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  • Video encoding in real time through node js ?

    15 mai 2018, par user717166

    Do Anyone know realtime encode video in node with ffmpeg ? I know transloadit was done well on this. Any idea ?

    https://transloadit.com/blog/2010/12/realtime-encoding-over-150x-faster

  • use ffmpeg to overlay a video on top of another using an alpha channel

    15 mai 2018, par cloudraven

    Similar to what alphamerge / alphaextract do, but instead of having two sources I want to use three

    InputVideo1, AlphaofInputVideo1, BackgroundVideo

    The idea would be to overlay inputvideo1 on top of backgroundvideo using AlphaofInputVideo1 to do a more accuracte blending. Is this possible? Using intermediate steps (e.g. using alphamerge and generate intermediate rgba bitmaps) is acceptable.

  • Node.js child_process TypeError : Cannot read property '_writableState' of undefined

    15 mai 2018, par functorial

    I am trying to wrap a piece of ffmpeg's functionality in a Node.js API, using the child_process library, but when I attempt to send any data to ffmpeg's stdin pipe, I get an error TypeError: Cannot read property '_writableState' of undefined.

    import {spawn} from "child_process"

export default frames => {
    // Spawn ffmpeg process
    const ffmpeg = spawn("ffmpeg", ["-f", "image2pipe", "-i", "-", "output.mkv"])
    // Send frames to ffmpeg as stdin
    frames.forEach(ffmpeg.stdin.write)

    // Listen for output and errors
    return new Promise((resolve, reject) => {
        const chunks = []

        ffmpeg.stdout.on("data", chunks.push)
        ffmpeg.stderr.on("data", reject(data))
        ffmpeg.on("close", code =>
            resolve(Buffer.concat(chunks))
        )
    })
}

    Error:

    TypeError: Cannot read property '_writableState' of undefined
    at Writable.write (_stream_writable.js:270:20)
    at Array.forEach ()
    at exports.default (/home/fiendfan1/workspace/nodejs/declare/dist/app/common/encodeVideo.js:21:12)
    at _callee$ (/home/fiendfan1/workspace/nodejs/declare/dist/app/tests/video.js:34:84)
    at tryCatch (/home/fiendfan1/workspace/nodejs/declare/node_modules/regenerator-runtime/runtime.js:65:40)
    at Generator.invoke [as _invoke] (/home/fiendfan1/workspace/nodejs/declare/node_modules/regenerator-runtime/runtime.js:303:22)
    at Generator.prototype.(anonymous function) [as next] (/home/fiendfan1/workspace/nodejs/declare/node_modules/regenerator-runtime/runtime.js:117:21)
    at Generator.tryCatcher (/home/fiendfan1/workspace/nodejs/declare/node_modules/bluebird/js/release/util.js:16:23)
    at PromiseSpawn._promiseFulfilled (/home/fiendfan1/workspace/nodejs/declare/node_modules/bluebird/js/release/generators.js:97:49)
    at Promise._settlePromise (/home/fiendfan1/workspace/nodejs/declare/node_modules/bluebird/js/release/promise.js:574:26)
    at Promise._settlePromise0 (/home/fiendfan1/workspace/nodejs/declare/node_modules/bluebird/js/release/promise.js:614:10)
    at Promise._settlePromises (/home/fiendfan1/workspace/nodejs/declare/node_modules/bluebird/js/release/promise.js:693:18)
    at Async._drainQueue (/home/fiendfan1/workspace/nodejs/declare/node_modules/bluebird/js/release/async.js:133:16)
    at Async._drainQueues (/home/fiendfan1/workspace/nodejs/declare/node_modules/bluebird/js/release/async.js:143:10)
    at Immediate.Async.drainQueues [as _onImmediate] (/home/fiendfan1/workspace/nodejs/declare/node_modules/bluebird/js/release/async.js:17:14)
    at runCallback (timers.js:696:18)

  • ffmpeg : given a video of any length, create timelapse video of 6-8 seconds long

    14 mai 2018, par CDub

    I have an application which consumes video of any length (could be a few seconds, could be several minutes) and I want to use ffmpeg to return a "timelapse" version of the input video which will always be between 6 and 8 seconds long.

