Koherence’s response to FCC Docket 16-142 and ATSC 3.0 DRM

As broadcasters have started turning on DRM for their services, viewers using HDHomeruns and other devices have started to lose access to those services. Here in the SF Bay Area, CBS, NBC, and Univision stations have encrypted their services while ABC, FOX, and the independent KRON remain in the clear. On a recent trip to Honolulu we also noted a number services have flipped the protection switch since our previous trip in February. As a result we have switched back to the ATSC 1.0 versions of these services, where we an record, watch, trick play, and stream throughout and outside the home via Project Entangle. (We are pleased that to date ABC has resisted the urge to protect their 3.0 service and enjoy ABC Nightly News via KGO’s 3.0 service.)

In response to the frustrations of losing access to protected 3.0 services, Lon Seidman started a change.org petition urging the FCC to take action and prevent broadcasters from encrypting their services. Readers of this blog know that we do not view protection of 3.0 services favorably – in particular services which are comparable to existing free and in-the-clear ATSC 1.0 services (which is at present basically all 3.0 services). There is a place for DRM in ATSC 3.0, and Evoca’s service was a great example.

If you haven’t signed the change.org petition, we urge you to do so. It can be found at:


Lon Seidman also filed a complaint with the FCC. In their reply the FCC provided a way for consumers to share their experiences and how they are harmed by ATSC 3.0 DRM. We encourage you to submit a comment via


under proceeding 16-142 Authorizing Permissive Use of the “Next Generation” Television Standard. We encourage you to watch Lon’s YouTube videos (he has a playlist on the DRM topic) as he provides some great information on how to craft your comment so it is relevant to the FCC commissioners.

Our own FCC response is included below and we hope it provides another nudge to the responsible implementation of content protection in ATSC 3.0.


Regarding GN docket No. 16-142 and Authorizing Permissive Use of the “Next Generation” Broadcast Television Standard, Koherence, LLC (DBA Koherence) respectfully submits that the FCC limit the application of DRM so that viewers continue to enjoy their fair-use rights as they have been defined for NTSC and ATSC 1.0. Such rights include the ability to time-shift, view programming on mobile or other devices (other than the receiving device), and to view programming at various locations inside or outside the home. We also wish to highlight the burden that DRM poses to developers of such advanced receivers beyond the implementation of the DRM itself.

Koherence is a consulting company with an extensive history of working with leading consumer electronics manufacturers to develop advanced over-the-air, cable and satellite set-top receivers and broadband streaming services. Koherence assisted its clients in allowing their platforms to stream live and recorded shows to other devices within the home, to mobile devices, and outside the home. Koherence’s founder, Mr. Michael Minakami, previously led development of numerous TiVo platforms and kickstarted, and subsequently led the development of, TiVo’s internal ATSC prototypes which ultimately led to the first commercially available high definition television DVR. Mr. Minakami is a strong advocate of free over-the-air television. He was also responsible for the US engineering organization for TGC America and the technology roadmap for TGC, Inc. TGC, Inc. was a licensee of TiVo’s technology and adapted and innovated within the set-top space for the Greater China market. Koherence is experienced with the intricacies of developing set-top boxes for cable and satellite and the requisite concerns for DRM as well as a the business concerns on both the CE device developer and service operator sides regarding content protection and rights management.

For the past five years Koherence has been involved with ATSC 3.0 while enhancing its OTA DVR platform to support ATSC 3.0. This solution is available for license to CE companies interested in adding ATSC 3.0 capabilities to their products. Koherence also has a presence in the OTA TV enthusiast community and operates the San Francisco Bay Area OTA Monitoring system (https://sfbayatsc.com) for the benefit of local broadcasters and OTA enthusiasts. Koherence has considered an open source version of its ATSC 3.0 platform along the lines of Myth TV or the early Plex to give an ATSC 3 boost to the enthusiast community. To date Koherence has made available pieces of its ATSC 3.0 receiver stack (https://in-koherence.com/atsc30-base-stack). Availability of the full DVR platform remains under evaluation.  Both the licensing and open source venues are negatively affected by the presence of DRM in the ATSC 3.0 standard and the decision of some broadcasters to enable that DRM on services comparable to their ATSC 1.0 offerings.


We respectfully request that the FCC require that broadcasters provide their ATSC 3.0 linear services free and in the clear as they always have with NTSC and ATSC 1.0 – without any encryption.

We respectfully request that the FCC require that broadcasters not apply rights management to those services.

We wish to distinguish between encryption and rights management. The two are often conflated under the umbrella of DRM as encryption is often the method by which rights management is enforced.  (Specifically, access to the decryption key is only provided if the receiver provides a secure method of storing and using that key, and adheres to the rights management policies.) However encryption may be employed without rights management as a method of preventing content theft, without otherwise restricting how the decrypted content is consumed.

Broadcasters have long had an uneasy relationship with consumer devices when it comes to new ways of consuming over-the-air television. This is evident from the days of the Betamax VCR to DVRs/Replay TV. The “broadcast flag” was another effort to control how viewers consumed broadcast TV.

At the end of the day broadcasters have a commercial interest in controlling viewers “eyeballs” (viewing habits). This is not surprising as features such as fast-forwarding through ad breaks posed a potential advertising revenue threat. The series of legal challenges has over time established what viewers may (and may not) do under the doctrine of fair use.  ATSC 3.0 should not be a backdoor to hobbling those rights.

