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Julian Frost August 23rd, 2008 11:23 PM

Rendering Thru Adobe Media Encoder & File Sizes
I've output a short 4 minute clip through PPro's Adobe Media Encoder at 1440x817 pixels (approximately 2.35:1). I then output the same clip through AME at 720x408 pixels. Both files were identical in size, which surprises me... shouldn't there be half as much data in the lower resolution file? There isn't, so obviously I'm missing something!

Paul Firth August 24th, 2008 06:20 AM

What codec are you using for rendering? Most likely, you are using a compressed codec like MPEG/MP4 and have set the data rate in the encoder to the same rate for both files. Adobe Media Encoder doesn't care what size the final image is in pixels--the compressor will decrease it down to the size you specify.

If you want files of different sizes, you will need to render them to an uncompressed format (Quicktime Animation or Microsoft AVI uncompressed), but that is really not necessary.

As for the 2 video sizes you specified, the second one can be rendered at about 1/4 the quality as the large one and still get the same apparent quality. Find a data rate that works well for the larger video, then try a data rate about 25% of that on the smaller one and see how you like it.

Julian Frost August 24th, 2008 12:13 PM

Thanks Paul. I think you're absolutely correct. I was using MPEG2 as my compression codec and had all the settings left the same between renders for the two aspect ratio tests.

I ran a couple of new tests this morning using different quality settings and the results were as you described. As far as selecting quality settings and data rates are concerned, is there a guide as to the settings which should be used for different delivery options (web, DVD etc)? For the specific footage I'm using for this test, the resulting MPEG2 files look decent at really low quality and bit-rate settings, but if there's a reason to use higher (or lower) settings due to the specific destination for the file, I'd like to know.

Paul Firth August 25th, 2008 06:07 AM

No--as far as I know, the only reason to use higher compression settings is for quality. If a lower setting has good quality to your eyes, go ahead and use it. One thing to remember, though, is that if you are wanting to output 2.35:1 on DVD, then export it to 720x480 widescreen. Media Encoder will add the black bars on top and bottom. Data rates between 5-6 Mbps will usually produce very good results at that resolution, but I've had many projects that looked fine at 4 if you use 2-pass VBR.

Julian Frost August 25th, 2008 01:01 PM

Thanks again, Paul. I start my weekend tomorrow and will be playing around with lights, camera and (I hope) some action. I'll try rendering some footage and burning it to DVD to see how it looks with different bit-rate and quality settings. I've stayed away from AME in the past as I've not been happy with the quality, especially burning direct to DVD. My work flow has mainly been to frameserve to TMPGEnc Xpress and import the MPG2 file into Encore and create the DVD there. It'll be interesting to see the differences between rendering through AME and TMPGEnc.

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