MP4 export gives blurry frame every 30 frames.

PaPa

PaPa

Major Contributor
Hey gang,

hopefully i can get someone's help here. I've just finished 4 hours of exporting to get my 22 minute short film as an mp4 file
I've had the same settings forever and this time around ( i've tried twice ) I get a really blurry/pulsating frame approximately every second to 2 seconds.

I don't have an example at the moment because to upload the file would use 500 mb of bandwidth, but if no one can think of what's going on then i'll extract only a clip of it to upload online and show yall.

i use premiere pro cs4 and i export to media encoder.

Then i select mp4, with 23.976 fps, 1920x1080, VBR between 3-4 mbps. Normally this gives me pleasing results... this time,,, strangeness.
 
Yes the pulse is noticeable.

Mainconcept's AVC encoder often does this - it has poor rate control and bitrate distribution. There is a big discrepancy between frame quality between I:P and P:B ratios, hence the "bump"

Because of the encode you uploaded, Youtube's encoder needs to work harder to encode the difference between frames, so overall quality is reduced. You can see in this upload of 720p version of subsequent frames, the "low" quality frame actually requires much larger coded frame size (because it's so much different than the other frames). If you examined the AME export, this is probably a I-P transition point and a fixed keyframe interval
http://www.mediafire.com/?ttx1g4m2c1k2xbj

You should use a higher bitrate (3-4Mbps isn't that much for 1080p24), or better encoder like x264
 
essentially, these are the settings i use to export, and i have never really changed them, as far as i can tell. So im confused why now there is this pulsing:

exportscreenshot.jpg
 
you think it's the bit rate?? That would definitely make sense. Where should i keep it approximately? I just don't want to upload a 2 gig file. lol

Would it dramatically reduce the file size if i did only 720 with higher bit rate?
 
Low bitrate is part of the problem, but the bundled encoder isn't very good either

3Mb/s for 1080p ? LOL

Think, your average blu-ray 1080p24 is ~25-30Mb/s . 3Mb/s is going to produce garbage even with a good encoder. You're using about 1/10 of what you should be.

For 1080p content like yours (slow, drama like, no action sequences), you would need >10Mb/s for mediocre quality, probably more if you are using AME

And if YT is your end goal, it's going to reduce the quality even more


Would it dramatically reduce the file size if i did only 720 with higher bit rate?
Click to expand...

Nope

Filesize = Bitrate x Running Time

Notice resolution has nothing to do with the filesize (but you need higher bitrates to maintain a certain level of "quality" for higher resolutions)

Bitrate and running time are the only determinants of filesize
 
hmmm.

what would you recommend to export some nice qualiyt footage.

and while im at it, since you seem like a little bit of a pro. I'm going to whore your brain for a moment.

I need to export this project to have

1) a master backup
2) DVD quality burn
3) Bluray quality burn
4) quality online viewing.

What would your recommendations be for exporting and encoding?

Thanks for your time and information PDR!
 
PaPa said:
hmmm.

what would you recommend to export some nice qualiyt footage.

and while im at it, since you seem like a little bit of a pro. I'm going to whore your brain for a moment.

I need to export this project to have

1) a master backup
2) DVD quality burn
3) Bluray quality burn
4) quality online viewing.

What would your recommendations be for exporting and encoding?

Thanks for your time and information PDR!
Click to expand...




This is a big topic, and your question is so generic. If you're looking for a push button solution, you're not going to find it . There is a lot more to high quality than just encoding settings. Pre-processing usually plays a large role.



Master backup archive implies lossless, so I would use RGB lossless format like lagarith (huge filesizes) . If you don't mind a bit of quality loss use something like cineform neoscene (Y'CbCr 4:2:2), but still huge filesizes, but less than RGB

AME 's MPEG2 encoder from mainconcept is OK for DVD , but the scaling algorithm used by AME isn't very sharp (uses bicubic). This might be ok for for your purposes, or it might not be. A better MPEG2 encoder is CCE, but not free . Interlaced scaling is completely FUBAR in AME, so don't do it. You can do a search, this is discussed in various forums. Workarounds are in avisynth or virtualdub. A bit of a learning curve for avisynth

Blu-ray AVC encoder in AME is not very good at all. Very weak on gradients, shadow regions because lack of adaptive quantization. It's blu-ray MPEG2 encoder is actually better in this regard, but worse in other (macroblocking, noisier, other artifacts). But if you use high enough bitrates on low complexity material it can look passable. I would use x264 and it's free. A bit of a learning curve on using x264 . Pre-processing is important, things like dithering are essential to improve gradient banding, and with blu-ray you have high enough bitrates to allow for it

Online viewing depends on what format. If you're using something like youtube or vimeo, they re-encode everything at a low bitrate, so you are at their mercy. You have to optimize your uploads for encoding with this in mind (so for example, they won't hold a dither and you will get more banding) . This includes denoising, stabilizing footage . If you're using your own hosting or CDN, you have many more options and can customize your footage more appropriately


Your question is too generic for any specific suggestions
 
kk, i'll get more specifics tonight when i open up my program and message you then.

Sorry for my ignorance on this topic. I'm sure you can understand that this is a whole other side of filmmaking that not too many bother investigating and look for the magic button, but I do appreciate your help very much.
 
I always use a dithering method of pre-processing on any footage I downsample to 4:2:0 colorspace. It helps to remove banding. It make a huge difference when exporting to sharing sites like Youtube:



Check out this clip I fixed up for a client:
His version out of Apple Compressor: http://www.youtube.com/watch?v=3qVwhnWrOEI&feature=player_detailpage#t=10s

amy-unfiltered.jpg




My frame cleaned up: http://www.youtube.com/watch?v=PE2GK-fjdes&feature=player_detailpage

amy-filtered.jpg


Watch in 720P.

Keep in mind that he changed the color correction slightly, and it's not a result of my pre-processing.
 
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