Video Codecs and Choosing Between HLS and DASH for Your Streaming App

As video streaming continues to dominate digital platforms, understanding how to deliver high-quality video efficiently is key for developers. Central to this process is knowing about video codecs and choosing the right streaming protocol, such as HLS or DASH, that aligns with your application’s needs. In this blog, we’ll explore what a video codec is, why it’s essential, and delve into a comparison of two popular streaming protocols: HLS vs DASH.

What is a Video Codec?

A video codec (short for coder-decoder) is a technology used to compress and decompress digital video files. Video codecs are essential for reducing the size of video files while maintaining acceptable visual quality, allowing for efficient storage and transmission over the internet. Without video codecs, high-quality videos would require enormous amounts of data and bandwidth, making streaming unfeasible.

Common video codecs include:

• H.264 (AVC): One of the most widely used codecs, H.264 offers efficient compression, good video quality, and compatibility across various platforms. It’s commonly used for streaming video, web video, and even mobile applications.
• H.265 (HEVC): This is the successor to H.264, offering around 50% better compression efficiency, meaning it delivers the same quality as H.264 at half the bit rate. It’s increasingly being used for 4K streaming and high-quality video on platforms where bandwidth is limited.
• VP8 and VP9: Developed by Google, these codecs are often used for web video and are the primary codecs for WebM, a container format supported by browsers like Chrome and Firefox.

Choosing the right video codec is crucial for delivering optimal video quality while ensuring efficient bandwidth use, particularly in apps with video players or streaming functionality. A well-chosen codec can help minimize buffering and reduce data consumption for your users.

HLS vs DASH: Which Streaming Protocol Should You Choose?

When building a video streaming app, selecting the correct streaming protocol is as important as choosing the right video codec. The two most popular adaptive streaming protocols are HLS (HTTP Live Streaming) and DASH (Dynamic Adaptive Streaming over HTTP). Both protocols provide adaptive bitrate streaming, meaning the video quality adjusts based on the viewer’s internet connection to prevent buffering.

However, they have different technical aspects that may make one more suitable than the other for your project.

What is HLS?

HLS is a streaming protocol developed by Apple that breaks video content into small, downloadable chunks and adjusts the bitrate in real-time according to the user’s network conditions. HLS is widely used due to its strong support across devices and platforms, especially Apple products like iOS and macOS. It uses the MPEG-TS container format and typically relies on the H.264 codec, though it also supports newer codecs like H.265.

Wide compatibility: HLS is natively supported by Apple devices and is also compatible with many other platforms, including Android and desktop browsers. This makes it an attractive choice for apps targeting a broad audience across different device ecosystems.

Reliable streaming: The adaptive bitrate streaming technology in HLS ensures smooth playback by adjusting video quality to match the user’s bandwidth, preventing issues like buffering or freezing.

Security features: HLS also supports secure streaming with AES-128 encryption and DRM (Digital Rights Management) options, providing protection for premium or sensitive content.

Drawbacks of HLS

• Higher latency: One of the main drawbacks of HLS is its higher latency compared to other streaming protocols like DASH. This may be problematic for live streaming events, where lower latency is crucial to ensure real-time interaction.
• Larger file sizes: HLS uses the MPEG-TS container format, which can be less efficient than other formats like MP4. This can result in slightly larger file sizes and higher bandwidth usage during streaming.

What is DASH?

DASH (Dynamic Adaptive Streaming over HTTP) is an open-standard streaming protocol that provides similar adaptive bitrate streaming functionality to HLS. However, DASH is codec-agnostic and allows for greater flexibility in terms of video containers and codecs. DASH uses the ISO BMFF (MP4) container format, which is more efficient and widely supported.

Benefits of DASH

• Lower latency: One of DASH’s biggest advantages is its lower latency, making it more suitable for real-time streaming applications like sports or live events where delays should be minimized.
• Efficient file handling: The MP4 container used by DASH is more efficient than the MPEG-TS format used in HLS, resulting in smaller file sizes and better streaming efficiency. This can save bandwidth and improve overall performance.
• Codec flexibility: Unlike HLS, which primarily uses H.264 or H.265 codecs, DASH is flexible in its codec use, supporting various formats like VP9 or AV1. This flexibility allows developers to optimize their video streams based on the devices and platforms they are targeting.

Drawbacks of DASH

Limited support on Apple devices: While DASH is widely supported across most platforms, it does not have native support on iOS or macOS devices. This means that developers who want to use DASH on Apple products may need to implement additional workarounds, such as using a custom player.

Complex implementation: Due to its flexibility and features, DASH can be more complex to implement compared to HLS. Developers may need to spend more time configuring and testing DASH-based streaming, especially if they are working across a wide range of platforms and devices.

Key Differences Between HLS and DASH

The decision between using HLS or DASH largely depends on the needs of your app and your target audience. HLS is favored for its broad compatibility, especially with Apple devices, and its ease of implementation. However, it tends to have higher latency, which may not be ideal for live streaming scenarios.

On the other hand, DASH is known for its lower latency and flexibility in terms of codec support, making it a strong choice for developers targeting multiple platforms or delivering real-time streaming services. However, its lack of native support on Apple devices can be a hindrance for apps catering primarily to iOS users.

If your app is focused on delivering video to a general audience with a mix of devices, HLS might be the simpler and more reliable choice. However, if you’re focused on low-latency streaming or need the flexibility to work with various codecs and video formats, DASH could be the better option.

Conclusion

Both video codecs and streaming protocols are essential components of a high-quality video experience in modern apps. The right combination can drastically improve user engagement and satisfaction. Understanding how video codecs like H.264 and H.265 work in conjunction with streaming protocols such as HLS and DASH will help you optimize video delivery for your app, ensuring smooth, high-quality playback regardless of network conditions.

Whether your priority is broad device support, efficient file handling, or low-latency streaming, knowing the strengths and weaknesses of HLS and DASH will guide you in making the right decision for your project.