To be clear we oppose DRM when applied to linear services in the same category of existing ATSC 1.0 services. We do see a place for DRM when providing new classes of services. For example we believe it appropriate for DRM to be applied:

  1. To OTA-delivered subscription services, such as Evoca had provided.
  2. To an enhanced viewing adjunct to a free-and-clear delivered service. Such enhanced viewing can be provided in ATSC 3.0 via an enhancement layer and provide higher resolution video (via SHVC) or enhanced audio. As an example, a broadcaster may provide a 1080i/59.94 base experience (equivalent to ATSC 1.0) and an enhanced 4k/60p experience perhaps with superior multichannel audio and other embellishments. We see audiovisual experiences superior to ATSC 1.0 as worthy of protection from theft. (We see this as similar to “downrezzing”, where a high quality source is degraded for broadcast or satellite broadcast. ATSC 3.0 enhancement layers now provide a path for viewers to enjoy the “fullrez” content while protecting the content’s commercial interest.)
  3. To services which are not audiovisual services, such as data delivery services. Strictly speaking these would be simply encrypted and not have a rights management component.

3.      Availability of Public Signature Verification Keys

We respectfully request that the FCC require broadcasters to make publicly available public signature verification keys and any other items required to receive and render an in-the-clear broadcast.

ATSC 3.0 utilizes public key cryptography, which is a well-established system in which certain keys (public keys) may be publicly shared so that holders of those keys may authenticate the signature associated with a received message.

With respect to reception of ATSC 3.0 emissions, the public key authenticating the signature contained in signed multitables is required by receivers. At present this key is not publicly available. It is our understanding that the existence of “signed signaling” is in the interest of broadcasters as a means of ensuring that their broadcasts are not hijacked. Provided that ATSC/A3SA have properly generated and secured the private keys, sharing the public keys in no way compromises the security of signed signaling and would permit all ATSC 3.0 receiving devices to participate in ensuring signaling tables are received as intended by the broadcaster.

To be clear we understand that decryption keys cannot be made publicly available.

4.      DRM Implications for Receiver Development

In addition to (potentially) restricting the rights of viewers to consume content when, how, and where they want, we also wish to share our perspective that DRM also harms the ATSC 3.0 ecosystem by placing a significant burden to receiver development that is not commensurate to its market opportunity.

Having driven many receiver platforms, including those for cable and satellite which employ DRM systems, we are familiar with the development/design and certification efforts associated with DRM. These efforts concern not only implementing and validating the encryption and rights restrictions, but also securing the platforms so that the encryption and rights restrictions cannot be bypassed. One potential client we discussed ATSC 3.0 with was rather concerned that the 3.0 specifications had a DRM requirement and were keen to understand if it was required. This client had developed many receiver platforms and worked with a number of DRM vendors and schemes and was well-equipped from a technical standpoint to produce a secured ATSC 3.0 receiver. But, to put it simply, the comparatively small market opportunity did not match the implementation and certification efforts they typically encountered with DRM-enabled platforms.

Advanced receivers which manipulate the decrypted (and sometimes decompressed) content or that do not preserve the original “network encryption” pose another challenge. Such receivers may do so for purposes of trick play, or transcoding/transrating so that content may be efficiently streamed within a home or for compatibility with mobile devices. Manipulation of content in this manner is usually at odds with DRM schemes and special accommodations are generally required between the CE developer and content provider.

We can only surmise that the delay and eventual cancellation of Nuvyyo’s ATSC  3.0-capable DVR was negatively affected by challenges in managing DRM within an architecture where such concerns did not apply. Their ATSC 1.0 Tablo DVRs transcode ATSC 1.0 content prior to recording it to a hard drive and in all likelihood did not employ the platform security characteristic of DRM-enabled devices.

Closer to home, the open source ATSC 3.0 version of our own OTA DVR platform has been placed on hold as we review whether it makes sense to make available a system that can handle some services but not others. This is the same problem initially faced by SiliconDust. However unlike SiliconDust, which distributes a closed-source application and was able to support DRM in a software update to that application, there is no way to secure an open source system for certification. We are faced with a situation where viewers would be able to record, pause, trick play, and otherwise view any ATSC 1.0 service without issue. They would be able to do the same for unprotected ATSC 3.0 services, but not for protected 3.0 services. That being the case the value of supporting 3.0 becomes questionable. We understand that the FCC may place a low emphasis on open source solutions. However we wish to emphasize that if broadcasters attempt to restrict viewing behaviors using rights management, then we again see that users will have a superior experience via ATSC 1.0 versus ATSC 3.0. The viewer may be able to record some 3.0 services or shows but not others. They may be able to pause or trick play some 3.0 but not others. Yet they would have unfettered access to ATSC 1.0 services. The viewing experience is as much influenced by the freedom to consume content when, how, and where a viewer sees fit as it is by its picture resolution, frame rate, colorimetry and other technical audiovisual aspects – the latter already highly variable depending on the feature set of televisions.

5.      Conclusion

In closing, we request that the FCC allow viewers to interact with ATSC 3.0 services in the same way they do today with ATSC 1.0 services and previously did with NTSC. Viewers should continue to be able to record, time shift, pause, and otherwise consume services how, when, and where they want – consistent with limitations of fair use. ATSC 3.0 should not be a venue to strip viewers of these rights. It also serves the greater industry in not burdening CE devices with the implementation and associated platform security “tax” imposed by DRM. At the same time we do not wish to restrict broadcasters’ ability to deploy new classes of services which may require encryption and/or rights restrictions and which may be optionally supported by CE devices as they evaluate the market opportunity for devices supporting such new services.