FLV vs. MP4: What’s the Difference and Which Is Better?

There is an intimidating number of different kinds of video file formats out there for newly minted videographers. It can be frustrating to figure out which one is best for you with all the information. Two of the most common file formats are FLV and MP4, but which one is better suited to your needs?

FLV and MP4 files produce similar quality videos, but FLV files take up more space on your computer. They’re also not compatible with as many video players as MP4s and are quickly falling out of mainstream use. However, recordings are more secure with FLV, and it is easy to convert them to MP4.

FLVs and MP4s are deceptively similar, but there are distinct advantages and disadvantages to each. Even if you don’t end up using these yourself, you will encounter them all the time. This article will explore some of the differences between these two popular file types and determine which is right for you.

What Are File Formats?

File formats are the structure of a file. Every document on your computer will have a file format attached to it—text documents, slideshows, spreadsheets, images, and videos. These formats essentially instruct your computer on how to display the contents of the file. Different kinds of content require different types of formats, which is why you can’t save a movie as a DOC or a spreadsheet as an FLV.

To understand the advantages of different formats, it’s helpful to know how they put together the instructions that make the file work. 

How File Formats Work

File formats are made up of containers and codecs. The container is how the file’s data is packaged, or “contained,” into one file that holds together. This is the video formats’ label—FLV, MP4, and so on.

The codec is a little more difficult to understand. “Codec” stands for “code” and “decode.” Essentially, the codec compresses the file so that the contents will be small enough to fit in the container, then expands them again when the document is being viewed or edited. This reduces the size of the file while it isn’t in use.

Different codecs deal with different kinds of data, and different video formats have different combinations of codecs. Video files require audio and image codecs, while text documents such as DOCs will need other kinds of codecs. Audio and visual codecs are not universal between file formats, which is why some videos will play on your computer and others won’t.

Think of it this way: The format’s container is a box, and the codec instructs you how to open the box. Without the codec, the box is sealed shut.

What Are “Codec Packs” and Do You Need Them?

When researching the world of file formats, you may come across the term “codec packs.” This can be confusing since you’ve almost certainly seen examples of different file containers but may not be sure what a codec is. Fortunately, you will probably not need to think about codec packs if you’re editing a standard video.

Codec packs are software you can download with several different codecs pre-installed, often beyond many media players’ capabilities. Common codecs are the Media Player Codec Pack, CCCP (Combined Community Codec Pack), Sorenson Spark, or VP6. Not all of these codecs will work with FLV or MP4, so make sure to double-check that they’re compatible with the format you need.

Most modern media players and editors will come with all the codecs you need pre-installed. However, some of them lack the codecs needed to play certain newer formats, including Windows Media Player. To give themselves more options, some people download codec packs to equip their limited program with more options.

The problem with codec packs is that they can interfere with each other or even carry computer viruses. Anyone can make a codec pack available for download. When so many media players will work just fine with their existing codecs, you may not want to take the chance of downloading something from an unsubstantiated website.

If you are not familiar with codec packs and are on a deadline, you’re better off sticking with the formats and codecs already available on your device. If you’d like to experiment with codec packs (some people prefer them), then be sure to do your research and be prepared with some antivirus solutions.

FLV File Format

Flash was released in 2002 by Macromedia and has been the standard file format for online streaming services such as VEVO and Hulu. (Netflix, meanwhile, has streamed their videos in VP9 since 2016.)

FLV stands for Flash Video and uses Adobe Flash Player or one of its later versions to deliver video files via the Internet. You can identify an FLV video by the filename extension, which is the three letters or numbers following the file’s name, such as “DocumentName.flv.” FLV extensions include .flv, .f4v, .f4p, .f4a, and .f4b.

FLV works with the codecs Sorenson Spark or VP6, though later versions of Flash may not work with the same ones. It’s commonly used with OBS or Open Broadcasting Software. OBS is an open-source program that offers streaming and recording capabilities. 

Streamers on Twitch or other platforms make frequent use of OBS. Chances are your favorite content creator has a video detailing their preferred technical specs, so you may want to browse your own home page.

MP4 File Format

MP4 is actually shorthand for MPEG-4 Part 14. In order to understand how MP4s work, it’s helpful to know a bit more about MPEG-4.

This refers to the standard method of compressing audio and visual, or “AV,” data for many different applications and distribution forms. The different “parts” of MPEG-4 simply describe different aspects of the whole thing—essentially different types of containers.  

MPEG-4 Part 1 set out the specifications of MP4s at first and was later made obsolete by Part 14 in 2003. Since MP4 is so prevalent, it works with various codec packs, including the Media Player Codec Pack and CCCP. (Again, it isn’t necessary to understand or use different codec packs to create MP4s or FLVs.)

Other File Formats

Of course, there are plenty of other video formats out there other than just FLV and MP4. While Flash has been the standard in the past, and MP4 is quickly becoming the standard today, some videographers prefer other formats. Frequently, videos are created in formats more suited to editing, then converted to MP4 later on.

There are many more video formats out there than those listed here, but these are among the most popular.

  • WMV:  WMV stands for Windows Media Video, and it was designed by Microsoft. WMV files have twice the compression ratio of MP4s, making the files even smaller. Interestingly, this makes the files smaller than some video players can read, meaning WMV files are compatible with fewer applications. WMV files have extensions of .wmv, .wma, or .wsf.
  • MOV: MOV refers to the QuickTime File Format, developed by Apple for products in their ecosystem. MOV files are high quality but are not accepted by most media players. They are also made for easier editing. MOV extensions are .mov or .qt.
  • AVI: Audio Video Interleave formats are preferred by some because they are lossless, and their quality will not be compromised when the data is compressed. However, this results in huge video files. AVI files are also a little more limited and cannot be coded to include clickables or subtitles. Its extension is .avi.
  • AVCHD: Advanced Video Coding High Definition, or AVCHD, was created by Panasonic/Sony in 2006. AVCHD format uses a very minimal amount of data to store extremely high-quality videos and supports 3D effects. However, it’s mostly used by high definition Sony camcorders and is not often used by consumers.
  • MKV: MKV formats, or Matroska Multimedia Containers, are also often used with OBS. This article will explore MKV formats later on.

