HLS vs DASH: A Detailed Comparison for Streaming Purposes

Streaming technologies are advancing rapidly, with two prominent standards emerging for adaptive bitrate streaming: HLS vs DASH. Each standard offers unique advantages and challenges, making the decision between them crucial for content delivery networks, developers, and businesses aiming to provide seamless streaming experiences.

In this article, we will examine HLS and DASH and their functionalities to determine which is better suited for specific streaming requirements.

What is HLS (HTTP Live Streaming)?

HLS is short for HTTP Live Streaming, an adaptive bitrate streaming protocol by Apple. While it initially was used to stream live and on-demand video over HTTP to iOS devices, Apple TV, and macOS computers, nowadays it’s platform-agnostic.

HLS works by segmenting a video into small fragments, where each can have multiple variants encoded at different levels of quality for any given resolution. This lets Client-side video dynamically request between alternate quality levels based on various factors such as internet speed and the abilities of the device in place, while keeping the resolution constant-representing the viewer with absolutely the best experience.

Pros of HLS

• High Scalability: HLS utilizes standard HTTP servers, allowing integration with existing web infrastructure for easy caching and scalability through CDNs. It facilitates live and on-demand video streaming by content providers. 
• Large-Scale Compatibility: Such a wide range of devices and platforms with which HLS is compatible works seamlessly on desktop browsers, smartphones, and tablets to even smart IPTVs, mainly due to the use of standard HTTP that’s supported by practically all.
• Wide Range of Features: HLS supports multiple audio tracks, subtitles, and closed captions and offers encryption and authentication. This makes it suitable for global audiences, providing secure streams with diverse language options and accessibility features for those with hearing impairments.

Although there are many advantages to HLS, these are the key points. Nevertheless, there are also some disadvantages of the video streaming protocol that you should consider.

Cons of HLS

• Higher Latency: One of the significant drawbacks of HLS is higher latency compared to RTMP. Chunking and playlist mechanisms in HLS can delay the stream. For on-demand content, this isn’t typically a problem. However, for live events, it could be an issue when it comes to real-time interaction.
• Increased Bandwidth Usage: Adaptive bitrate in HLS increases bandwidth use. It streams and caches multiple quality levels of the video. This might be an essential consideration if unlimited bandwidth costs are a concern.
• Complex Implementation: Segmented video is required in HLS. The playlist is managed by HLS. This added layer of complexity could increase the initial setup and maintenance effort in general.

What is DASH?

DASH, or Dynamic Adaptive Streaming over HTTP, is an open-source streaming protocol developed by MPEG. It delivers video over the internet using adaptive bitrate streaming. The video is broken into small chunks. Each chunk is encoded at various bitrates. Smooth playback is ensured regardless of network conditions. MPD (Media Presentation Description) is the name of the manifest file used by this system, which distinguishes it from HLS. This file outlines the layout and locations of audio and video segments for easy access. DASH is popular for adaptive bitrate and secure private streaming.

Pros of DASH

• Reduced Costs: DASH is an open standard that supports royalty-free codecs like VP8/VP9 for video and Opus for audio, eliminating licensing fees for DASH streams. 
• Customizable: Being codec-agnostic, DASH allows content creators to optimize stream quality and reliability based on their codec choices. 
• Ideal for Low-Latency Streaming: With Chunked Transfer-Encoding and flexible segment sizes, DASH is better suited for low-latency applications than HLS. It supports CMAF, enabling low-latency delivery with reduced buffering and faster startup times without the need for multiple content copies.

Cons of DASH

• Lack of Standards: DASH’s open-standard nature allows for customization without licensing fees, but it leads to inconsistent developer experiences due to the absence of prescribed encoding and segmenting standards.
• First-Mile Delivery: Using DASH for ingesting streams can introduce considerable latency. A better approach is to encode the video feed with RTMP/WebRTC to a server and then use DASH for last-mile delivery.
• Compatibility Concerns: Although DASH is designed to be platform agnostic, it lacks support for Apple products and requires third-party HTML5 players and Media Source Extensions API to function in browsers.

