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Bob Cole
digital projection compression advice
on Sep 4, 2013 at 12:10:55 pm

I need to compress a video of a lengthy lecture, shot in 1080P30, which has nice crisp graphics (Power Point slides animated slightly using After Effects, and often superimposed to one side). I'm editing on a Mac (FCP) and have Flip4Mac.

The client plans to project the show using a digital projector. Unfortunately, I have no details as to the type of projector, or the type of computer. The client is unavailable today, and the show is due tomorrow, so I can't even ask questions. My natural instinct would be to create a variety of files, but I'd rather minimize the confusion.

WWYD? I've created a few .wmv files, 1280x720, data rate around 2500 kbps, 24fps and 29.97 fps, and found that they play well on a PC, not so well on my MacBook Pro (with Flip Player). I am guessing that the client uses a PC, but these days there are a lot of Macbooks out there.

I'd appreciate any specific advice as to data rate, frame size, and file format. Due to the Power Point graphics, I want as crisp an image as possible, but I want to minimize the possibility of playback jerkiness too. The "action" is limited to the lecturers' gestures and a few zoom-ins on the Power Points.

Thanks!

Bob C


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Paddy Uglow
Re: digital projection compression advice
on Sep 4, 2013 at 1:21:59 pm

I usually create h.264/MP4 as a practical codec/wrapper for playing on as many platforms as possible.
I hope that helps.
I've recently been looking at projectors which will play media directly from SDHC or USB stick, like Optoma ML1000. Some of them will play Powerpoint presentations too.
Good luck
- Paddy


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Craig Seeman
Re: digital projection compression advice
on Sep 4, 2013 at 2:28:09 pm

To expand on Paddy's comment.
H.264 .mp4 not only plays in Quicktime Player, it also plays in Windows Media Player 12. That means any Windows 7 or later OS can play it in WMP.

BTW you can only do your best but if a client makes themselves "unavailable" without giving you delivery info or someone to contact to get that info, ultimately they bear the burden.



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Bob Cole
Re: digital projection compression advice
on Sep 4, 2013 at 2:36:55 pm

[Paddy Uglow] "I usually create h.264/MP4 as a practical codec/wrapper "

A big thank you to Paddy and Craig. Interesting that Paddy uses the term "wrapper," as that can be deceptive.

I take it, Paddy, that you aren't using FCP as your compression vehicle. Using "Quicktime Conversion," the first option provides a file with the ".mov" extension. You can specify h.264 here, but the file stills says ".mov."

At the bottom of list under "Quicktime Conversion" is an MP4/h.264 option which yields a file with the ".mp4" extension. When I try to run the resulting file on my Mac, it plays through MPEG Streamclip. But I can change the extension from ".mp4" to ".mov" and it will run fine through Quicktime Player. Is that a dangerous practice?

Do you have any recommendation about data rates/frame rates/pixel dimensions? (btw, I totally agree with you, Craig, about the unavailability of the final user being inconvenient, but in this case there was a totally unforeseeable medical issue so I'm trying to do the best I can without adding to the stress level. On another level, dealing with this lack of ability to test is actually a useful question, as I would really like to know a good baseline solution for digitally-projected files.)

Thanks again.

Bob C


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Paddy Uglow
Re: digital projection compression advice
on Sep 4, 2013 at 2:51:15 pm

Hi Bob,
Ach, I was trying to avoid confusion ;-)
A movie can be encoded as h.264 (for example) but either be a MOV, MP4, AVI (or some others too I think). The MOV can have all kinds of other things embedded in it too, which might only work in QuickTime Player. MP4s can have all kinds of metadata embedded too, but they're a bit more cross-plaform than Apple's QuickTime MOV format.
Changing the file extension DOESN'T change what kind of file it is.

