Tag Archives: GPAC

HTML 5 Media Source Extensions in SVG

In a previous post, I described a bit the support in GPAC for the HTML 5 video and audio elements in SVG documents. My initial idea was to be able to play, with the Media Source Extensions API, adaptive streaming content (such as DASH) in SVG. So I started implementing MSE and it is now possible to play DASH content within an SVG presentation using GPAC. This post details how it was implemented. Continue reading HTML 5 Media Source Extensions in SVG

WebVTT in MP4

As you probably know from my previous posts, MPEG is standardizing a way to deliver WebVTT files as streams (or tracks) in the ISO Base Media File Format (e.g. MP4 files). The standard is still at draft stage but I recently added VTT-in-MP4 support to GPAC (no playback support yet), as reported in the contribution below. Not that this support might change in the future depending on how the draft standard progresses, in particular in response to some comments we’ve made, as reported in the contribution referenced in this post. Continue reading WebVTT in MP4

HTML 5 media elements in SVG documents

As a follow-up of the work I did some time ago on the implementation of SVG Tiny 1.2 in GPAC (see this paper), and following the SVG WG decision to adopt the HTML 5 media elements in SVG 2.0, I decided to implement some support for these elements in GPAC, to better understand the differences between the old SVG Tiny 1.2 <video> element and the HTML 5 <video> element. As a result you can now run for example the following markup in GPAC:

Continue reading HTML 5 media elements in SVG documents

Live streaming over HTTP of video and subtitles (cont’d)

Here are the slides describing the demo I gave during the ACM MMSys 2013 conference, in Oslo, February 2013. It is an update of the demo I gave during the MPEG meeting in Shanghai, October 2012. Source code should be published soon in GPAC and if I can, I’ll set up a running live server (or, if not possible, I’ll put a video of the demo). Stay tuned.

and the paper:

C. Concolato and J. Le Feuvre, Live HTTP Streaming of Video and Subtitles within a Browser, ACM MMSys, Oslo, Norway, February 2013 [PDF] [DOI 10.1145/2483977.2483997 ].

Automated Testing Script Generation

During a recent SVG Working group discussion, we talked about how to improve the SVG test suite. Part of the problems in the development of the test suite is the sheer number of tests to be produced (i.e. written + reviewed + approved) and then tested against every implementation. The purpose of the testing is to check if every feature passes in at least two independent implementation: that is the criteria to exit Candidate Recommendation. The SVG Tiny 1.2 test suite already contains 496 tests, the SVG 1.1 2nd edition has 526. The SVG 2 spec will probably have more. Having one person test all features is not realistic anymore.

The CSS WG has been working for a long time on this issue. CSS 2.1 has 9685 tests! Together with a team from W3C, the WG set up a test suite server, where one can browse the CSS Test Suite, test its viewer and report the results. All results are then aggregated. The W3C architecture allows for 2 types of tests:

  • ref tests (see Mozilla’s use of ref tests), where a test is provided together with an alternative way of producing the same result (visually).
  • JavaScript tests, where together with the test, one provides JavaScript calls to test that the DOM tree is in the expected state.

Both of these types require quite some work to produce either the reference image or the expected results. This can be tedious. Also, for interactive cases, one would have to create the script to test all interaction paths. And for animation, one would have to author the JavaScript to test changes at some point in time.

In GPAC, we experimented a different approach. Continue reading Automated Testing Script Generation

New GPAC installer for Windows

Some people might be interested in trying out the latest version of the GPAC tools, but don’t have time to compile it from scratch. For those persons, I have generated an installer for Windows from the SVN (revision 2634). It contains the usual things (audio/video support, MPEG-4 Systems stuff (BIFS and LASeR)) but also our latest developments on MPEG-U Widgets and on MPEG-B DASH (Dynamic Adaptive HTTP Streaming).