Gordian Knot Bitrate

BillyWilly · 27th November 2009, 07:48

Hey guys,

I've read every help file and guide I could get my hands on for Gordian Knot. I prefer to do the settings myself and do not use Auto GK. I'm having a bit of trouble with the conversion of a DVD I've got. I'm trying to convert it with good enough quality to go through a second conversion on a separate program (long story). But I need it in AVI first. I want to retain most of the original quality from the DVD, so it doesn't degrade further after the second conversion, but I seem to running into a wall with Gordian Knot's bitrate. In the bitrate tab under the Video 100% section, I put for Average Bitrate: 6000, because that is about 1000 kbps less than the DVD's bitrate. I expect a video with about 4-5 gigs on it and that bitrate. Yet, every time the conversion finishes, I have a video with around 716 kbps and is about 1 gig. Under normal backup circumstances, that would be great, but I don't think that's good enough to use as a source file.

Can anyone shed some light on why it's not working for me?

Thanks,

BillyWilly

manono · 28th November 2009, 05:32

You probably max'd out the quality for your settings. It's called 'saturating the codec'. It can't get any bigger unless you do such things as increase the resolution, don't use B-Frames, don't use filters to try and 'clean up' the picture, use a sharper resizer, use a better quantisation matrix, etc.

Also, because MPEG-4 compresses much better than MPEG-2, just because the source DVD might use 6000 doesn't mean you'll be able to get the same bitrate when recompressing to XviD or whatever.

And as you seem to know already, making an XviD or DivX intermediate AVI isn't such a good idea. If you really need an AVI on the way to making something else, make a lossless HuffYUY or Lagarith AVI. I use Lagarith quite a bit myself. Just open the GKnot generated script directly in VDub(Mod), go to Video and choose and configure the codec. It's very easy.

http://www.videohelp.com/tools/HuffYUV
http://www.videohelp.com/tools/Lagar...ss_Video_Codec

BillyWilly · 29th November 2009, 05:57

Thanks for the reply manono! I tried the huffyuv and got a file that's about 35gigs. That's a bit bigger than I wanted. Is there any way to compress it, but retain good enough quality for another conversion? I don't need it perfect, just good enough. Also, is there any way to add more than 2 audio tracks in Gordian Knot? I can do that in Auto GK, but there doesn't seem to be an option in Gordian Knot.

manono · 29th November 2009, 09:25

In this day and age of terrabyte hard drives, 35 GB isn't so big anymore. Lagarith makes slightly smaller files. DV will be quite a bit smaller yet, but it isn't lossless. I might suggest installing Cedocida if you want to try making an DV intermediate AVI. It'll have to be 720x480/576 and 29.97/25fps. It uses just under 13 GB per hour of video. Me, I would never use XviD for an intermediate AVI. Maybe others would. I do use Lagarith all the time.

http://www.videohelp.com/tools/Cedocida_DV_Codec

Yep, it looks like you can have only 2 audio tracks when using GKnot. You could add another one afterwards easily enough, I think.

BillyWilly · 29th November 2009, 16:55

Thanks for the codecs, I've installed all of them. I was just concerned that I hadn't done it right because the file was bigger than the source. I do have plenty of room on my drive.
For the audio, let me make sure I have the process to add extra tracks down. This is how I would do it. I'd open up the converted file in VirtualDubMod, go to video, and set it to Direct Stream Copy. Then I'd go to the stream tab, click Stream List, and add the audio files, right? If that's true, how do I make sure all of the audio files have the same sampling rates (like I can in Nandub)? I'm planning on joining the two AVIs.

manono · 29th November 2009, 22:58

Yes, your procedure is correct. If from DVD, all your audio tracks will most likely have the same sampling rate (48 kHz). That'll be the least of your worries if you're trying to join 2 AVIs.

Quote:

I was just concerned that I hadn't done it right because the file was bigger than the source.

It's lossless; it'll always be much larger than the source. You want big? Save one as uncompressed some time.