You're right about my compression workflow - I'm not able to run Compressor any more, so I'm not sure whether you can export directly to mp4.
If not, in your situation I'd export a high quality quicktime "master" file (Animation codec might be suitable if it's slides, or Pro Res or Apple Intermediate codec). I'd then use QuickTime Pro or MPEG Streamclip to make various MP4 versions (at the same frame rate).
Data rate is a bit hit and miss - try encoding small section at some different data rates and look for compression artefacts - make sure there are some fades in the section you export - compression artefacts show up badly on fade-to-black or cross fades. But too high a data rate might not play from a slow disk. And too LOW a data rate might give trouble to a slow CPU...!

Not knowing the pixel size of the projector (or aspect ratio!) is a problem! But MPEG Streamclip (it's free and really useful) will allow you to crop a source movie when you export.

PS: I realise I haven't read you mail properly, but I've got no time to alter this now. Sorry! :-(

Paddy, CreativeMedia.org.uk


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Craig Seeman
Re: digital projection compression advice
on Sep 4, 2013 at 3:03:49 pm

[Paddy Uglow] "You're right about my compression workflow - I'm not able to run Compressor any more, so I'm not sure whether you can export directly to mp4."

Compressor 4.x can produce H.264 .mp4. Compressor 3.x can not.
Quicktime 7 itself has been able to do H.264 .mp4 for some time so that would be available when doing Quicktime Conversion out of FCP7 for example.

I'd also note that Apple's H.264 codec is just about the least efficient in any commonly used encoder. That would also impact MPEGStreamclip which uses Apple's H.264.

Handbrake would give you better results as it uses x264.
Telestream Episode has an x264 option but even its MainConcept H.264 is much better than Apple's
Sorenson Squeeze also can use x264.

There's a freely available x264 encoder for Quicktime which will work in Compressor as well. Even version 3.x Its development stopped well over a year ago so I'm not sure how it works on the current OS or Compressor.



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Craig Seeman
Re: digital projection compression advice
on Sep 4, 2013 at 2:57:46 pm

The meta data in H.264 .mov and .mp4 are different. Do not change the extension as it can confuse some players. .mp4 plays in Quicktime just fine. There/s no reason to use .mov.

On Windows .mov may open Quicktime Player instead of WMP. WMP12 can play H.264 .mov though. Many people don't realize that.

The issue is that on Windows, you may actually get better playback on WMP12 than QT7 so using .mp4 is more likely to open in WMP12 (although that can be controlled to some extent in settings).

[Bob Cole] "Do you have any recommendation about data rates/frame rates/pixel dimensions?"

This is entirely up to the capabilities of the playing computer. Ultimately you would have to test. Older computers have weaker CPUs and may not have great GPU assisted H.264 playback.

[Bob Cole] " in this case there was a totally unforeseeable medical issue so I'm trying to do the best I can without adding to the stress level."

Ideally you should have the name of the person or company responsible for playback. I always get these details up front from the client since I don't expect clients to be technicians.

[Bob Cole] "I would really like to know a good baseline solution for digitally-projected files.)"

There's too many variables. Some would leave it at Standard Def frame size given the number of old projectors still in service. Any assumption always carries risk. Since final judgement on the quality of your work will always be delivery and playback it is the one thing you should never overlook. It is often the most important bit of information and I get that at the start of the job because it can dictate many aspects of the workflow. In fact, where possible, I get this info at the pre-production phase because it can impact everything from the choice of camera on forward.



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Bob Cole
Re: digital projection compression advice
on Sep 4, 2013 at 4:07:16 pm

Thank you and Paddy so much for such thorough answers. I appreciate the advice and agree with all of your suggestions for better management.

[Craig Seeman] "Standard Def frame size"

That is a great idea, and for safety's sake I will create an SD version. For digital projection in an SD size, should I assume square pixels? And if so, should I be using 720x404 or 640x360? I've looked online for projector manuals, but have not found an answer to that question.

As a born coward, I will be outputting a playable DVD as well.

Thanks again.

Bob C


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