What is Flash Video (FLV) File Format? Security Concerns and Why Steve Jobs Discontinued It?

The digital ecosystem has witnessed an evolution in multimedia file formats over the years, each designed to cater to specific needs. Among these formats, one that has left an indelible mark, particularly during the earlier days of the internet, is FLV, or Flash Video.

What is FLV?

FLV, short for Flash Video, is a multimedia container file format developed by Macromedia (acquired by Adobe Systems in 2005). Each FLV file consists of a short header, synchronized audio and video data streams (encoded like the standard .SWF format used in Adobe Flash), and metadata packets. The FLV format requires the Adobe Flash Player to play which reached End of Life in 2021 and is no longer supported by Adobe.

In its early days, Flash primarily served as a platform for crafting basic animations. Yet, owing to the user-friendly and intuitive nature of Adobe's Flash creation tools, it swiftly gained traction among both professional developers and hobbyists. This accessibility enabled a wide range of individuals equipped with the requisite tools to design Flash animations and videos for websites and applications, facilitating rich interactivity for users.

There are two different Flash Video file formats: FLV and F4V.

The Flash File Formats: FLV vs. F4V vs. SWF

FLV Format

FLV files represent the initial foray into Flash video files, originating from Adobe (formerly Macromedia).

FLV files rely on the H.263 standard for their video data, employing the FourCC FLV1 codec. As for audio data, it is typically encoded in the MP3 format.

F4V Format

Succeeding the FLV format, F4V files have emerged as the next iteration in Flash Player.

Deriving its container structure from Apple’s Quicktime video format, F4V uses a boxed data storage mechanism. It employs the H.264 video codec and supports AAC audio encoding.

SWF Format

The SWF file extension, initially conceived by Macromedia (and subsequently by Adobe), originally had a specific purpose—it was primarily designed for the Shockwave Player and was initially termed the "Shockwave Flash" file.

SWF files have the capability to showcase animated graphics, execute ActionScript, and even present text. While they can be used for video playback, SWF files primarily shine in the realm of animating vector graphics, complete with embedded text and JPEG images.

Key Characteristics of FLV

FLV is renowned for several key characteristics that set it apart in the world of multimedia file formats:

1. Compactness: FLV files are known for their efficient compression, which allows for the storage of high-quality video and audio in relatively small file sizes. This was crucial during a time when internet connection speeds were not as fast and reliable as they are with the 4G and 5G technology today.
2. Cross-Platform Streaming Capabilities: One of FLV's standout features was its ability to stream video content seamlessly over the internet. This made it an ideal choice for online video platforms and live-streaming events, where buffering delays were minimized.
3. Interactive Content: FLV files often incorporated interactivity, allowing developers to embed clickable elements within videos. This interactive layer was instrumental in creating engaging multimedia experiences.
4. Integration with Flash: FLV's deep integration with Adobe Flash allowed for the creation of dynamic web applications and multimedia-rich websites.

Early Days of Flash Video

In the late 1990s, Adobe Flash (formerly Macromedia Flash) emerged as a powerful multimedia platform for web content. Alongside Flash, FLV was introduced as a container format tailored to deliver video content seamlessly within web browsers. This marked the beginning of FLV's journey.

FLV's Pioneering Role in Web Video

The early 2000s witnessed the proliferation of Flash-based websites and applications, making FLV a dominant player in the realm of web video. Websites like YouTube, Vimeo, and Dailymotion relied heavily on FLV for streaming video content. Its efficient compression and streaming capabilities made it the go-to choice for delivering video online.

The Transition to HTML5 and Beyond

HTML5, with native video support and improved standards for multimedia, began to replace Flash.

Why Steve Jobs (and Apple) Discontinued FLV Support?

While Flash was undeniably versatile, groundbreaking, and innovative, it didn't escape criticism. One of its most notable and influential critics was Apple Inc. Adobe, too, eventually declared the discontinuation of Flash development.

