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Poor video playback via broadcast output
When playing long files (1 min or longer) the video stutters on fast horizontal pans. This timeline does not require rendering and media is optimized. Prefs set to “better performance”. This is not dropping frames. The video stutters for a few seconds and then seems to “catch up” and play normally. This is with a Blackmagic Design Decklink HD Extreme 3D card. Also audio glitches when you first starts to play the timeline.
This all seems like the software is giving priority to the UI and then the broadcast output signal to the card is secondary. Definitely not reliable and in no way acceptable. It may be Apple’s way of correcting video refresh to prevent horizontal tearing. It doesn’t seem that playback through broadcast output hardware is as solid as it is with other apps. Probably the signal is simply being passed off through the OS to the card and never really “locked”. This video definitely would never pass QC is you tried to record a live output from the card. I guess that’s why Apple calls it “monitoring” and not “output”. It really seems like Apple added this as an afterthought to appease the complaints. Pretty embarrassing to constantly have to make excuses to the client in the room.
Media is ProResHQ 23.98fps. Fast RAID for storage. Same clips play fine on the same hardware using FCP 7, Premiere Pro CS6 and Avid Media Composer. Mac Pro 12-core, 32GB RAM, ATI 5870, Fibre Channel SAN and local RAID storage.
– Oliver
Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com -
50 Replies
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Does setting it to Better Playback not fix it? I
John Davidson | President / Creative Director | Magic Feather Inc.
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And what are your bmd settings? 23.98 I’d hope.
I have identical playback through my bmd ultrastudio express. Analog and SDI scopes on the FSI are exactly the same whether X or 7. Well, more rt from X but rendered quality is the same.
My guess is they call it monitoring because that’s how Apple sees it now. If they called it output they get grief that there’s no tape control. Output to them is a file.
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What was the camera original source? The horizontal stuttering can be artifact of CMOS sensors. In other words, it may not be FCPX, but rather baked into the footage.
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No. It’s been running that way the whole time. I tried it both ways. No difference.
– Oliver
Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com -
[Bret Williams] “And what are your bmd settings? 23.98 I’d hope. “
Yes. This is not a settings issue, because it happens in the middle of playing a clip or a timeline. Occasionally stutters and then corrects itself. Source media is ProResHQ 1920×1080 23.98. Output is from the card via SDI to a TV Logic and HDMI to a Panasonic plasma. BTW – 29.97 projects aren’t especially better.
[Bret Williams] “My guess is they call it monitoring because that’s how Apple sees it now.”
As far as I’m concerned, it was an afterthought at Apple and simply accomplished through an OS hack. There is no direct interaction with the hardware or an abstraction layer. Simply the OS handing off A/V to the driver of the card. A more sophisticated version of desktop display of the video. AJA may handle this better than BMD and the T-bolt devices better, yet. I don’t care. It’s unprofessional as it currently stands. On the plus side, the Apple solution tends to be more in sync between the viewer and the output (when it’s right) than with FCP 7.
The other interesting part is the audio glitches. These happen in the first few seconds of a sequence. Right after I start to play (J key or space bar). It often happens at connecting points, though that might be coincidence.
– Oliver
Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com -
[Michael Hadley] “The horizontal stuttering can be artifact of CMOS sensors.”
Not the case here. Most of the source media is from a C300 and 5DMk3 converted externally to ProResHQ using FCP 7 L&T by the DIT. Other sources are ProRes4444 direct from an Alexa. The stuttering is an intermittent playback issue and has nothing to do with the camera source. I can play it fine in FCP 7 with all the same hardware and settings.
– Oliver
Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com -
To make matters worse, as I focus in on the audio, I now hear little audio ticks in the background ambience. It’s like the little crackles you get from sample rate mismatches. I had this before with FCP X with media recorded on a Sound Devices PIX 240 and at the time blamed the recorder. Went through a round of troubleshooting with Apple to no avail.
That recorder isn’t a factor on this job and I’m hearing it again. The audio sounds clean in other apps (like FCP 7) but has the random crackles in FCP X. If I were to export the audio the ticks would be baked in. In this case, I’ll relink in FCP 7 and export an OMF, so I’m OK. But clearly the problem is inside FCP X.
Maybe X cannot properly resolve the sample rates on 23.98 (23.976) media files. Or at least ones converted through external sources rather than native camera media. Frankly I don’t care, since this is the second time I’ve been burned. Arghh!!!
– Oliver
Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com -
Did this just start happening or is this a new phenomenon?
My Kona3 does not display this kind of movement. I don’t know if that has any impact, Aja va BMD.
I assume you have the latest BMD drivers? There’s a new build from a few weeks ago.
