6 ms·

Wifibroadcast – Analog-like transmission of live video data

129 points by infodroid 11y ago

lovelearning 11y ago
From the advantages quoted in the article, this seems useful for recording wifi-enabled security camera feeds too.
nickpsecurity 11y ago
Cool stuff. Good to see them recognize and use advantages of analog. I could tell them digital transmission of data has always been done with analog circuits but analog's invisible ubiquity is beside the point. ;)
- coryrc 11y ago
  Amen. Now if someone could get DVDs or streaming services to offer fast-forward and rewind that works as well as a VCR we'd be caught up to the 1980s!
  - nickpsecurity 11y ago
    Hell yes! Or even hardware acceleration for starting in random parts of videos on my PC so they don't break up and delay as often. This is the digital era. It's supposed to work more reliably than old, analog tech. I used to be able to stop my rewind or fast-forward on VCR within a few seconds of the target moment with clean play. Still not reliable with digital streaming. (sighs) Note: I do like how, even with errors, it still takes under 20 seconds for me to get to any random part of the vid. That's an improvement over the rewind/fast-forward speeds. :)
    - lfowles 11y ago
      > Note: I do like how, even with errors, it still takes under 20 seconds for me to get to any random part of the vid. That's an improvement over the rewind/fast-forward speeds. :) Don't forget not having to rewind after watching/before watching. Glad that whole class of annoyance is gone, much more annoying than poor random access :)
      - nickpsecurity 11y ago
        That's what this meant: "Note: I do like how, even with errors, it still takes under 20 seconds for me to get to any random part of the vid. That's an improvement over the rewind/fast-forward speeds. :)"
    - zdw 11y ago
      Modern video codecs use data in frames before and sometimes after the current frame to compress more: https://en.wikipedia.org/wiki/Group_of_pictures https://en.wikipedia.org/wiki/Group_of_pictures whereas analog media stored full resolution versions of every frame. Seeking is much easier when you can pick any random location and have all the data right there ready to use, and you don't have to backtrack and try to recreate things from previous frames.
      - nickpsecurity 11y ago
        That's true. Hence me asking for "hardware acceleration" to improve the speed to real-time if possible.
    - soylentcola 11y ago
      Isn't a lot of that related to how the video is encoded/decoded though? I have only a basic understanding of how it works through working with video (not developing or tweaking actual codecs) but when I'm doing VJ-type stuff in Resolume (for example) I use a setup where all clips are encoded with a keyframe every frame. It makes for some huge clips but I can scrub or jump around or manipulate clips with no delay at all. On the opposite end you've got streaming video or even many common formats and settings for ripped/downloaded video. Those do a keyframe every (x) frames and then between keyframes the file only contains the data for changes to the keyframe. This gets you smaller files so your downloads are quicker and your streams look nicer while using less bandwidth. I know there's a lot more to it but at least with locally stored files, I thought it mostly had to do with keyframes. With streaming I'd imagine it's related more to how the stream is managed to download in chunks and maximize quality versus bandwidth (rather than focusing on quick scrubbing or quick access to random points of the video). I'm interested in this stuff so if there's something I'm missing or flat-out wrong about, feel free to educate me.
