How long video can i record in Quicktime

I am using MacOS X Yosmite 10.10.5

I have Quicktime 10.4

How long a video can i record in this version of Quicktime (10.4)?

To be a bit more specific—it depends on the amount of storage space available, how fast you are filling up the available storage space and assumes nothing occurs to prematurely terminate the recording process.

Since current MacOS versions (Mavericks thru Sierra) store the "scratch" video data on your startup drive (internal or external), the amount of storage space available on this drive will determine your "how long" recording baseline.

The next consideration is the rate at which storage space is being consumed by the recording. This is determined by the combined total data rate of the recording. So anything that affects a change in the data rate of your recording will affect "how long" you can record. For instance, in the "New Movie Recording" mode, the "Quality" setting can greatly change how long you can record. I.e., for any given set of display dimensions, the "High" quality mode encodes your recording using H.264 video with Low Complexity AAC audio which is more "space" efficient than the "Maximum" quality settings which encodes as Apple ProRes 422 video with LPCM audio. On the other hand, in the "New Screen Recording" mode, recording the entire monitor screen display area uses up your storage space much faster than making a recording of a partial screen area of the monitor. Even the graphic complexity of the content being recorded can affect the data rate. (E.g., multiple objects with independent motion vectors, scene lighting, object textures, rapid object motion, etc. can affect the data rate.)

Lastly, there is an implicit assumption that the recording system can "keep up" with recording requirements. The simultaneous running of multiple apps and/or system processes can slow recording processes adversely. Normally, a system will attempt to compensate by reducing the recording frame rate to maintain a target level of quality (i.e., an average data rate per unit of time) but if a system cannot "keep up," the recording app may simply abort recording without comment. Thus older, less powerful systems may be unable to record as long as newer, more powerful systems simultaneously running the same apps and/or processes while recording the same material. Remember that your system is an aggregate sum of its specific configuration in terms of hardware and software components.

Even the same systems may operate somewhat differently dependent on a specific user's configuration and settings. This, together with other possible operating permutations, make it virtually impossible to provide concrete estimates regarding recording times. Basically, the system will strive to record AS LONG AS IT CAN or until the recording is terminated manually by the user.

Depends on how much free space you have left on the hard drive you are recoding to.