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H264 compression pixelises edges on bright colors

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Rami Nasr
H264 compression pixelises edges on bright colors
on May 26, 2009 at 1:48:21 pm

Hello Everyone,

I am trying to compress a none compressed AVI to an MP4 format with the H264 codec. After trying several settings I still can't understand why the compressor loses the softness around the edges of bright colors.

One weird thing noticed is when I play my MP4 in VLC the edges are smooth and with flash player and quicktime it isn't.

here is what I mean exactly :

http://farm4.static.flickr.com/3646/3563660543_146e744c9b_o.jpg

Thanks in advance for your help !


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Daniel Low
Re: H264 compression pixelises edges on bright colors
on May 26, 2009 at 2:47:22 pm

You have given us very little information to go on. Please read this post:

http://forums.creativecow.net/readpost/20/862073



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Rami Nasr
Re: H264 compression pixelises edges on bright colors
on May 26, 2009 at 3:27:30 pm

Sorry, I am new to this forum.

here are more details :

I am using a PC with Windows Xp 64bits, also tried on a Xp 32bits and on a vista 32 bits and a vista 64 bits and I am having the same problem

the softwares I used :

After effects CS4 to create a clip, I then rendered a none compressed AVI

Then I used sorenson squeeze 5.0.2 To create either an FLV either an MP4 H264 codec for the web.

Much Thanks !


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Daniel Low
Re: H264 compression pixelises edges on bright colors
on May 26, 2009 at 4:04:26 pm

[Rami Nasr] "After effects CS4 to create a clip, I then rendered a none compressed AVI

Then I used sorenson squeeze 5.0.2 To create either an FLV either an MP4 H264 codec for the web"


Can you tell us some more information on the source clip? (Dimensions, interlaced or progressive etc....)

Can you tell us exactly what settings you used in Squeeze?



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Two years from now, spam will be solved. - Bill Gates, World Economic Forum 2004


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Craig Seeman
Re: H264 compression pixelises edges on bright colors
on May 26, 2009 at 4:19:12 pm

I'll also add that Main Concept and Squeeze fixed several issues with H.264 encoding with the Squeeze 5.1 update so the first thing I'd recommend is do that update and test again.



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Rami Nasr
Re: H264 compression pixelises edges on bright colors
on May 26, 2009 at 5:55:34 pm

My source clip is a 526 width 320 height none compressed AVI exported from after effects with the default settings :

Video for windows (avi)
channels : RGB
Depth : million of colors
color : premultiplied (matted)

This avi has perfect quality like in the screenshot i posted in my first thread.

then after importing this avi in squeeze here are my video settings (Itried so many different settings but unfortunately always had the same result)

codec : sorenson H264
Method : i tried one pass CBR and 2 pass VBR
data rate : again I tried many but i would like 1000kpbs
frame size : same as source
frame rate : 30 fps
quick compress : unchecked
keyframe every : 33 frames
auto keyframe on scene change : 50
B-frames : off


I really hope you guys can help me out !

Thanks



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Daniel Low
Re: H264 compression pixelises edges on bright colors
on May 26, 2009 at 7:02:01 pm

[Rami Nasr] "My source clip is a 526 width 320"

Can I ask why that size - it's a totally non-standard size

[Rami Nasr] "keyframe every : 33 frames "

Try every 300 frames.

Do you have any filters applied in Squeeze - like deinterlacing?



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Two years from now, spam will be solved. - Bill Gates, World Economic Forum 2004


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Rami Nasr
Re: H264 compression pixelises edges on bright colors
on May 26, 2009 at 7:21:46 pm

526 by 320 is the size of the video my client requested, it's to fit in that specific zone on his website.

I also just tried keyframe every 300 frames, no luck...


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Daniel Low
Re: H264 compression pixelises edges on bright colors
on May 26, 2009 at 9:13:53 pm

[Rami Nasr] "526 by 320 is the size of the video my client requested, it's to fit in that specific zone on his website."

FLV and H.264 don't work well when odd frame sizes are used and in this instance the requested frames size is most likely the reason for the poor picture quality. The frames size he's given you is neither 4:3 or 16:9 and each side needs to be equally divisible by 16 or 8

You should explian to the client that he should fit his page around the video not the other way around if he wants the quality to be better than it is:

Use the recommended frame sizes that this calculates for you:

http://www.adobe.com/devnet/flash/apps/flv_bitrate_calculator/





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Two years from now, spam will be solved. - Bill Gates, World Economic Forum 2004


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