# Transitioning Broadcast to Cloud
## 2 Processing Chains in Broadcast and Cloud-Based Online Video Systems
### Distribution Formats  
As mentioned earlier, in broadcast, distribution is always done using MPEG-2 transport streams [17]. They carry audio and video elementary streams, program and system information [18], SCTE-35 ad markers [19], and other metadata as prescribed by relevant broadcast standards and guidelines [21; 25; 27; 30]. TS in cable systems may also carry EBPs and other cable-specific metadata. In streaming, things are more diverse. There are several streaming formats and standards currently in use. The most prevalent ones, as of time of writing, are:  
1. HTTP Live Streaming (HLS) [5],
2. Dynamic Adaptive Streaming over HTTP (DASH) [6], and
3. Microsoft Smooth Streaming (MSS) [7]. There are also several different types of digital rights management (DRM) technologies. The most commonly used ones are:  
1. FairPlay [66],
2. PlayReady [67], and
3. Widevine Modular [68]. The support for these technologies varies across different categories of receiving devices. Hence, in order to reach all devices, multiple streaming formats and combinations of formats and DRM technologies must be supported. We show few common choices of such combinations in Table 3.  
HLS, DASH, as well as MSS use multi-rate, segment-based representation of media data. Original content is encoded at several different resolutions and bitrates, and then split in segments, each starting at GOP boundary, such that they can be retrieved and decoded separately. Along with media segments (either in TS [17], ISOBMFF [69], or CMAF [70] formats) additional files (usually called manifests, playlists, or \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Device** & **Players/Platforms** & **HLS** & **DASH** & \begin{tabular}{c} **HLS +** \\ **FairPlay** \\ \end{tabular} & \begin{tabular}{c} **HLS +** \\ **Widevine** \\ \end{tabular} & \begin{tabular}{c} **HLS +** \\ **Widevine** \\ \end{tabular} & \
\begin{tabular}{c} **DASH +** \\ **PlayReady** \\ \end{tabular} &
\begin{tabular}{c} **DASH +** \\ **PlayReady** \\ \end{tabular} \\ \hline \multirow{4}{*}{PCs/Browsers} & Chrome & ✓ & ✓ & ✗ & ✓ & ✓ & ✗ & ✗ \\ \cline{2-8}  & Firefox & ✓ & ✓ & ✗ & ✓ & ✓ & ✗ & ✗ \\ \cline{2-8}  & IE, Edge & ✓ & ✓ & ✗ & ✗ & ✗ & ✓ & ✓ \\ \cline{2-8}  & Safari & ✓ & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ \\ \hline \multirow{2}{*}{Mobiles} & Android & ✓ & ✓ & ✗ & ✗ & ✓ & ✓ & ✓ \\ \cline{2-8}  & iOS & ✓ & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ \\ \hline \multirow{4}{*}{Set-top boxes} & Chrome-cast & ✓ & ✓ & ✗ & ✗ & ✓ & ✓ & ✓ \\ \cline{2-8}  & Android TV & ✓ & ✓ & ✗ & ✗ & ✓ & ✓ & ✓ \\ \cline{2-8}  & Roku & ✓ & ✓ & ✗ & ✗ & ✓ & ✓ & ✓ \\ \cline{2-8}  & Apple TV & ✓ & ✗ & ✓ & ✗ & ✗ & ✗ & ✗ \\ \cline{2-8}  & Amazon Fire & ✓ & ✓ & ✗ & ✗ & ✓ & ✓ \\ \cline{2-8}  & TV & & ✓ & ✗ & ✗ & ✓ & ✓ & ✓ \\ \hline \multirow{4}{*}{Smart TVs} & Samsung/Tenzen & ✓ & ✓ & ✗ & ✓ & ✓ & ✓ \\ \cline{2-8}  & LG/ webOS & ✓ & ✓ & ✗ & ✓ & ✗ & ✗ \\ \cline{1-1} \cline{2-8}  & SmartTV & ✓ & ✓ & ✗ & ✗ & ✗ & ✓ & ✓ \\ \cline{1-1} \cline{2-8}  & Alliance & & & & & & & \\ \cline{1-1} \cline{2-8}  & Android TV & ✓ & ✓ & ✗ & ✗ & ✓ & ✓ & ✓ \\ \hline Game Consoles & Xbox One/ 360 & ✓ & ✗ & ✗ & ✗ & ✗ & ✗ & ✓ \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Combination of streaming formats and DRMs that can be used to reach different devices. Orange tick marks indicate possible, but less commonly used choices. Descriptor) files) are provided, describing locations and properties of all such segments. Such manifests are used by players (or streaming clients) to retrieve and play the content. The carriage of metadata in streaming systems is also more diverse. Some metadata can be embedded in media segments, while others may also be embedded in manifests, carried as additional \"sidecar\" tracks of segment files, or as \"event\" messages [6], or ID3 tags [71]. For example, in addition to \"broadcast-style\" carriage of CEA 608/708 [62; 63] closed captions in video elementary streams, it is also possible to carry captions as separate tracks of WebVTT [72] or TTML [73] segments, or as IMSC1 timed text data [74] encapsulated in XML or ISOBMFF formats [45].