is quite lossy and does not hold up terribly well to multiple compressions (especially at bitrates that one archives to CD)

[bongo]

so the only way to archive editable video is to save it in AVI raw format? The problem I have is that I have several hi8 tapes with stuff on it I want to keep, but I will soon no longer have access to a hi 8 camera...so I would still like to access to the hi8 films I have made but preferably on a digital medium...any suggestion?

[wkulecz]

I'm beginning to think that DV on Maxtor 80GB drives may be the best "archive" for editable video on a personal scale.

~$250/80GB = ~$3.20/GB

D8 on Hi8 tape: ~$4.50/13GB is only ~$0.35/GB but you're stuck with 1 hr chunk sizes, non-random access and the potential problems with the future viability of D8 as a video format.

DVHS costs so much for the deck, that I can buy more than enough Maxtors for my needs so far for a good deal less money.

CD-R is about the same as D8 on Hi8 in cost/GB but needs ~18 disks to equal one D8 tape!

Is there something better I don't know about?

Note that a D8 camcorder will play your Hi8 tapes and convert them to firewire "on-the fly". You could capture them onto a hard drive and write them back over firewire to a digital 8 or DV tape and have a digital tape backup of your Hi8 analog originals.

--wally.


[This message has been edited by wkulecz (edited 18 December 2000).]

[bongo]

that is a tempting idea about the 80g hd, but the only problem is that if your drive crashes all your data is toast

And I know about D8 cameras but I figure if I am to jump to a higher quality step in video, it may as well be pure digital...maybe I should just keep my eye out for a cheap hi8 camera to just use for playback and hook it up to a digital camera if I want to do editing.

[John Wray]

OK, after playing with TMPGEnc for a while now, I'm very impressed with its video quality, except for one problem. Every so often, in a fast-moving sequence, I get an effect that looks like two fields from different source frames have been combined into a single frame of the output MPEG-1 stream - i.e. alternate scan lines are displaced horizontally by a significant amount. The source MJPEG doesn't show this effect, so it's either an artifact of TMPGEnc, or (hopefully) something I'm doing wrong in my settings. I've tried exactly what Doc Mordrid suggested (2-pass VBR, 1850/1550/300kbps, highest quality motion search), and apart from this interlacing artifact, the output video quality is excellent. I've set the source properties to interlaced, field order B (bottom field first), and haven't set any filters.

Any ideas on what's causing the problem?

John

[Lucas Orion]

ok, now what would people suggest for archiving hi8 tapes of basketball games onto cds? each game is about 45-50 minutes of video and I don't mind having one game per disc. Is it possible to do this with DivX and not lose too much quality due to the constant motion?