The only difference is where the decoding of Dolby is happening. In case of 5.1 PCM output, the decoding is happening at the STB and in the other case its happening at the home theater.
This is not true. The place of decoding (digital to analog) depends on how you connect your STB to your receiver. If you connect it via a HDMI cable (some receivers support HDMI input), then digital audio (whether it's PCM or Dolby digital) will be decoded and played by the receiver. If you use a digital coaxial audio cable (connecting the S/PDIF output of your STB to your receiver), then again, your STB sends out digital audio, and the decoding is done at the receiver. However, if you connect the analog out (L/R) outputs of your STB to your receiver or
TV, the decoding is done at the STB. Note that in this latter case, you get 2-channel audio, whether or not the original audio was Dolby digital. Since receivers are likely to have superior decoding capability, one should send in digital audio directly from the STB to the receiver (via HDMI or digital coaxial); it will decode and play it back on all your speakers. Perhaps, what you really mean is that, some processing is done at the STB when you select PCM (dolby digital to pcm); yes, but this pcm is 2-channel; so there is a downmix done.
---------- Post added at 08:21 PM ---------- Previous post was at 08:18 PM ----------
Can you please specify 'coaxial cable' and where it is to be connected to the STB?
🙁
Thanks!
The coaxial cable is a digital coaxial cable. It should be connected to the S/PDIF output port of your STB, and the other end to the digital coaxial in on your receiver. S/PDIF is a digital audio interconnect.
---------- Post added at 08:29 PM ---------- Previous post was at 08:21 PM ----------
I saw two options under audio settings : PCM and dolby digital. I was wondering which one is better for HD content like world cup. I have connected my STB to my LCD using an HDMI cable and STB to my
Sony home theater system using an optical cable.
At the moment,
Tata Sky's PCM ouput is 2-channel. So, if you choose PCM, you'll lose 5.1 dolby digital sound that most of their HD channel content comes with. As for the world cup on HD channels, as far as I remember, it was broadcast with dolby digital and I had got 5.1 channel audio on my receiver. I currently get dolby digital with Natgeo and Discovery (didn't check others), and the quality is very good. If your receiver can decode Dolby Digital (in all certainty it will), you should select "Dolby Digital". You should also mute your TV speakers while you do this, since there is no need to play the audio that's sent to your TV via the HDMI cable as you have another digital audio cable connected to your receiver; also you might get an
echo if the processing delays are different.
---------- Post added at 08:44 PM ---------- Previous post was at 08:29 PM ----------
Does this setting make any difference when connected to LCD via HDMI cable and no Home theater?
If you just are connected to your TV via HDMI cable and no home theater, it shouldn't make a difference; why don't you listen to it and check?
🙂 Since you connected via HDMI, the digital to analog conversion is done at your TV. If you select Dolby digital and when your STB sends in HD content encoded with Dolby Digital, and your TV can't decode dolby digital, you won't get any audio (I'm not sure about this; Dolby digital is a discrete channel encoding, not matrixed unlike Dolby Surround). If it does, you'll just get audio on your 2 tv speakers (I haven't heard of a TV connected to 5.1 speakers). In this latter case, it wouldn't have mostly made a difference if you had just let the STB send out PCM (TataSky sends out 2-channel PCM); however, this latter option is better since your TV is not expected to have any sophisticated decoding capability, and it's better to get the 2-channel PCM straight from the STB. Note that in both cases, you are sending in digital audio to your TV. So, if you are just connected to your TV via a HDMI cable, I would recommend setting the STB audio output to PCM.
---------- Post added at 09:00 PM ---------- Previous post was at 08:44 PM ----------
Tata Sky PCM does not works with HDMI. You have to have a coaxial cable to transmit the 5.1 Dolby from STB to Home theater - and it is awesome sound quality
🙂
The way TataSky HD is doing it at the moment, you are right: the audio sent out via HDMI is 2-channel PCM while the audio sent out via its digital coaxial out (S/PDIF) is dolby digital (whenever there is HD content encoded in DD). However, this was not true about a month ago. I was able to playback Dolby Digital via their HDMI output. I have the STB directly connected to my receiver via HDMI, and it used to decode and playback Dolby Digital (it's shown in its display). However, I only get PCM now via their HDMI. However, if I use its digital audio out (S/PDIF) connected via a coaxial cable to my receiver, I do get 5.1 dolby digital. My theory is that they changed it because some users who were just directly connected to their TV had trouble playing back whenever dolby digital was sent out. I'm not sure though why such users couldn't have just selected PCM and 2-channel PCM could have been sent out. Note that now, if you select "PCM", PCM is sent out via both HDMI and digital out; whereas if you use Dolby, you get Dolby on digital out (whenever you have such content) but 2-channel PCM on the HDMI.