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A2Stream

A2Stream simultaneously receives an .a2stream file from any HTTP server and plays it through the stock Apple II speaker circuit using pulse-width modulation at 22050Hz sample rate with ~5.17 bit resolution.

Hardware requirements:

  • Enhanced //e (with extended 80 column card) or IIgs
  • Uthernet II Ethernet card in any slot

To view demo videos:

To stream an .a2stream file:

  • Run A2STREAM.SYSTEM and enter the URL of an .a2stream file
  • Use these shortcuts to make use of persistent history and auto-complete:
    Key Function
    Left Move cursor one char left
    Right Move cursor one char right
    Ctrl+A Move cursor to start of line
    Ctrl+E Move cursor to end of line
    Delete Delete char left of cursor
    Ctrl+D Delete char under cursor
    Up Move to previous history entry
    Down Move to next history entry
    Tab Move to next auto-complete
    Ctrl+C Quit from auto-complete
  • Find sample .a2stream files at these (case-sensitive) URLs:
    • http://a2retro.de/a2s/Levels.a2stream
    • http://a2retro.de/a2s/Sandstorm.a2stream
    • http://a2retro.de/a2s/1984.a2stream
    • http://a2retro.de/a2s/HighwayToHell.a2stream
    • http://a2retro.de/a2s/HowsItSupposedToFeel.a2stream
    • http://a2retro.de/a2s/TimeToSayGoodbye.a2stream - shows progress bar
    • http://a2retro.de/a2s/HealYou.a2stream - shows default cover art
  • Find URLs of .a2stream files for all Open Apple podcast episodes on https://www.open-apple.net/a2stream/
  • Use Esc to quit at any point
  • Use 1-9 to fast-forward 1-9 minutes
  • Use any other key to pause streaming

To config the Ethernet slot:

  • Put the Uthernet II in slot 3 or
  • Create a file named ETHERNET.SLOT. Only the first byte of that file is relevant. This byte can either represent your Uthernet II slot as binary value (e.g. $04 for slot 4), as ASCII digit (e.g. $34 for slot 4) or as Apple TEXT digit (e.g. $B4 for slot 4).

To get decent sound quality on the enhanced //e:

  • Create a file named OUTPUT.TAPE. The content of that file is not relevant.
  • Connect an amplifier/speaker to the tape output jack

To get decent sound quality on the IIgs:

  • Connect an amplifier/speaker to the headphone jack

To prepare an .a2stream file for streaming:

  • Create a header-less .raw file with 22050Hz mono 32-bit-float PCM data (e.g. with Audacity)
  • Generate an .a2stream file from the .raw file with gena2stream (source code)
    • Put a standard 16kB .dhgr file beside the .raw file for custom cover art (optional)
    • Use the option to -p switch the visualization from level meter to progress bar
  • Put the .a2stream file onto any HTTP (not HTTPS) server
    • Run a simple local HTTP server on Windows
      • Run the HTTP File Server and drop the file you want to stream in its Virtual File System
    • Run a simple local HTTP server on Linux
      • cd to the directory containing the file you want to stream and enter python -m SimpleHTTPServer or python3 -m http.server depending on the Python version you want to use

To play an internet live stream:

  • Install MPlayer
  • Run srva2stream (source code)
    • Provide on the command line the TCP port number you want to use
    • Put a standard 16kB srva2stream-<port number>.dhgr file beside srva2stream for custom cover art (optional)
  • Wait for the message waiting on pipe <pipe name>
  • Run MPlayer
    • Provide command line parameters
    • -nocache -af pan=1:0.5:0.5,volnorm=1:0.8,resample=22200:0:1,format=floatne -ao pcm:nowaveheader:file=<pipe name> <stream url>
  • Wait for the message connect on pipe
  • Run A2STREAM.SYSTEM and enter as URL <name or address of machine running srva2stream>:<port number>
  • Use the step-by-step guide to install srva2stream on a Raspberry Pi (optional)