Helix media activity

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Helix "Watch & Listen" Media Activity

These notes relate to the "Watch & Listen-1.xo" release of the activity. Currently, the activity is bundled with the Helix media engine all in one package for easy installation. Eventually this engine, and the python bindings providing access to it will be moved to a location allowing any activity to easily use the media engine.

Helix Activity Installation Notes

  • Download the activity (see the ticket for instructions, or look here). Then just unzip the activity in /home/olpc/Activities. Restart Sugar.
  • Play the OLPC test clip via the open location button (see below):
    • rtsp://judas.osuosl.org/olpc.smil


  • Then you can download a packet of videos to go along with it. If you're downloading something larger than 15MB, you should do it from the command line via wget; downloads via the browser currently go to /tmp and use up memory.
    rtsp://judas.osuosl.org/SesameFull.rv
    rtsp://judas.osuosl.org/testMusic.mp3
    rtsp://judas.osuosl.org/SesameStreet_21.rv

We will be adding more content as it becomes available (email us, olpc-player-dev at helixcommunity.org with suggestions, or leave them here on the discussion page)

You can also try them via HTTP or download them via 'wget' to try them locally.

Helix "Watch & Listen" Media Activity Version 1 Usage Notes

Please refer to this screen grab of the activity running:

http://staff.osuosl.org/~jirwin/foo.png

Starting at the upper left and going right you have the following buttons and functions:

  • Back button, this seeks the clip back 1/20 of its duration.
  • Play/pause button.
  • Stop button.
  • Forward button, this seeks the clip forward 1/20 of its duration.
  • Progress bar (non-clickable, non-dragable), this shows the current time and total duration of the clip.
  • Open File button.
  • Open Location button, this allows you to type in streaming links.


The activity has not been through QA (so YMMV), but this version of the engine should support:


  • 3GPP-Rel6 file parsing and 3GPP-Rel6 audio and video playback
  • 3G2 audio depacketizers and QCelp decoder hooks
  • AAC and aacPlus decoder - More info
  • AAC and aacPlus playback from .3gp, .m4a, .aac or .ra files and 3GPP, ISMA or ice-cast streams
  • AMR-NB and AMR-WB audio playback from .3gp and .amr files and 3GPP streams
  • H.261 video from standard RTP streams
  • H.263 video from .3gp files and standard RTP streams
  • H.264 video from .3gp files and standard H.264 RTP streams
  • I420 video rendering
  • MJPEG video playback from .avi files
  • MP3 audio playback from .mp3 files, standard RTP streams and shout-cast streams
  • MP3 playlist parsing and playback
  • Helix MP3 Decoder
  • Helix MP3 Encoder
  • MPEG1/2 file parsing
  • MPEG4 audio (no video) playback from .mp4 or .3gp files and ISMA or 3GPP streams
  • Ogg Vorbis and Ogg Theora (with some known problems streaming over RTSP).
  • Uncompressed PCM from .wav, avi, .aiff or .au files and standard RTP streams
  • PCM a-law and u-law from .wav, avi or .au files and standard RTP streams
  • RAM metafile parsing and playback
  • RGB video from .avi files
  • RealAudio/RealVideo Codecs
  • RealAudio and RealVideo playback from RealMedia file format and RealMedia streams.
  • RealEvents and RealImageMap from .rm files and RealMedia streams
  • RealText from .rt files and RealText streams
  • SDP file parsing
  • SMIL 1.0/2.0 multimedia
  • Still images (JPEG, GIF, PNG, WBMP)
  • Text - plain from .txt files
  • TimedText from .3gpp files

Helix "Watch & Listen" Media Activity Version 2 Bugs

Here is a list of bugs and limitations of the current implementation.

  • You can not click and drag or just click in the progress bar to seek a clip.
  • Clips will always scale to as much screen as can be used, the engine supports arbitrary scaling and full screen but we do not yet have GUI controls for it yet.
  • Green tint over controls while playing video. This is a hardware issue, as noted in the hardware release notes, and should be resolved in the next revision of the hardware.
  • Some error messages are not in our localized strings resource file (they may be non-obvious)

Helix "Watch & Listen" Media Activity Version 3 upcoming features

  • Full screen support and multiple scaling options
  • Velocity controls (<1x speed, >1x speed (cpu limited).
  • Video color controls (sharpness, contrast, brightness, hue)
  • Meta data, display of title, author and other meta data about the clip.
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