Apple's and many Linux users' reservations about Flash stem primarily from its resource-intensive nature. High CPU usage was a major pain point. Additionally, for seamless playback of high-definition videos, alternatives to Flash became a necessity due to the demand for more advanced codecs than what Flash offered.

Another pivotal factor was the availability of open-source solutions for web animation. Many alternatives to Flash provided cost-effective, open-source tools for creating animations for the web, while Adobe Flash and similar proprietary programs proved to be less budget-friendly in comparison, especially when weighed against the likes of HTML5.

FLV vs. Other Video Formats

Let's take a closer look at how FLV stacks up against some of its counterparts:

1. FLV vs. MP4:

Advantages of FLV:

• FLV was specifically designed for web-based streaming, making it an excellent choice for online videos initially.
• FLV supports alpha channels, allowing for transparent backgrounds, which is advantageous for overlaying graphics or animations.

Advantages of MP4:

• MP4 is a widely accepted and compatible with a broad range of browsers and devices.
• It provides better video quality at lower bitrates, making it suitable for high-definition content.
• MP4 supports a variety of codecs, offering more flexibility in terms of video and audio encoding.

Use Cases:

• Choose FLV for web-based streaming, especially when transparency or small file sizes are essential.
• Opt for MP4 when you need compatibility across multiple devices and platforms or when high-quality video is a priority.

2. FLV vs. AVI:

Advantages of FLV:

• FLV outperforms AVI in terms of web compatibility and streaming capabilities.
• It offers better compression and smaller file sizes, ideal for online distribution.
• FLV's support for alpha channels is a unique feature not found in AVI.

Advantages of AVI:

• AVI is a widely recognized format on Windows-based systems, making it suitable for local playback.
• It provides better compatibility with older multimedia software and hardware.
• AVI offers less compression, which can be advantageous for preserving maximum video quality.

Use Cases:

• Prefer FLV for web-based content delivery and when transparency or smaller file sizes are required.
• Consider AVI for local playback on Windows systems, especially when compatibility with legacy software is crucial.

3. FLV vs. MKV:

Advantages of FLV:

• FLV excels in web-based streaming scenarios, offering efficient compression and streaming capabilities.
• FLV's compatibility with Adobe Flash technology makes it a legacy format with a unique history.

Advantages of MKV:

• MKV is a versatile and open-source container format that can store multiple audio and subtitle tracks.
• MKV's flexibility allows for the inclusion of various codecs and advanced features.

Use Cases:

• Choose FLV for web streaming and when integrating videos into web applications with Flash compatibility in mind.
• Opt for MKV when working with high-definition videos or projects that require advanced audio and subtitle options.

Diving Deeper into the FLV Format

Exploring FLV Encoding

Within FLV files lie the Sorenson Spark video bitstreams, presenting a proprietary adaptation of the H.263 video standard. Notably, this compression format finds its utility in Flash Player 6 and 7. However, with the advent of Flash Player 8, a transition occurs towards the embrace of the more sophisticated On2 TrueMotion VP6 video bitstream format—a shift that stands as the favored choice for subsequent iterations.

LV format exhibits remarkable versatility when it comes to audio. It accommodates audio streams from an array of sources, including:

1. The Nellymoser Asao Codec
2. The Open Source Speex Codec
3. MP3 Audio
4. Uncompressed Audio
5. Audio in ADPCM Format

Furthermore, the more recent incarnations, specifically Flash Player 9 and its successors, extend their support to Advanced Audio Coding (AAC) in various profiles, encompassing AAC Main Profile, High-Efficiency AAC (HE-AAC), Advanced Audio Coding Spectral Band Replication (AAC SBR), and Advanced Audio Coding-Low Complexity (AAC-LC). This diverse audio compatibility underscores FLV's adaptability and appeal in handling audio content.

The FLV File Format Structure

An FLV file has a distinctive structure, comprising two essential components: the header and the packet. Delving into the header, we encounter the following key fields:

1. Signature: The signature field invariably holds the value "FLV".
2. Version: With a default value of 1, only 0x01 is deemed valid.
3. Flags: This field adopts values such as 0x04 for audio, 0x01 for video, or 0x05 for the dynamic duo of both audio and video.
4. Header Size: This defaults to 9 but serves as a means to convey an extended file header if needed.

