Recherche avancée

Sur d’autres sites (6926)

• How to reproject and join these two clips with ffmpeg ?

  20 janvier 2023, par jumpjack

  I have two videoclips embedded in this single video :

  


  https://sci.esa.int/web/cassini-huygens/-/39218-huygens-descent-to-titan-surface

  


  Download lo-res : link

  


  The timings which I calculated to sync the two clips are :

  


  

  • 01:33.233 - 02:24.133

  


  • 02:33.700 - 03:24.600

  


  


  I want to join them into a single view ; I thought that cropping the video between the dots which mark east and west was enough, but it is not : I tried this, but with terrible results :

  


  #echo off
# Cut east and west clips:
@echo cut east...
ffmpeg -ss 01:33.233 -to 02:24.133 -i %1 -vf "crop=900:450:73:0, pad=w=iw:h=2*ih:x=0:y=ih:color=black" -y east-crop.mp4
@echo cut west...
ffmpeg -ss 02:33.700 -to 03:24.600 -i %1 -vf "crop=900:450:73:0, pad=w=iw:h=2*ih:x=0:y=ih:color=black" -y west-crop.mp4

@echo merge...
ffmpeg -i west-crop.mp4 -i east-crop.mp4 -filter_complex hstack=inputs=2 -y combined.mp4


  


  I think I have also to reproject... but I have no idea of which is the projection used.

  


  Any suggestion ?

  


  Example east/west frames :

  


  

  


  

  


  I would like to obtain a single equirectangular image which reprojects into a full sphere when seen into a VR viewer.

  


  Instead, I am getting this :

  


  

  


• Slightly wrong color in MP4 videos written by PyAV

  26 septembre 2024, par Yossi Kreinin

  I am writing MP4 video files with the following PyAV-based code (getting input frames represented as numpy arrays - the sort produced by imageio.imread - as input) :

  


  class MP4:
    def __init__(self, fname, width, height, fps):
        self.output = av.open(fname, 'w', format='mp4')
        self.stream = self.output.add_stream('h264', str(fps))
        self.stream.width = width
        self.stream.height = height
        # these 2 lines can be removed and the problem still reproduces:
        self.stream.pix_fmt = 'yuv420p'
        self.stream.options = {'crf': '17'}
    def write_frame(self, pixels):
        frame = av.VideoFrame.from_ndarray(pixels, format='rgb24')
        packet = self.stream.encode(frame)
        self.output.mux(packet)
    def close(self):
        packet = self.stream.encode(None)
        self.output.mux(packet)
        self.output.close()


  


  The colors in the output MP4 video are slightly different (apparently darker) than the colors in the input images :

  


  Screen grab of an image viewer showing an input frame :

  


  

  


  Screen grab of VLC playing the output MP4 video :

  


  

  


  How can this problem be fixed ? I variously fiddled with the frame.colorspace attribute, stream options and VideoFrame.reformat but it changed nothing ; of course I could have been fiddling incorrectly.

  


  As you can see, the input has simple flat color regions, so I doubt it's any sort of compression artifact, eg YUV420 dropping some of the chroma info or other such.

  


• FFMPEG in Node.js : Conversion Failed

  11 juillet 2024, par cuneyttyler

  I have a small node.js web app. I use like this in a get request :

  


  app.get('/api/voice/:gender/:voice/:pitch', function(req, res){
        if(req.params.pitch == "1" || req.params.pitch == "1.0") {
            const file = "./voices/" + req.params.gender.toLowerCase() + "/" + req.params.voice + ".mp3"
            res.download(file);
            return
        }

        const inputFile = "./voices/" + req.params.gender.toLowerCase() + "/" + req.params.voice + ".mp3"
        const output_file = "./Audio/Temp/" + req.params.voice + ".mp3"
        ffmpeg()
                .input(inputFile)
                .audioCodec('pcm_s16le') // Set the audio codec to PCM with 16-bit depth
                .audioFrequency(44100) // Set the sample rate
                .on('error', function(err) {
                    console.error('Error while converting:', err);
                })
                .on('end', function() {
                    // res.download(output_file)
                })
                .save(output_file);

    });


  


  It gives Conversion Failed error :

  


  [2024-07-11T18:11:22.880Z] Error while converting: Error: ffmpeg exited with code 1: Conversion failed!&#xA;&#xA;    at ChildProcess.<anonymous> (d:\Dev\Anima\Client\node_modules\fluent-ffmpeg\lib\processor.js:180:22)&#xA;    at ChildProcess.emit (d:\Dev\Anima\Client\lib\events.js:519:28)&#xA;    at ChildProcess._handle.onexit (d:\Dev\Anima\Client\lib\internal\child_process.js:294:12)&#xA;    at Process.callbackTrampoline (node:internal/async_hooks:130:17) {stack: &#x27;Error: ffmpeg exited with code 1: Conversion …Trampoline (node:internal/async_hooks:130:17)&#x27;, message: &#x27;ffmpeg exited with code 1: Conversion failed!&#xA;&#x27;}&#xA;</anonymous>

  


  When I use same code in a node.js desktop(.exe) app, it successfully runs. When I use it in an express.js app, it fails. Error message is not clear. What is the issue ?