Why is 3.6Gb to large to Burn to DVD?

[snogger]

Here's a little history:

I captured a 2 hour and 15 minute VHS tape to my computer using a ATI VE Wonder card, using Cyberlink's PowerDirector Pro http://www.gocyberlink.com/english/products/product_main.jsp?ProdId=45

The first time I cptured I used the DVd settings(I beleive 752X480?) which made a 6GB file. Even after editing that one I could only get down to 4.4GB so I started over.

I captured this one at 640X480, 5,000 BitRate.. this created a 4.4GB file so I thought I had it made..

After editing, adding Text/Transitions/Audio I ended up with what Win XP reports to be a 3.6GB file.

When I go to the final process of burning the DVD and select the file PowerDirector's graph shows the file as being over 4.7GB and also reports that the file is too large and will not let me continue.

First question is, anyone have any clue why it would Add basicly a GB to file?

2nd question, what would be the best way to reduce the file and still keep the quality?

Last time when I tried to take an existing MPG file and recreate it at a lower BitRate the quality and sound was so bad that it was unwatchable and that is why I did the recapture.
I'd hate to have to restart over again recapturing and editing it and even if I did, I'd have no idea what to recapture it at to keep it under the right size..

Thanks for any help,
Shane

[bugster]

First off I have to say I know nothing about Cyberlink's PowerDirector Pro, all this is just (educated?) guesswork.

Take a look to the left column where it says WHAT IS and click the DVDR link. This will tell you the resolutions that are valid for DVD video.
The size of an mpeg is dependant entirley on bitrate and movie length, nothing else matters. Use a bitrate calculator (there are several in the tools section) to determine the max bitrate you can use for the length of the movie you are trying to capture.
Next check your audio settings. DVD audio can be uncompressed PCM, AC3 (dolby digital) or mp2, though the US spec requires players support only Ac3 and PCM, the european spec requires mp2 support. There is a pretty good chance you are capturing in some compressed form (mp2?) but your authoring program wants to convert to PCM, as this is supported by ALL players. This would cause the reported increase in file size you are seeing. See if you can change it to mp2 (AC3 support is unlikley). Note though that not all US players can play mp2 audio.


Hope this helps

[Cornucopia]

snogger,
you didn't say what bitrate your original capture was, but I did a little calculation. here's what I see:

Orig length: 135 min (=8100 sec)
If size = 6GB, then bitrate must have been 6.06Mbps
With that bitrate, editing down to 4.4GB would trim video down to 99 min.

Using bitrate calc on 99 min (=5940 sec),
you want to almost completely fill a 4.37GB DVD recordable
Bitrate should be 6.02Mbps, so cap at 6Mbps. (Not accounting for audio)

Now, what's probably happening during the authoring is that the app sees that your 2nd capture was done at non-standard resolution (640x480) and so had to re-encode to std rez (720x480), creating a larger temp file in the process. This file is what is too big. Also check to make sure you're not soaking up available space by using PCM audio.

You know, now that I look at what I just wrote, I wonder whether you were accounting for audio to begin with.?

I think what you should do is :
1. see how long your edited file is
2. use a bitrate calc to figure what bitrate you should use for audio and video
3. recapture once more, this time using the calc-suggested bitrate and using standard resolutions and sample rates so nothing will need to be re-encoded.

This all assumes you're capping directly to MPEG, right?

HTH,
Scott

[snogger]

snogger,
you didn't say what bitrate your original capture was, but I did a little calculation. here's what I see:

Orig length: 135 min (=8100 sec)
If size = 6GB, then bitrate must have been 6.06Mbps
With that bitrate, editing down to 4.4GB would trim video down to 99 min.

Using bitrate calc on 99 min (=5940 sec),
you want to almost completely fill a 4.37GB DVD recordable
Bitrate should be 6.02Mbps, so cap at 6Mbps. (Not accounting for audio)

Now, what's probably happening during the authoring is that the app sees that your 2nd capture was done at non-standard resolution (640x480) and so had to re-encode to std rez (720x480), creating a larger temp file in the process. This file is what is too big. Also check to make sure you're not soaking up available space by using PCM audio.

You know, now that I look at what I just wrote, I wonder whether you were accounting for audio to begin with.?

