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• How can I programmatically write and read random video watermarks ?

  13 novembre 2017, par GreenTriangle

  I spent a few minutes trying to think of a clearer way to word my title, but I couldn’t manage it, sorry.

  I want to essentially canary trap video files : I am (hypothetically, this is not real but a personal exercise) offering them up to 5,000 different people, and if one gets leaked, I want to know who leaked it. Metadata is too easily emoved, so what I’d like to do is add a random and subtle watermark to each file, and store information about that in a database.

  For example : on Joe Smith’s copy, a 10x10 pixel 80% transparent red square in the upper left corner for 5 frames. On Diane Brown’s copy, a full-width 5-pixel 90% transparent black bar on the bottom edge for 15 frames. Then, if I find a leaked copy, I could check it against the database.

  I know this still isn’t foolproof : cropping would break co-ordinates, hue/brightness transforms would break colour reading, cutting time would break timestamps. But if I did want to do this anyway, what would be a good strategy for it ?

  My idea was to generate PNG overlays randomly, split the video into parts with mkvtoolnix/ffmpeg, re-encode the middle part with ffmpeg + overlay filter, and then rejoin them. But is this silly when there’s a "proper" way to do it ? And what would I be doing to read the watermarks, which I can’t even really conceive of ?

• Encode uncompressed avi from webcam

  17 août 2013, par shaun

  I have to record videos for a project I'm doing. Two of these are USB cameras and another is a n IP overhead camera.All three are connected to a laptop computer. After recording the videos I need to be able to open them in an editor (not for editing particularly but for modeling stuff in them for which I need a timeline). I have chosen Sony Vegas Pro for my editor. I have been able to record the uncompressed avi using gstreamer with this command :

  gst-launch v4l2src device=/dev/video0 ! 'video/x-rawyuv,width=640,height=480,framerate=10/1' ! mux. avimux name=mux ! filesink location=temp.avi

  I had to set the framerate to 10 because I was using two USB cameras and a framerate of 30 on both could not be accomodated in the bandwidth of the USB controller. I do not care about audio in my file so I don't grab audio. Similary, while encoding I wouldn't care about audio as well. This is raw uncompressed avi. I was not able to open this in Sony Vegas Pro. I believe I need to encode this uncompressed avi using a codec that will be opened by Sony Vegas Pro (I don't know which codecs Sony likes, so I'll probably try different ones until one of them opens).

  For encoding this video, I have several options : mencoder, ffmpeg, gstreamer. But I am not able to figure out how to use these tools to get what I want. Ideally, I would like just to sort of "insert" a codec with other settings remaining the same. I don't really care about the how much space the resulting video takes since the length of the videos are not going to be more than 3 minutes and I have space available, so lossless codecs also work. I believe Sony reads mpeg avi's so if I can get that, it'll be great.

  Thanks for reading and I appreciate all the help.

• Is there a way to use youtube-dl in async

  8 octobre 2024, par Stam Kaly

  I have an application where I use zmq with asyncio to communicate with the clients who have the ability to download a video with youtube-dl to the server. I tried adding await to youtube_dl's download function but it gave me an error since it was not a coroutine. My code right now is simply looking like this :

  



  import asyncio
import youtube_dl


async def networking_stuff():
    download = True
    while True:
        if download:
            print("Received a request for download")
            await youtube_to_mp3("https://www.youtube.com/watch?v=u9WgtlgGAgs")
            download = False
        print("Working..")
        await asyncio.sleep(2)


async def youtube_to_mp3(url):
    ydl_opts = {
        'format': 'bestaudio/best',
        'postprocessors': [{
            'key': 'FFmpegExtractAudio',
            'preferredcodec': 'mp3',
            'preferredquality': '192',
        }]
    }

    with youtube_dl.YoutubeDL(ydl_opts) as ydl:
        ydl.download([url])


loop = asyncio.get_event_loop()
loop.create_task(networking_stuff())
loop.run_forever()


  



  which gives the following output :

  



  Received a request for download
[youtube] u9WgtlgGAgs: Downloading webpage
[youtube] u9WgtlgGAgs: Downloading video info webpage
[youtube] u9WgtlgGAgs: Extracting video information
[youtube] u9WgtlgGAgs: Downloading MPD manifest
[download] Destination: The Cardigans - My Favourite Game “Stone Version”-u9WgtlgGAgs.webm
[download] 100% of 4.20MiB in 00:03
[ffmpeg] Destination: The Cardigans - My Favourite Game “Stone Version”-u9WgtlgGAgs.mp3
Deleting original file The Cardigans - My Favourite Game “Stone Version”-u9WgtlgGAgs.webm (pass -k to keep)
Working..
Working..
....
Working..
Working..


  



  whereas I would expect the Working.. message to be printed in between youtube-dl's messages as well. Am I missing something here or is this impossible with async/await ? Is ffmpeg blocking ? If so, can I run the download in async without converting to mp3 or is using threads the only way ?