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where can I learn about keeping compression settings within standards?

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Andy Engelkemier
where can I learn about keeping compression settings within standards?
on Feb 8, 2012 at 1:00:32 pm

I end up having to use WMV mostly because people want to be able to throw a video in powerpoint. I'll create a clip using the standard WMV 720p30 setting, then someone just wants it smaller. Ok, so I adjust the bitrate down to something that still looks "good enough", adjust the audio down since my starting audio probably wasn't that great anyway, and compress.

Sometimes the files play well, and sometimes they don't work at all. I have similar problems with mp4 format.

Is there a book I can read or a class I can take? It seems like trial and error. And often times something works on my computer, but not others....with the Same format, but Slightly changing a couple numbers.

This definitely seems to be something I should be an expert on, but I am probably only an novice at best.

Any suggestions?


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Craig Seeman
Re: where can I learn about keeping compression settings within standards?
on Feb 8, 2012 at 2:54:11 pm

A great site for learning
http://www.streaminglearningcenter.com/
And the excellent book he wrote
http://www.streaminglearningcenter.com/video-compression-for-flash-apple-de...

To target accurately you MUST know as much about the playback equipment. There's no magic bullet solution unless you go to a poor quality lowest common denominator. An old Pentium 4 is going to be very different than an i7 Quad Core with a good GPU and then figuring a good bit per pixel relative to frame size and frame rate of the target is important as well.



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Andy Engelkemier
Re: where can I learn about keeping compression settings within standards?
on Feb 8, 2012 at 3:28:16 pm

looks like a useful site.

What I'm trying to learn is why doing something like changing nothing but the bitrate on the audio and video lower will make the same file not play back.

The type of information I'm finding though, is more related to when you can move up/down in bitrate and what quality is acceptable.

Sometimes I'm already below what we want in terms of quality, so all I want to do is make sure it's under a certain file size so it can be emailed. That's usually the request. This last time I had a several minute video and I was just trying to make it as reasonably small as I could so I could send review files.


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Craig Seeman
Re: where can I learn about keeping compression settings within standards?
on Feb 8, 2012 at 3:34:43 pm

[Andy Engelkemier] "What I'm trying to learn is why doing something like changing nothing but the bitrate on the audio and video lower will make the same file not play back. "

Lowering the bit rate won't make the file not play back. You have another problem if that's happening. This is assuming you're using the same computer. If the computer changes, your target changes. If stuff on the computer is using the resources simultaneously, your target changes.



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Bill Hall
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 3:40:36 pm

If you push the bitrate too high you may have issues with playback. Some computers won't have the required power to play them back. Also if the bit rate is too high it may have playback issues over a network because you are sending too much information.

As Craig said lowering the bit rate won't make a file not play back.


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Andy Engelkemier
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 3:51:11 pm

Ugh, It must be a problem with Adobe Media Encoder then.
Because I saved 10 files, just to confirm what you guys are saying. I started at 720p30 HQ preset on WMV and continually lowered the bitrate setting.
Wouldn't you know it, 2 of them wouldn't play back.

I agree, simply lowering the settings doesn't necessarily make a file not play back, but that doesn't mean at certain specific bitrates it may cause some ugly math and make it not play back. That's what I was trying to find out.

It seems though, that the information that is out there is either So technical that I don't want to bother with trying to understand it, or it's so simplistic that it doesn't help. I've got all the basic concepts down. It's what to do when something strange like this goes on that I have troubles with.


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Bill Hall
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 5:52:33 pm

So what are the bit rates you're talking about? Is it something ridiculous like 10 kbps? Also you may want to adjust the frame size as you lower the bit rate.


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Andy Engelkemier
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 6:00:23 pm

No, really low for 720p30, but not terrible.

Somewhere between 500-1000kbps is where it likes to fail.
The odd thing is, if I lower it just a little more, sometimes it ends up playing back fine. Also in different players it may/may not play.

I need to make sure anything I give someone ends up working in powerpoint (ugh). But usually they also want an emailable file. So if the file is 3 minutes long, and our limit is 8MB it can get a little problematic. Doable, but the quality starts to suffer.


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Bill Hall
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 6:09:56 pm

I'm not familiar with Adobe Media encoder. What version of the WMV codec does it's preset use? I know that if you use the WMV-9 advanced profile you must have windows media 12.

Also if you are lowering the bit rate to 500 kbps there is no reason to leave it 720P. This should give you an idea of what frame size to use http://www.streaminglearningcenter.com/blogs/the-essential-key-to-producing...


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Andy Engelkemier
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 6:22:50 pm

good to know the advanced profile is only 12. But I do have 12. I haven't been using the advanced profile either.

I agree, 500 is a bit low for anything moving at a decent speed on 1280x720, but I'm already reducing their originals from 1920x1080, so any further and they'll notice it.

Unfortunately it's pretty impossible to dummy proof. One guy will open it in VLC, the next guy will double click to open it and only has the default, and another might try and open it on a Mac and doesn't know anything other than quicktime exists. Well that's rare in the corporate world so I chose to ignore the last one. ;) If you're in a corporation and insist on using a Mac then you better learn how to convert things for compatibility on your own right?

And the reason I use media encoder is to save time and space. You can render premiere and afterEffects file without having to render uncompressed first, otherwise I might see about getting Squeeze.


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Bill Hall
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 6:32:13 pm

They most likely will not notice a reduction in frame size. The apparent video quality will be higher because you will have more information for less pixels.

Are you using WMV 9 or WMV 8 or WMV 7? Those are the most common underlying codecs for a WMV file. If you are using 9 try using 8 instead. Sometimes it takes a bit of trial and error. Although 9 should work.

Tell the Mac guy about Flip4Mac to playback the WMV.


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Andy Engelkemier
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 6:47:13 pm

I tried changing the frame size and they noticed immediately. If I am able to create the powerpoint, I agree because then I can just scale it. In fact, half of the video I'm working on now was recorded at 480i and I have it stretched up to 720 and no one noticed.

Now if you have some trick that I can save it at something smaller like 480x960 then have the codec tell the player what size to stretch too, I'm all ears. The only time I've gotten away with that is by providing the slide, or embedding it in a webpage For them. Something like that. When the deliverable is a straight video I'm stuck with the size they ask for. I've already told them they won't notice a quality change from 1080 to 720. 90% of the time I wouldn't even notice on a large screen either unless they are played back to back.

I'll give the profile 8 a try next time and see how that fairs at lower bitrates. If they don't care about size I just check the 720p HQ and render. Done! Sure it's a 500MB presentation, but that's why you have that 3TB hard drive on your desk. haha


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Bill Hall
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 7:09:46 pm

Ok. It's not a profile it's a different codec. If you don't care about size why do you keep lowering the bit rate?


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Andy Engelkemier
Re: where can I learn about keeping compression settings within standards?
on Feb 17, 2012 at 7:25:41 pm

Oops, mistype. Thanks for the correction on profile. It's confusing because it says "advanced profile" for 9-advanced. I know they are different codecs though.

And that should have been written, When they don't care about size. Occasionally they don't, so I give them high quality. I usually take it down a little bit just to make sure it's not so insanely high that their drives can't keep up. Plus, in case someone plays it off of a network drive then it needs to keep up too. But I've found the preset for 720p HQ works great in those cases. The audio is usually way overkill for what I've got, but I'd rather not mess anything up since it's seems finicky sometimes.

I'm more concerned about the Premiere bug I've just encountered now though.


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