Audio options: PCM vs. Dolby digital AC3

dnsjo

Which is the best decoder for 5.1 sound, the cable box or the receiver?

I have Cox HD programming going to a Motorola DCH3416 cable box, audio output to my Yamaha 663 by optical cable (the HDMI cable goes stright to the TV so we don't have to always use the receiver). My audio menu options on the cable box are PCM or Dolby digital AC3. If I select Dolby, I set the receiver to "straight" or "pure direct". When choosing PCM, I set the receiver to "surround decode" and it diplays "Pro Logic", for example. I then get 5.1 sound, vocals to the center, etc. (My box gets stuck often in PCM until I unplug it to reset it.)

Which would be the better way to leave it?
Thanks.

Loves2Watch

I would suggest leaving it on Dilby Dogital AC3. That way you won't have your box getting stuck and the receiver will play back everything it is sent.

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Shark2k

So you know the difference, I found this on Audioholics Home Theater Forum:

Bitstream - will send the raw digital audio without processing out of the DVD player so your receiver can process

PCM - the player will convert everything to and output as 2 channel PCM

So if you want your receiver to process DD and DTS multichannel tracks then you must set the player to Bitstream

Just replace DVD player with STB.

Also, with PCM, I think that only happens with digital optical. I think if you had the HDMI go into the receiver and set to PCM it might give you the surround, but bitstream will always give you the surround sound (if available) because it is sending the raw data.

-Shark2k

joekewl1971

Welcome to High Def Forum.

For my dads HDMI TV I have the audio set to auto. The cable box detects that the TV will only take PCM and outputs that. All cable is Dolby Digital, also known as AC3. DTS is not used with cable, likely because it has a higher data rate. The cable box will convert to PCM if your TV needs it. That is the only purpose of converting. Taking a lossy codec, like AC3 and converting it to a better codec, like PCM is not a good idea if you can avoid it. It is liable to make the sound worse. Your stereo is capable of AC3, including true 5.1 surround sound. PCM is 2 track only. Your setup confuses me. The TV and the stereo hooked up at the same time might have different requirements. Perhaps if you choose auto, the cable box will output both. I have not tried it. Otherwise you might want to switch back and forth. Or you may see if your TV will accept the AC3.

Good luck to you. I hope you figure out a solution.