Should You Use FLV or MP4?

Even with this wide range of video formats, in all likelihood, you will still want to use FLV or MP4 if you’re new to videography since both of them will be compatible with the greatest number of media players and editors.

Rather than mixing and matching formats depending on your needs, it’s better to become comfortable with both of these popular file types. Once you become a bit more advanced, the other file types may become a part of your repertoire.

If you still plan on using one of the two most popular video file types, you may not be sure of each’s advantages. Is FLV or MP4 better suited to your project? It depends on what you plan on filming and how you plan on presenting it.

Advantages of MP4

MP4s offer high-quality videos with relatively small file sizes. The obvious advantage of this is that it helps keep storage on your devices free for other files. Smaller file sizes are also much easier to send to others, and you are less likely to run into capacity issues with GMail or DropBox.

It is also generally more compatible with media players than FLV, particularly in recent years. FLV has been going out of vogue since 2007 when Apple opted not to use Flash on the new iPhone. FLV isn’t compatible with many mobile devices at all, making MP4 more and more convenient as time goes on.

You will almost always want to use an MP4 file format for your video. If you are a video streamer, you may want to record the video in another format (such as Flash) and convert it to MP4 afterward.

Advantages of FLV

Why use FLV at all if there are so many advantages to MP4? If you are a streamer or a YouTuber, you may actually want to use an FLV format, especially if you tend to record for long periods of time. FLVs make it much harder to lose video if something goes wrong.

If your video camera suddenly stops working, your computer crashes, or something else goes wrong when recording in FLV format, the file will be uncorrupted, and you will most likely be able to recover what you’ve already filmed. The same is not true for MP4 files. If your recording suddenly stops in MP4 format, you will lose everything you’ve recorded.

MP4 videos go through a finalization process at the end of the recording, which takes the data and codes it into an index of metadata, kind of like the file’s DNA. This helps the MP4 compress and store the data without taking up as much storage.

It also means that if the video cuts out in the middle, the data doesn’t go through that crucial finalization process, and the index isn’t made. Since the MP4 format relies on the index to play, it will show up as a blank file.

This video goes into more detail as to how FLV file formats are advantageous for YouTube content creators and streamers:

What About MKV File Format?

Since Flash is becoming less and less popular, you may have also heard of the MKV format. MKV files are also commonly used with OBS by live streamers. But is it better than FLV?

MKV was created in 2002 and was designed to be “future proof,” meaning the file will still be playable as updates are made to the program. Just like FLV files, it does not require the finalization process used by MP4 formats – if your recording is suddenly interrupted, you will probably not lose your data.

MKV and FLV will produce similar files but have minor differences that will suit different kinds of videos. With MKV, you can use multiple audio tracks on the same video, which may be useful for video game streams. FLV, on the other hand, is compatible with more kinds of editing software.  

Otherwise, they produce very comparable video files. Neither is “better” than the other, and the one you use will depend on the kinds of videos you make.

Keep in mind that videos can be recorded in MKV or FLV and then converted to MP4 after the fact. This might be desirable if you want to make the file smaller without losing quality.

How To Convert Videos to MP4

Given that the MP4 file format is more widely usable, it makes sense that you would choose it. However, due to its limitations with finalizing files, it might be better to work with FLV initially, and then convert the file to MP4 for better distribution. That way, you can record with the knowledge that your file is safe, but still have the flexibility that MP4 files can offer. 

Many editing programs will make a conversion from video files to MP4 for you. Some will cost you money, but others are free and available for download online or even browser use. Features and compatibility will vary from program to program, so make sure to research what editor will work best for you before purchasing anything.

Movavi Video Editor Plus 2021

Movavi Video Editor Plus 2021 is available for download on Amazon for under $60 for both Mac and PC. Movavi will allow you to convert your video to MP4, as well as MOV and AVI. Reviews of Movavi note that it has a relatively basic interface but a fair amount of editing options and effects.

VLC Media Player

VLC is free and will also allow you to convert your video to MP4. It’s widely regarded as the best free video editor out there and doesn’t have any ads. It’s also known for being much faster than other editors. There are some limitations, but if you’d like to test out a free product before taking the plunge on a paid one, VLC is a good place to start. It’s available for a free download on Mac, Windows, Android, and Linux.

This video explains how MKV files can be converted to MP4 using VLC:


HandBrake offers significantly more features than VLC, though user reviews note that it tends to be slow. HandBrake is also free to download and will easily allow you to convert videos to MP4.

Online Converter

Online Converter isn’t so much a video editor, but it is a free way for you to compress any video file and convert it to MP4. It will accept a wide variety of formats, including WMV, MKV, MOV, AVI, and of course, FLV and MP4. Note that Online Converter’s only capability is compressing and converting to MP4, not any other video file type.

There are other editors out there, but these are tried and true. If one of them isn’t working for you, give another a try before giving up completely.

Final Thoughts

FLV and MP4 video formats will produce similar files, but Flash tends to take up much more space for the same quality. In most cases, you’ll want to have your video in MP4 format since it’s compatible with more players and will keep your storage free. Luckily, there are plenty of easy ways to convert your Flash file to MP4.

It can be extremely frustrating to learn about video file formats when you just want to put creative work into your project. However, knowing what video files work best in different situations can save you headaches and heartbreak down the line.


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