Maximum size Quicktime file?

I think I did say in a reply on my first post on this issue that there were no files in the folder where Quicktime stores them.

Did not search for other possible posts by you with which to crosscheck. Response was made to this post in answer to your question regarding file size restriction but did mention other related restrictions as other possible causes for a file not to open. Suggest you open the "Autosave Information" folder before making your recording. In this ay you can monitor whether or not any recording is actually made and whether or not it aborts/deletes itself prematurely leaving nothing to be opened and saved later. This is the "scratch" file. If it doesn't exist then you need to determine what is preventing the recording or what is deleting the recording before you can open it.

If the unable to open file error occurred as soon as I started the save, that might be relevant, but that is not what happens. It starts to save the file and only when it is nearly finished does it throw that error.

Once again I would recommend you monitor the file as it is recording. If you stop recording and the scratch file remains stored in the "Autosave Information" folder, then you can rescue it before attempting to save the video normally. On the other hand, if the file disappears as soon as you stop recording, then you know why the data can't be opened/saved in the normal manner and can concentrate on why the file is disappearing which shouldn't have anything to do with file size, data rate, resolution, or frame rate limitations. I.e., check the relationship between when the scratch file disappears and what action is taking place... e.g., does the file disappear when you stop recording, when the save action starts, or just about the time the file save is finishing? Does the error appear before or after the scratch file disappears?

That suggests to me a size issue as does the fact that I have no problem saving the video when I am not in full screen.

The recoding algorithm is context adaptive with frame rates and data rates adjusting for the changes in recording resolution. File size should not be an issue normally as long as sufficient RAM, disk storage, and/or CPU power does not fall below critical levels. I.e., are you making recordings of normal duration or of abnormally long (?hours?) duration or while running multiple CPU intensive apps and/or processing threads/activities?

This is NOT a problem of a file not loading or playing. This is a problem of a file not being saved.

The message The error I got on the failed saves was "unable to open file." implies the temporary "Screen Recording.mov" file in the "Unsaved QuickTime Player Document.qtpxcomposition" container could not be opened for one reason or another. You have yet to indicate whether or not this file exists/existed or whether or not you attempted to move the MOV file to another location before aborting the QTX player window, or whether or not you had sufficient RAM available to open/save the recording if in fact it did exist.

If there is such a size limit (it may be undefined/unlimited), then it will be much larger than the disk size of a MacBook Pro. I think your issue is unrelated to the file size per se.

I had some saves of large full screen Quicktime files fail. I posted that. I just retried one of the saves without going to full screen, and it saved with no problems. The error I got on the failed saves was "unable to open file." I assume that a full screen video save creates a much larger file than just saving the video as is. So, I'm wondering the error meant that I exceeded a maximum file size. I'm looking for documentation on that.

Was waiting to see if anyone else was going to try and tackle this question. Unfortunately the question is a bit more complex than it may appear on the surface.

Originally, the addressing length determined the file size limitation. For example, an MP4/M4V file container using short addressing was limited to a total of 4GB with apps like HandBrake allowing the user to manually opt for either short or long addressing as needed. At this point I believe most, if not all modern encoding apps automatically default to long addressing which can, at least theoretically, support file sizes associated with 4-K, 5-K, and even 8-K resolutions at data rates and/or frame rates compatible with current Profile and Level standards. Unfortunately, this is where things become more complicated.

The current use of VBR (Variable Bit Rates) and/or VFR (Variable Frame Rates) to improve coding efficiency further complicates matters dependent on the Profile and Level settings used to encode the video content. These settings place limits on the number of Luma samples and/or Macroblock samples that can be decoded per second, the max number of Luma samples and/or Macroblocks used per frame, the max video bit rate used for the video coding layer, and/or the maximum resolution supported at a particular frame rate. For instance, a video may have an average data rate or an average frame rate that meets Profile/Level standards but may contain excursions in either the data rate or the frame rate that exceeds the maximum allowed standard for the same Profile/Level encode setting combination.

Not sure if this makes sense to the majority of users so let me say this... There are a number of different limitations that could prevent your file from loading and playing in an "standards compliant" app like QTX. On the other hand, the same file might play perfectly in a less "standards compliant" app like VLC. To actually know what is causing a problem with a particular file and player, it may be necessary to actually examine/analyze all of the specs for the file and compare them with Profile/Level setting combination for both encoding standards and encoding feature compliance.