Intermittent audio IDV AGA MK3 4000-D-

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Don't Panic. Please wash hands.
  • I would like to report that HDMI audio output from my IDV3 is unreliable i.e. intermittent on my A4000 system. However frequent enough for me to raise this issue.


    Workbench running in HighGFX 1024x768
    IDV outputing in Pre 1024 X 768 70Hz VESA

    More often then not the problem is like this after starting any WHDLoad'ed game at random with a screen resolution change...


    1. Sound works fine.
    or
    2. Sound starts, slight interruption for about half a second and then resumes with no issues.
    or
    3. Sound starts after a few seconds sound is lost. I disconnected and reconnected the HDMI cable just in case it is the TV losing sync...

    or

    4. No sound - switching to analogue sound on my LCD TV shows sound working at the native hardware level.


    I am using a low-end standard Panasonic HD-Ready 720p LCD TV, it needs the HDMI mode in IndivisionAGAmk3 config to be set to 96kHz audio.


    The following scenario was also reproduced on my system several times at different times.


    1. Start Audio Engineer Plus 1.0

    - Screen mode defaults to regular PAL High Res.

    - IDV switches to Pre 800x600 Auto+VSync.

    2. Load sample.

    3. Play sample.

    4. NO HDMI audio output..

    5. Switch to Component Video and Analog Audio.

    6. AUDIO output normal.

    7. Switch back to HDMI.

    8. TV displays message showing "No HDMI audio"


    Inexplicably at this moment it is working...

    Please advise...

  • Is the HDMI output board mounted on the included metal bracket? This also serves grounding purpose, and you should *only* use the included 22-pin cable. Further, please try with a different vendor's HDMI cable. It wouldn't be the first time that a bad HDMI cable causes problems like this.

  • Yes definitely using original accessories. I have swapped HDMI cable and also used a different input on the LCD TV display. The image is super steady which is why I did not previously try swapping cables. Unfortunately I encountered symptoms 2 and 3 above.


    I am hoping this is a firmware issue and not faulty hardware due to the prohibitively high shipping prices.


    I will next try another monitor and see if it can accept something other only 96kHz audio input.

  • I forgot to mention clearly for the games it is standard PAL and NTSC displays being converted to the Pre 800x600 Auto+VSync


    I just switched to a LG 4K monitor but have not changed any of the config. settings or re-read the monitor EDID apart from finding out that 96 and also 88kHz audio input works. By not changing the config the Pre 800x600 Auto+VSync display is squashed vertically due to the timings not being correct.


    With the 4K monitor, I do hear that there is sometimes audio distortion, i.e. faint "popping" like the sound dropping out and cutting in very quickly.
    However with this monitor I have yet to experience the no sound or sudden sound cut-off. Could the no sound/cut-off problem be VSync related? For example, audio extraction losing sync with the video?


    In case anyone is wondering the Panasonic TV HD Ready 720p yields superior "scanline" image compared to the 4K LG when used with IDV3.

  • Could the no sound/cut-off problem be VSync related? For example, audio extraction losing sync with the video?

    If you are using the "auto resolution" feature, this can pretty much be excluded. I'd only expect an influence on audio if you *only* use VSync (although we would have had reports about that earlier!), but not with "Auto". Still, if you want to dig deeper, why don't you just switch the output mode and see if you get the same problem without VSync?

  • Switched back to the regular LCD TV now.

    Chose output EDID 1280x1024@60 for both input Pre 800x600 PAL and Pre 800x436 NTSC.

    Turned OFF VSync., AutoRes ON


    Unfortunately still the same results...


    The fact my LCD TV can report "No HDMI audio" when switching back from Analogue component/audio to HDMI would indicate definitely the HDMI audio stream is interrupted.... :(

  • Try again with auto resolutuion off as well - this will switch over to the "local" crystal for the whole output stage (which is both audio and video).


    Also, is the chipset crystal PAL or NTSC? Has that ever been altered in your system?

  • My A4000 is an original PAL machine and using the original PAL frequency crystal. I have made some new observations and "progress"


    When using the Pre 800x600 Auto Sync Auto Res mode (best quality scanline scaling) on all games that play sound as soon as an intro screen appears e.g. "Indianapolis 500", I notice the music always has missed the first few notes after the screen is visible. Obviously no issue on the analogue side. I'm not sure whether this is related to the problem being discussed...


    I believe the issue is not specifically related to Auto Sync/Rec. I tried multiple pre-defined resolutions and discovered that some resolutions exhibit the symptoms while some don't. Unfortunately the quality of a lot of the other resolutions are not suited to my LCD TV and produce a very poor image so I didn't even bother testing the sound. It is also unfortunate the best Auto Sync/Res modes are those affected. I have found some compromised screen quality modes where after extensive testing I can confirm that the sound does not cut-out.


    What other information (config file?) do you need to look into this further?

  • I notice the music always has missed the first few notes after the screen is visible. Obviously no issue on the analogue side. I'm not sure whether this is related to the problem being discussed...

    This sounds like Indivision has found a new screenmode and changed the output mode. This will cause your TV to re-sync and of course mute audio until it's fully synced again.


    Especially with autores, this can be the case if a VBlank came at an unexpected time: The TV will assume that there was an error and mutes audio to not let possible trash come through, possibly causing damage to speakers.

    I tried multiple pre-defined resolutions and discovered that some resolutions exhibit the symptoms while some don't.

    My guess is that if you use a normal framebuffer mode without VSync, and you further choose that same output mode for most (if not all) Amiga-screen modes, you will not get these audio-muted-periods any more.


    I'm afraid that Indivision AGA MK3 cannot do anything on it's end; it appears to be the TV that decides to mute audio for a fixed amount of time.

  • My other LG monitor exhibits the same symptoms.. Recap my original post:


    "2. Sound starts, slight interruption for about half a second and then resumes with no issues.

    or

    3. Sound starts after a few seconds sound is lost."


    In the latter case, the sound does not return. Now if I had an HDMI splitter and HDMI audio extractor it would show conclusively whether there was audio or not being sent...

  • On the other hand, you're reporting that if you choose certain output modes, the effect goes away. Once again: The Amiga can change it's screen mode any time, and during a change, a Sync (both H and V) can come at any time, confusing the target device when Autores is active. Like I wrote in my last post, you can verify this by choosing a non-VSynced output mode, and choosing the same mode for all Amiga-screen modes. This will reduce the output mode changes to zero, and leave audio active all the time.


    We're sending audio data to the HDMI encoder chip all the time. Can't do more than that - if two display devices mute audio on an input anomaly, it's not a proof that there is a fault in Indivision AGA MK3. Certainly not when the audio part isn't advertised, so not even part of the contract.