As far as Apple putting this in to appease, isn’t this what AVFoundation and the “core” layers were built for?
I don’t know. I could be just a bad driver install as I don’t see these problems unless there’s a specific underrun due to a lack of resources/need to render.
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[Jeremy Garchow] “Did this just start happening or is this a new phenomenon?”
No, it’s always done this, but seems to be worse on this job. I think it’s related to the amount of media. Over 1TB, over 800 clips and nearly all ProResHQ. I think that’s about the limit of what X can effectively deal with. Although I have a low tolerance for buggy, glitchy software.
[Jeremy Garchow] “I assume you have the latest BMD drivers?”
Yes.
[Jeremy Garchow] “isn’t this what AVFoundation and the “core” layers were built for?”
I doubt it. It’s a media architecture that replaces QT. It lets the OS deal with things like H264 in a native fashion. I doubt it has anything to do with hardware interaction like a hardware abstraction layer or actual direct hooks.
Rant to follow….
However, I see similar issues without any cards on various machines, so I tend to think it’s how X interacts with the whole graphics subsystem, such as the display card by itself or in tandem with broadcast cards.
Basically, my entire experience since day 1 with X is that smooth playback with zero visual anomalies – like stuttering, the appearance of dropped frames (but not from hard driver performance) – has been problematic and not yet addressed by Apple. I tend to get the feeling that the system is optimized for H264 and little else, regardless about ProRes, etc.
I hate to invoke the iMovie reference, but that’s what this all feels like. The under-the-hook architecture had the same target – H264, MP4, etc. Everything else is bolted on. I also think some of this is directly related to skimming. Not whether it’s on or off, but rather the technology that makes it possible, also makes it harder to solidly pass video through the system.
And please don’t bring up iMacs versus Mac Pros. As one can see by the various discussion threads on forums about the latest iMacs and FCP X performance, it appears Apple’s QA was subpar on that one. I don’t see any better performance on iMacs than Mac Pros with these issues that I’m complaining about. It all seems to boil down to how well – or not – the OpenCL implementation is. At least that’s what it feels like, since performance with a Quadro 4000 (not a qualified OpenCL card) is significantly worse.
Sorry about being so negative, but I’m starting to give up on this ever getting better.
– Oliver
Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com -
[Oliver Peters] “No, it’s always done this, but seems to be worse on this job. I think it’s related to the amount of media. Over 1TB, over 800 clips and nearly all ProResHQ. I think that’s about the limit of what X can effectively deal with. Although I have a low tolerance for buggy, glitchy software.”
You certainly could have fooled me! What is weird is that I find video out in fcpx to be better than Pr. I have much more issues in Pr but I attribute it to aging computers with no CUDA based GPU. I frequently has to change to 1/2 res on 1080 video out in Pr. I keep everything at best quality in X and it works pretty well.
[Oliver Peters] “I doubt it. It’s a media architecture that replaces QT. It lets the OS deal with things like H264 in a native fashion. I doubt it has anything to do with hardware interaction like a hardware abstraction layer or actual direct hooks.”
Perhaps, but Apple has their own reasons to have a hardware based output system for iTunes/AirPlay/etc. Most of their new computers have hdmi ports right on them. While it might be for streaming or h264 based downloads, it’s still 709 video.
AVFoundation is relatively new, starting on 10.7 on the OSX side.
[Oliver Peters] “Rant to follow….”
In the AJA Beta days, “A/V Output” as X refers to it, was poor. It was buggy and weird. Over the next few updates, things were much better.
[Oliver Peters] “And please don’t bring up iMacs versus Mac Pros. As one can see by the various discussion threads on forums about the latest iMacs and FCP X performance, it appears Apple’s QA was subpar on that one. I don’t see any better performance on iMacs than Mac Pros with these issues that I’m complaining about. It all seems to boil down to how well – or not – the OpenCL implementation is. At least that’s what it feels like, since performance with a Quadro 4000 (not a qualified OpenCL card) is significantly worse.”
Did I mention that it works better on a tricked out iMac? I’m just kidding.
The nvidia and Mac problems are seeming to continue. I don’t know how much you pay attention to the windows side, but CUDA drivers are weird there too. None of this is perfect. It it was, you wouldn’t be here and you’d be using the perfect NLE.
[Oliver Peters] “Sorry about being so negative, but I’m starting to give up on this ever getting better.”
It’s frustrating, there’s no question. I’ve been looking around outside of fcpx and there’s no clear answers anywhere I look. Every pro NLE option is really good at some things, not so good at others.
These days, it seems decisions come from a list of what it doesn’t do instead of a list of what it does well.
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