Technology Blog: MainConcept

The Seemingly Incompatible Becomes Reality: Dolby Digital Audio in FFmpeg

Written by Frank Schönberger | Sep 26, 2024

Until now, using FFmpeg to create and process AC-3 or E-AC-3 audio streams has been a challenge for many workflows and services using the popular open-source multimedia framework. While the quality of the available solutions is inconsistent at best, the more critical issue is that they were neither officially approved nor certified by Dolby. However, there is a new solution entering the market that solves these challenges.

FFmpeg and Dolby Digital Audio – A Complicated Relationship

FFmpeg is arguably the most well-known and widely used open-source multimedia framework worldwide. It offers numerous codecs and related libraries to support a large number of formats. There are only a few professional production formats and codecs that are either not available at all or have limited backing.

The popular AC-3 (Dolby Digital) and E-AC-3 (Dolby Digital Plus™) codecs, introduced by Dolby in the early 1990s, have become the de-facto standards for many specifications and CE devices. Dolby’s AC-3 and E-AC-3 surround technology delivers high-quality digital audio for up to 7.1 discrete channels. Whether you are looking at physical discs like DVD or Blu-ray, streaming formats like HLS or MPEG-DASH as well as broadcast TV formats ISDB, ATSC and DVB, the Dolby Digital audio formats are either mandatory or optional. This means many workflows and services require AC-3 or E-AC-3 processing capabilities to serve their customer needs.

So far so good, but if your environment or solution was – or still is – based on FFmpeg, you had some issues that shouldn’t be ignored. One issue, audio quality from FFmpeg’s native AC-3 and E-AC-3 implementation is much lower compared to Dolby’s own libraries, which do not even exist for direct usage with FFmpeg! But by far the biggest issue is that FFmpeg’s native AC-3 and E-AC-3 offering is neither approved nor certified by Dolby, making it essentially an unauthorized deployment of Dolby’s patents. Admittedly, the last Dolby AC-3 patent expired in 2017, but the E-AC-3 patents are still active until early 2026. In fact, using E-AC-3 today can be interpreted as a patent violation which could result in a lawsuit. In addition, while the royalty situation is unclear, you are officially responsible for paying fees for using this Dolby technology. In the end, these issues can be a threat to any business!

These are likely the main reasons why Dolby Digital plays a small role in FFmpeg. However, this would change if there was an official solution to process AC-3 and E-AC-3 within an FFmpeg environment.

MainConcept FFmpeg Plugins for Dolby Digital

The baseline was obvious: How to integrate our certified MainConcept Dolby Digital Plus Pro libraries into FFmpeg with Dolby’s support? This idea had been discussed with Dolby over the years. It took a while to come to a technical and business solution that satisfied Dolby’s and ours prerequisites.

All that work has paid off as MainConcept is now the first (and only) company that offers officially approved and certified Dolby Digital Plus Pro Plugins for FFmpeg. The Dolby authorized plugins are available in encoder or decoder versions allowing content producers and broadcasters to process AC-3 and E-AC-3 audio technologies natively within an FFmpeg workflow or service. The simple plugin approach integrates Dolby Digital’s AC-3 and E-AC-3 audio software encoder and decoder into new or existing FFmpeg 4.4 (Rao), 6.0 (Von Neumann) or 7.0 (Dijkstra) environments.

Another benefit for the user is that the MainConcept Dolby Digital Plus Pro Plugins seamlessly integrate with other MainConcept video encoder, multiplexer or decoder plugins for FFmpeg, plus FFmpeg’s built-in libraries. As with other MainConcept FFmpeg Plugins, these can be deployed using on-premise servers, in the cloud or within a hybrid approach to significantly boost both performance and quality of your audio as well as video use-case.

Last but not least, there are strong business and financial reasons for licensing the MainConcept Dolby Digital Plus Pro Plugins for FFmpeg. Integrating our plugins into your workflow or service is done directly with MainConcept, it does not require separate negotiations and agreements with Dolby. We are your sole contact for licensing, integration and support of the AC-3 and E-AC-3 technologies, i.e. the only agreement you will sign is with us. This also means you do not need to worry about royalties, these are handled by MainConcept as well.

In the end, there are very clear reasons for taking a closer look at the MainConcept Dolby Digital Plus Pro Plugins for FFmpeg.

Do the plugins fit into my FFmpeg workflow?

We cannot say for sure but why don’t you have a look at the AC-3 and E-AC-3 decoder or encoder plugins yourself? There are free demo versions as well as paid trials available. Both are fully functional and valid for 30-days. The free demo does mute the audio from time to time.

Interested? Check out the Dolby FFmpeg page for all the information you need to decide which version is right for you. Seize the opportunity to enhance your workflow by adding officially authorized Dolby AC-3 and E-AC-3 audio processing today!