Digital audio capture via soundcard - is there any software to do what I want?

Discussion in 'Computers' started by Rob Gillespie, May 10, 2003.

  1. Rob Gillespie

    Rob Gillespie Producer

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    What I'm after is the ability for the capture software to start recording the instant it detects an incoming signal. I've done a test tonight with Sound Forge recording the PCM audio from a LaserDisc. It works fine, but relies on me clicking the 'record' button. If it could start recording as soon as it detects a signal it would save me the hassle of syncing with the captured video signal.

    You see, I can capture the video from LD to one machine (which will house my new ADVC-1394 when it arrives) and the use the second PC to capture the digital audio. If I can get the audio to auto-record as soon as I hit Play on the LD player, I should end up with a video and audio capture of exactly the same playing time and in-sync with each other.

    So, is there any software out there that can do what I want?
     
  2. Wayne Bundrick

    Wayne Bundrick Cinematographer

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    My experience with capturing digital-to-digital has been to just record it and then trim it later using a good waveform editor. With digital capture it becomes easy to recognize the start of the signal. If you zoom in on the silence before the start you'll see that the waveform is absolutely flatlined zero, pure digital silence that never exists in the analog world.

    In any case I wouldn't trust what appears to be the start of the audio signal to be matched with the start of the video. I'd look for a scene at the beginning of the movie, maybe even something in the studio logos before the movie, that can serve as a good clapstick slate for synchronizing the sound with the picture.

    Once you have the picture and sound at the start of the movie synchronized, it's a good idea to check a scene at the end of the movie to be sure they are still synchronized, because as soon as you neglect it, there will be a sync problem. There can be issues with the audio sample rate not being "locked" to the video frame rate and the audio will drift out of sync and be off by many seconds by the end of the movie. But I'm thinking this won't happen since you're capturing digital-to-digital.
     
  3. Matt DeVillier

    Matt DeVillier Supporting Actor

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    Rob,

    for my LD transfers to HD, I used the previously mentioned canopus box to digitize the video, and input the audio digitally via my Hercules GTXP sound card. I used a program called iuVCR to "capture" the audio and video together - it allowed me to select the source I wanted for each and kept them in sync. I can't imagine why you'd want to try and use 2 PCs to do this when one will work much better.
     
  4. Vince Maskeeper

    Vince Maskeeper Producer

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    Sound forge can do it, but it will be based an an audio threshold- which the audio on the LD might not immediately kick in sound. Even if it did, it should be really easy to zoom in after the fact and trim off whatever you need (basically manually doing what you're looking to do by finding the start of the sound yourself).

    -Vince
     
  5. Wayne Bundrick

    Wayne Bundrick Cinematographer

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    If you capture analog audio with the video, in addition to capturing the digital audio on the other computer, then the analog audio track can serve as a guide for synchronizing the digital track which will replace it.

    For archiving laserdisc to DVD, you'll have to transcode the digital track from 44.1k to 48k.
     
  6. Rob Gillespie

    Rob Gillespie Producer

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  7. Rob Gillespie

    Rob Gillespie Producer

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    Mind you, this brings up another question. Is what I'm attempting worth the bother? What is the analogue audio capture quality likely to be with Canopus card? Bearing in mind that it will probably end up going through BeSweet and coming out at DD 192kbps anyway.

    That said, I wouldn't mind trying to do Pink Floyd's Pulse with an intact uncompressed PCM track. Nice [​IMG]
     
  8. Wayne Bundrick

    Wayne Bundrick Cinematographer

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    Rob, you should try a short sample clip to make the decision for yourself. Record the same audio both ways, then encode to DD and try to hear a difference.
     
  9. Matt DeVillier

    Matt DeVillier Supporting Actor

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    Rob,

    I just did a test with my machine and the CPU usage barely moves when recording via the digital inputs, so I'm not sure why yours would be at 100%. what sound card do you have?
     
  10. Rob Gillespie

    Rob Gillespie Producer

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    Hercules Fortissimo II, software is Sound Forge 5.
     
  11. Steven K

    Steven K Supporting Actor

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    Rob,

    Have you tried TotalRecorder from High Criteria?

    It's a very nice piece of software... it installs a virtual sound card driver on your system which automatically starts recording whenever any sound comes through your normal sound card, and then stops as soon as the sound ceases.

    I use it all the time to record internet radio broadcasts (sporting events). It digitizes any analog sound that comes through the sound card.

    Also, CoolEdit Pro 2 will do this, but it is significantly more expensive than TotalRecorder.
     

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