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how to achieve the same quality as apple QT 720p trailers?

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peta zdepa
how to achieve the same quality as apple QT 720p trailers?
on Jan 15, 2008 at 12:36:08 pm

hi,

i cannot setup compressor or quicktime export to get good results below 20 mbps... i use h.264 codec, 1280x720 size (as apple in that trailers) - the original clips are from sony hdr-fx1

below 20mbps can be seen "jpg artefacts" while apple's picture at 7mbps is super clean..

whats wron? thanks!
FCstudio2.0


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Daniel Low
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 15, 2008 at 4:30:07 pm

This question gets asked a lot!

The one main reason that Apple has such great looking clips is that they have access to much higher quality source material than most people get access to. It's usually only a few steps away from the film source or is close to uncompressed 1080p 4:4:4, HDCAM SR etc.. If deinterlacing is necessary then they use the highest quality settings, not simply dropping or blending fields like most tend to do.

Next thing is that they are unlikely to use a simple QuickTime export. Compressor is probably used and I hear that they still use Autodesk cleaner for some tasks (cropping and scaling?). It's possible that they do some sort of segment re-encoding if necessary.

The guys working on these trailers are very experienced, know how to colour correct and generally make stuff look and sound great.

If you had access to much higher quality source than your Sony can output then you can get pretty close to the quality Apple get, using Compressor or Episode.


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peta zdepa
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 16, 2008 at 10:52:03 am

thanks for reply!

but..

i wanted to say that i want to retain original quality of my clip, not to improve them to apple trailer quality..

im talking about "jpeg" artefacts at 15mbps bitrate (which is not in my original clip) while their 6mbps clips are free of this artefacts..

really no solution?




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Daniel Low
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 16, 2008 at 11:04:57 am

Ah, OK.

An export from Quicktime is not the best transcode workflow. Compressor should give you good results, what settings have you tried?

Is your source 1080i or 720p?


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peta zdepa
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 16, 2008 at 12:37:07 pm

my source is 1080i, for export from fcp i use compressor, mov with h.264 codec, 1280x720, 25fps and the best result gives me bitrate 25mbps..

then six minutes gives about 1gb clip while (at thesame copressing quality) apples trailer would be 200mb size max



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Daniel Low
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 16, 2008 at 12:53:41 pm

In compressor......

What deinterlace settings are you using?

Are you using constant bitrate (CBR) or variable bitrate (VBR)?

What are your keyframe intervals?

The Apple 1080 trailers come in between 8 and 25Mb/s (Megabits) so your 720 transcodes should come in between 3 and 12Mb/s


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peta zdepa
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 16, 2008 at 1:00:34 pm

about deinterlacint got to make sure at home..

bitrate i set average "xx" and maximum "yy" so that is VBR i quess

keyframe every 0,5 sec



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Daniel Low
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 16, 2008 at 1:11:49 pm

OK,

Get back to us with the deinterlace and datarate settings.

Your keyframes setting should be somewhere between a keyframe every 5 to 10 seconds, not every half a second, (if that's what you mean by '0,5'?)


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peta zdepa
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 16, 2008 at 1:20:16 pm

the final export i have has average 20mbps and maximum 25mbsp - the most compressor alowed :)

keyframes: i thought the more often, the better



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Daniel Low
Re: how to achieve the same quality as apple QT 720p trailers?
on Jan 16, 2008 at 2:22:10 pm

Keyframes:

Most modern CODECs are perfectly good at inserting keyframes automatically. By setting a keyframe interval of 10 seconds all you are telling your transcoder is that you want to manually force a keyframe every 10 seconds, the codec will still insert it's own in between your manually forced ones.

Forcing more keyframes will actually hurt picture quality and, as you have found, encoding efficiency.

Remember that the 25Mb/s you are getting is actually a higher datarate than your source! (1280x720 HDV is 19Mb/s)


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