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sourse is 1920x1080 but after its 1920x814 why

Posted: Fri Aug 21, 2009 3:55 pm
by bazza-61
sourse is 1920x1080 but afterencoding its1920x814 why, any help on this please.
and can the aspect ratio be changed or does it select same as source.
thanks.

Re: sourse is 1920x1080 but after its 1920x814 why

Posted: Fri Aug 21, 2009 4:41 pm
by TedJ
Because 1920x1080 equals a ratio of 1.78:1 (16:9) while the movie in question is 2.35:1 - the frame on your source is matted with black top and bottom to make up the difference. During the encode this black has been automatically cropped.

Re: sourse is 1920x1080 but after its 1920x814 why

Posted: Mon Aug 24, 2009 11:22 am
by bazza-61
ok thanks, but can this be changed so the outcome is the same as the sourse.

Re: sourse is 1920x1080 but after its 1920x814 why

Posted: Mon Aug 24, 2009 1:15 pm
by TedJ
Well, you can manually set the cropping to zero, but why would you want to? Cropping the matting won't affect the picture at all and you'll save bits by not encoding the black.

Re: sourse is 1920x1080 but after its 1920x814 why

Posted: Tue Aug 25, 2009 10:15 pm
by fprietog
TedJ wrote:Well, you can manually set the cropping to zero, but why would you want to? Cropping the matting won't affect the picture at all and you'll save bits by not encoding the black.
Sometimes the auto cropping values are not correct. Reading this post I remeber that, for example, all the extras of the DVD "The Hollow Man" mixed images from the film in 16:9 and interviews in 4:3 but the auto crop values cropped to 16:9 all these extras. I don't know how the program calculates the crop values but maybe it takes the start of these extras that were few seconds of the film images (in 16:9) in order to calculate the values...

Unfortunately, using the GUI there is no way to mantain active the custom crop values to 0 because the values are always overwritten when change the source even if you changed the option to "Custom" (maybe it's a bug).

Best regards.

Re: sourse is 1920x1080 but after its 1920x814 why

Posted: Tue Aug 25, 2009 10:46 pm
by JohnAStebbins
To calculate cropping, hb looks at a collection of preview frames distributed evenly throughout the video. The number of frames used in the 0.9.3 release is 10. In the current snapshot, the number of frames can be customized in the preferences. The amount of crop is calculated for each frame and then the crop values are sorted according to the amount of crop. The median of this sorted list of crop values is chosen as the autocrop value. The practical side effect is that short segments of the video may go outside the chosen crop boundaries. This is actually desirable as many broadcast programs will show the station logo for short periods in the area that should be cropped.

However, I've encountered the problem with too much being cropped myself. There may be some tuning possible here to improve our choice. Perhaps a value off center in the list would work better (the median being the center item in the list). But this would take a lot of testing on a variety of sources before we would consider a change.

Re: sourse is 1920x1080 but after its 1920x814 why

Posted: Tue Aug 25, 2009 11:03 pm
by fprietog
JohnAStebbins wrote:The number of frames used in the 0.9.3 release is 10. In the current snapshot, the number of frames can be customized in the preferences.
JohnAStebbins, thanks for you quick answer. I'm currently using SVN2773 Snapshot and I want to test this option but I don't see the option in the GUI.

Please, can you point me how to change the number of frames used? I'm using WINDOWS XP SP3.

Thanks and best regards.

Re: sourse is 1920x1080 but after its 1920x814 why

Posted: Tue Aug 25, 2009 11:24 pm
by JohnAStebbins
hmm, it looks like the windows version hasn't implemented this option in preferences. I hadn't realized this till I looked at the code just now. Sorry. You will have to use the query editor to add to the CLI command line option. The option is "--previews 20" if you want 20 preview frames.

Re: sourse is 1920x1080 but after its 1920x814 why

Posted: Tue Aug 25, 2009 11:38 pm
by fprietog
JohnAStebbins wrote:hmm, it looks like the windows version hasn't implemented this option in preferences. I hadn't realized this till I looked at the code just now. Sorry. You will have to use the query editor to add to the CLI command line option. The option is "--previews 20" if you want 20 preview frames.
Thank you very much, I'll use it.