Why You Can’t Import a Section of a Video Clip for Editing

A question I get all the time is: “How do I import just a section of a clip? The original is really long and I don’t want to waste disk space.”

Regardless of the video editing software (NLE) you use, the answer is not initially encouraging: “You can’t. And, more importantly, most of the time, you don’t want to.”

NOTE: Before you reach for your keyboard, there are a few video formats where you can copy just a portion of a clip. I’ll explain more in a minute. But, most of the time, you can’t. This is true for Windows, Linux and Mac systems.

HOW COME?

The process of bringing media into our NLE is called “importing.” While this term is well known, it isn’t actually accurate. We are not “importing” media, we are actually “linking” to it.

With the exception of Final Cut Libraries, no NLE actually imports media. All media is referenced, “linked,” by a path name.

The path name is a short piece of text that describes exactly where a file is located. All path names start with “/Volumes” which indicates the file is stored on a device.

The next “/Thunderblade” is the name of the device. This might be “/Macintosh HD” for your internal drive or “/Murgatroyd” for an external drive.

The next words in the series are a list of all the folders that contain the referenced file. Each folder is separated by “/“. Each folder is contained in the folder listed to its left.

Finally, is the file name itself.

It is this path name, this text, that gets imported. Not the file itself.

WHY?

There are several huge benefits to importing path names, rather than media itself:

• Linking to a path name is blindingly fast, copying files is not.
• Path names are tiny, which keeps project files small.
• There’s always the risk of data errors creeping in when a file is duplicated. Not a likely risk, but a risk nonetheless. Importing path names avoids unnecessary duplication.
• Duplicating some codecs, like H.264, HEVC, AVCHD and other highly-compressed files, creates artifacts in the video due to the lossy compression algorithm. Not duplicating the file prevents that.

SO, UM, BACK TO IMPORTING

Yeah, about that. Since we only import the path name, there’s no way to indicate that we want to bring in only a portion of a clip.

There is a way around it, which Apple tried in the initial release of Final Cut Pro X: They allowed you to select a range for some clips, then, behind the scenes, FCP would duplicate just that range of the clip.

But this caused file sizes to explode because all this media was getting duplicated. And, depending upon the codec, errors were getting introduced into the visuals. This wasn’t Apple’s fault – it’s always a problem when you recompress an already compressed clip.

So, the reason you can’t import a portion of a clip, is that the NLE itself is only references media file; it doesn’t physically move or duplicate it.

The good news is that referencing links is very fast, works fine, and prevents wasting storage space. The bad news is that if you move or rename any file or folder that contains the file, this link breaks. At which point you need to relink files to reset all the path names.

BUT… AREN’T THERE EXCEPTIONS?

Yes. Two:

1. Apple allows you to import media into a Final Cut Pro Library. This actually copies the source file into the Library container. It may look like it’s a single file, but the Library is actually a collection of files. The benefit is that since this is a copy of the source file and it is always stored in the same location, you minimize the risk of broken links. You also simplify backing up a project, because all you need to copy is the Library container. However, that Library can get HUGE because every media file is stored in two locations: its original place on your hard disk and a copy, stored in the Final Cut Pro library.
2. Some camera codecs, AVCHD comes to mind, don’t store media as a single clip. Video is stored in one location, audio in another, timecode in a third and metadata is often in a different location still. Since there is no single file to link to, some NLEs combine all these separate streams into a single clip. This duplicates the source media and converts it into a format suitable for editing. This combined file is always stored separately.

BUT WHAT IF I ONLY NEED A TINY SECTION

Keep in mind that all you actually imported into your NLE is a text link. So, even if the source file is a bajillion gigabytes, no additional file storage was needed. No copies were made. And no extra storage is required.

But, if you need to save disk space for the long term, the easiest thing to do is import the source file, define and export your selections as separate files, then trash the source file. Yes, this involves copying portions of the source file, but you can quickly check the output files to make sure it looks OK.

Then, when you have the sections you need, you can trash that gigantic source file to reclaim space.

SUMMARY

Path name links were invented as a way to connect files to an NLE without wasting storage space. They are fast, small, portable and easy for programmers to work with. They also provide the highest-possible audio and video quality because you are actually editing the source file itself.

It doesn’t get better than that.

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