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Topic: Capturing digital audio stream from TV (Read 1359 times) previous topic - next topic
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Capturing digital audio stream from TV

Hi there,

Long time reader, first time questioner here.

Basically, what I'm wanting to do is to stream a concert through my TV in 4K (for the best audio) and somehow route the audio to my computer so that I can capture/record it. My goal is to then use this audio to make my own album for future listening so that I don't have to always stream the full A/V concert. Your advice is needed!

My TV is a 4K/UHD LG smart TV, and has digital optical output as well as HDMI ARC and the usual RCA connections. The A/V data stream is coming into the TV from an Apple TV 4K unit via HDMI.

My computer is a Dell XPS 15 9560 and lists the following sound cards listed in Speccy:
   - Intel Display Audio
   - NVIDIA Virtual Audio Device (Wave Extensible) (WDM)
   - Realtek Audio

As far as the recording software goes, I had thought to use Audacity's 'record' function as it seems like a fairly straightforward setup.
My intention is to see if I can capture the unbroken digital audio signal in the easiest way possible - but reading around on the different forums, unfortunately I could not see a way to do this. I understand that one complication is that the digital streams are encrypted (is this the case?) or have some form of DRM which prevents 'capturing' them digitally.

I had a few ideas on where to begin in terms of the recording setup:
   - TV => HDMI ARC => Computer
   - TV => HDMI ARC => USB adaptor => Computer
   - TV => Digital optical cable => HDMI adaptor => Computer
   - TV => Digital optical cable => USB adaptor => Computer
   - TV => Digital coax cable => M-Audio Audiophile 2496 PCI Digital Audio Card => ? => Computer

I also know that there are external sound cards that can convert from digital to analogue, which could then feed into my computer - but my worry is about the fidelity loss in converting from digital to analogue to digital again. I'm happy to be corrected as to whether this is actually an issue. I've also suggested above using the M-Audio Audiophile 2496 PCI Digital Audio Card as it has digital pass through. But I appreciate that another card might be a better fit for what I'm trying to do here.

Has anyone here had success with their own setup? Is there anything here I'm missing or which is technologically not possible due to incompatible parts of the path? Or is there something I'm not understanding about the way the digital transmission works?

Any help or guidance appreciated. As are links to another post which offered a successful solution (as said above, I couldn't find anything over a number of google searches).

With thanks in advance,

Paul.

Re: Capturing digital audio stream from TV

Reply #1 –
NOTE - Removing/bypassing copy protection is illegal (here in the U.S.) and it's a violation of TOS #9 to discuss any details here.

What's the source?  I don't know if there is any way to decrypt a digital stream.  

There are (illegal) applications for removing the copy protection from DVDs & Blu-Rays.  There are couple of good free DVD rippers so I wouldn't pay for a DVD ripper.   I'm not sure if there are any free Blu-ray rippers.

I'm not going to directly mention any of that illegal software but here are a couple of websites that might have information on that kind of thing:
VideoHelp.com
AfterDawn.com

Quote
I also know that there are external sound cards that can convert from digital to analogue, which could then feed into my computer - but my worry is about the fidelity loss in converting from digital to analogue to digital again.
With a decent soundcard you should get good results.  If you don't get excessive noise it might be "audibly perfect".  (Distortion and frequency response are rarely an issue...  Usually noise is the only issue.)    And, it's not illegal (for personal use) if are not cracking/bypassing copy protection.
 

Re: Capturing digital audio stream from TV

Reply #2 –
Ideally you want to capture the actual audio source/transmission. If it's being transmitted via satellite then it's likely to be mp2. So a DVB card is likely required.

If it's available to be viewed on your computer then there are programs that can capture the various streams. If this is for personal use then I don't think it's a violation of TOS #9 to discuss this, but for my HA.io safety I'm not going to mention the programs (until it's confirmed it is ok).

You could always - as you suggested - capture the audio using a prog like Audacity - once you've set up your hardware to direct the data to your computer. If it's not been altered via the TV, then it'll be the same (audio quality wise) as the source transmission if you save it in a lossless format. This method is akin to how many of us would've recorded radio and/or TV programs: onto our cassette tapes, DATs or even VHS tapes.