Lagarith in VirtualDub is increasing our Bitrate.

[Dib00]

We have been trying to convert a 1080p Mpeg2 into a Lagarith in order to store the file while taking up as little hard disk space as possible. The big problem we keep running into is that the file size increases significantly.

We have traced it down to VirtualDub increasing the videos Bitrate.

The original video was 13.4 Mbps

The smallest we have gotten it is about 30 Mbps using the Reduced Resolution option

We are trying to figure out how to get the Mbps down to at least what the original video was using Lagarith.

[Baldrick]

Lagarith is a lossless codec and you can not set any bitrate/compression so it's not just possible. You will get the size it produce and it's HUGE compared to the heavily compressed mpeg2 video.

But what is you goal with converting the mpeg2 video?

[Dib00]

The goal is to decrease the file size without losing any video quality for archiving purposes. (does not need to play)

[Vidd]

I don't think you understand what Lagarith is. Lagarith is a lossless codec. 1080p lossless is going to be huge. You will never get the file size smaller than the original MPEG-2 HD stream using Lagarith. Since Lagarith is lossless, you can't set a specific bitrate.

If the MPEG-2 HD file size is too big for you, you can compress it with x264. Of course that would be reencodeing and there would be a loss of quality.

[poisondeathray]

If it doesn't have to play, use some archiving software like winrar or 7-zip. You should be able to get ~5-15% smaller

[Dib00]

We were trying to avoid lossy while decreasing size. I guess it might not be possible

Thanks for your help.

[jagabo]

Recompressing a compressed video involves decompressing the video back to uncompressed frames, then compressing those frames with the new codec. Recompressing an MPEG video with a lossless codec almost alway results in a much larger file (the exception might be simple computer graphics like flat shaded graphs and charts). Recompressing with a lossy codec always results in a reduction in quality (it many not be noticeable if with "good" settings).

Some examples for a 720x480 30 fps video:

uncompressed RGB: 249 Mbit/s
uncompressed YUY2: 166 Mbit/s
uncompressed YV12: 125 Mbit/s
HuffYUV (YUY2): ~60 to 90 Mbit/s
Lagarith (YUY2): ~40 to 70 Mbit/s
DV (4:1:1): 29 Mbit/s
MPEG2 (YV12): ~4 to 8 Mbit/s
AVC (YV12): ~2 to 4 Mbit/s

[Soopafresh]

Just keep it as mpeg. Hard disk space is cheap these days.