CBR V VBR?

texanman

Just as a matter of interest would there be much of a difference in using
9Mbs cbr one pass over 9Mbs vbr 2 pass ?

Average-Ro

Hey texanman,

Thanks again for your kind PMs about my blabbering in the wedding forum:)

Forgive me if I sound condecending in the following reply.

I always go for VBR, two pass. CBR stands for constant bit rate, and as it's name says; it sets the bitrate to one level (9Mbs) and uses that throughout. There are some scenes that wouldn't need that much bitrate (static shots of objects that don't move for example), and some that might need more (wide shots with loads of people moving), so you'll get an uneven product in the end (uneven in terms of quality)

With Variable Bit Rate, you get to set the minimum, average and maximum Mbps, depending on the length of the movie. With VBR, it analyses the the footage and decides whether it needs a higher or lower bitrate depending on the shot. Because of that, you get a higher quality product in the end, though it would take longer to render.

Hope that makes sense? Ca I ask what editing software you use?

TommyGun

Average-Ro wrote: »

Hey texanman,

Thanks again for your kind PMs about my blabbering in the wedding forum:)

Forgive me if I sound condecending in the following reply.

I always go for VBR, two pass. CBR stands for constant bit rate, and as it's name says; it sets the bitrate to one level (9Mbs) and uses that throughout. There are some scenes that wouldn't need that much bitrate (static shots of objects that don't move for example), and some that might need more (wide shots with loads of people moving), so you'll get an uneven product in the end (uneven in terms of quality)

With Variable Bit Rate, you get to set the minimum, average and maximum Mbps, depending on the length of the movie. With VBR, it analyses the the footage and decides whether it needs a higher or lower bitrate depending on the shot. Because of that, you get a higher quality product in the end, though it would take longer to render.

Hope that makes sense? Ca I ask what editing software you use?

I always use 8mbs and VBR 2 pass.

texanman

Average-Ro wrote: »

Hey texanman,


Forgive me if I sound condecending in the following reply.



Hope that makes sense? Ca I ask what editing software you use?

Hi Average Ro

I didnt think you were. I guess the point I was making was, would there be a difference in the end product when the footage is approx 45min.

I always use 9Mbs Vbr 2 pass. And I'm happy with the footage. I understand what you are saying about VBR & CBR . According to Adobe encore the encoded file size is the same.Thats what made me think about overall picture quality.

I think I'll stick to VBR .

I'm using Adobe premier as as mentioned Adobe encore to create the DVd's.

Thanks Tommygun for your reply.

TommyGun

texanman wrote: »

Average-Ro wrote: »

Hey texanman,


Forgive me if I sound condecending in the following reply.



Hope that makes sense? Ca I ask what editing software you use?

Hi Average Ro

I didnt think you were. I guess the point I was making was, would there be a difference in the end product when the footage is approx 45min.

I always use 9Mbs Vbr 2 pass. And I'm happy with the footage. I understand what you are saying about VBR & CBR . According to Adobe encore the encoded file size is the same.Thats what made me think about overall picture quality.

I think I'll stick to VBR .

I'm using Adobe premier as as mentioned Adobe encore to create the DVd's.

Thanks Tommygun for your reply.

The extend the post a little, I know that 9Mbs is better than 8. The reason I use 8mbs is my understanding is that 9Mbs will play fine on new DVD players but may stutter on older players.

stcstc

actually depending on your footage and encoder, you shouldnt need anywhere near 9 or 8 Mbs per second

BUT more importantly, specifying a VBR encode with 8 or 9 Mbs doesnt actually give enough details, as there are 3 variables to a VBR bitrate

min, max and average

most dvd movies which i have authored have an average around 4 -5

and a max around 7.6

as the DVD spec says the max bit rate is 9.8, which includes video streams, audio stream and subtitles

depending on the audio stream 7.6 is a good max to use

also it keeps within the spec for doing multiangle authoring

NealB

texanman wrote: »

I think I'll stick to VBR .

I found 2 pass VBR produced noise in dissolves so switeched to 7mbs CBR. Once the project isn't too long and will fit on a DVD so everything gets plenty of detail and the pic stays clean. I know that in theory VBR is better but CBR is giving me better results. Using compressor for DVD Studio Pro.

On an aside, has anyone used Bit Vice, heard it's good. I also have Autodesk Cleaner but just use that for converting funny formats to something FCP can easily handle.

N

NealB

texanman wrote: »

I think I'll stick to VBR .

I found 2 pass VBR produced noise in dissolves so switeched to 7mbs CBR. Once the project isn't too long and will fit on a DVD so everything gets plenty of detail and the pic stays clean. I know that in theory VBR is better but CBR is giving me better results. Using compressor for DVD Studio Pro.

On an aside, has anyone used Bit Vice, heard it's good. I also have Autodesk Cleaner but just use that for converting funny formats to something FCP can easily handle.

N

Lump

2 pass VBR will give you better quality to size ratio. If you have the time always use VBR particularly if you're using a lower bit rate.

John

jadespark

VBR is almost always better, because it's more sensitive to the needs of the audio. It gives you a bit higher bit rates in the parts of the song that need it most, and makes up for it by saving space in the sections that don't need as much. Definitely the smarter way to go.

redstarmark

When I used to use Premiere I used a calculation that a friend showed me that I completely forget now. Here is a specific calculator online that will do it for you http://www.videohelp.com/calc.htm

But yea I usually would have used VBR 2 Pass