CMAF... This is the Way

The debate is over. Common Media Application Format (CMAF) has delivered on its promise: one package to serve them all. Two of the highest profile direct-to-consumer (DTC) streaming service launches recently made the leap, validating that the time has come for CMAF.

CMAF provides a number of advantages that make it attractive for video services to adopt:

Reduced costs to prepare, store, and deliver content

Enhanced cache efficiency and origin offload

Improved support for low-latency livestreaming

Looking back at 2015

Before CMAF, most of the modern streaming world was divided between Apple's HTTP Live Streaming (HLS) and MPEG's DASH. As you know, CMAF is an encapsulation format -- a way of packaging up the data for transport. Historically, HLS relied on MPEG-TS encapsulation, an easy transition from legacy broadcaster video infrastructure. But HLS was burdened with arcane data structures and unnecessary overhead due to the noise protection required in the radio networks it was built to serve.

The implementation of MPEG DASH, on the other hand, tended to lean into the more optimized and IP network-friendly ISO Base Media File Format (ISOBMFF) encapsulation based around fragmented MP4. It is not all gravy with DASH -- the technique's flexible and open approach can lead to some complex integrations between components.

CMAF is an evolutionary step forward from ISOBMFF, adding important structures and options that make it compatible with all current and forward-looking data types that content publishers are interested in supporting. While Apple's decision to enable HLS support of CMAF was the catalyst for this change, it left operators with several important decisions.

CMAF is just a box we put media and data in. Most of the interesting stuff -- like ad insertion -- occurs at the manifest or application level. That's where we need to choose whether to address the CMAF segments from an HLS and/or DASH manifest.

If you want to use Apple's native player (and most people do), you must supply an HLS manifest. As a practical matter, this gave operators one choice: go HLS everywhere, since other devices are less prescriptive. But HLS isn't perfect, and some inefficiencies in it pushed other folks to adopt a DASH everywhere (except Apple) strategy.

Maintaining two manifests drives up operational overhead but does not impact storage or delivery efficiency. The major gains are realized from having a common set of data objects. The manifests are relatively small text files that can be derived from one another.

Premium content

The big sticking point impacts premium content owners. While Apple acceded to support CMAF, it stuck to its preferred approach of AES128 encryption: Cipher Block Chaining Sample (CBCS) mode. The debate will rage over the incremental benefit versus the Counter (CTR) method, but the hard truth is that it left us with a population of devices in people's hands that were hard coded to one or the other.

The good news, now that more digital water has run under the bridge, is that developers have been building CBCS support into all new devices. At least from here on out, they will support CBCS. Ladies and gentlemen, we have reached the moment.

If you don't have premium content you are all set -- go forth and package once!

Let's take a look at a couple of the sticking points for premium-content owners: SmartTVs pre-2020 and PlayStation 4 (PS4).

SmartTVs pre-2020

The two biggest players in the SmartTV segment are Samsung and LG, accounting for 11% of viewing time according to Conviva's State of Streaming Q2-2020 report.

In the last two years, viewership has exploded on native SmartTV apps because of the convenience for the end user. There is an irony here -- this shifted viewers from platforms with CBCS support to a patchwork of TV platforms that do not.

Samsung and LG, like others in industry, define the core firmware of the TV by the year model and crucially do not offer an upgrade path...

The debate is over. Common Media Application Format (CMAF) has delivered on its promise: one package to serve them all. Two of the highest profile direct-to-consumer (DTC) streaming service launches recently made the leap, validating that the time has come for CMAF.

CMAF provides a number of advantages that make it attractive for video services to adopt:

Reduced costs to prepare, store, and deliver content

Enhanced cache efficiency and origin offload

Improved support for low-latency livestreaming

Looking back at 2015

Before CMAF, most of the modern streaming world was divided between Apple's HTTP Live Streaming (HLS) and MPEG's DASH. As you know, CMAF is an encapsulation format -- a way of packaging up the data for transport. Historically, HLS relied on MPEG-TS encapsulation, an easy transition from legacy broadcaster video infrastructure. But HLS was burdened with arcane data structures and unnecessary overhead due to the noise protection required in the radio networks it was built to serve.

The implementation of MPEG DASH, on the other hand, tended to lean into the more optimized and IP network-friendly ISO Base Media File Format (ISOBMFF) encapsulation based around fragmented MP4. It is not all gravy with DASH -- the technique's flexible and open approach can lead to some complex integrations between components.

CMAF is an evolutionary step forward from ISOBMFF, adding important structures and options that make it compatible with all current and forward-looking data types that content publishers are interested in supporting. While Apple's decision to enable HLS support of CMAF was the catalyst for this change, it left operators with several important decisions.

CMAF is just a box we put media and data in. Most of the interesting stuff -- like ad insertion -- occurs at the manifest or application level. That's where we need to choose whether to address the CMAF segments from an HLS and/or DASH manifest.

If you want to use Apple's native player (and most people do), you must supply an HLS manifest. As a practical matter, this gave operators one choice: go HLS everywhere, since other devices are less prescriptive. But HLS isn't perfect, and some inefficiencies in it pushed other folks to adopt a DASH everywhere (except Apple) strategy.

Maintaining two manifests drives up operational overhead but does not impact storage or delivery efficiency. The major gains are realized from having a common set of data objects. The manifests are relatively small text files that can be derived from one another.

Premium content

The big sticking point impacts premium content owners. While Apple acceded to support CMAF, it stuck to its preferred approach of AES128 encryption: Cipher Block Chaining Sample (CBCS) mode. The debate will rage over the incremental benefit versus the Counter (CTR) method, but the hard truth is that it left us with a population of devices in people's hands that were hard coded to one or the other.

The good news, now that more digital water has run under the bridge, is that developers have been building CBCS support into all new devices. At least from here on out, they will support CBCS. Ladies and gentlemen, we have reached the moment.

If you don't have premium content you are all set -- go forth and package once!

Let's take a look at a couple of the sticking points for premium-content owners: SmartTVs pre-2020 and PlayStation 4 (PS4).

SmartTVs pre-2020

The two biggest players in the SmartTV segment are Samsung and LG, accounting for 11% of viewing time according to Conviva's State of Streaming Q2-2020 report.

In the last two years, viewership has exploded on native SmartTV apps because of the convenience for the end user. There is an irony here -- this shifted viewers from platforms with CBCS support to a patchwork of TV platforms that do not.

Samsung and LG, like others in industry, define the core firmware of the TV by the year model and crucially do not offer an upgrade path...