27th November 2009, 07:48	#1 \| Link
BillyWilly Registered User Join Date: Feb 2009 Posts: 11	Gordian Knot Bitrate Hey guys, I've read every help file and guide I could get my hands on for Gordian Knot. I prefer to do the settings myself and do not use Auto GK. I'm having a bit of trouble with the conversion of a DVD I've got. I'm trying to convert it with good enough quality to go through a second conversion on a separate program (long story). But I need it in AVI first. I want to retain most of the original quality from the DVD, so it doesn't degrade further after the second conversion, but I seem to running into a wall with Gordian Knot's bitrate. In the bitrate tab under the Video 100% section, I put for Average Bitrate: 6000, because that is about 1000 kbps less than the DVD's bitrate. I expect a video with about 4-5 gigs on it and that bitrate. Yet, every time the conversion finishes, I have a video with around 716 kbps and is about 1 gig. Under normal backup circumstances, that would be great, but I don't think that's good enough to use as a source file. Can anyone shed some light on why it's not working for me? Thanks, BillyWilly Last edited by BillyWilly; 27th November 2009 at 08:53.

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28th November 2009, 05:32	#2 \| Link
manono Moderator Join Date: Oct 2001 Location: Hawaii Posts: 7,406	You probably max'd out the quality for your settings. It's called 'saturating the codec'. It can't get any bigger unless you do such things as increase the resolution, don't use B-Frames, don't use filters to try and 'clean up' the picture, use a sharper resizer, use a better quantisation matrix, etc. Also, because MPEG-4 compresses much better than MPEG-2, just because the source DVD might use 6000 doesn't mean you'll be able to get the same bitrate when recompressing to XviD or whatever. And as you seem to know already, making an XviD or DivX intermediate AVI isn't such a good idea. If you really need an AVI on the way to making something else, make a lossless HuffYUY or Lagarith AVI. I use Lagarith quite a bit myself. Just open the GKnot generated script directly in VDub(Mod), go to Video and choose and configure the codec. It's very easy. http://www.videohelp.com/tools/HuffYUV http://www.videohelp.com/tools/Lagar...ss_Video_Codec

29th November 2009, 05:57	#3 \| Link
BillyWilly Registered User Join Date: Feb 2009 Posts: 11	Thanks for the reply manono! I tried the huffyuv and got a file that's about 35gigs. That's a bit bigger than I wanted. Is there any way to compress it, but retain good enough quality for another conversion? I don't need it perfect, just good enough. Also, is there any way to add more than 2 audio tracks in Gordian Knot? I can do that in Auto GK, but there doesn't seem to be an option in Gordian Knot.

29th November 2009, 09:25	#4 \| Link
manono Moderator Join Date: Oct 2001 Location: Hawaii Posts: 7,406	In this day and age of terrabyte hard drives, 35 GB isn't so big anymore. Lagarith makes slightly smaller files. DV will be quite a bit smaller yet, but it isn't lossless. I might suggest installing Cedocida if you want to try making an DV intermediate AVI. It'll have to be 720x480/576 and 29.97/25fps. It uses just under 13 GB per hour of video. Me, I would never use XviD for an intermediate AVI. Maybe others would. I do use Lagarith all the time. http://www.videohelp.com/tools/Cedocida_DV_Codec Yep, it looks like you can have only 2 audio tracks when using GKnot. You could add another one afterwards easily enough, I think.

29th November 2009, 16:55	#5 \| Link
BillyWilly Registered User Join Date: Feb 2009 Posts: 11	Thanks for the codecs, I've installed all of them. I was just concerned that I hadn't done it right because the file was bigger than the source. I do have plenty of room on my drive. For the audio, let me make sure I have the process to add extra tracks down. This is how I would do it. I'd open up the converted file in VirtualDubMod, go to video, and set it to Direct Stream Copy. Then I'd go to the stream tab, click Stream List, and add the audio files, right? If that's true, how do I make sure all of the audio files have the same sampling rates (like I can in Nandub)? I'm planning on joining the two AVIs.