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:

• Visit https://youtu.be/YcYEnYsI-_M
• Visit https://youtu.be/7kxo0l3t1LM

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)