    I've been fiddling with the following:

    ffmpeg -y -i in.mp4 -r 10 -vf setpts='0.01*PTS' -an out.mp4

    Which seems to be a good start, but still generates very dynamic results given what in.mp4 is.

    I also don't fully understand the verbiage in the ffmpeg documentation, so I'm not even sure what arguments to use for setpts, or if setpts is the correct filter I want to use.

  • Set input frame rate in pygame.Camera

    14 mai 2018, par Thomas Hubregtsen

    I am trying to get an input stream from a webcam on OS X

    self.capture = pygame.camera('/dev/video{}'.format(camera),
                                 (640, 480), 'RGB')

    I get an error (see below), but there are 2 pieces of information that I can not really stitch together. On first sight, it looks like I do not have the correct camera (not video4linux). However, when running

    ffmpeg -f avfoundation -list_devices true -i ""

    I get it listed

    [AVFoundation input device @ 0x7fbb45700340] [1] FULL HD 1080P Webcam

    The next part of the error talks about frame rate. It appears that the frame-rate is slightly off, and that I just next to select a different frame rate. Would this be possible with pygcam? Would this solve my problem?

    Error:

    Traceback (most recent call last):
  File "webcam2.py", line 129, in 
    VideoStreaming("52.191.118.156", 5558, 1)()
  File "webcam2.py", line 22, in __call__
    with self.get_camera_context(self.camera_id) as frames:
  File "webcam2.py", line 89, in __enter__
size=(640, 480))
  File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/core/functions.py", line 129, in get_reader
return format.get_reader(request)
  File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/core/format.py", line 169, in get_reader
    return self.Reader(self, request)
  File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/core/format.py", line 218, in __init__
    self._open(**self.request.kwargs.copy())
  File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 327, in _open
    self._load_infos()
  File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 476, in _load_infos
    (self.request._video, ffmpeg_err))
IndexError: No video4linux camera at .

FFMPEG STDERR OUTPUT:

ffmpeg version 3.4.1 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
  configuration: --prefix=/Users/q433100/temp/brew-master/Cellar/ffmpeg/3.4.1 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
[avfoundation @ 0x7fbb9e000a00] Selected framerate (29.970030) is not supported by the device
[avfoundation @ 0x7fbb9e000a00] Supported modes:
[avfoundation @ 0x7fbb9e000a00]   160x120@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   176x144@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   320x240@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   352x288@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   640x360@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   640x480@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   800x600@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   1024x576@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   960x720@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   1280x720@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   1392x768@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   1280x960@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   1600x896@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   1920x1080@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   160x120@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   176x144@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   320x240@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   352x288@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   640x360@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   640x480@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00]   800x600@[20.000000 20.000000]fps
[avfoundation @ 0x7fbb9e000a00]   1024x576@[8.000000 8.000000]fps
[avfoundation @ 0x7fbb9e000a00]   960x720@[15.000015 15.000015]fps
1: Input/output error

    Update: If I try to force one of the mentioned supported frame rates with ffmped, I get a new error

    $ffmpeg -f avfoundation -r 30.000030 -i "1" out.mpg
ffmpeg version 3.4.1 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
  configuration: --prefix=/Users/q433100/temp/brew-master/Cellar/ffmpeg/3.4.1 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
[avfoundation @ 0x7fb3c8802600] An error occurred: The activeVideoMinFrameDuration passed is not supported by the device.  Use -activeFormat.videoSupportedFrameRateRanges to discover valid ranges.1: Input/output error

    Update 2: Setting the input frame rate to 15 directly in ffmpeg works. Now I just need to figure out how to do this in python with pygame.camera

    $ ffmpeg -f avfoundation -r 15.000015 -i "1" out.avi

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