From: lennon at orcon.net.nz To: ffmpeg-user at mplayerhq.hu Date: Mon, 1 Sep 2008 19:23:05 +1200 Subject: Re: [FFmpeg-user] Forcing format, crop and aspect ratio
On Mon, 2008-09-01 at 07:18 +0000, Steve R. Bennen wrote:
I've been Googling questions in order to understand some basic parameter settings and I haven't been able to find a clear answer. (Actually, some more advanced settings make sense to me thanks to the link provided by Stefano Sabatini http://thread.gmane.org/gmane.comp.video.ffmpeg.user/16235/focus=16283 ) I am deciding between a few different scenarios. My problems are as follows. With a Player screen size at 576 x 432, which is 4:3, I will have source video uploaded in different aspect ratios.
1. If I use -s 576x432 will that force it? What will happen if I use the -s but I don't use the -aspect parameter? 2. If I use -aspect 4:3, what will happen to a source video file with a 16:9 aspect ratio? Will it automatically scale to 576 x 324 (16:9) because 576 is the defining dimension? 3. What if I want the screen size to be 576 x 432, regardless of the source aspect ratio, but I want both 16:9 and 4:3 sizes to fully fit in the 4:3 screen. Do I cropleft and cropright for the 16:9, but leave the 4:3? I want the ouput to show the "middle" of 16:9 and the 4:3. Can both be done?
What I do is test if its 16x9 and then --padtop 60 --padbottom 60 and it will add the black bars top and bottom for you and make it look correct.
Thanks, Craig, but I will have user-generated videos of all different sizes and aspect ratios being uploaded for encoding. If I knew it was 16x9, I would definitely try your suggestion. I am trying to understand how FFmpeg handles different variations. My first two questions may be asking the same question in different ways, but the third question is unique, I believe. Correct? _______________________________________________
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