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Discussion in 'DirecTV TiVo Powered PVRs & Receivers' started by jjmpeters, Jun 28, 2004.
So...has anyone gotten DirecTV to admit to the problem?
In my opinion this is not a Directv/Tivo problem but a design flaw in the way certain receivers/pre-pros handle DD bitstreams.
I noticed this as soon as I upgraded from a Denon DD decoder to an H/K Signature 2.0 pre/pro years ago. Using an older Sony SAT-A1 (don't remember the exact model number) the Denon had no problem when I switched from a Stereo to DD channel. However, when using the H/K, I get a loud pop every time I go from a stereo channel to one with a DD stream (i.e. every HD channel).
I am currently using a Sony SAT-HD200 and it has the same problem- pops every time. I just accepted it as a flaw in the H/K and hope my next preamp can handle it better.
I had the same problem with a Series one DirecTivo and my Denon 4800 over a year ago. It was a know problem with the Denon receiver. There were threads all over about it here and other places. It turned out to be the mute circuit on the Denon. My 4800 was still under warrenty so I had it fixed. I haven't had a problem since and I have the HDTivo also.
I have the same issue on my Onkyo with my Tivo, but it doesn't happen with my 921 or my 721. This is a Tivo 10-250 issue in my opinion.
It seems they are sending only a portion of a compressed data stream to the receiver. If they don't synchronize the packet streams, then the a/v receiver will play out the raw bits of the compressed data until it finds a new packet boundary that it can understand and uncompress successfully.
I don't think you'll see this when decoding PCM because it is a raw stream, but it depends on what part of the MPEG data stream has been decoded from the satellite before it was sent to the a/v receiver.
If they are only taking the first portion of the mpeg stream and don't have a fully decoded audio packet when it's sent to the receiver, then it will play out binary garbage until the audio is buffered and synchronized.
I believe the 921/721 receivers wait until they have buffered enough of the audio and skip past the first portion to make sure they have a valid continuous audio stream before sending it to the a/v receiver.
If you send garbage to the a/v receiver you will hear garbage... i.e. garbage in, garbage out... The pops occur because the binary data is modulated back to a frequency signal... If the binary bytes of information jump all across the board you will see varied high and low frequencies in an extremely short period of time. This will cause the pop sound.
In your opinion is this something that can be solved by a DirecTV firmware download?
Yes. I think it can be fixed in software, but I can't guarantee it because I have no internal knowledge of the hardware or software for the 10-250. That would be my best guess from what I can tell. I would suspect the audio driver implementation they are using or the way they are decoding the audio stream from the mpeg stream.
It is still possible this is some kind of hardware issue on the optical interface that talks to the a/v receivers, but I would bet it's more in the software. I'm sure they are using something standard to output the optical audio.
After I called to notify D that I would be returing the replacement unit, I asked to talk to tech support. I think they referred to it as advanced tech support, and the guy I talked to referred to it as the TiVo department.
He said that he would escalate this as an issue and that I should hear back in less than a week as to what direction D would be taken with this problem.
I'll let you know when I hear anything. Its not like I plan to live without the HDTiVo, but if they can't fix I'd like some dollars off.
Would you believe that I'm having this same very problem with my SA 8000 (HD DVR that the cable company rents me) used in conjunction with a new Denon AVR 1705?
Problem goes away when I tell the SA 8000 to output only PCM, instead of Dolby Digital. Otherwise, the reciever loses the DD lock (and clicks) every time I hit RW, FF, play, switch channels, hit guide, etc. But I can't live with PCM audio alone.
I looked into this a little closer to see why my 10-250 has the static pops and my 921 does not. My Onkyo is very specific about showing me what protocol format is being sent to it. I was able to detect the formats being sent to the a/v receiver:
1. DD5.1 = Dolby (3 / 2.1 ) i.e. 5.1 Audio
2. DD2.0 = Dolby Digital II ( 2 / 0) i.e. Left/Right PCM
3. PCM = PCM (Pulse Code Modulation)
The static pop only occurs when switching from DD2.0/PCM to DD5.1 (non-PCM)
The static pop does not occur if you are switching from DD5.1 to DD5.1
The static pop does not occur if you are switching from DD2.0 to DD2.0
The static pop does not occur if you are switching from DD5.1 to DD2.0/PCM
The 921 seems to delay switching the a/v receiver until the video has already started. It looks like the 10-250 tries to switch modes and doesn't wait for the a/v receiver to exit the PCM format before attempting to send it DD5.1.
