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Old 4th March 2010, 20:24   #1  |  Link
nj2010
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newbie trying to resize hd video down to a smaller, specific size with Avidemux

Hello Guys,

Iím new to the forum. I am a web designer who built a site that has a flash video player. I created the player myself in flash/actionscript. The video player supports loading HD videos (mp4 and H264 supported).

Due to space limitations on this specific site, the videos must be a size of 590 x 250. ( im not offering a full screen button )

I just picked up one of those compact cameras that shoot HD video: Below are the 2 choices that it will shoot video in:

AVCHD Format:
VIDEO: MPEG-4 AVC/H.264 1920 X 1080/60i or 1440x1080/60i
AUDIO: DOLBY DIGITL 2 CH.
-----------------------------------------------------------

MP4 Format:
VIDEO: MPEG-4 AVC/H.264 1440 x 1080/30
AUDIO: MPEG-4 AAC-LC 2CH

I plan to shoot 1-2 minute short HD video clips and then I plan to stream them thru the player.

What I need to do is take the HD video and resize it to 590x250 using avidemux but I do not want to lose any picture quality. Iím really confused on the proper steps/settings that I need to follow so that I can resize the video to the size but keep it very very sharp. Being that the final size is uncommon dimensions, I thought I can find some help here.


Q1: which of the 2 formats above do you suggest that should I be shooting in so will make it easiest to resize to 590x250? I didnít know if I should be using the AVCHD format or not.


Q2: As soon as I open a video in avidemux, it says h264 detected and it gives a choice to use another mode that will lose frame accuracy or, you can select no. That is what I did. I selected no. Then it says index is not up to date, do you want to rebuild. If you say yes, program will crash. If you say no, it lets you proceed. This is already confusing me. What am I suppose to do? There must be a way to properly edit these types of videos.


If any of you can help get me started inthe right direction, I would really learn a lot and can eventually do this on my own. Im not sure what setting need to be adjusted to keep sharp video when I re-encode and im stuck on getting the video to the size I need.

In a nutshell, I want to shoot HD videos, resize them to 590x250 and keep as much video clarity as possible.


Thanks in advance.
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Old 5th March 2010, 09:02   #2  |  Link
Ghitulescu
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Your desiderata are incompatible with each other.
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Old 5th March 2010, 17:43   #3  |  Link
nj2010
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Im sorry I did not understand the response. Perhaps it is terminology I do not know. if it helps at all, I am aware that I will have to crop off some of the top and bottom of the video to get my dimensions of 590 x 250. I keep that in mind when shooting the video. I keep my subjects centered.


I just need to shoot the video in either of the formats I mentioned and get it down to my desired size but keeping the video quality very good.
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Old 5th March 2010, 18:03   #4  |  Link
Ghitulescu
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Quote:
Originally Posted by nj2010 View Post
Due to space limitations on this specific site, the videos must be a size of 590 x 250. ( im not offering a full screen button )

AVCHD Format:
VIDEO: MPEG-4 AVC/H.264 1920 X 1080/60i or 1440x1080/60i
AUDIO: DOLBY DIGITL 2 CH.
-----------------------------------------------------------

MP4 Format:
VIDEO: MPEG-4 AVC/H.264 1440 x 1080/30
AUDIO: MPEG-4 AAC-LC 2CH

What I need to do is take the HD video and resize it to 590x250 using avidemux but I do not want to lose any picture quality.
The only way not to loose quality in digital domain is to COPY/PASTE (and similar). Any transformation would inherently incure losses. Try downsizing 1920x1080 to 590x250 then upsize it again to 1920x1080. No quality loss would mean that you'll end with identical videos.

Secondly the quality is pretty much dependent on your senses (subjective) and on your displaying device. Eg a 65" plasma vs. a cell phone.
I'm not aware of any standalone using this strange resolution so I assume it should be progressive, that is, you need to quest for a deinterlacer too.
Both the choice of the scaler (resize algorithm) and the deinterlacer is solely dictated by the video source.
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Old 6th March 2010, 02:37   #5  |  Link
Blue_MiSfit
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You cannot simply display 1080p at 590x250

You have to first scale the image to the desired dimensions (thus destroying much resolution), and then re-encode the stream with a good flash compatible codec like x264.

BTW, why did you pick a strange display size with a 2.36 aspect ratio? Anything shot on your camera will be 16x9 (1.78), thus requiring pillar boxes (side matte) to display correctly in your player, which means your effective resolution can only be 445x250, which is simply dreadful

Now, you can definitely make things look good if you do your transcode smartly. Do use x264, for sure. It's the best H.264 encoder available (and is free btw )

Ghitulesco brings up a good point about deinterlacing as well. Your camera probably has a natively interlaced sensor, in which case you will want to shoot interlaced mode, and deinterlace prior to scaling and transcoding. You can do this all in one step, no worries.

~MiSfit
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Old 6th March 2010, 20:35   #6  |  Link
nj2010
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Guys, im not sure that you are understanding what I am doing yet. There is no need to discuss interlacing etc.

I need to take the hd video and even keep the aspect ration. I just need to take it down to 590 px wide. then.. once scaled down, I need to crop off a portion of the top and bottom of the video so the new height is 250px. I know ill be losing a bunch of the video but it has to be done.

youtube does this all the time. When a new movie comes out in theaters and they put that long movie trailer advertisement across the top of the whole screen. it is somewhere around 900px wide and only 75 px in height. obviously they just cropped off the top and bottom of the video to get that custom size. we know that the movie was not shot like that. it was cropped.

that is what I need to do. If my original video is 1920 x 1080 and I keep the aspect ration of 16 x 9. I will scale it down to 590 x 332. right? then I just need to crop off 41px from the top and 41px from the bottom using the crop tool. then just encode the video using x264 in a mp4 container using the highest quality settings.

Does this sound correct? You see movie trailer advertisements all of the time like I mentioned on Youtube and also on myspace and they always use very strange sizes. we know the movie are HD origionally so they must be simply cropping.
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Old 7th March 2010, 19:24   #7  |  Link
b66pak
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ok...record a 15-20 sec sample in:

Quote:
MP4 Format:
VIDEO: MPEG-4 AVC/H.264 1440 x 1080/30
AUDIO: MPEG-4 AAC-LC 2CH
and post it...use m e d i a f i r e . c o m...m u l t i u p l o a d . c o m
_

Last edited by b66pak; 8th March 2010 at 17:16.
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Old 15th March 2010, 19:06   #8  |  Link
Ghitulescu
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Quote:
Originally Posted by nj2010 View Post
If my original video is 1920 x 1080 and I keep the aspect ration of 16 x 9. I will scale it down to 590 x 332. right? then I just need to crop off 41px from the top and 41px from the bottom using the crop tool. then just encode the video using x264 in a mp4 container using the highest quality settings.

Does this sound correct?
Well, yes, this is what I expected to do. But since you asked, I thought you might run into problems. Now, did you encountered any problems?
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