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Apple HD Gallery quality playback

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George
Apple HD Gallery quality playback
on Mar 6, 2007 at 1:33:16 am

Clips from Apple's QuickTime HD Gallery play back smoothly on the desktop in my G5. http://www.apple.com/quicktime/guide/hd/

Clips I encode in compressor skip badly when played in QuickTime. I'm using the same settings shown in Quicktime Movie Info when playing HD Gallery clips.

How do I get the desktop playback quality of the HD Gallery clips? Can this be done in Compressor?

I'm shooting HD 1280x720p30 and trying to make desktop playable HD files from 640x360 to 1280x720, all 30p.

George
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Rich Rubasch
Re: Apple HD Gallery quality playback
on Mar 6, 2007 at 3:34:06 am

Are the Apple clips 23.98 fps by chance? Those extra 6 frames per second can make a big difference in playback and decompression.

Rich Rubasch
Tilt Media


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Charles Simonson
Re: Apple HD Gallery quality playback
on Mar 6, 2007 at 5:38:18 am

I wonder if the encoder you're using is dropping frames on encode? Is there any way you can post a small sample file that exhibits the playback issues?


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George
Re: Apple HD Gallery quality playback
on Mar 6, 2007 at 6:14:32 pm

I should have said "I'm shooting HDV 1280x720p30" Capturing in HDV or AIC codec in Final Cut Pro 5.1.2

Rich - Some of the files on HD Gallery are 24p. This file from NASA plays very smoothly and it is 30p. http://www.apple.com/quicktime/guide/hd/nasaspaceshuttle.html

Charles - Here is a link to a test file I have encoded as much like the NASA file as I know how to in Compressor. http://download.yousendit.com/778C8C7D6D2CA012

None of the traffic, pans, zooms or the Apple Engineering test animation should stick or hang. All play fine when laid back to tape. All of the frames are present when I scrub through the video in QT using the cursor keys, so they haven't been dropped in encoding.

I'm hoping to find out what they are doing differently on the videos that play back so smoothly.

George
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Rich Rubasch
Re: Apple HD Gallery quality playback
on Mar 7, 2007 at 12:30:35 am

Interesting.....I opened them both in cleaner and looked at the graph. Your clip has a much lower bitrate but does not contain audio. Both played back perfectly smooth but I'm on a MacBook Pro. Hmmm. I didn't see any appreciable difference between the two clips.

Perhaps duration between keyframes?

Rich Rubasch
Tilt Media


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George
Re: Apple HD Gallery quality playback
on Mar 7, 2007 at 6:25:54 pm

Rats! I posted the wrong clip. Try this one. http://download.yousendit.com/F577AE4C25EB66A1

I was shooting the Bill Clinton appearance in San Diego last night. Rushing around to get setup for that project. Sorry.

George
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Rich Rubasch
Re: Apple HD Gallery quality playback
on Mar 8, 2007 at 3:53:21 am

I get the old "you must log in to see the clip" mesage...

Rich


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George
Re: Apple HD Gallery quality playback
on Mar 8, 2007 at 7:18:26 am

This is going well, don't you think?

Posted again. I hope this link works better.

http://www.yousendit.com/download/T2djclVKTlFGOFEwTVE9PQ


George
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Rich Rubasch
Re: Apple HD Gallery quality playback
on Mar 10, 2007 at 4:22:48 pm

This time I get the "The person who sent you this is using the free version of YouSendIt and if they send files over 20 megs you must register to use the site."

Sorry...I may sign up someday, but not today. If you plan to use YouSendIt a lot in the future, go for a pay version and we won't have to register each time. Sorry to be a pain. I'd love to see the clip and see what's going on.

Rich Rubasch
Tilt Media


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George
Re: Apple HD Gallery quality playback
on Mar 11, 2007 at 10:03:41 pm

Thanks for getting back to me. That is the pay version, it just doesn't work as advertised. When I checked the link from my computer no log-on sceen came up. They must be auto logging so fast I don't even see a screen. I'll dump them.

I can post a mid size file to my ISP, but they don't allow over 15MB in one file, so no 1:1 version. I'll send you an email off the forum with the link (If a ton of people hit the link my web service will shut down) since you seem to still be interested inspite of yousendit.

Thanks

George
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Rich Rubasch
Re: Apple HD Gallery quality playback
on Mar 12, 2007 at 2:31:19 am

Ok, saw the file...interesting. The bit rate is lower than the NASA clip. I did see a skipping as you describe when I viewed the clip on the web site (it was fully downloaded when I viewed it), but when I played it after copying to the desktop it was perfect. Are you talking about playback off the web after loading or playback off the desktop?

I wonder if it is a streaming server issue....I cannot see, at least at first glance why the files would playback differently, except to say that the last movie you put up skipped exactly as you described ONLY when I played it in the Safari browser.....off the desktop it was perfect.

Rich Rubasch
Tilt Media


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George
Re: Apple HD Gallery quality playback
on Mar 12, 2007 at 4:46:20 pm

The data rates are just roughly matched. Minor changes in data rate seem to have no effect on the skipping. The Nasa 540p30 clip shows 1974.67 kbps in Movie Info from QT Player, my 540p30 clip shows 1896.1 kbps.

I see the skipping from an internal hard drive or from a server. Most of the 15 computers I have tested have played from internal hard drive and all skipped in almost eaxctly the same pattern on a given test file, except the MBPs.

Are you using your MacBook Pro? As I mentioned, the MBP skipped the least of any computer I tested. They still skipped some, but much less. According to Matrox, the best computer LCD monitor to use with their MXO Mac DVI output converter is the Apple 20" or 23", the only computer monitors with a 59.94 refresh rate, so they are the only computer monitors that will play skip free after you plug into their $1,000 box to make the external display skip free. Apparently the issue is the refresh rate clock inside of the monitor. If Apple put this technology in the MBP screen, that might explain it's better playback. I have also heard thay lose this advantage if viewed on an external DVI monitor.

Of course, the smoother screen display on an MBP doesn't make compressions from an MBP playback any smoother on other computers. Tried that. No soap.

What format is the source video you generally compress from? Do you compress from any progressive formats? I didn't notice objectionable skipping until I stared shooting progressive video.



George
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