Smart Video Compression

[Malc_b]

Hi,

 

I'm newbie to Creator 2009 so please be gentle with me . I was told that this program had what I call smart video compression. That is if you give it a MPEG2 file it does not expand and recompress the video (rather pointless as you don't get more quality that way you get less). Of course around edits you need to re-compress but only up to the next I-frame. So I've got a bit of MPEG2 footage and dropped it into MyDVD, but the finished size at the bottom varies on the quality selection. This is with an unedited file or one that I've edited and saved in 2009. So where is this feature? The fact the finished size line varies suggests it will expand and re-compress.

[Malc_b]

I don't know of ANY software that completely analyzes an entire file before just to give you an estimated final size.

 

You miss my point. Creator says video A is x minutes, bit rate is y so time is z. A more clever approach is to say video A is mpeg2 and is a bit rate of n so if fit to disk is on then that is my bit rate and hence my used size (i.e. same as video file size) Gspot can work out the average bit rate in a minute so it not hard to do. And Nero does this.

 

I think you thinking of avi input not mpeg with no recompression.

 

[ggrussell]

You have way over simplified the issue. What you suggest wouldn't work in many situations. What if you had one MPEG 2 file using 6Mbps VBR with very little motion and then edited in another MPEG 2 @9Mbps CBR with lots of real fast motion. Your calculations would be seriously off base.

 

Not everyone uses MPEG file format. There is DV AVI, AVI, DivX, Xvid, M2T, MTS, etc. So do you expect them to write an estimation code for each type of file type? Just not reasonable. I'm sure Nero does the same thing as Roxio. The estimation is based on video length and average amount of motion and compression (depending on file type). Broken down to an algorithm that can be quickly calculated. I've used a dozen or more video applications and none of them are very accurate at guessing an estimated final size.

[Malc_b]

Aren't you assuming that the mpeg is re-encoded. If the only re-encoding is around the cuts then the estimate would be the imported file size (which is easy to get) with an adjust for the cuts. And if the re-encode around the cuts are small then any error in the total file size is small even if the cut calculation is say x2 out.

 

I would agree not everyone uses mpeg-2 but it is that feature I'm interested in at the moment. I merely point out that the work around suggested by sknis, use gspot to get bit-rate and then set project to that bit-rate, seems to be done automatically by Nero so Roxio ought to think about doing the same as the program probably has all the required info just is not using it.

 

[sknis]

QUOTE (Malc_b @ Mar 1 2009, 05:14 AM) <{POST_SNAPBACK}>

Aren't you assuming that the mpeg is re-encoded. If the only re-encoding is around the cuts then the estimate would be the imported file size (which is easy to get) with an adjust for the cuts. And if the re-encode around the cuts are small then any error in the total file size is small even if the cut calculation is say x2 out.

 

I would agree not everyone uses mpeg-2 but it is that feature I'm interested in at the moment. I merely point out that the work around suggested by sknis, use gspot to get bit-rate and then set project to that bit-rate, seems to be done automatically by Nero so Roxio ought to think about doing the same as the program probably has all the required info just is not using it.

 

You missed the point. Roxio products do that also if the video is already DVD compliant. I posted that information since it seemed that your original mpg2 file was not. You get the same thing if you select the fit to disc option except if the video is longer than one hour, it may drop the quality too far. Burning to an ISO file at best quality and then copying that image file to a disc will give you the best quality for the length of the project.

 

This thread is getting to be an esoteric exercise. If you don't like what Creator 2009 does, then stick with Nero. I doubt that Roxio will modify the program just because "but it is that feature I'm interested in at the moment".

[ggrussell]

QUOTE (Malc_b @ Feb 28 2009, 07:51 AM) <{POST_SNAPBACK}>

The fact the finished size line varies suggests it will expand and re-compress.

Not sure what you mean by that. When you output to file, you should see a gray preview with light gray circle and the work MPEG. This means the video is not being re-encoded. If you see the actual video in the preview, that means it is being encoded.

 

Same thing when you burn to disc, ISO or video folder. Just a different dialog box.

[sknis]

QUOTE (Malc_b @ Feb 28 2009, 06:51 AM) <{POST_SNAPBACK}>

Hi,

 

I'm newbie to Creator 2009 so please be gentle with me . I was told that this program had what I call smart video compression. That is if you give it a MPEG2 file it does not expand and recompress the video (rather pointless as you don't get more quality that way you get less). Of course around edits you need to re-compress but only up to the next I-frame. So I've got a bit of MPEG2 footage and dropped it into MyDVD, but the finished size at the bottom varies on the quality selection. This is with an unedited file or one that I've edited and saved in 2009. So where is this feature? The fact the finished size line varies suggests it will expand and re-compress.

 

Download and run gspot on the video. It will give you the particulars on the video file. In MyDVD, Project settings, select the bitrate that matches your mpg2 video and it should not re-render. When you go to burn, the preview screen will display a gray background with white swirls and tect.

[Malc_b]

Thanks for the replies. I tried a burn to folder and its seems like smart is automatic, if you have set fit to disk. Set SP etc. and it will recoded. If the front has been trimmed then you see a flash of picture for the bit that is recoded then you get the gray box which as you say and I guessed means it is not re-encoding. The speed also shows it can't be re-encoding. I think the only benefit you get from setting the bit rate the same is that the calculated size is closer.

 

But if fit to disk is set and the calculated size is too big it re-encodes so you have to set bit-rate same or greater than the actual bit-rate. Not sure how it works that out as bit rate varies and it doesn't seem to analyse imported videos to check their bit rate otherwise the size estimate should be more accurate with fit to disk (which seems to use 9MB/s x length). Nero does this better. At encoding stage you can see % of video and audio that will be re-encoded and the disk use is worked out for you (Nero basically does the gspot bit and sets bitrate, smart is an option).

[ggrussell]

QUOTE (Malc_b @ Feb 28 2009, 11:23 AM) <{POST_SNAPBACK}>

it doesn't seem to analyse imported videos to check their bit rate otherwise the size estimate should be more accurate with fit to disk

I don't know of ANY software that completely analyzes an entire file before just to give you an estimated final size. How much a video can be compressed depends on a lot of things like motion and MPEG is compressed using frame to frame comparison. One hour of video is over 100,000 frames. So how long are you willing to wait for a 'accurate' final estimated size? An estimate is just that - an educated guess. How close any software estimate is to the final size just depends on how they do their math.