macroblocking issues with h.264 encoding

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spacedog
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macroblocking issues with h.264 encoding

Post by spacedog » Sun Mar 09, 2014 8:13 am

I have a source video that is 1920 x 1080 in WMV format. I need to convert it to MP4 in h.264 so it plays properly in web browsers and on iOS devices.

The video is basically a slideshow style presentation with lots of pictures cross-fading into each other. During the cross-fades I am seeing lots of macroblocking / pixelation. I have tried upping the bitrate to 5000 and i still some blocking occurring.

Interestingly enough, I tried transcoding the video using VLC and I ended up with a file that was 30mb, looked crystal clear, and had no macroblocking. Unfortunately, there is something with that transcode from VLC that makes the video incompatible with iOS devices and it won't play in Chrome either. The video will play fine when loaded into Windows Media Player and VLC,though.

So why cannot I get Mediacoder to give me a clean transcode with no blocking? I have checked h.264 and the deblocking loop filter is enabled. I have tried encoding using CUDA or my CPU. I have set the encode speed down to placebo level and still, not much improvement.

I am using Mediacoder x64 0.8.28.5588 on Windows 7 with an i5 haswelll processor and 16gb of RAM.

meRobs
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Re: macroblocking issues with h.264 encoding

Post by meRobs » Sun Mar 09, 2014 8:47 am

I have not seen this problem before at such a high bitrate, especially with H.264 (x264).
However, there are a number of Guides that may help. They are listed under Tips & Guides (link below).
For example, there is one on 'Encoding to H.264' (in MP4) and one on 'MediaCoder for YouTube' (format suits iOS) and, of course, the 'Encoding Guide'..
Have you checked out the Tips & Guides for MediaCoder? Try: http://forum.mediacoderhq.com/viewtopic.php?f=17&t=8061
Also, get older builds at: http://www.videohelp.com/tools/MediaCoder/old-versions#download

Valagard
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Re: macroblocking issues with h.264 encoding

Post by Valagard » Mon Mar 24, 2014 8:04 am

Unfortunately when it comes to x264 there is really no quick fix

That said, if this helps, try my x264 settings, its the best possible settings I managed to wring out of out it using mediacoders UI

http://www.filedropper.com/mainelineand ... stasneeded

flagpole
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Re: macroblocking issues with h.264 encoding

Post by flagpole » Wed Mar 26, 2014 9:00 pm

if you are getting macroblocking on the transitions it sounds like you are using a constant bitrate encoding method.

any chance you could chuck over the file so we can have a go.

x264, with a decent profile, is usually very good at that sort of thing. it has clever bidirectional methods.
my quant puzzles http://puzzles.nigelcoldwell.co.uk go look :)

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