Author Topic: loss of detail  (Read 4204 times)

rabbit

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loss of detail
« on: March 19, 2012, 03:32:45 AM »
I have been trying to convert an mpeg-2 file to mpeg4-avc using both Avidemux and Handbrake. I noticed that almost regardless of the compression settings there seems to be a significant loss of detail from the Avidemux conversions. This seems odd considering both applications use x264 and that the loss of detail is so great.

I have since noticed that this loss of detail is apparent even when opening the source mpeg-2 file in Avidemux and viewing the still image within the Avidemux window - prior to any attempt at conversion. If I open the mpeg-2 file in Avidemux and VLC without pressing play on either and view the image of the first frame of the movie, the image displayed in VLC is more detailed than that displayed in Avidemux. Somehow Avidemux is losing the image detail from the source prior to conversion.

Anyone have any idea what might be causing this?

Thanks,

Phil T.  :)

zakk

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Re: loss of detail
« Reply #1 on: March 19, 2012, 08:08:03 AM »
Be careful with this, because image in the first instance of VLC is always better.

rabbit

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Re: loss of detail
« Reply #2 on: March 19, 2012, 09:38:28 AM »
But if I create an mpeg4-avc file with Avidemux, and then look at it in VLC, it still has the lost detail.

mean

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Re: loss of detail
« Reply #3 on: March 19, 2012, 12:41:43 PM »
post processing is activated by default for mpeg2
Try disabling it

spiderwheels

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Re: loss of detail
« Reply #4 on: March 22, 2012, 04:27:07 PM »
Hello.

I am having the same issue. I am trying to convert an old home video DVD (interlaced) I made to AVC and spent hours tweaking any encoder setting that had something to do with sharpness. Even CRF0 was blurry!

I am using yadif deinterlacer to turn it in to 50fps progressive scan.

So can I just clarify, by turning off post-processing of the mpeg2 file do you mean hit F4 and uncheck Horizontal Deblocking and Vertical Deblocking?

I've tried that but it doesn't seem to help. Particularly my hair is quite detailed in the original mpeg2 but just comes out as coloured bands in the AVC version.

Thanks

nibbles

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Re: loss of detail
« Reply #5 on: March 23, 2012, 11:41:28 PM »
If possible upgrade to Avidemux-2.5.6, and also try the 2.6 branch.
I will pull up a couple of MPEG-2s I have and run it through myself.

rabbit

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Re: loss of detail
« Reply #6 on: March 25, 2012, 11:13:10 PM »
post processing is activated by default for mpeg2
Try disabling it

That was it. Turned off horizontal and vertical de-blocking and the problem went away.

Thanks.

 :)
« Last Edit: March 25, 2012, 11:14:47 PM by rabbit »

zakk

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Re: loss of detail
« Reply #7 on: March 26, 2012, 09:20:50 AM »
I'm VERY interested.
Does the post-processing have an effect on Avidemux window only, or on encoded video as well?

mean

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Re: loss of detail
« Reply #8 on: March 26, 2012, 09:29:37 AM »
encoded video also