{"id":301,"date":"2014-07-22T22:57:40","date_gmt":"2014-07-23T05:57:40","guid":{"rendered":"http:\/\/kaytat.com\/?page_id=301"},"modified":"2024-01-28T19:44:46","modified_gmt":"2024-01-29T03:44:46","slug":"simple-protocol-player","status":"publish","type":"page","link":"https:\/\/kaytat.com\/blog\/?page_id=301","title":{"rendered":"Simple Protocol Player"},"content":{"rendered":"

Play store link<\/a><\/p>\n

Why?<\/h1>\n

I want to be able to watch movies and videos on the TV, but I want the audio to be heard only through headphones.<\/p>\n

And I had a few requirements:<\/p>\n

    \n
  1. Wireless<\/li>\n
  2. Broadcast<\/li>\n
  3. Low latency<\/li>\n<\/ol>\n

    Wireless<\/h3>\n

    One solution is to run a headphone extension cable from the TV.\u00a0\u00a0 But that gets unwieldy pretty quickly for distances greater than a few feet.<\/p>\n

    Broadcast<\/h3>\n

    I want the audio to be heard by multiple people at the same time through each individual set of headphones.<\/p>\n

    Low-latency<\/h3>\n

    The audio has to be rendered with the least amount of latency possible so that the video could be watchable.\u00a0 If the audio is delayed, then the dialog\/sound effects\/etc wouldn’t be in-sync with the video.<\/p>\n

    PulseAudio<\/h1>\n

    Since my HTPC is Ubuntu 12.04 running XBMC, I figured I could reuse some existing OSS software to stream audio from Ubuntu to a mobile device.\u00a0 And since I have an Android phone, I figured I would start there.<\/p>\n

    This project was really easy to implement because PulseAudio on Ubuntu already supports a TCP stream of uncompressed PCM audio.\u00a0 The only requirement is to add a few lines (below) to enable the module.<\/p>\n

    The documentation for the module is at http:\/\/www.freedesktop.org\/wiki\/Software\/PulseAudio\/Documentation\/User\/Modules\/#index20h3<\/a><\/p>\n

    And the Android app simply reads data from a socket and uses Android’s AudioTrack to render the audio.\u00a0 The app is based on the random music player SDK example.<\/p>\n

    It’s so glitchy<\/h1>\n

    The challenge is to try to keep the video on the TV synced with the audio.\u00a0 And that means rendering the audio with the lowest latency possible.<\/p>\n

    The very first versions of the app do not handle this well.\u00a0 Basically,\u00a0 when the app detects it’s falling behind, it simply starts dropping data left and right.\u00a0 This results in obvious glitches in audio.\u00a0 It sacrifices quality for latency because delayed audio while watching movies sucks.<\/p>\n

    Improvements will be made.<\/p>\n

    Setting up PulseAudio<\/h1>\n

    [Also check out the link to the module documentation above]<\/p>\n

    There are only a couple of steps:<\/p>\n

      \n
    1. Determine which source to stream<\/li>\n
    2. Edit config files so with the proper parameters<\/li>\n
    3. Restart PulseAudio<\/li>\n<\/ol>\n

      I am running Ubuntu 12.04.<\/p>\n

      Determine which source to use<\/h3>\n

      Open up a terminal in Ubuntu and type<\/p>\n

      pactl list sources short<\/pre>\n
      This will spit out a bunch of text, but what you’re looking for is the ‘analog-stereo.monitor.’\u00a0 I have edited the output from my machine and highlighted important items in red.<\/p>\n
      0\u00a0\u00a0 \u00a0alsa_output.pci-0000_01_00.1.hdmi-stereo.monitor\u00a0\u00a0 \u00a0module-alsa-card.c\u00a0\u00a0 \u00a0s16le 2ch 44100Hz\u00a0\u00a0 \u00a0SUSPENDED\n1\u00a0\u00a0 \u00a0alsa_output.pci-0000_00_1b.0.analog-stereo.monitor<\/span>\u00a0\u00a0 \u00a0module-alsa-card.c\u00a0\u00a0 \u00a0s16le 2ch 44100Hz\u00a0\u00a0 \u00a0SUSPENDED\n2\u00a0\u00a0 \u00a0alsa_input.pci-0000_00_1b.0.analog-stereo\u00a0\u00a0 \u00a0module-alsa-card.c\u00a0\u00a0 \u00a0s16le 2ch 44100Hz\u00a0\u00a0 \u00a0SUSPENDED\n\n<\/pre>\n
      Look for “analog-stereo.monitor” and take note of the index number on the left.\u00a0 In my case, it’s 1.<\/p>\n
      Edit config files<\/h3>\n
      You will need to edit the config files to load this module with the specific parameters.\u00a0 To do so, type (you will need the sudo password)<\/p>\n
      gedit admin:\/\/\/etc\/pulse\/default.pa<\/pre>\n
      Add the following line near the bottom, substituting your source index:<\/p>\n
      load-module module-simple-protocol-tcp source=1 record=true port=12345<\/pre>\n
      I had problems with the default port of 4711 because it seems to be already in use and so I just choose 12345.<\/p>\n
      For mono, you can use channels=1 and for a lower sampling rate rate=24000. \u00a0The app has been updated to include support for this in an attempt to reduce latency.<\/p>\n
      If you are hearing static, try changing the audio format generated by pulse from 32bit little endian to 16bit little endian (link<\/a>).<\/p>\n
      load-module module-simple-protocol-tcp source=1 record=true port=12345 format=s16le<\/pre>\n
      Restart Pulse<\/h3>\n
      Restart PulseAudio with the new configuration.<\/p>\n
      pulseaudio -k\n# The following might not be necessary because pulse will autospawn\npulseaudio --start<\/pre>\n
      And that should be it.<\/p>\n
      Start up the app, type in IP address\/port of the Ubuntu box and stream audio to your Android device.<\/p>\n
      Windows server<\/h1>\n
      A corresponding Windows server has been published to github.\u00a0 Please see the following for more information: https:\/\/kaytat.com\/blog\/?p=332<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
      Play store link Why? I want to be able to watch movies and videos on the TV, but I want the audio to be heard only through headphones. And I had a few requirements: Wireless Broadcast Low latency Wireless One solution is to run a headphone extension cable from the TV.\u00a0\u00a0 But that gets unwieldy … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-301","page","type-page","status-publish"],"_links":{"self":[{"href":"https:\/\/kaytat.com\/blog\/index.php?rest_route=\/wp\/v2\/pages\/301","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kaytat.com\/blog\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/kaytat.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/kaytat.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kaytat.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=301"}],"version-history":[{"count":22,"href":"https:\/\/kaytat.com\/blog\/index.php?rest_route=\/wp\/v2\/pages\/301\/revisions"}],"predecessor-version":[{"id":475,"href":"https:\/\/kaytat.com\/blog\/index.php?rest_route=\/wp\/v2\/pages\/301\/revisions\/475"}],"wp:attachment":[{"href":"https:\/\/kaytat.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=301"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}