I think what you should do is :
1. see how long your edited file is
2. use a bitrate calc to figure what bitrate you should use for audio and video
3. recapture once more, this time using the calc-suggested bitrate and using standard resolutions and sample rates so nothing will need to be re-encoded.

This all assumes you're capping directly to MPEG, right?

HTH,
Scott

Thanks for replying.

Too anwer a few questions:
Yes, I am capturing directly to MPG2. The edited file went from 2 hours 15 minutes to 1 hour 50 minutes.

Yes, the first capture was at 6,000 Bit rate.

Before I left home this morning I set the program up to recode the MPG to a Bit Rate of 3550.
My guess is that, like last time, this will allow it to fit, but the quality will be worst than the VHS copy.

I REALLLY was hoping to not have to recapture it and go through the hours of editing again, but may not have a choice.

If I recapture, since my last recapture was at 640X480 5,000 Bit Rate.. Should I recapture at 720X480 at say 4,000 Kbps bit rate??

Guess what I'm saying is if I have to recapture yet again, I would like to make this my last one for this vacation video.. I have 9 Other vacation videos to do, before I start on my 3 Home movie VHS tapes.

I'm also going to try using TMPG to create smaller MPG file and see if the quality is any better.

Thanks again,
Snogger

[Cornucopia]

Here's a walk thru of what I would do:

Round up desired length to 151 min. (=9060 sec)
Max size is 4.37GB (=35799Mb), so desired combined AV bitrate is 3.951Mbps. Kinda low. Wait, that's not all. Now figure that your audio is to be captured at, say 192kbps, that leaves available video bitrate of just 3.763Mbps. This is the bitrate you should capture at for video.

The big question now becomes--CAN YOU DO VBR? If not, you are stuck with this kind of quality. (Since you're capping live from a card, I doubt that you can)

2 choices - capture at full D1 resolution (720x480) and live with the quality, or capture at 1/2 D1 (352x480) and live with decreased horizontal resolution, but with higher quality per pixel. This depends on the material and what your source is. If VHS/8mm/TV/Sat, I'd go with 1/2D1. If SVHS/Hi8/etc, harder to say. You could even go to SIF (aka 1/4D1 or 352x240) MPEG1, but that doesn't make the most sense to me at the bitrate you're trying to capture. Many cards won't let you capture MPEG1 higher than 1.86Mbps, anyway.

Let us know how it turns out.

Scott

edit...
P.S. If you can cap as AVI and do an encode via TMPGEnc, assuming you have the full program or are at least within the 30days for MPEG2, you could then do a VBR encode, which would make your video quality much better. (2pass VBR--Set AVG bitrate to the level suggested above, MAX br to 9.8Mbps, MIN to 0? This will give you a nicer looking file with roughly the same size as originally suggested.) But you must have the available temporary HD space for the HUGE AVI files.

[Thorn]

Remember that since DVD needs to be 720x480 (for NTSC, different for PAL), we KNOW that video captured at 640x480 would have to be re-encoded by the authoring software. That alone can affect file size. After that, the audio is a major issue if you're leaving it as pcm (which will take about 1.2GB just for the audio).

If you're using PAL systems, mpeg audio is ok and this wasn't your problem. If you're using NTSC (basically the US and related areas) you can only have PCM (uncompressed) or AC3 audio. If your authoring software handles AC3, you can try to encode the audio to save space for the video. Otherwise, you're limited to about 3GB for the video portion. For two hours, uncompressed audio is not desirable!

As cornucopia said, 1/2 D1 may be a good option for you also because lower resolutions require lower bitrates to look acceptable.

[Nolonemo]

The big advantage of capping to avi instead of mpeg is that you can do all your edits and then encode, and if you miscalculated the bitrate you can reencode from the avi again without having to start from scratch again.

[snogger]

Thanks for all the replys..

I will start looking into this tonight, and if nothing else recapture again with the suggested settings.

By Monday I "Should" have some results I can post.

And just as an FYI, I am in the US, so am using NTSC. so thanks Thorn for pointing out my Mess up on capturing at 640X480

you know, I've probably spent over 30 Hours so far.. and haven't finished my first Copy!!! I will say though some part(i.e. Editing, transitioning and others) are going faster now that I understand the Software I'm using.. If ONLY I can get it to fite on a DVD

Can't wait to see the hell I'll go through to try and bring a 3 Hour Canada Fishing Trip over to DVD!

Thanks Again,
Snogger