      - nickpsecurity 11y ago
        Oh I'm not a subject matter expert on video compression. I just know the difference between using a general-purpose CPU and the ASIC version of decoders is huge. It's why you have all these weak, low-power SOC's that can do 720/1080p etc. That's the hardware acceleration. I doubt it's designed for the random access I'm describing, though. So, one for that might solve the problem. Might also need to be integrated with a good, storage subsystem if that causes any difficulties. Cool, though, that yours lets people jump around at will. :)
- woah 11y ago
  I don't think that most people need to be reminded that digital data is transmitted with electricity.
  - nickpsecurity 11y ago
    Not electricity but analog circuits. Many people think they have one or the other while they have a mix of both leaning heavily toward digital. So many misconceptions about the topic.
- Animats 11y ago
  This isn't analog video. It's one-way broadcast digital video. Like current broadcast TV.
  - nickpsecurity 11y ago
    I know man. It's a semi-joking and semi-serious post where I point that people step from one mental, model (reliable/p2p/digital) to another (lossy/continuous/analog) to come up with a good solution to a problem. In this case, kind of reinventing one but with a medium that has plenty of cheap HW supporting it. It's technically digital but most like analog for the average person's experience with the attributes.
0942v8653 11y ago
Does this allow encryption of the video stream? Graceful signal degradation is a great feature, but I don't see how that would work when there is encryption.
- taterbase 11y ago
  Encryption won't work for this scenario as it reintroduces the problem of all or no data. Degraded encrypted data can't be decrypted successfully (yet?)
  - danellis 11y ago
    How much security do you lose if you encrypt each frame individually?
  - est 11y ago
    encrypt with a redundant parity data?
    - 0942v8653 11y ago
      Even then I think it would still be all-or-nothing. That may increase the chances of "all" over "nothing" but not allow graceful degradation of the video.
      - prutschman 11y ago
        Hierarchical coding: send a low quality version of the video with high redundancy, and a higher quality refinement of the video with lesser redundancy.
    - mantasm 11y ago
      How would you implement analog parity? Parity doesn't translate well as a concept into the analog space. You can take an analog signal and "quantize" it into sixteen possible values so that you can apply a parity algorithm that returns sensible results and doesn't fail with expected noise, but you're digitizing the signal.
mintplant 11y ago
> Note: Before using wifibroadcast you have to check if the regulatories of your country allow such a use of wifi hardware. Any guesses as to whether this would be legal in the US?
- mplewis 11y ago
  Here's a page with info on operating at 2.4 GHz: http://www.afar.net/tutorials/fcc-rules http://www.afar.net/tutorials/fcc-rules
- nuand 11y ago
  Monitor mode is a MAC level concept, and doesn't alter any of the RF characteristics that would make operating this device illegal. (This is not legal advice. Consult with an attorney, etc etc)
Yaggo 11y ago
This is awesome project. I'm currently building a fixed wing drone with dual wifibroadcast links, downstream for (stereo) video and upstream for control.

