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AMA and H.264 format problems? What problems?

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Nick Griffin
AMA and H.264 format problems? What problems?
on Jan 25, 2013 at 8:16:52 pm

Here's my second set of newbie to Avid questions. Your indulgence and especially wisdom is appreciated.

I have been reading in this forum that it is unwise to edit using AMA-linked files and H.264 files and that they should be transcoded first. Admittedly I'm still playing around using some of my older shows and XDCam footage, but I haven't had any problems whatsoever. Is this something that was a problem prior to version 6.5 and now is no longer problematic? Is there a delay in responsiveness that I'm just not seeing in creating a mostly cuts and dissolves show? Is H.264 from a DSLR different, and therefore more buggy than the H.264 Codec I'm using to render out finished shows and now ingesting to play around with? What am I missing?

I've also been exporting segments edited from AMA-linked XDCam footage out to Quicktime files with no problem. In fact I ran a small test between exporting a timeline edited from XDCam footage and the same timeline edited using transcoded footage. To my surprise the transcoded footage created the export only about 8-10% faster than the native footage timeline. I was expecting much more. As Peggy Lee sang "Is that all there is?"

The one thing I did find irritating with AMA was accessing XDCam disks from the Sony PDW-U1 drive. Anytime there was a second or third video track access became an issue and real time playback wouldn't work. Is this kind of problem why transcoded footage is needed? My work-around has been to simply copy the footage from the disk to an un-used internal hard drive and AMA-link to that. Anything wrong with that? Seems to be working just fine for me.

Completely un-related, but hopefully someone can explain to me, when I move an XDCam file to the timeline it brings in audio, creating the 3rd audio track position. This happens even when I have the source selector turned off. Why and how can I stop it? Is there a way of eliminating the audio tracks from the source prior to importing into the timeline and so far I've just missed it?

Thanx in advance for any answers you can provide.


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Nick Griffin
Re: AMA and H.264 format problems? What problems?
on Jan 25, 2013 at 8:46:00 pm

OK, so most of Danielle's thread below on "AMA vs. Import" was in progress while I was composing my post above. That said, my questions remain the same. Editing AMA-linked files seems to be working just fine for me so what am I missing?


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Shane Ross
Re: AMA and H.264 format problems? What problems?
on Jan 25, 2013 at 9:24:28 pm

If you have small clips, and are editing short form things (under 10 min), things might go OK. This is far from optimal...but it will work. Longer H.264 clips choke the Avid, as well as longer projects.

Shane
Little Frog Post
Read my blog, Little Frog in High Def


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Michael Phillips
Re: AMA and H.264 format problems? What problems?
on Jan 25, 2013 at 10:51:16 pm

There's a tipping point as Shane points out that will be different based on code type, drive speed, drive connection speed, resolutions, etc. Native codecs have better performance than non-native. Native codecs can be seen when doing a transcode and you see the list of what you can transcode to. For example, ProRes has recently been made a native codec. Anything else is being managed by the plug-in that creates another layer to play through.

Add to that the need for multicam or not, etc. will usually drive a decision to transcode up front, or at the end. H.264 is not a native codec, and as a codec is CPU intensive, so don't expect a lot of "performance" with longer clips and bigger projects.

Michael


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Robert Ober
Re: AMA and H.264 format problems? What problems?
on Jan 30, 2013 at 8:24:48 pm

[Shane Ross] "If you have small clips, and are editing short form things (under 10 min), things might go OK. This is far from optimal...but it will work. Longer H.264 clips choke the Avid, as well as longer projects."

Yep,

But it is not just Avid and not just the native bit.

H.264, except for AVC Intra, is long gop. Most or all XDCAM using mpeq2 is long gop. Google it if you do not know about long gop.

Editing using a long gop codec increases the chance of having unwanted artifacts. I learned years ago from Philip Hodgetts ranting repeatedly on the Buzz about getting footage into an intraframe codec.

Y'all be cool,
Robert


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Neil Goodman
Re: AMA and H.264 format problems? What problems?
on Jan 28, 2013 at 10:32:56 pm

yup Shane and them hit it on the head.

For example i just did a 2 minute sizzle reel. All pro ress 422. About 3 hours of footage and 2 minute final cut. No big deal. AMA linked everything and started to cut. Only noticed slow downs after piling on a bunch of FX.

That worked.

Cut to this morning. New cards on my desk. 3 cam Multicam interview - DSLR all h264 12 minute takes.

Avid starts dropping frames and losing sync about 3 minutes into the first clip from cam a, just watching it in the source window at yellow/green res. Obviously i cant cut this whole interview in h264 as it wont be able to play even one of the clips back in entirety. So i will transcode it.

Some things like DVC PRO HD, Pro res 422, even XDCAM you can get away with it, but h264,mp4,uncompressed unless on the biggest baddest machine with the fastest storage available, your gonna want to to transcode.

Neil Goodman: Editor of New Media Production - NBC/Universal


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Miłosz Koziol
Re: AMA and H.264 format problems? What problems?
on Jan 29, 2013 at 10:54:07 pm

I cut a multicam weekly show (25+ min) on four XDCAM EX cameras and since I finish around 11 and broadcast is on 18 you can say Im on a tight timeline. And I do it entirely on AMA - sometimes I dont transcode - just render titles and send it do XDCAM deck via blackmagic ultrastudio (whole thing happens on laptop). Just tried to cut a 1:30 showreel on ama with multiple mp4 and h264 - a horrid experience - I had to do a rough cut - it was all on external firewire 400 disk but still - a XDCAM works quite well from that redundant drive. My point is - h264 is really tricky to work on in avid AMA... I wouldnt do that


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Michael Phillips
Re: AMA and H.264 format problems? What problems?
on Jan 29, 2013 at 11:51:25 pm

As long as the codec is part of the Avid native codec library, the performance is a lot better than going through the "frame provider" or whatever it's called going through QuickTime to do the decode. You can see what those codecs are when you do a consolidate or transcode - the list is part of the menu selection. H.264 is not one of them.

Michael


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Paul Harrington
Re: AMA and H.264 format problems? What problems?
on Feb 1, 2013 at 4:35:31 am

Same here AMA works well with XDCAM, but H264 is a pain.Just completed a job with 12 hours of 5D vision. Importing into Avid was taking hours. But Adobe Media Encoder transcodes and rewraps into a XDCAM50 .mxf file faster than real time on 1080P vision. A huge timesaver....


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