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AVCHD Format Discussion
Inexpensive High Definition H.264 encoding to DVD, Hard Disc or SD Card.


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Old August 8th, 2006, 09:52 AM   #1
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H.264 issues...

Just curious if any of you know a little about this codec and how it works...

In order to match the quality of the trailers on the apple web site, I need to save my video with the quality slider set for 90%, but the file size is ridiculous, and in order to match there file sizes... i need to save at 40% but all the picture quality is out the window.

How do they manage to pull this off?
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Old August 8th, 2006, 10:08 AM   #2
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I've had the same issue, and have had an easier time going out with a .wmv file.

One of the things I've seen recommended is to add saturation to your original project to get a more saturated color in the H.264 render.

Also, a lot of these films are actually running at 15 fps, to reduce file size.
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Old August 8th, 2006, 10:24 AM   #3
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15 fps, that totally makes sense, never even thought of it. Reducing an entire 9-10 fps is huge when the total is 24, i think that would certainly allow for much higher image quality.

added note - I just checked a quicktime HD h.264 trailer (texas chainsaw massacre - the beginning), running 1280x688, believe it or not, it's 24 frames a second right on the money...

I'd love to know how they keep 24 frames a second, near perfect image and sound, and being 2 minutes and 53 seconds. at a measly 106mb....

it's all in the picture, becuase you can get away with a 4 mb sound file for a trailer that short...
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Old August 8th, 2006, 10:38 AM   #4
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Well, actually I thought frame rate would make a big difference to filesize too, but it didn't!!! Honest. I encoded the clip in H.264 shown here originally at 12.5fps (it was PAL originally) and it looked pretty rough. So I re-encoded it at 25fps, and it was much smoother - and practically the same size!. Also: they were both only 2.7MBytes per minute!
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Old August 8th, 2006, 10:47 AM   #5
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Quote:
Originally Posted by Curtis Bouvier
In order to match the quality of the trailers on the apple web site, I need to save my video with the quality slider set for 90%, but the file size is ridiculous, and in order to match there file sizes... i need to save at 40% but all the picture quality is out the window.

How do they manage to pull this off?
If you want to match a certain file size, then the secret is to look to the data rate. I've got an Apple HD H.264 trailer open right now. The duration is 2:24 at a data rate of 822 KB (kilobytes, not kilobits) per second, for a total size of 115MB.
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Old August 8th, 2006, 10:59 AM   #6
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Anyone have another recommendation on resolving the "washed out" look ?
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Old August 8th, 2006, 11:00 AM   #7
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One other factor here is keyframing interval. According to my FCP manual regarding output, a lot of the suggested keyframe rates are outdated. They recommend pushing it out to as much as every 300 frames if there isn't much motion. Also, the use of compression markers can help where you have transitions (ie a lot of pixels changing every frame) and other high motion areas. Compression markers force the encoder to create only I frames in that area before resuming the GOP structure.

There are people these days who's job title is 'Compressionist'. They analyze every frame and compress accordingly to maximize quality/filesize ratio. I suspect they are involved in creating these movie trailers on the Apple site.

By setting only a quality slider, most of us are applying a one size fits all approach to compression which helps in some areas and hurts in others.


my .02 worth,

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Old August 8th, 2006, 11:05 AM   #8
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theres no options to do anything, you cant even configure the codec....

You'd think it would have a $$$tload of options like Divx pro does lol.. but Divx is done with.

all there is, is a crummy slider bar that doesnt really do anything.

I'd limit the data rate, but I can't even select it. It's unavailable to use.

maybe theres a full version of the codec you need for "encoding" work???

and we all simpley have the viewing codec...

Kind of like having divx, and not divx pro with all the encoding options.
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Old August 8th, 2006, 11:14 AM   #9
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Yeah Curtis, it might require purchasing a stand alone H.264 encoder. I have a freeware program called Super on my Wintel machine that allows for many settings of the encoder. Might want to Google for it.

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Old August 8th, 2006, 11:19 AM   #10
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Quicktime Pro as an H.264 encoder???? (Also available for Windows!) :D
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Old August 8th, 2006, 11:54 AM   #11
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Greg.

I would have to agree completely about key framing, it's the only possible explanation for the quality vs file size.

One thing I noticed about the trailers, is where area's are very dark, that part of the picture is completely removed, and it absolute black with no flicker of any kind. and you can sorta see where it meets with the actual picture.

OR that could be an actual post production technique they used for the film to eliminate heavy film grain in dark area's.... either way it doesnt look bad at all.

But this calls for some research, and I would like to have this encoding business down pat for when I get my Canon H1. I can't see Key framing being very hard.. it would just take a little practice, and I would probably need a program made specifically for encoding, rather than using the generic adobe premier pro one.
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Old August 8th, 2006, 12:43 PM   #12
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Quote:
Originally Posted by Curtis Bouvier
But this calls for some research, and I would like to have this encoding business down pat for when I get my Canon H1. I can't see Key framing being very hard.. it would just take a little practice, and I would probably need a program made specifically for encoding, rather than using the generic adobe premier pro one.
You are using Premiere Pro? Then you can set both the bit rate and the key frame distance when encoding H.264 QuickTime files in the Adobe Media Encoder.
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Old August 8th, 2006, 12:48 PM   #13
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Quote:
Originally Posted by Chris Barcellos
Anyone have another recommendation on resolving the "washed out" look ?
You might want to check out this topic: H.264 Brightness / Contrast issue...
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Old August 8th, 2006, 02:28 PM   #14
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Quote:
Originally Posted by Christopher Lefchik
You might want to check out this topic: H.264 Brightness / Contrast issue...
Thanks. I'm getting updates on that thread via email, so I can be the first to know when you brains have this figured out.
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Old August 16th, 2006, 02:31 AM   #15
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Martin asked-
[Quicktime Pro as an H.264 encoder???? ]

Since version 7.0.3. Currently it's 7.1.x. It's great. IMHO, WMV can't touch it. Totally scalable from HD to iChat conference to celphone screen.

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