129 points by infodroid 11y ago

From the advantages quoted in the article, this seems useful for recording wifi-enabled security camera feeds too.

Cool stuff. Good to see them recognize and use advantages of analog. I could tell them digital transmission of data has always been done with analog circuits but analog's invisible ubiquity is beside the point. ;)

coryrc 11y ago
Amen. Now if someone could get DVDs or streaming services to offer fast-forward and rewind that works as well as a VCR we'd be caught up to the 1980s!
- nickpsecurity 11y ago
  Hell yes! Or even hardware acceleration for starting in random parts of videos on my PC so they don't break up and delay as often. This is the digital era. It's supposed to work more reliably than old, analog tech. I used to be able to stop my rewind or fast-forward on VCR within a few seconds of the target moment with clean play. Still not reliable with digital streaming. (sighs) Note: I do like how, even with errors, it still takes under 20 seconds for me to get to any random part of the vid. That's an improvement over the rewind/fast-forward speeds. :)
  - lfowles 11y ago
    > Note: I do like how, even with errors, it still takes under 20 seconds for me to get to any random part of the vid. That's an improvement over the rewind/fast-forward speeds. :) Don't forget not having to rewind after watching/before watching. Glad that whole class of annoyance is gone, much more annoying than poor random access :)
    - nickpsecurity 11y ago
      That's what this meant: "Note: I do like how, even with errors, it still takes under 20 seconds for me to get to any random part of the vid. That's an improvement over the rewind/fast-forward speeds. :)"
  - zdw 11y ago
    Modern video codecs use data in frames before and sometimes after the current frame to compress more: https://en.wikipedia.org/wiki/Group_of_pictures https://en.wikipedia.org/wiki/Group_of_pictures whereas analog media stored full resolution versions of every frame. Seeking is much easier when you can pick any random location and have all the data right there ready to use, and you don't have to backtrack and try to recreate things from previous frames.
    - nickpsecurity 11y ago
      That's true. Hence me asking for "hardware acceleration" to improve the speed to real-time if possible.
  - soylentcola 11y ago
    Isn't a lot of that related to how the video is encoded/decoded though? I have only a basic understanding of how it works through working with video (not developing or tweaking actual codecs) but when I'm doing VJ-type stuff in Resolume (for example) I use a setup where all clips are encoded with a keyframe every frame. It makes for some huge clips but I can scrub or jump around or manipulate clips with no delay at all. On the opposite end you've got streaming video or even many common formats and settings for ripped/downloaded video. Those do a keyframe every (x) frames and then between keyframes the file only contains the data for changes to the keyframe. This gets you smaller files so your downloads are quicker and your streams look nicer while using less bandwidth. I know there's a lot more to it but at least with locally stored files, I thought it mostly had to do with keyframes. With streaming I'd imagine it's related more to how the stream is managed to download in chunks and maximize quality versus bandwidth (rather than focusing on quick scrubbing or quick access to random points of the video). I'm interested in this stuff so if there's something I'm missing or flat-out wrong about, feel free to educate me.
    - nickpsecurity 11y ago
      Oh I'm not a subject matter expert on video compression. I just know the difference between using a general-purpose CPU and the ASIC version of decoders is huge. It's why you have all these weak, low-power SOC's that can do 720/1080p etc. That's the hardware acceleration. I doubt it's designed for the random access I'm describing, though. So, one for that might solve the problem. Might also need to be integrated with a good, storage subsystem if that causes any difficulties. Cool, though, that yours lets people jump around at will. :)
woah 11y ago
I don't think that most people need to be reminded that digital data is transmitted with electricity.
- nickpsecurity 11y ago
  Not electricity but analog circuits. Many people think they have one or the other while they have a mix of both leaning heavily toward digital. So many misconceptions about the topic.
Animats 11y ago
This isn't analog video. It's one-way broadcast digital video. Like current broadcast TV.
- nickpsecurity 11y ago
  I know man. It's a semi-joking and semi-serious post where I point that people step from one mental, model (reliable/p2p/digital) to another (lossy/continuous/analog) to come up with a good solution to a problem. In this case, kind of reinventing one but with a medium that has plenty of cheap HW supporting it. It's technically digital but most like analog for the average person's experience with the attributes.

0942v8653 11y ago

Does this allow encryption of the video stream? Graceful signal degradation is a great feature, but I don't see how that would work when there is encryption.

taterbase 11y ago
Encryption won't work for this scenario as it reintroduces the problem of all or no data. Degraded encrypted data can't be decrypted successfully (yet?)
- danellis 11y ago
  How much security do you lose if you encrypt each frame individually?
- est 11y ago
  encrypt with a redundant parity data?
  - 0942v8653 11y ago
    Even then I think it would still be all-or-nothing. That may increase the chances of "all" over "nothing" but not allow graceful degradation of the video.
    - prutschman 11y ago
      Hierarchical coding: send a low quality version of the video with high redundancy, and a higher quality refinement of the video with lesser redundancy.
  - mantasm 11y ago
    How would you implement analog parity? Parity doesn't translate well as a concept into the analog space. You can take an analog signal and "quantize" it into sixteen possible values so that you can apply a parity algorithm that returns sensible results and doesn't fail with expected noise, but you're digitizing the signal.

mintplant 11y ago

> Note: Before using wifibroadcast you have to check if the regulatories of your country allow such a use of wifi hardware. Any guesses as to whether this would be legal in the US?

mplewis 11y ago
Here's a page with info on operating at 2.4 GHz: http://www.afar.net/tutorials/fcc-rules http://www.afar.net/tutorials/fcc-rules
nuand 11y ago
Monitor mode is a MAC level concept, and doesn't alter any of the RF characteristics that would make operating this device illegal. (This is not legal advice. Consult with an attorney, etc etc)

Yaggo 11y ago

This is awesome project. I'm currently building a fixed wing drone with dual wifibroadcast links, downstream for (stereo) video and upstream for control.