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Update on root cause of Digital Audio Service error

Update on root cause of Digital Audio Service error

  • Comments 35

I posted a blog entry about a month ago about an issue that started appearing after customers install Update Rollup 2 for Media Center 2005.  Sometimes, while playing back live or recorded content, Media Center will stop displaying video and show a blue overlay screen with the text Digital Audio Service.  When I originally posted my previous blog entry, I had only heard from 2 people who were running into this issue, and both of them were able to resolve the issue by updating video and TV tuner drivers on their systems.  Since then, I have heard from many more people, and updating drivers has not helped in most cases (as you can see in the comments on that previous blog post).

Unfortunately, I don't have an exact root cause or fix to pass on yet, but I have been able to learn more about what we think is happening in these scenarios.  Some of this is still speculation because we are trying to reliably reproduce this issue in our test lab and are so far basing our investigation on the diagnostics reports that some of you have been kind enough to send me so far.

There is an algorithm in the stream buffer engine (SBE) that detects dropped frames and attempts to synthesize replacement frames to minimize glitches and freezes while watching video from analog signals.  Once the dropped frame rate gets high enough, this algorithm stops being effective because there are not enough good frames to use to synthesize replacements from and we will halt video playback.  Media Center sets a threshold for dropped frames to decide when to stop trying to create replacement frames in this scenario.

The Digital Audio Service overlay message is a new message introduced in Update Rollup 2.  It is designed to catch and report low frame rates in DVB-T signals as opposed to letting the video glitch and freeze.  There is a different threshold that controls when Media Center decides to show this Digital Audio Service overlay than the threshold I previously described in the stream buffer engine for analog signals.  It appears that the threshold for this frame dropping rate is set lower than the frame rate threshold for the stream buffer engine for analog signals and therefore Media Center shows this error prematurely in some cases.

Possible causes for high dropped frame rates include the following:

  • Outdated drivers
  • Older tuner cards
  • Non Media Center processes running on the system that are CPU-intensive (because processor time otherwise used to process video frames is being spent elsewhere)
  • Weak signal strength

In cases where the Digital Audio Service overlay appears, you will see that playing back the same video in Windows Media Player will work because WMP does not have this frame replacement algorithm or varying thresholds.  However, it is likely that you will see some type of glitching around the same time in the video playback as you start seeing the overlay in Media Center.

The frame dropping thresholds that I mention above are all controlled within Media Center code, so unfortunately that means there is not a way to configure a registry setting to make the Digital Audio Service overlay appear less frequently or never.

We will be spending more time trying to isolate a repro case and determine possible fixes or workarounds for this issue and I will post additional updates as I get them.

 

  • Thanks for the update, Aaron. Much appreciated.

    It seems you've made good progress in figuring out that the root cause is glitches in the stream. If newer drivers produce more glitch-free performance, maybe that's why some people report that shows recorded after updating the drivers are OK, but not the ones before.

    But since glitches can and do occur regularly (and are actually acceptable, given the PC is multitasking), is it even appropriate to assume a stream is audio-only when video frames are missing in a period of a couple seconds? Should you not show the message only when there is NO video present for a much longer time?

    At any rate, perhaps you should only show the Dgitial Audio Service message when a DVB-T (not analog) stream is being played. All my streams are analog, so I should never see this message. It's inappropriate anyway, since I'm playing back an analog TV show, not Digital Audio!

    If you can't do this, then I really, really encourage you to add a registry setting to disable this Digital Audio Service overlay. We got along without it before, and if there are video glitches, we'd rather see those then the overlay!

    Would it help to have one of us burn a data DVD of a malfunctioning clip and send it to you? The glitch is probably in the recording, because the message appears in the same location (within 30 seconds of starting the show from the beginning) repeatedly, no matter the load of the CPU at playback time.

    Thanks,
    David
  • Thank you for your help. I have to same problem but i'm seeing something no one else hs posted.
    I did get the same problem with R2. I created restored my system from the restore pont right before I installed R2 and watched the recorded shows from when R2 was installed. The quality of the recording was horrible. Every two seconds the image pauses and restarts. When I watch shows recorded on the same channgel before R2 the quality is very good. So it seems that something is making the quality of the picture poor in R2. I have not any problems with quality or skippy images when watching live tv or recorded images. Even with R2 installed live tv has very good quality.
  • While this explanation sounds good, I don't buy it. I've been using MC for a year or so with analog cable and I've never had a problem playing back recorded shows no matter what the quality of the video. Further, the recorded shows I have that cause the Digital Audio Service message to appear were recorded from various channels and the video quality of each is good. Not only do they work in Media Player, but also in other apps (DVR Edit for example) that support DVR-MS files. There are no frames missing (at least to the naked eye). It happens in about the same amount of time no matter where the recording resumes, so I don't buy that it's missing frames. If it were, I could send you one of my recordings and you should be able to see this problem. And then, suddenly all my recordings are working again? I don't think so. Keep trying.

    Greg
  • Make sure that all Xbox Extenders, other Media Center Extenders, and especially the brand-spanking-new Xbox 360 get this update!

    I can't watch my TV through my Xbox 360 because of this, and uninstalling Rollup 2 won't help people like me because the decoding (I believe) is done on the Xbox 360.

