Pixelation playing back mp4 files


New Member
Interesting one this...

Playing back .mp4 files created using XVid4PSP and at certain points which seem to correspond to high sound levels (especially high frequency treble) and the video has a burst of pixelation.

Was first noticed on action films where there are explosions/gunshots/sword fights but was also quite apparent on the film Rock of Ages (wife watches it a lot, so thought I'd put it on the external drive to play through the hummy to save her getting the dvd out all the time)

The files play back perfectly on a PC using FLV player.

Any ideas?
It may be more to do with high levels of action rather than high levels of sound, I would think that the Humax can't cope with every pixel on the screen changing at the same time, are the movies encoded at high resolution ? e.g. large format
I also thought this could be the case, but with it happening on Rock of Ages, with little movement on screen and also thinking back to other films where for example there is a clash of swords but actually little changing on screen I don't think this is what's happening.

The movies are encoded to their native 1920*1080p H264, the audio is encoded using the AC3 CBR 640kbps MultiChannel preset in XVid4PSP as the DTS won't play back on the Humax.
It is possible that the conversion is at fault given that the program you are using is a beta. I haven't used this myself but I would suggest trying to encode using another program and comparing the results. ;)
The files play back perfectly on a PC though using FLV player which made me think it must be the Humax.

Is there a program you would recommend?
Thanks, I have used Handbrake for converting files to my sons tablet, however the reason I was using XVid4PSP is that you can just have the video as a direct copy since it doesn't actually need re-encoding. I can imagine running Handbrake for a Blu-Ray sized .mkv file in full hd would take a very long time, unless I'm missing something?

I may try it, just to see if it has the same issue but since the PC can play the files without a problem I can't see it being the file as such at fault?
Are you using XVid4PSP to convert from mkv? If so, a couple of suggestions:
1) try setting the audio to recode to AAC-LC ABR 192k. AC3 sound is not an mp4 'standard'; also recoding the audio normalises out any peaks. It adds a little to the time, but not like recoding the video.
2) instead of XVid4PSP, try GotSent. Set it to normalise audio and use safe sync. It's not as pretty as XVid4PSP, but it's quicker.
I also use Handbrake and have had no problems. I have had issues in the past with a number of videos not playing correctly on the Hummy even though they play perfectly on my PC (and phone) and put it down to the codecs. You could also try Avidemux which I also use.