Venturing further, we encounter the packets—FLV files partitioned into discrete packets colloquially known as "FLV tags," each adorned with a 15-byte header. These packets are repositories for a diverse array of content, encompassing audio, video, script, encrypted data, and payload metadata.

The FLV packet is distinguished by the subsequent attributes:

1. Reserved: Reserved exclusively for Flash Media Server (FMS) utilization and mandated to hold a value of zero.
2. Filter: This field assumes a value of 0 for cases where no preprocessing is requisite. Conversely, it adopts a value of 1 if pre-processing, such as decryption, is a prerequisite for the packet.
3. Packet Type: This parameter defines the packet's content type.
4. Data Size: A crucial indicator, it elucidates the message's length.
5. Timestamp Lower: This compartment accommodates the timestamp of the tag data in milliseconds, with the initial packet initializing it as NULL.
6. Timestamp Cap: This extension comes into play to formulate a uint32_be value.
7. Stream ID: For the maiden stream, this field resides in the realm of NULL, whereas subsequent streams possess sequential numbering.
8. Payload Data: The heart of the matter, this section is home to the invaluable video or audio data.

Optimal Delivery Methods for FLV Videos

When it comes to delivering your engaging Flash video content, you've got a variety of options at your disposal. Let's explore these FLV delivery options:

Standalone FLV File: Typically, FLV video players take charge of delivering your Flash video files. FLV players are specially designed to handle FLV content. You can also opt for third-party FLV players to get the job done.

Embedded: Flash Player versions 6 and beyond provide support for embedded FLV videos within SWF files. This approach involves using Flash's authoring tool to create SWF files with embedded FLV content. However, it's worth noting that modifying the video requires rebuilding the entire SWF file.

Progressive HTTP Download: Flash Player versions 7 onwards introduce support for progressive FLV downloads via HTTP. ActionScript plays a pivotal role here, allowing you to incorporate externally hosted FLV Flash files on the client side. The benefits include effective buffering, compatibility with generic HTTP servers, and the ability to use the same SWF player for different sources of Flash video. Moreover, Flash Player 8 offers the added advantage of random access to video files through HTTP's partial download feature, often referred to as "streaming." Keep in mind that HTTP streaming doesn't support live broadcasting. To enable this method, you'll need a custom video player for HTTP streaming. Additionally, you must inject relevant Flash video metadata specifying timecodes for keyframes and starting positions (in bytes). This information empowers the custom Flash video player to request specific segments of the video file based on the provided keyframes. Notable platforms like YouTube, Google Video, and Bitgravity employ progressive downloads via HTTP, allowing users to seek any part of the video even before buffering is complete.

RTMP Streaming: For a robust video streaming experience to Flash Player, the Flash Media Server offers support for Real-Time Messaging Protocol (RTMP) streaming. This method ensures smooth and reliable video delivery.

iPad and iPhone Streaming: Flash Media Server 4.5 takes it up a notch by enabling video streaming to iPads and iPhones. It achieves this by delivering video content via an MPEG-2 stream using the HTTP Live Streaming video format.

How to Play FLV Files?

Playing FLV files may seem straightforward, but it's essential to use compatible software or methods due to the unique nature of this format.

FLV-Compatible Media Players

The most common way to play FLV files is by using media players specifically designed for the format. Here are some options:

VLC Media Player: VLC is a versatile open-source media player that can handle FLV files effortlessly. It's available for various operating systems and is well-known for its wide codec support.

MPC-HC (Media Player Classic - Home Cinema): This lightweight media player is another excellent choice for playing FLV files. It's known for its simplicity and resource efficiency.

Adobe Animate/Flash: Adobe's Flash software, which was instrumental in the creation of FLV files, can still play them. However, due to Flash's end-of-life status, it's crucial to use it sparingly and only for legacy content.