    -Ted
  • I have a Dell Demension 8400 3.2Ghz, 1GB memory, Creative Audigy sound card, with a RADEON X850 XT Platinum Edition video card. All of the drivers are as up to date as possible. In addition I have an XBOX 360 being used as a MCE.

    All recent analog video recorded gets the blue screen "Digital Audio Service" when played back thru Media Center or the XBOX 360. The video plays fine in Windows Media Player 10. All old recorded video plays back fine in MC, XBOX, and WMP.

    Nothing has changed in the video signal quality. It is analog cable.

    If you cannot reproduce this problem in your lab I am more than happy to have you come to my house. This is not an intermittant problem or an unusual system configuration.

    At the moment your automatic update has made my media center PC useless. This machine was purchased specifically for its DVR capabilities which worked great until the update.
  • Hi Jan - I am very sorry that you are running into this issue. Can you please take a look at the blog post at http://blogs.msdn.com/astebner/archive/2005/12/02/499643.aspx and see if this suggestion helps you?

    If it does not, can you please use the steps listed at http://blogs.msdn.com/astebner/archive/2005/10/30/487031.aspx#492289 to gather a system diagnostics snapshot and send it to me via email?

    Thanks!
  • Thanks for he quick reponse. The new drivers worked. Leave it to Dell to ship a MCE certified machine without qualified drivers.
  • Aaron,

    I encountered this too and attributed it to some codes I had been playing with and also the possibility of a silent update/incompatible driver.

    I did some diagnostics and no longer get the error, but am not (according to my diag utility) running an MPEG-2 compliant codec.

    drop me a line or post when you guys discover more, would love to help beta the problem.

    mikehill33 (hotmail)

  • Has any progress been made on this since December. I encountered this problem last week for the first time. The "Digital Audio Service" screen appears on only one channel of live TV, in spite of re-scanning signals and re-assigning the guide. I am using two Black Gold digiatl cards purchased approx 3mths ago. Any help would be appreciated.
  • Hi, I experience this problem quite often while watching both live TV and recorded TV. However I'm only affected when I fast forward or rewind. It appears that there are several speeds for fast forwarding and rewinding as when I press the buttons once it works fine, but if I press it again to speed up the process I get the Digital Audio Service screen. I believe this could be evidence that Media Centre does think that it is missing frames as when I fast forward or rewind I’m effectively skipping frames (I think).
    Any further thoughts on this would be great.
  • Hi Mike - This is the first I've heard of this error happening only during FF/rewind actions. I will pass this information on to our TV team. What configuration do you have on your system (is it NTSC, PAL, DVB-T, etc?) Also, just to be sure, have you updated your TV tuner and video drivers?
  • Hi, I'm using PAL through a composite video cable from a satellite receiver box (sky+ UK). I found a newer Graphics driver and tested that as you suggested, but when I FF/RW the Digital Audio Screen still appears and will not go away unless I restart media centre: I have:
    Radeon X700SE graphics
    Creatix SAA7134 TV tuner
    Thanks
  • I think this is starting to become a big issue here in the UK where many people are starting to use the MCE 2005. I have this problems along with many other people in the UK. Please see the forum posts at:
    http://www.thegreenbutton.com/community/shwmessage.aspx?ForumID=41&MessageID=153076&TopicPage=3
    and
    http://www.avforums.com/forums/showthread.php?t=293428&page=2

    The problem occurs in Live TV seeing the 'Digital Audio Service' on one of the mainstream UK channels.

    My post is:
    Here in Whitstable, Kent from the BlueBell Hill Transmitter I get the same ITV1 issue. My problem occurs with live TV. When changing to the ITV1 channel it shows the 'Digital Audio Service' message. It records likes this too. I was already running Rollup 2 and was receiving ITV1 no problem before.

    I have updated all drivers and put on all patches but to no avail.

    My machine is not a Dell, as has been suggested in other forums/blogs may be the issue but a custom made machine.

    Also the change seems to have coincided with the appearance of CITV on the channel list - I did not see/notice this channel before.

    However, now after updating my machine I have another problem. If I am on BBC1 then switch to watch something on Recorded TV and the switch back to live TV, I get the message 'No TV Signal'. However, if I then change to another non BBC channel (e.g. Channel 4) and back to BBC1 it comes up fine.

    John

    M/Board: Asus P5GD2 Intel 915P
    Processor: 3Ghz P4 630 2MB S775 800FSB
    Video: GeForce PCX6600 256MB PCI-E
    RAM: 1GB PC2-4300
    Tuner: Hauppauge WinTV-HVR 1300 MCE/PCI
    HD: 160GB SATA + 200GB SATA

    My Decoder is:
    Company Name:CyberLink Corp.
    Version: 6.0.0.1402
  • I'm getting this same error, just since I upgraded to the latest Media Center rollup. Can I undo the rollup, or any other tips that might help?

    Thanks,

    Jude
  • Hi John - We have received several reports of this issue for some specific channels in the UK. We are currently investigating this issue because it appears to be different than the other cases we've seen up until now. I apologize for the inconvenience. I will post more about this issue when I know more.

    Hi Jude - You might want to try the workaround listed at http://blogs.msdn.com/astebner/archive/2005/12/02/499643.aspx. Hopefully this will help!

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