I think because they switch and start playing the audio too soon, then they are playing garbage to the a/v receiver for that split second. Once the video and audio are both playing they are synchronized. It looks like I hear the pop on the 10-250 before I can see one frame of video. The 921 looks like I see the first video frame, watch the a/v receiver switch modes, and then hear the audio stream without a pop.
Since we've seen this in the advance/skip and anytime the video is set to another position in the stream, then it looks like they are having trouble synchronizing the audio with the video when they have to start playing. I don't hear the pops that often during a 30 second skip. This might be happening because during a commercial it is DD2.0/PCM and during a movie it goes back to DD5.1. I'll be looking to see if that's what seems to happen when I notice it doing that again.
The reason you don't hear the pops when going from DD5.1 to DD2.0/PCM is because it doesn't just play a raw stream. If they send garbage, then it will get ignored by the a/v receiver unless it's in the proper format. The pops occur when leaving the DD2.0/PCM format because it plays whatever binary data is sent to it. If they attempt to send DD5.1 packet headers, then it will play those first set of headers as audio sound.
That's my best guess so far from what I can tell. Try to watch all 5.1 shows or keep it all on PCM to prevent the pops. For me, it's annoying, but it's not a critical defect. I'm sure they will address this in the future if it keeps coming up. And it will...
I'll post more if I find anything new. I'd like to hear what DirecTV/Tivo's response is on this item...
Have you spoken to DirecTV? Seems that everyone that has contacted then on this is told that they are the only ones with the problem.
I was waiting to hear back from John (jjmpeters) and see his response from DirecTV. I should probably call and file my own defect with them too. I was hoping they will acknowledge the problem and prevent all of us from having to call.
Many of us have called and pretty much everyone is told "This is the first we've heard of this problem!"
Give them a call and let us know what they say.
I've had the issue on two hdtivos and when i called they told me (shocker) that i was the first to call. They offered to send me replacements but I declined. Maybe we need to start a petition page or something and once we have a couple hundred people we could send them the url.
problem is some people don't believe it's a Dtv/Tivo problem
Ok, the more I think about this, the more it worries me.
My SATHD200 pops when I change channels to a DD station and I can handle that. But with a Tivo I'm gonna be pausing and fast-forwarding all the time. I don't think I could put up with it popping all the time.
How widespread is this problem? Does it happen with SD DirecTivos too?
I agree it is definately a dtv/tivo problem. If anyone thinks otherwise they are FOS. I have had over ten components hooked up to my denon 3802 and never had problems like this. Frankly I am sick of DTV not fixing their problems such as dropouts and video problems. They deny it or say that they have never heard of such issues.
We aren't just talking popping sounds here. We're talking static thunder claps that are so loud and sudden that the receiver mutes itself for it's own protection.
An occasional little pop sound here or there is one thing but this is entirely something else.
And as the poster above said, I have also had numerous digital devices hooked-up to this same receiver and even the same input with no problems until the HD/Tivo.
I have this problem as well through an RDC - 7.
(plus the aspect issue on my 4:3 RPTV)
I'm sure others have said this.. but this isn't just a problem with Denon. My Pioneer 49TXi also has the same issue.. I'm really afraid it's going to blow out my speakers one of these times. (And my speakers arn't exactly "cheap"...)
I'm not sure what to do about it.. I'll probably file a complaint with Pioneer and DirecTV.. but I doubt either will care.. (Sad that my original assumption is neither cares...)
FWIW, I can't get it to "pop" on my Parasound AVC-2500. I see the OSD go from Digital PCM, then briefly to "Unknown Digital", then to Dolby Digital 3/2.1.
Switching from DD to PCM, DD to DD, or PCM to PCM I don't see the brief "Unknown Digital" message.