Results 1 to 10 of 12

Thread: Mystified? excuse the pun, no Sound from HD channels

Hybrid View

  1. #1
    Join Date
    Jun 2006
    Location
    Kent, UK
    Beans
    206
    Distro
    Ubuntu

    Mystified? excuse the pun, no Sound from HD channels

    Hi chaps.

    I am a little confused. I am in the UK and have a number of HD channels that are received via DVB-S2, and a number of other channels from the same card are in Standard Def.

    The odd thing is that the Sound from HD is working on the server itself, via the frontend I use for testing. All my slave machines (Acer revo) will give sound on standard channels, but none on HD?
    The revo's are connected via HDMI to the TV's.

    This all worked fine till I bit the bullet and went from 11.04 to 12.04 and from .24 to .26 have passed briefly through .25 of Myth.

    Suggestions?

    Regards Paul.
    Infamy, Infamy, they all got it in for me!

  2. #2
    Join Date
    Mar 2012
    Beans
    44

    Re: Mystified? excuse the pun, no Sound from HD channels

    HD broadcasts in the UK are MPEG-4 H.264/AVC where SD broadcasts are MPEG-2.
    Freesat broadcasts both standards, so your DVB-S2 card is passing both stream types to myth for decoding.
    To make matters more interesting the HD audio stream can switch dynamically between stereo and surround sound signals. There are also multiple audio streams within the HD signal. See http://www.freeview.co.uk/Resolution...th-Freeview-HD.

    So when watching SD broadcasts a simple stereo signal is sent out. For HD the decoder has to deal with a more complex stream.
    The problem should be resolvable by re-scanning the audio hardware in mythfrontend audio setup and using the test facility to check the interface is working. If I remember correctly, mythtv cannot automatically determine the audio parameters of the ion 1 chip on the Acer Revo so you may have to try out the various combinations manually.
    Are you using HDMI or analogue out?

  3. #3
    Join Date
    Jun 2006
    Location
    Kent, UK
    Beans
    206
    Distro
    Ubuntu

    Re: Mystified? excuse the pun, no Sound from HD channels

    Thanks for the reply.

    I am using HDMI. Did not think of re scanning, just set it to what it was on previous versions, worked ok up till now. But thanks for the advice.

    Just really threw me that analogue playback machines were fine, those with HDMI worked fine except for any HD channels, then just got cracking audio.

    Regards Paul
    Infamy, Infamy, they all got it in for me!

  4. #4
    Join Date
    Mar 2012
    Beans
    44

    Re: Mystified? excuse the pun, no Sound from HD channels

    I used to have an Acer Revo but have recently moved to an Ion 2 based system. I remember that I had to set - in advanced audio settings - Stereo PCM only. Otherwise the HDMI interface did not work properly. Note this does not stop surround sound working it just overcomes a problem in the Ion HDMI interface.
    Hope this is of some use - best of luck.

  5. #5
    Join Date
    Jun 2006
    Location
    Kent, UK
    Beans
    206
    Distro
    Ubuntu

    Re: Mystified? excuse the pun, no Sound from HD channels

    Thanks for all the advice.
    I have found a setting that gives audio in both standard and high def, however unlike how it used to be set, which had the work HDMI in it, this time it just says hware? Also noticed that the audio level is much quieter on tv than via mythmusic, or mythvideo. I did not need the PCM option set, seemed to make little difference. Hopefully I will have time this weekend to mess with all options.

    Regards Paul
    Infamy, Infamy, they all got it in for me!

  6. #6
    Join Date
    Apr 2009
    Location
    Aotearoha
    Beans
    2,661
    Distro
    Ubuntu 10.04 Lucid Lynx

    Re: Mystified? excuse the pun, no Sound from HD channels

    The ION (& earlier) HDMI HDA audio do not support ELD audio capability reporting & alsa assumes full capability in the receiver (8x192KHz & DTS-MA etc).

    I'm not sure how but it is possible to fake the ELD info for alsa but it is easier to limit MythTV audio output to channels/codec formats/sample rates that your receiver/TV/display can handle.

    Might find forcing 48KHz sample rate (MythTV audio/advanced audio settings?) allows it to work..

    You are using nVidia proprietary driver ?

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •