Question about Dolby audio recording/output on HD TiVo

[ayrton911]

Hi.

Question about my HR10-250. Right now I am just using stereo speakers, with the television.

However, I'm ordering a receiver and some speakers this weekend, so anything I record in the next few days I want to make sure it is recording the Dolby Digital, if available.

I changed the setting in settings, for it to record and output dolby digital. However, will it still record the regular stereo sound too, so that I can watch these shows, before I get my receiver, if I want? Also, does this use up a lot more disk space, when it is set to record dolby digital?

Finally, I have the final 5 Alias still on my receiver. Since I didn't have the option of "record/output dolby digital" when those recorded, they won't have the dolby digital in them, no? Only stereo?

Thanks.

[stevel]

Yes, it still records the stereo sound. Enabling the option means that the TiVo records the Dolby Digital audio (when present) in addition to stereo and sends that over the optical audio connection (again, when present.) If a program was recorded with the option off, you get stereo.

[ayrton911]

Many thanks! Any idea how much more HD space is taken up, when recording DD?

[stevel]

No idea.

[TyroneShoes]

None, or very little, depending on how the transmit is configured.

Audio streams are typically 384kbps for OTA HD, at least, and with metadata included it typically never ramps up above 400. This is AC-3 compressed audio, which is also the format for DD 5.1, and full-blown 5.1 will fit in that same bit stream size, I'm pretty sure.

As you can see, this is about 1/50th of the available bandwidth, and about 1/30th to 1/40th the size of the typical video stream. The difference in size between a non-DD program and one that is DD is probably insignificant, if not identical, all else being held equal. There is significantly more difference between video bit rates of one program compared to another.

In any case, we as customers have no control over it. IOW, if there is DD attached, we can't opt out of it during the recording process to save on bandwidth for storage, whether we are set up to reproduce DD or not.

[ayrton911]

None, or very little, depending on how the transmit is configured.

Audio streams are typically 384kbps for OTA HD, at least, and with metadata included it typically never ramps up above 400. This is AC-3 compressed audio, which is also the format for DD 5.1, and full-blown 5.1 will fit in that same bit stream size, I'm pretty sure.

As you can see, this is about 1/50th of the available bandwidth, and about 1/30th to 1/40th the size of the typical video stream. The difference in size between a non-DD program and one that is DD is probably insignificant, if not identical, all else being held equal. There is significantly more difference between video bit rates of one program compared to another.

In any case, we as customers have no control over it. IOW, if there is DD attached, we can't opt out of it during the recording process to save on bandwidth for storage, whether we are set up to reproduce DD or not.

Then why is there this audio setting on the DirecTiVos HD to not record DD? Could it be that the audio setting to not record DD, only applies to non-HD channels like regular Showtime, HBO, Starz, etc, and that the HD channels always record DD?

[TyroneShoes]

Is that really a setting that affects what is recorded or is it a setting that just tells it to default or not default to DD on playback if it is/is not available? I don't bother with DD so I don't have mine set up for it (I prefer analog processed to PLIIx so that I can compress and equalize it), but it was my understanding that this was just to prevent "silent" playback issues for folks who have it configured a particular way (so that once configured it will always provide audio of one flavor or another depending upon the setup, whether DD is available or not).

Unless DTV is doing something further to process it (which makes little sense) recordings made from HD that they receive from OTA stations, as well as direct recordings of OTA, should always record the AC-3 audio track, and whether there is DD 5.1 available within that is determined by whether it was put there by the broadcaster in the first place, so it should be transparent since all the recorder knows is to record the AC-3 track regardless of whether it is 5.1 or non-5.1 AC-3.

It's only my guess, not knowing how DTV processes other HD channels sent them, but since most content source vendors prefer to provide all options locked into the feed for technical and signal management reasons and then allow anyone downstream to do whatever extraction is necessary after decode, the 5.1 if it is available probably passes through DTV untouched. I also think that the Tivo is not smart enough to either record or not record the 5.1, but just dumbly records whatever is sent, and then parses out what is necessary to the various ports per customer setup during playback, which is technically much simpler to do after decoding than before recording to the HDD. I think which tracks are routed for play back are triggered by the flags identifying whether the track is DD 5.1 or not (the same flags that tell your AV receiver to process it as 5.1) which are available after decode, and the setting on the PVR then routes it to the optical output as 5.1 if you have the Tivo set to do that. That's my understanding, but I freely admit I don't always understand everything, especially why DTV does what it does.

But bottom line, whether you record more actual data or not by setting the Tivo for DD will make little difference, as the AC-3 track is a drop in the bucket.

[ayrton911]

TyroneShoes,

You were right. My receiver and speakers arrived today. All my Aliases that were recorded with the "do not record Dolby Digital" checked, do indeed still have 5.1! Sounded great.

[shacky]

A short thread hijack here......

I have the HDMI cable hooked up and when I switch the reciever over to DD, I lose audio on my digital channels (pretty much everything except analog OTA). Is this expected? I am wondering if I need to connect an optical or something?
Not too concerned with this but just found it puzzling since I expected the HDMI connection to handle DD.

[leftcoastdave]

A short thread hijack here......

I have the HDMI cable hooked up and when I switch the reciever over to DD, I lose audio on my digital channels (pretty much everything except analog OTA). Is this expected? I am wondering if I need to connect an optical or something?
Not too concerned with this but just found it puzzling since I expected the HDMI connection to handle DD.

Funny you should mention this. I had precisely the same experience when setting up my new 32" Sony Bravia this week and connecting it to my equally new HR10-250. I set up the Tivo to record and playback Dolby Digital and connected the Sony via the HDMI connector. When I tuned to a channel (it happened to be ESPN HD during the US Open) broadcasting Dolby 5.1, I had no audio.

I was assuming that the HDMI port carried digital audio as well as video and I further assumed this would include DD 5.1. When I switched back to component video and standard stereo connection to the TV, the audio was fine on all channels. My first thought was that I had a new HD Tivo with a bad HDMI card, but after seeing this post, I am not so sure.

Currently my setup is for the Tivo to output DD 5.1 and the Sony is connected via component and stereo audio. This requires an optical connection to my A/V receiver to get DD 5.1 but that is normal operation for my other HR10-250 - TV combinations so it is no big deal.

I called Sony and they verified I should receive digital audio via the HDMI port, so I am wondering is there a problem with the Tivo HDMI port or what?

Can any of you audio wizards explain what is going on here?

Dave

[shacky]

My HDMI is connected directly to the TV and then I have audio out to the reciever. I do this since my receiver's Ir is bad so I use the TV to adjust the volume.
Anyways, after scouring the TV manual, I found this:
"To use the benefits of DD sound from an HDMI device, connect the digital audio ouput of the HDMI device directly to the A/V receiver."
I guess this means my TV does not support DD via HDMI.
I'm off to buy another toslink to play with.

[blb]

the HR10-250 only outputs stereo over hdmi. for 5.1 you need to use an optical cable. i checked with dtv, and its in the manual.

[Deja-vue]

the HR10-250 only outputs stereo over hdmi. for 5.1 you need to use an optical cable. i checked with dtv, and its in the manual.
That Statement is simply not true.

[phox_mulder]

HDMI goes to the HD-TV,
HD-TV has 2 speakers.
What's the point in sending 5.1 over HDMI to the TV?

Do high end TV's take the 5.1 from the HDMI and pass it through to their optical output,
which you can then run to a 5.1 decoder/receiver?
Or, do high end TV's have a 5.1 decoder and surround speaker outputs?

99% sure my HDTV doesn't do any of the above, but it does had an HDMI input.
Digital optical goes from the HR10-250 to the A/V receiver.


phox

[shacky]

That Statement is simply not true.


To elaborate on this statement, what I have found after a lot of searching, is that HDMI is perfectly fine for transmitting digital audio. The problem arises in companies getting lazy and only setting up their HDMI input to stereo only...especially with television companies who manufacture televisions that have speakers. Why enable dolby digital if there are only two speakers and stereo will work just fine?
For the end user this is, of course, unsatisfactory. But what can we do? At least DirecTV gives us the alternate audio out resources to bypass this problem.

[HomieG]

To elaborate on this statement, what I have found after a lot of searching, is that HDMI is perfectly fine for transmitting digital audio. The problem arises in companies getting lazy and only setting up their HDMI input to stereo only...especially with television companies who manufacture televisions that have speakers. Why enable dolby digital if there are only two speakers and stereo will work just fine?
For the end user this is, of course, unsatisfactory. But what can we do? At least DirecTV gives us the alternate audio out resources to bypass this problem.

I think a lot of the TV manufacturers have given up paying the DolbyDigital decoder licensing fee. They may have figured that the audio amp/receivers have the DD decoder, and most consumers probably only need one DD decoder. Why pay the licensing fee and pass it along to the consumer if you don't need two of them? Just a guess. Don't get me wrong, I'd love to have DD at least pass-through my TV via HDMI to my audio amp, but it doesn't. So I just use the optical output on my Comcast DVR to my amp input, and use the HDMI to the TV for video only. I'd rather have the TV input switch its optical output to the audio amp, but it doesn't. The amp has the DD decoder, and that's fine, at least for me.

Edit: YAMM 2,000, whooppee!

[flnsx]

I have the same problem. I have a Samsung HL-S5687W DLP hooked up through HDMI.

When I have the 250 record 5.1 I can't hear any sound coming from the TV when it records 5.1.

I have to have the Digital Audio hookup up to my HK receiver to hear anything.

It sucks because I use my TV's sound 96% of the time.

So I turned 5.1 off. Sucks

[tvl76]

I was also reluctant to use my A/V amp all the time. It did not make sense to me to run my amp just to watch the news or something. But what am I saving my amp for? Why watch HD and not get the full benefit of fantastic audio too? All this electronic stuff is old after 3 or 4 years anyway. Might as well run it to death and then have a good excuse to get the latest and greatest. Thing is, running the amp is what I have it for.
I've got an optical connection to my amp, HDMI connect to my TV. DD switched on. The audio is fantastic for all my TV viewing. I programmed my Denon remote with "on" and "off" macros to make it easy to turn on the TV, Amp and set the inputs and outputs with the press of one button.
Some of the new commercials have really good soundtracks.