HLS vs DASH Comparision Table

Features	HLS (HTTP Live Streaming)	DASH (Dynamic Adaptive Streaming over HTTP)
Platform Compatibility	Apple products are dominant but are now also widely supported on other platforms.	This product works with Android, Windows, and smart TVs.
Latency	Higher latency	Low latency
Encryption and DRM Support	Uses FairPlay DRM	Multiple DRM systems like Widevine and PlayReady
File Segmentation	Uses Transport Stream for segmentation	Relies on MP4 fragments
Adoption and Popularity	More Popular	Less Popular

Platform Compatibility Between HLS vs DASH

HLS is a technology that primarily thrives within Apple’s ecosystems, seamlessly integrating with devices like iPhones, iPads, and Apple TVs. However, its versatility has grown, as it is now being increasingly adopted across various other platforms. In contrast, DASH is specifically crafted to achieve universal compatibility. This means it works effectively across a wide range of devices and operating systems, including Android smartphones, Windows PCs, and an array of smart TVs, making it a more flexible option for cross-platform media streaming.

HLS vs DASH Latency Comparision

Historically, HTTP Live Streaming (HLS) has been challenged by higher latency rates, primarily due to its use of longer segment sizes. This can lead to noticeable delays in media playback, which is particularly problematic for live events where real-time interaction is crucial. However, the introduction of Low-Latency HLS (LL-HLS) has significantly mitigated these latency concerns. LL-HLS employs smaller segment sizes and better handling of evergreen content, allowing for more timely delivery of media.

On the other hand, Dynamic Adaptive Streaming over HTTP (DASH) is designed to address latency issues from the outset, providing natively lower latency for streaming applications. This inherent advantage makes DASH a more favorable option for live-streaming scenarios, where quick response times and real-time audience engagement are essential.

Data Encryption and DRM Support

HLS (HTTP Live Streaming) utilizes FairPlay for data encryption and Digital Rights Management (DRM), making it particularly well-suited for environments centered around Apple devices. In contrast, DASH (Dynamic Adaptive Streaming over HTTP) is compatible with a variety of DRM systems, including Widevine and PlayReady, which provides greater flexibility and adaptability across different platforms.

File Segmentation Between HLS vs Dash

HTTP Live Streaming (HLS) utilizes Transport Stream (TS) for segmentation, which is a method for breaking down video content into smaller, manageable parts. On the other hand, Dynamic Adaptive Streaming over HTTP (DASH) employs MP4 fragments, which typically offer improved compression. Consider using an affordable SSD dedicated server. This can increase storage, making it suited to more extensive, well-resourced content providers using DASH. This difference in segmentation approaches contributes to the efficiency and performance of each streaming protocol.

HLS vs Dash: Adoption and Popularity

HTTP Live Streaming has gained significant popularity due to its association with Apple and its widespread use across Apple devices. On the other hand, DASH, or Dynamic Adaptive Streaming over HTTP, with reliable social network hosting, is increasingly gaining traction in the streaming industry due to its open standard and flexibility, making it a versatile option for various platforms and services.

Use Cases: When to Choose DASH vs HLS

Here are some reasons when to choose between DASH and HLS:

When to Choose DASH

1. Cross-Platform Streaming: Ideal for diverse audiences across devices.
2. Low Latency: Critical for live streaming events.
3. Flexibility: Offers more options for codecs and encryption systems.

When to Choose HLS

1. Apple Ecosystems: If your audience primarily uses iOS or macOS.
2. Ease of Implementation: For developers seeking straightforward implementation
3. Broader Wider CDN Support: HLS is well-supported across Content Delivery Networks.

Conclusion

When it comes to HLS vs DASH, the choice depends on your audience, platform requirements, and streaming goals. HLS excels in Apple-centric ecosystems, while DASH’s open standard and low latency make it a versatile choice for diverse platforms.

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