Bit rates - how do I know what video bitrate to choose??

[yowie]

Gooday Guys

I have a Videomate Live 2.0 USB capture device. I havent had it long and Im still trying to perfect the capture process. Being new to video editing and related video media and techno stuff doesnt help.

Ive had a partual win with the device and managed to hook up a VCR and convert a Vcr tape to dvd and burn it- with sound this time!! cool.

But the thing that I dont understand very well is Video Bitrates. I know that as you increace the bitrate that you capture at so the size of the file increaces and Im assuming so does the quality.

I converted the tape at default value in the VideoMate software 0f 4. Whats that 4 bps. Im not sure, but the picture quality was not the greatest. This resulted in a clip of about 2.3 GB's in size.

Now when I put the bitrate up to 10 I ended up with a file of about 6 GB's in size. I didnt burn that to disk as it would have had to be split in two.

My Question is :-

How do I work out what the bitrate of my source is so that I can adjust my capture bitrate accordingly., and can I get good quallity and still fit it to one dvd??

At the end of the day whether it is one or two dvd's is not really the issue but I have a lot of converting from old and new Camcorder footage and VCR to disk to do and I was wondering if someone can tell me how to work out this bitrate thing so I acheive good Quallity and keep my file size within sensible reason. Is there a formula or something??

Thanks Yowie

[timmyp]

Well, that's kind of a big subject, but in general....

Higher bitrate means better quality.

A bitrate of 6000 Mbps will give you a little over 1 1/2 hours on a DVD-+R assuming you are using a compressed audio stream. Use the VideoHelp Bitrate calculator (available in the Tools section) to help you determine what will fit onto one DVD-+R including both video and audio.

What bitrate you ultimately use depends on the quality you are willing to live with. For example, a bitrate of 4000 Mbps will allow you to get more on a DVD (2 hrs 20 min, roughly), but your picture quality will suffer. Maybe this acceptable to you, maybe it's not. You kind of have to decide what's more important.. best quality vs. trying to get the entire capture onto 1 or 2 or however many DVD's.

To complex matters more, you can encode in a "half D1" resolution for better quality with lower bitrates, giving you a middle ground between quality and amount of material that can fit on a disc.

Do some searching on this site for "best bitrate" or some such search term and you will find several threads that talk about this subject and you can see what other people do.

Read, read, read and then test, test, test until you find a result that makes you happy. (Oh, and use a DVD-+RW in the meantime, LOL).

Good luck!!


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[yowie]

Thanks I'll have a look

[Cornucopia]

If you want MAXIMUM quality, you want the HIGHEST bitrate (combined A+V+otherstuff) available that will still allow you to fit within your available space.

Let's say you've got a DVD-R SingleLayer (=4.37GB). It's empty and you want to fill it up (and/or maximize the quality).
If your material is <1 hour, you can bump the bitrate up to the DVD spec max (~9.8 Mbps) and not quite fill the disc. That's doing it CBR also. No need to waste time with VBR for less than that length.

If it's longer, divide your available size by your available time and that'll give you your target bitrate. This # is CBR or the AVG. bitrate for VBR.
Subtract whatever you want to give to Audio (as this IS a constant), plus a little more subtracted for menus, subtitles, etc. What's left is available for Video.

As mentioned above, if you go below ~4Mbps, you should think about 1/2 D1 resolution (352x480/576). If you go below ~2Mbps, you should think about using 1/4 D1 aka MPEG1 SIF resolution (352x240/288). -or-
Think about splitting the file onto more than 1 disc.

Best thing is to use the Bitrate Calcs available in the Tools section (and elsewhere).

Scott

[guns1inger]

You also need to take into account the quality of your source material. VHS, even good VHS, is poor quality compared to DVD. Giving it the highest available bitrate will not make it look better than it originally did. Most VHS looks fine at 1/2 D1, or at medium bitrates (around 5000 - 6000). I am assuming the videomate software is capturing to mpeg-2. If so, and you have little control over the bitrates other than a simple 1- 10 range, consider capturing at the highest bitrate available to you, authoring, then using DVD Shrink to bring the size back down to a single disk.