Browser Compatibility

Modern web browsers have largely phased out support for Flash and, by extension, FLV. However, you can still play FLV files in certain situations:

Google Chrome: Chrome discontinued support for Flash in 2020. To play FLV files in Chrome, you may need to use Flash Player plugins or other workarounds, but this is not recommended due to security concerns.

Firefox: Similar to Chrome, Firefox has deprecated Flash support. Playing FLV files in Firefox may require enabling Flash through browser settings, but it's advisable to use alternative methods.

Convert FLV to More Common Formats

Given the dwindling support for FLV, you might find it necessary to convert your FLV files to more widely accepted formats like MP4 or AVI. Several free and paid conversion tools are available for this purpose.

Front.Space allows you to convert FLV files to modern formats like MP4 or WebM on-the-fly.

How Can Front.Space Convert Your FLV File to MP4 or WebM?

The FLV format is no match for the superior capabilities of MP4 and WebM. With Front.Space, you can seamlessly transition from FLV to these modern video formats, ensuring quicker load times and an upgraded user experience.

Front.Space's cloud-based solution simplifies the process into three straightforward steps:

1. Utilize dynamic URLs to transition from FLV to either MP4 or WebM.
2. Modify the newly formed videos from the first step through resizing, cropping, and other transformations.
3. Propel the revamped videos' performance with the aid of an efficient content delivery network (CDN).

The conversion capability is available in all Front.Space plans, including the free tier. Do check it out.

FAQs About FLV Format

1. What is FLV format, and why is it used for videos?

• FLV stands for Flash Video, a popular video format developed by Adobe. It is commonly used for web-based videos due to its small file size, high-quality compression, and compatibility with Flash Player.

2. Is FLV still relevant in the era of HTML5 video?

• While HTML5 video formats like MP4 have gained popularity, FLV is still relevant, especially for legacy content and Flash-based applications. Converting FLV to modern formats is common for better compatibility.

3. How can I play FLV files on my computer?

• You can play FLV files using media players like VLC, Adobe Flash Player (deprecated), or by converting them to more widely supported formats like MP4.

4. Can I convert FLV files to other formats without losing quality?

• Yes, you can convert FLV to other formats like MP4 or AVI without significant quality loss, especially when using professional video conversion software.

5. What are the advantages of using FLV for web videos?

• FLV files are known for their small size, making them ideal for online streaming. They also support alpha transparency, making them suitable for interactive content and animations.

6. Are there any disadvantages to using FLV?

• One major disadvantage of FLV is its decreasing support due to the decline of Flash technology. Modern browsers and devices may not natively play FLV files, requiring additional plugins or conversions.

7. Can I edit FLV videos easily?

• Editing FLV videos can be more challenging than widely supported formats. You may need specialized software or conversion to a more editable format for easier editing.

8. Are FLV files still used for online streaming?

• While FLV usage has declined, it is still used in some cases for online streaming, especially on websites with legacy content or those using Flash-based players.

9. How can I convert FLV to a more modern video format?

• You can convert FLV to formats like MP4 or WebM using video conversion software or online converters. This process allows you to maintain quality while ensuring compatibility with modern devices and browsers.

10. Is there a recommended alternative to FLV for web videos?

• Yes, MP4 (H.264) is a widely supported format for web videos and is recommended for its compatibility with HTML5 video players and modern devices.

11. Can I still create new FLV files for web content?

• While it's possible to create FLV files, it's no longer a recommended practice due to the decline of Flash technology. Using more modern video formats like MP4 or WebM is advisable for better compatibility.

12. Are there any copyright or licensing issues associated with FLV files?

• FLV itself is not subject to copyright or licensing restrictions. However, the content within FLV files, such as videos or audio, may have copyright protections, so it's important to respect intellectual property rights when using FLV files.

13. Why did Flash shut down?

• Adobe's decision to discontinue support for Flash stems from its diminishing relevance. Numerous robust alternatives, including HTML5, WebGL, and WebAssembly, have emerged. Major tech companies are seamlessly integrating these alternatives into their web browsers, rendering Flash obsolete.