Can you render up an MPEG2?

[akagi]

I have a large no. of video files at 6000-8000 kbps vbr that will not fit 2 to a video but 1 to a video leaves a lot of space.

My question is can you render up? One would think not as once any ‘excess’ movement etc that cannot be ‘fit’ into that 6000 kbps parameter would be ignored and gone for good.

However if I am going for 1 video per disk I might as well get the best quality possible, however, so as an experiment I passed a 6000 kbps vbr video file through Ulead Video 7 at 14000 kbps vbr. I expected to get the same size video file out the other end (2.0GB) at the same vbr i.e 6000kbps. However the file was a wapping 3.68 GB and at 14000 kbps - not what was expected at all.

Where has this additional data/size come from as it makes no sense to me and will it result in better picture quality?. As much help here as possible would be appreciated. I will render up all my videos but only if there is something to be gained.

[Tommyknocker]

You can increase your bit rate, but it will not make your video any better. The short answer being you have no where to get the extra video from to sharpen your image. All you have is the video on your disks, and in order to get a better image, you need the source video not the finished video.

[ZippyP.]

Re-encoding video always results in quality loss. If your bitrate is high enough then you might not notice too much. I think you're wasting your time, it won't get any better.

[flaninacupboard]

added to which of course, 14,000 kbps is above the DVD rate, so totally unplayable.

the reason your 14000 kbps file is bigger than your 6000kbps file is quite simple. if you allocate 14000 kilo bits per second to your video instead of 6000 kilo bits per second, you allocate more than twice as many bits, i.e. you file is more than twice as large.

Filesize is quite simply
Bitrate * seconds = filesize.

[akagi]

This is where I am getting confused. I would understand if we were talking constant bit rate so for each second 14000 kb was being assigned (regardless of whether it needed to be) However we are talking about variable bit rate so presumably the 14000 is the MAXIMUM allocation per second so if a 6000 vbr KBPS file is put through at the latter level there should ALWAYS be 8000 Kbps leeway spare/never used - the produced file should be of the same quality, bit rate (6000) and size as before. So how come its bigger - where is the extra size coming from?

I'm not disputing what peolpe are saying just confused by the latter annomaly.

Any comments or do I not inderstand this vbr thing.

[flaninacupboard]

I think generally when people quote a VBR bitrate they are quaoting the average, as for DVD we are restriceted by 9.8mbps, so most people just use that as their maximum, and it's the average that is important. i assumed you meant 14mbps VBR average.

[akagi]

I must confess that I have come away more confused (no disrespect) but something I have read above might help - as the bitrate of a movie is reduced how is the quality reduced? Does the jerkiness that you sometimes see with MPEG2's increase or does the image become more undefined as implied above?

[whatever]

The image becomes less defined, blockiness can increase (depending on bitrate) and it will have more artifacts, although it will not become "jerky"