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Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

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Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#91

Post by joshu »

JonnieCache wrote: post #86
baddox wrote: post #54

Earlier quoted context omitted.

The idea I'm talking about should provide a single consistent audio signal. I know nothing about audio processing, but it seems like it should be possible to take multiple bad audio signals and combine them into one signal that's better than any constituent audio source. Perhaps one audio source captured low frequencies well, while another captured higher frequencies better.

>take multiple bad audio signals and combine them into one signal that's better The problem eventually comes down to the fact that "better" is subjective. We're in the murky realm of art here. Should your algorithm keep that fret noise or the squeaking of a vocalist's intake of breath? Are they "noise," or are they part of the performance? >I know nothing about audio processing Not wishing to be rude, but this much i…

Presumably one would get rid of per-device degradation and compression artifacts.

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#92

Post by PStamatiou »

pavedwalden wrote: post #38

I love it. Any chance you would expand to more general "news" applications? The audio wouldn't be as good for syncing against, but I've always wanted an interface like this for watching protest videos.

Take a look at this: http://blog.switchcam.com/uc-davis-pepper-spray-incident-fro...

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#93

Post by ugh »

ljf wrote: post #85
allbutlost wrote: post #80

Earlier quoted context omitted.

This is unfortunately so unlikely to as to be practically impossible (currently!). If the microphones, ADCs etc on both phones are incapable of capturing frequencies of above e.g. 15Khz below a certain range, combining those signals definitely won't bring you any closer to the original signal. You may be able to cancel out a fair bit of noise given enough processing but you won't get back what hasn't been originally…

Sorry to be off topic here... but this is why I don't understand HN sometimes - the post above isn't nasty, augmentative, hurtful or 'bad' in any way, but instead of people responding to the poster they've downvoted him. Isn't downvoting for removing bad content, not trying to silence someone you don't agree with? Thoughts/comments? (edit - post is no longer showing as greyed out/downvoted - but still, any comments?)

There will always be idiots who downvote great comments. I have on occasion been such an idiot myself (it happens). I wouldn’t let me bother by that, it usually all works out in the end. (Remember: It can take only a single person to grey out a comment.)

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#94

Post by anjc »

JonnieCache wrote: post #86
baddox wrote: post #54

Earlier quoted context omitted.

The idea I'm talking about should provide a single consistent audio signal. I know nothing about audio processing, but it seems like it should be possible to take multiple bad audio signals and combine them into one signal that's better than any constituent audio source. Perhaps one audio source captured low frequencies well, while another captured higher frequencies better.

>take multiple bad audio signals and combine them into one signal that's better The problem eventually comes down to the fact that "better" is subjective. We're in the murky realm of art here. Should your algorithm keep that fret noise or the squeaking of a vocalist's intake of breath? Are they "noise," or are they part of the performance? >I know nothing about audio processing Not wishing to be rude, but this much i…

I presume he means better in the sense that you'd try to remove overt noise, e.g. small conversations in the background, maybe wind noise. That sounds like it'd be possible to do. Improving a single video from multiple video sources would surely be impossible. Even with scene reconstruction etc you're not going to be improving the quality of any single video source...(?)

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#95

Post by anjc »

rhizome wrote: post #62
baddox wrote: post #54

Earlier quoted context omitted.

The idea I'm talking about should provide a single consistent audio signal. I know nothing about audio processing, but it seems like it should be possible to take multiple bad audio signals and combine them into one signal that's better than any constituent audio source. Perhaps one audio source captured low frequencies well, while another captured higher frequencies better.

You can certainly automate crossfaded audio between multiple sources to try to get the cleanest copy, but it's hard. For instance, how do you decide whether it's noise or the letter "s" or the "chk" of a pick across muted guitar strings? The heuristics for "better than any constitutent audio source" can be extremely nuanced, algorithmically intensive, and still difficult to pin down, akin to speech recognition. Speak…

I don't know anything about audio processing algorithms, but (assuming there's a way), presumably with enough audio sources, there'd be a commonality between each one that describes the 'correct' sound. I.e. if there's different noise going on in each source (people talking around each microphone, at a gig, intermittently), you don't really need to decide which sound is 'clean' because you'd know which sounds are inconsistent...(?)

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#96

Post by Roritharr »

femto wrote: post #83
jackpirate wrote: post #77

Earlier quoted context omitted.

If you haven't captured any frequencies above 15kHz (which an average cell phone mic is unlikely to do), no amount of averaging, filtering, or combining will get them back. I think this is technically not quite true. If two cell phones right next to each other are both sampling at 15kHz, in the best case you could combine their samples to get an equivalent sampling of 30 kHz. (Best case meaning phone 1 samples exactl…

Only if the two phones are under-sampling the signal. Chances are that there is a low pass filter in front of the phone's ADC, blocking signals above the Nyquist limit from reaching the sampler. Assuming brick wall filters (ie perfect cutoff), combining the signals will reduce variance (noise) but not give any information on frequencies above the cutoff frequency of the filter. Brick wall filters don't exist though.…

You are suggesting the Networked Cellphone Echolocation Device of Batman at the end of the Dark Knight... Cool!

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#97

Post by jhealy »

This perfect circle gig is a good sample:

http://switchcam.com/event/a-perfect-circle-lollapalooza-201...

Some of these concerts may have bootleg audio available, often recorded by audiophiles with decent equipment. It'd be amazing if supported syncing that up so you'd get great audio with multi-camera video

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#98

Post by GraemeL »

brettwelch wrote: post #42
autrefoius wrote: post #35

Earlier quoted context omitted.

The error I'm receiving on Firefox Aurora 10.0a2 (2011-11-27) is: VKLog is not defined http://switchcam.com/assets/js/utils/facebook.js?ver=2011112... Line 81 VKLog.dlog("checkSessionStatus()"); It does seem to work with Adblock disabled, so I'd guess a subscription is blocking something essential.

Thank you! I think you must be right about the adblock thing. We once had a similar thing with a Chrome plugin that borked things. We'll look into it; thanks again.

For me it was Adblock blocking your http://switchcam.com/assets/js/utils/logging.js script. Things work fine once I let that script load.

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#99

Post by missing_cipher »

baddox wrote: post #37

Cool idea, but I was sad that it wasn't finally an implementation of an idea I've had for a long time. My idea is to actually use video and audio information from distinct sources to create a single video/audio stream that is of better quality and/or completeness than any of the constituent parts. Essentially, my idea would do to video what Photosynth does for photos. http://photosynth.net/

There's something along those lines in the works, I don't see a name: http://grail.cs.washington.edu/projects/videoenhancement/

It combines a few high-resolution still images with a low-res video to improve the video quality:

Static scene: http://vimeo.com/1513129 Dynamic: http://vimeo.com/2937785

(Looks a bit old (3 years) so I don't know if it's still in development)

Re: Show HN: Entire concerts algorithmically "reconstructed" from YouTube videos

#100

Post by exDM69 »

andrewfelix wrote: post #50

Sweet execution. Finally a use for all those dickheads who hold up their phones in the middle of a live performance.

Yeah, now that you can't see anything but camera phones while you're actually at the concert, you can watch it from youtube when you get home.

Thankfully this isn't too much of a problem at heavy metal gigs. No-one wants to take their smartphone to the moshpit :D

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