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Old May 15th, 2006, 02:25 AM   #1
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22 hour downconvert

I am downconverting a 2 hour long native HDV timeline (FCP) to SD MPEG2. Compressor states 22 hours (using the 120min./2pass preset.) Is there a quicker way to achieve the same result ?
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Old May 15th, 2006, 07:39 PM   #2
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That's exactly why I switched back to PC. My single G5 1.8GHz was too damn slow when it came to renders and transcoding. It annoyed the heck out of me. But compressor is notoriously inaccurate when it comes to estimating the time it takes to transcode.
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Old May 16th, 2006, 01:35 AM   #3
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This is on a G5 dual 2.0

And yes, the estimate was wrong. This took 28 hours.http://www.dvinfo.net/conf/images/attach/png.gif
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Old May 16th, 2006, 03:12 AM   #4
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maybe you should have just captured the HDV footage... probably would have been quicker.
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Old May 16th, 2006, 03:45 AM   #5
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Quote:
Originally Posted by Leo Pepingco
maybe you should have just captured the HDV footage... probably would have been quicker.
what are the schools of thought? native or intermediary?
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Old May 16th, 2006, 04:10 AM   #6
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Quote:
Originally Posted by Leo Pepingco
maybe you should have just captured the HDV footage... probably would have been quicker.
Meaning ???

--------

Listen to this. After 28 hours rendering using the 120min.SD preset in Compressor, video & audio files summes up 6 gigabytes. Way over the limit, making the files unusable.
I guess I could use some expert advice at this point.
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Old May 16th, 2006, 07:55 AM   #7
 
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First, if you're using HDV in FCS for SD delivery, my recommendation is to use the downconvert in-camera. IMO, nothing downconverts really well (currently) on the Apple front. Even if it did, the final resulting difference between a software downconvert and a cam/hardware downconvert are miniscule. Might as well capture as widescreen DV from the cam instead. You'll lose a tiny bit going from 4:1:1 (DV) to 4:2:0 (mpeg) but that too, isn't enough to warrant a 28 hour render difference on that particular machine, IMO.

Second, use a bitrate calculator to help you figure your final bitrate. That's very important if your final project is longer than one hour. Figure at least 5% in menu overhead as well. If you're REALLY close to size and don't want to reduce bitrate, consider converting the project to 24p and raising the bitrate. This may or may not work for you, depending on motion in your project. Little motion will look great in 24p. This will provide up to 25% more space for your media on the DVD.
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Old May 16th, 2006, 03:13 PM   #8
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Thanks. Turns out compressor did not calculate the bitrate that bad after all.
The audio file was a AIC 1GB something. My mistake. When compressed to dolby2, video and audio together is 4,328GB. Still when imported in DVD studio the size meter states 4.8GB. No menu, just a singel track.

Any ideas ?
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Old May 16th, 2006, 03:31 PM   #9
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Quote:
Originally Posted by Per Kristian Indrehus
Thanks. Turns out compressor did not calculate the bitrate that bad after all.
The audio file was a AIC 1GB something. My mistake. When compressed to dolby2, video and audio together is 4,328GB. Still when imported in DVD studio the size meter states 4.8GB. No menu, just a singel track.

Any ideas ?
You may be able to lower the bitrate for the Dolby but you'll need to get down to about 4.5 to have room for menus. Eeek.

Have you reviewed the video after the downconvert??? Are you satisfied with the quality? I did two test downconverts of HDV1080i to SD. One I downconverted to DV50 in FCP timeline, render, then submit to compressor. The other I submitted to compressor as HDV. I used high quality 60min 2-pass VBR for both and there werre no filters, transitions, or effects applied. I thought they both looked like crap. Total garbage. I'm convinced once again (as I was with the original compressor) that Compressor 2 blows.
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Old May 16th, 2006, 04:18 PM   #10
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I can do without menus on this. I can even live with inferior quality for the SD version, but the problem remains. How come 4,3GB reads 4,8 in DVD Studio. Seems to me that Compressor - whatever quality - has calculated a bitrate that should fit on a 4,7 DVD-R disk.
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Old May 20th, 2006, 03:40 AM   #11
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For others sharing the same problems. Here´s what I found.

1. The DVD size problem.
If DVDSP doesn´t get a proper Dolby2 file to work with, it just re-renders the file to something uncompressed, taking up a hole lot of DVD space.

2. HDV Downconvert
I ended up copying the HDV native sequence to a DV50 timeline in FCP. The render then took about 4 hours. I then exported directly from FCP to QT.mov
The DV50 file was imported into DVDSP so the render to MPEG2 took place there. I deleted the audio track and made a separate dolby2 file in compressor using the DV50 file export. With a two hour long program and a 4,0 bit-rate, motion artifacts certainly starts to appear. Apart from that the quality was good enough.

Note. When downconverting in the DV50 timeline a second layer didn´t show up right. It was a picture in picture thing and the second layer simply went off/outside the screen. Easy to overlook when everything else seems to be OK.
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