Category Archives: DASH

Official AV1 and VP9 support in GPAC

Dear reader,

GPAC has added support for new codecs recently:

  • AV1 support is available in nightly builds since July 10th, 2018. This include file creation with MP4Box (including MPEG DASH generation) and file playback with MP4Client. Support for AV1 encryption was added on September 20th, 2018.
  • VP9 support was completed on October 14th, 2018.

This article gives you some useful command lines to use AV1 streams, but the same can be applied for VP9 streams.

Command-line for importing AV1 streams into MP4 files

To store an AV1 bitstream into an ISOBMFF/MP4 file , use the following command line. If the input file is called *.av1, its content can be OBUs (as specified in Section 5 of the AV1 specification), IVF or Annex B bitstreams. WebM streams are not supported. You can also call OBU-based bistream *.obu and IVF files *.ivf:

If your file extension is not recognized by MP4Box, you can indicate the bitstream format with “:fmt=obu” or :fmt=AnnexB or fmt=IVF (case insensitive) as follows:

AV1 bitstreams may not contain frame rate information, you can use the following to indicate it:

Command-line for AV1 adaptive streaming preparation

You can use the usual MP4Box command line parameters to segment your AV1 MP4 file and prepare it for adaptive streaming. The following command line will generate an MPEG-DASH onDemand manifest based on an AV1 representation (with its ‘codecs’ parameter) and it will create a segmented MP4 file with segments starting at AV1 KEY FRAMEs and targeting 1 second duration.

Command-line for AV1 encryption/decryption

Encryption of AV1 streams in MP4 files follows the general principles given by MPEG’s Common Encryption specification.¬† To use MP4Box for encryption or decryption, use the following command lines where the file ‘info.xml’ is an XML file that provides encryption parameters, as described in more details here. Example of such XML files can be found in our test base.

Encryption:

Decryption:

Acknowledgements and conclusion

The work on AV1 and VP9 was largely sponsored by Alliance for Open Media and Netflix. Kudos to them ūüôā

As usual, if you find any bug or miss documentation, let us know.

Live DASH audio/video encoder: DashCast

Dear GPAC users,

We’ve just released a new application which might be of interest to some (hopefully many) of you. It’s called DashCast. It’s an application which allows you to:

  1. transcode a live/non-live stream in multiple qualities (eg. bitrate and resolution).
  2. segment a continuous stream in small chunks and packetize them for delivery via Dynamic Adaptive Streaming over HTTP (DASH) standard.

For more information, check out the dedicated page.