The Pros & Cons of Using Hi-Res Files for Subtitles Video Translation

Most of our subtitles translation posts have centered on questions that we get from you, our clients. For today’s post, we’re going to flip the script, and instead look at a question we ask for every single project: Do you have a high-resolution version of the video that you’d like us to use? Many clients aren’t sure either what this video would look like, or how to ask for it – and sometimes it’s not even available. However, getting high-res source videos can raise the quality of the final subtitling deliverable, so it’s crucial for multimedia localization professionals to know what they are.

Today’s post will look at the pros and cons of using a high-resolution video file for your subtitling video localization project.

[Average read time: 4 minutes]

What exactly is a high-resolution video file?

We should start by clarifying this term, since it can be confusing. In a production setting, “resolution” specifically refers to the number of lines of information that a video has from top to bottom. Videos with more lines of resolution look crisper because they contain more visual information in the frame. Videos with more than 720 lines of resolution are generally called “high-definition” – this is where the term HD comes from. HD videos most often come in two sizes – 720 lines of resolution, and 1080 lines of resolution. (You’ve probably seen these numbers on TV’s that advertise 720p and 1080p – they’re advertising the resolutions that the TV’s can support.) All things being equal, videos with higher resolution (or, hi-res videos) are generally better-quality that videos with lower resolution.

There’s one more element that affects video quality – compression.  Compression is just a process in which a file is re-encoded (effectively, re-interpreted) so that it takes up less space on a hard drive. When videos are compressed, each frame of video is re-encoded so that it uses less information – effectively, this means that it’s now a lower-quality image. This process is specifically called “lossy compression.” In the past few years, compression has gotten really great – with it, videos can be made much smaller (crucial for transferring over the internet), but still look really great.

The takeaway – in general, the high-resolution and uncompressed version of a video is also the highest-quality version of it.

Before starting, we should note that these tips only really apply to burned-in subtitle deliverables, and not to text-based ones. If you’re not sure about the distinction, check out our previous post, Video Translation 101: Burned-in vs. Text for Subtitles Delivery.

The cons of using hi-res, uncompressed video files

We should look at the cons of using high-resolution files for video subtitle services first, since they’re very compelling – especially within a localization context.

1. Bigger files & longer transfer times: High-resolution/uncompressed files are usually very large. But it’s difficult to overstate just how much larger they are than compressed versions. In the screenshot below, an uncompressed HD video that lasts just 60 seconds is 2.6 GB. A compressed version of it – which still looks really good – ins only 280 MB – about 10% of the original file size.

As you can probably imagine, localization project managers and clients prefer to transfer the compressed video.

2. Usually harder to find files: Published files are almost always compressed, as required by disc media and streaming applications. The higher-resolution versions are usually in a hard drive somewhere, which the client may not want to locate, or be able to, for that matter.
3. Compression is really good these days: It’s hard to overstate just how good. Excellent compression codecs are the reason that we have Blu-ray discs and streaming HD – more about them in this previous post. This means that most subs projects can use compressed files and still get very good results.

Less storage required, files more readily-available, and decent localization results… why would anyone ever want to dig through old drives for the high-resolution versions?

And now, the pros

The pros are pretty compelling as well, especially for high-quality productions:

1. Higher-quality deliverables. This is obvious – the higher the quality of the video that’s being subtitled, the higher the quality of the deliverable. Likewise, this may seem to be unnecessary, especially since compressed HD videos can still display crisp text. However, there are two things to consider. First, burning subs to video reprocesses them somewhat. Again, codecs are really good, so changes in color space and image quality are often imperceptible by most people, but this is just a fact of the process. Using the highest-resolution file ameliorates this somewhat. Second, some languages with more complex scripts can benefit from even a small increase in video quality – think of Thai, Arabic or even Chinese subtitling, in which the characters are much more complex than Latin ones.
2. A high-resolution/uncompressed video file can be compressed for use with many applications – streaming, disc media (DVD and Blu-ray), theatrical projection, etc. A compressed video is harder to use for multiple applications – for example, if it’s been compressed for YouTube, chances are it’s not high-res enough for Blu-ray usage. Using a high-res file for subs means those deliverables can be ported from one application to another.
3. Likewise, high-res/uncompressed videos are much easier to edit than compressed ones. While most clients don’t make changes to videos after they’ve been subtitled, this gives them the ability to make small tweaks down the line if they need to, like changing company addresses or other kinds of information.

While these issues are make-or-break for premium productions like TV spots and feature films, they may not be as compelling for corporate, e-Learning, or other kinds of internet-based videos.

What if the highest-resolution video file isn’t available?

The final verdict? You can work with compressed versions of a video – especially if the compression isn’t too lossy. In some cases, you won’t have any other options, especially for legacy content that’s being translated years after it was created. But if it’s available, using the high-res version of a video for subtitling can ensure the highest-quality deliverable, and the most reusability for future productions.