DBSTalk Forum banner
1 - 6 of 6 Posts

·
Mentor
Joined
·
36 Posts
Discussion Starter · #1 ·
Lots of people have posted problems with audio dropouts. I have an HR24/100 and have experienced audio dropouts. My receiver is hooked to my AVR with a HDMI cable.

I was wondering if audio dropouts are a problem with the receiver, firmware, cables, dish alignment, or on the DTV end? Part of me thinks it's a signal problem, but if you're getting high 90's, it kind of blows that idea away. Then part of me thinks it's a coax cabling problem. And another part of me thinks it's a firmware problem. Just wondering what the experts think.

Thanks!
 

·
Hall Of Fame
Joined
·
7,058 Posts
RoberMR said:
I still get these audio dropouts occasionally (much less than before). In my case, it only happens when I have 5.1 audio selected. If I change to regular DD, the dropouts go away.

Rob
Its either DD, or PCM audio...there is no regular DD just to be clear. We all have occasional audio dropouts, I even get the occasional audio dropout on OTA channels straight from the tv. Part of it is just broadcast HDTV in general, part of it is the mpeg encoding or errors in the decoding...due to dropped packets etc...
 

·
Broadcast Engineer
Joined
·
4,153 Posts
Audio dropouts without accompanying video freezes or pixellation are rarely "broadcast HDTV" issues or reception issues, and it would be rare indeed for a station or network to broadcast anything but the briefest of audio dropouts unless it was GIGO, and QC keeps that to a bare minimum. There are virtually no errors in encoding, which means virtually all errors are decoding (local STB) or reception errors. Reception issues typically manifest with audio and video issues that occur at the same time.

Generally audio-only dropouts are a local problem with reclocking of digital audio and are not related at all to reception. Often this can be fixed by upgrading the firmware for HDMI in the AVR. Optical seems to be more problematic than HDMI or other copper digital connections.

Stations broadcast either 2.0 DD or 5.1 DD as AC-3. That is also the only audio they send, meaning that PCM is reconstituted at the STB. That implies that if there is a drop out in DD that is not there in PCM, that the problem is most assuredly not a broadcast, transmission, or reception problem.

But, if the problem occurs only at the transition from network to local, that might indicate that the AC-3 bit rate is different from local to network. They should really match to keep the decoder from muting at the switch points. That particular issue will manifest on PCM as well, but has become somewhat rare now that most stations have either complied or use 5.1 generators so that they either send real or simulated 5.1 at all times.

If you switch to DD 2.0 in your AVR, you are really getting the same audio as 5.1, but remixing it to 2.0. Bass management is removed (bass below the LFE cutoff is mixed back in) and dialog Center is mixed evenly to L and R along with stereo music and FX, and the rear channels are phase-inverted and added back into L and R also. So it is really just a rematrixing of existing 5.1 channels (of course many AVRs will sense the change to 2.0 and then invoke Pro Logic or other methods to simulate and redistribute the audio to all channels so that your audio does not simply collapse into L and R). But that may be a clue; if you get dropouts in a 5.1 broadcast and change the downmix to 2.0 (in the same 5.1 broadcast) and don't get them, possibly that points to the firmware in the AVR. Hard to know for sure, but that would be the educated best guess.

Certain AVR models are notorious for this. Denon (a truly great brand) comes to mind. But owners sometimes interpret that FACT as a personal denigration of their purchasing intelligence when this gets reported, so don't be surprised if this brings the trolls out from under the bridge pretty quickly.
 

·
Super Moderator
Joined
·
42,754 Posts
Tomcat,
I've had some fairly lengthy conversations with a broadcast engineer at DirecTV, and through this I know there are processes and problems, that you've omitted.
Not sure why, and maybe it's because your [extensive] experience is from the local broadcaster, but you're not understanding/considering the errors/problems at the uplink/transcoding point.

While this thread doesn't address EVERYTHING, it does try to explain the most common: http://www.dbstalk.com/showthread.php?t=182017
 
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top