It depends on what equipment will be screening the MP4 file. What is the native resolution of the projector? What is the computer that will be playing back the file? Encode the file to the maximum resolution and bitrate that the system can handle, and no more.

Usually a 1080p master should be encoded at 20 megabits per second, two-pass variable bit rate encoding. This is Blu-ray standard quality.

Certain types of footage, especially fast motion or flicker, may benefit from setting the compression keyframe distance explicitly. There's no way to recommend what that distance should be, it's totally footage-dependent. I would do an encode without a specific keyframe distance and see if the result looks good. If you are seeing frame blending or other artifacts, set the keyframe distance to 24 or 30, depending on source frame rate. That's one keyframe per second. If you still see artifacts, reduce the keyframe distance incrementally. If keyframe distance is set to the minimum of 1, then each frame is compressed individually (interframe) and there is no interpolation across frames (intraframe). This is an extreme setting that may cause more problems than it solves, but I'm describing options.

The potential issue with high bitrate encoding is that the playback computer has issues playing it back. If the processor or hard drive is not fast enough, the playback will stutter and drop frames. This has happened to me personally, and it utterly sucks in ways I can't begin to describe. Therefore I suggest also encoding a 720p file as a backup in case the target playback system chokes on the 1080p file. Encode the 720p file at 10 megabits per second, two pass variable bit rate.

Aaron



At 2/15/2014, you wrote:
While we're on this topic, I've just been asked for mp4 files for projection from a computer. Would any Frameworkers care to share settings they've used successfully? I'm working from 1080 masters, and I'm on a Mac, where I understand that all the mp4 presets sacrifice quality to compression. Thanks in advance, Peter Envoyé de mon iPad > Le 15 févr. 2014 à 02:31, "Aaron F. Ross" <aa...@digitalartsguild.com> a écrit : > > Hey Sandra... > > You need an MP4 file. That means it's encoded using H.264 compression. Don't bother with Quicktime. Don't bother with any other compression types. They will take too long to upload. > > If it's standard definition (DVD quality), make sure it's encoded with a bitrate of at least 3 megabits per second. > > For 720p extended definition, go for 10 megabits per second. > > For 1080p full high definition, the bitrate should be 20 megabits per second. > > To give you an idea of resulting file sizes... > > 3 megabits per second will yield a file size of 23 Megabytes per minute of footage. > > 10 megabits/sec will be 75 Megabytes per minute of footage. > > 20 megabits/sec will be 150 Megabytes per minute of footage. > > Let me know if you have more questions. > > Aaron > > > > At 2/14/2014, you wrote: >> This is embarassing...as a FILMmaker I finally got used to submitting on DVD, and now...its Withoutabox to submit to Edinburgh Black Box. I have attempted to weed my way through the application but the first thing I need to know is what specs to give to the person doing the video transfer - what type of file are we talking about. Can someone help !?!?!?!? thank you, Sandra Davis _______________________________________________ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks </x-flowed> > > > -------------------------------------------------------------- > > Aaron F. Ross, artist and educator > http://dr-yo.com > http://digitalartsguild.com > > _______________________________________________ > FrameWorks mailing list > FrameWorks@jonasmekasfilms.com > https://mailman-mail5.webfaction.com/listinfo/frameworks _______________________________________________ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks


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      Aaron F. Ross, artist and educator
      http://dr-yo.com
      http://digitalartsguild.com

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