Understanding Streaming Media: From RTMP to MPEG‑DASH Explained

What Is Streaming Media?

Streaming media refers to media formats (audio, video, or multimedia files) delivered over a network using a streaming transmission technique that allows continuous real‑time playback, eliminating the need to download an entire file before viewing.

1. RTMP

RTMP (Real Time Messaging Protocol) is an open protocol developed by Adobe for transmitting audio, video, and data between Flash players and servers. It offers low latency (around 2 seconds), high stability, broad support, and strong codec compatibility.

RTMP Workflow

2. HTTP‑FLV

HTTP‑FLV packages media data into the FLV container and delivers it via standard HTTP (port 80), which bypasses firewalls and supports HTTPS encryption. Its drawbacks include client‑side caching that reduces confidentiality. Before Media Source Extensions (MSE), playback relied on Flash; with MSE, JavaScript‑based soft decoding of FLV is common.

3. HLS Protocol

HTTP Live Streaming (HLS), introduced by Apple, is an HTTP‑based streaming protocol that segments the media into small files listed in an extended M3U8 playlist. Clients can switch between different bitrate streams based on network conditions, and because it uses standard HTTP ports, it avoids firewall blockage.

HLS Workflow

Client playback of an HLS stream involves downloading the index.m3u8 playlist, selecting an appropriate variant, and sequentially fetching the TS or fragmented MP4 segments.

Typical index.m3u8 file structure:

Protocol Comparison

4. HDS

HTTP Dynamic Streaming (HDS) is Adobe’s counterpart to HLS. It also uses HTTP to deliver media, but its manifest files are .f4m (or .bootstrap) and its segments are stored in the fragmented MP4‑based .f4f format.

Typical HDS request flow:

Client requests a .f4m manifest (e.g., http://www.example.com/media/httpDynamicStreaming.f4m).

Server forwards the request to the HTTP Origin Module.

Origin Module returns the manifest to the client.

Client parses the manifest, builds segment/fragment pairs, and requests individual fragments (e.g., http://www.example.com/media/httpDynamicStreamingSeg1-Frag1 or ...Seg1.f4f).

Server returns the requested video fragment.

Client assembles and plays the fragments.

DASH Protocol

MPEG‑DASH (Dynamic Adaptive Streaming over HTTP) is an international standard (MPEG, 2014) that unifies adaptive bitrate streaming across HTTP. It supports multiple container formats (MPEG‑2 TS, MP4, etc.) and selects appropriate segments based on current bandwidth and codec support.

DASH Workflow

Broadcaster uploads live stream.

Server encodes and packages the stream.

Media distributor creates an MPD manifest and segmented media files.

Client loads the MPD.

Client parses MPD to generate download URLs.

Based on network speed and supported codecs, the client fetches and plays the appropriate segments.

MPD File Content

MPD tags – attributes such as profiles, mediaPresentationDuration, minBufferTime, type, availabilityStartTime, minimumUpdatePeriod.

BaseURL – root directory for segment URLs; can appear at multiple hierarchy levels.

Period – a time interval (e.g., 0‑15 s, 16‑40 s); multiple periods may exist in a live stream.

AdaptationSet – groups interchangeable Representations; may contain video, audio, or other media types.

Representation – describes a specific bitrate/codec combination (e.g., codecs="avc1.640028", bandwidth=3200000).

SegmentTemplate – URL template for segment retrieval using placeholders like $RepresentationID$, $Bandwidth$, $Number$, $Time$.

Frontend Processing

Load the video and fetch the MPD file.

Parse MPD to discover available AdaptationSets and Representations.

Measure current bandwidth and select the first suitable segment.

Feed the segment data to the Media Source Extensions (MSE) API for playback.

Continuously monitor download speed and switch to higher or lower bitrate segments as needed.

Build Your Own DASH Demo

1. Download the MP4Box tool (the slicing utility) from https://gpac.wp.imt.fr/downloads/gpac-nightly-builds/. The executable is located at /Applications/GPAC.app/Contents/MacOS/MP4Box.

2. Run the following command to generate a live‑profile DASH package:

sudo /Applications/GPAC.app/Contents/MacOS/MP4Box -dash-strict 5000 -profile dashavc264:live -rap /Users/lijiancheng/Documents/mse/assert/foo.mp4#video /Users/lijiancheng/Documents/mse/assert/foo.mp4#audio -out index.mpd

3. Include the open‑source dash.js library in your HTML:

<script src="https://cdn.dashjs.org/latest/dash.all.min.js"></script>

4. Add a video element that points to the generated MPD:

<video data-dashjs-player autoplay src="./assert/index.mpd" controls></video>

Other DASH Demos

http://reference.dashif.org/dash.js/nightly/samples/dash-if-reference-player/index.html

http://demo.theoplayer.com/test-your-stream-with-statistics

https://bitmovin.com/demos/stream-test

DASH Slicing Tools

FFmpeg

MP4Box

DASH Open‑Source Library

dash.js (frontend playback)

Related Documentation

Adaptive Streaming (Part 4) – Deep Dive into MPD: https://blog.csdn.net/nonmarking/article/details/85714099

MP4Box Command Reference: https://gpac.wp.imt.fr/mp4box/dash/

DASH Overview and Usage (FFmpeg, MP4Box): https://blog.csdn.net/yue_huang/article/details/78466537

Installing and Using MP4Box: https://www.jianshu.com/p/c801e8dd041e

DASH Protocol and Adaptive Bitrate Comparison: https://juejin.im/post/5a697868f265da3e3f4ce17d

Azure Media Services Support for DASH: https://blogs.msdn.microsoft.com/azchina/2014/12/04/azure-dash/

Reducing Broadcast Latency with Adaptive Bitrate Tech: https://aws.amazon.com/cn/blogs/china/compete-broadcast-latency-bitrate-tech4/