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| YEgvnLDOgMQ4 |
| Posted: Sep 4 2013, 09:35 AM |
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Newbie
Group: Members
Posts: 2
Member No.: 37072
Joined: 3-September 13
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I'm very new to VirtualDub, running 1.9.11 on Win XP Pro SP3 with dual core processors. I'm capturing old VHS tapes in NTSC format and saving the capture as an uncompressed .avi. If I open the .avi and save it with/without making changes, the resulting saved .avi is 50% larger than the original. For example, a file of 17.9GB becomes 26.8GB.
The capture is done with resolution of 720x480, so the key frame size of the original file is 691200 (2*720*480). The key frame size for the saved file is 1036800 (3*720*480). These numbers are taken from the File Information display for each file (I can't seem to paste in the window shot of the AVI Information.). The decompressor changes from YUY2 to ' ', and the Data Rate changes from 165546 kbps to 248583 kbps.
Why does VirtualDub change the key frame size? and what can I do to prevent it?
Thanks in advance,
Rod
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| Abrazo |
| Posted: Sep 4 2013, 10:34 AM |
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Advanced Member
Group: Members
Posts: 775
Member No.: 28995
Joined: 5-November 10
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Only if you put VirtualDub's Video- and the Audio-menu to "Direct stream copy", the frame size should remain the same.
Probably you have set one or the two of these menus to "Full processing mode" ?
In that case it may be that the color depth changes, as well as the number of frames, compression, etc., depending on your settings/choices.
Normally it is not the intention to keep video and audio in an uncompressed way.
That is what encoders are for, like DivX, Xvid, H264, MPEG2, ... for video and AC3, AAC, MP3, ... for audio.
Only when you have to do several changes to a video before making the final one, you can leave it in uncompressed/raw format, or use a 'lossless' encoder. |
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| YEgvnLDOgMQ4 |
| Posted: Sep 4 2013, 12:30 PM |
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Newbie
Group: Members
Posts: 2
Member No.: 37072
Joined: 3-September 13
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Thank you for your prompt and informative reply.
I did have 'Full Processing Mode' set, changing to 'Direct stream copy' made a huge difference.
Actually, I do not intend to save these .avi file on my hard drive; once I've written them to DVD, I plan to delete them.
Thanks again,
Rod
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| Abrazo |
| Posted: Sep 4 2013, 02:30 PM |
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Advanced Member
Group: Members
Posts: 775
Member No.: 28995
Joined: 5-November 10
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Even when saving and keeping your videofiles on a DVD, you have a lot of space to win by compressing them.
You may count about 20MB per minute for an acceptable high quality in DivX at a resolution of 720 x 404 pixels and 25 fps.
For audio you may count about 1 à 2MB per minute in MP3.
If you use a more recent video-codec like H.264 (x264vfw encoder) you can even compress further by keeping the same quality. |
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