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• Google Colab Runtime Error please install ffmpeg (version 4.2 is currently supported) andbuild torchvision from source

  4 juillet 2021, par Iman

  I'm using Google Colab to write a program using torch vision to extract frames from an mp4 video in my google drive. Thus far, I haven't wrote the full code yet but have been experimenting with torch vision.io library. Upon running the code, I get the following errors.

  


  Mounted at /content/gdrive&#xA;---------------------------------------------------------------------------&#xA;RuntimeError                              Traceback (most recent call last)&#xA; in <module>()&#xA;      6 &#xA;      7 video_path = "/content/drive/MyDrive/Training-Data-Videos/MASKED/00_MASKED_0_0.mp4"&#xA;----> 8 reader = torchvision.io.VideoReader(video_path, "video")&#xA;      9 reader.seek(2.0)&#xA;     10 frame = next(reader)&#xA;&#xA;/usr/local/lib/python3.7/dist-packages/torchvision/io/__init__.py in __init__(self, path, stream)&#xA;    106                 &#x2B; "to enable video_reader support, please install "&#xA;    107                 &#x2B; "ffmpeg (version 4.2 is currently supported) and"&#xA;--> 108                 &#x2B; "build torchvision from source."&#xA;    109             )&#xA;    110         self._c = torch.classes.torchvision.Video(path, stream)&#xA;&#xA;RuntimeError: Not compiled with video_reader support, to enable video_reader support, please install ffmpeg (version 4.2 is currently supported) andbuild torchvision from source.&#xA;&#xA;</module>

  


  The code that I have written in the notebook so far is the following :

  


  import os 
import torchvision 
from google.colab import drive
drive.mount('/content/gdrive', force_remount=True)

video_path = "/content/drive/MyDrive/Training-Data-Videos/MASKED/00_MASKED_0_0.mp4"
reader = torchvision.io.VideoReader(video_path, "video")
reader.seek(2.0)
frame = next(reader)
print (frame)



  


  To solve the problem, I tried to install ffmpeg on colab as this post says but it did not work. Can someone tell me what is the error ?

  


• How to save data of packet.data in ffmpeg using c language ?

  10 juin 2015, par patrick

  I’m try to build an app in c that extract audio from video and save it as audio file. I write the below code. I’m able to extract the audio but now the problem is how to save it. Thanks in advance.

  My code is :

  int main(int argc, char *argv[]) {
  
  AVFormatContext *pFormatCtx = NULL;
  
  int             i;
  
  AVCodecContext  *pCodecCtx = NULL;
  
  AVCodec         *pCodec = NULL;
  
  AVFrame         *pFrame = NULL; 
  
  AVPacket        packet;
  
  
  
  AVDictionary    *optionsDict = NULL;
  
  
  
  if(argc < 2) {
  
  printf("Please provide a movie file\n");
  
  return -1;
  
  }
  
  av_register_all();
  
  if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)
  
  return -1; 
  
  
  
  if(avformat_find_stream_info(pFormatCtx, NULL)<0)
  
  return -1; 
  
  
  
  av_dump_format(pFormatCtx, 0, argv[1], 0);
  
  
  
  int audioStream=-1;
  
  for(i=0; inb_streams; i++)
  
      if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO) {
  
          audioStream=i;
  
          break;
  
      }
  
  if(audioStream==-1)
  
  return -1; 
  
  
  
  pCodecCtx=pFormatCtx->streams[audioStream]->codec;
  
  
  
  pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
  
  if(pCodec==NULL) {
  
      fprintf(stderr, "Unsupported codec!\n");
  
      return -1; // Codec not found
  
  }
  
  
  
  if(avcodec_open2(pCodecCtx, pCodec, &optionsDict)<0)
  
  return -1; 
  
  
  
  pFrame=avcodec_alloc_frame();
  
  packet.data = NULL;
  
  packet.size = 0;
  
  
  
  while(av_read_frame(pFormatCtx, &packet)>=0) {
  
      int got_frame = 0;
  
      int ret = avcodec_decode_audio4(pCodecCtx, pFrame, &got_frame, &packet);
  
      if(got_frame && packet.stream_index==audioStream) {
  
          //save result but how???
  
      }
  
      av_free_packet(&packet);
  
  }
  
  av_free(pFrame);
  
  avcodec_close(pCodecCtx);
  
  avformat_close_input(&pFormatCtx);
  
  return 0;
  
  }

• google function : TypeError : Cannot read property 'name' of undefined

  9 décembre 2019, par Juggernaught

  I’m trying to use Google cloud function to transcode videos from a storage bucket and outputs into another bucket using code posted online but with a few adjustments.

  but I get the following error :

  TypeError : Cannot read property ’name’ of undefined at transcodeVideo
  (/srv/index.js:17:56) at /worker/worker.js:825:24 at at
  process._tickDomainCallback (internal/process/next_tick.js:229:7)

  Index.js

  const {Storage} = require('@google-cloud/storage');
  
  const projectId = 'cc18-223318';
  
  const storage = new Storage({
  
      projectId: projectId,
  
  });
  
  const ffmpegPath = require('@ffmpeg-installer/ffmpeg').path;
  
  const ffmpeg = require('fluent-ffmpeg');
  
  
  
  const transcodedBucket = storage.bucket('2400p');
  
  const uploadBucket = storage.bucket('inpuut');
  
  ffmpeg.setFfmpegPath(ffmpegPath);
  
  
  
  exports.transcodeVideo = function transcodeVideo(event, callback) {
  
    const file = event.data;
  
    // Ensure that you only proceed if the file is newly created, and exists.
  
    if (file.metageneration !== '1' || file.resourceState !== 'exists') {
  
      callback();
  
      return;
  
    }
  
  
  
    // Open write stream to new bucket, modify the filename as needed.
  
    const remoteWriteStream = transcodedBucket.file(file.name.replace('.webm', '.mp4'))
  
      .createWriteStream({
  
        metadata: {
  
          metadata: file.metadata, // You may not need this, my uploads have associated metadata
  
          contentType: 'video/mp4', // This could be whatever else you are transcoding to
  
        },
  
      });
  
  
  
    // Open read stream to our uploaded file
  
    const remoteReadStream = uploadBucket.file(file.name).createReadStream();
  
  
  
    // Transcode
  
    ffmpeg()
  
      .input(remoteReadStream)
  
      .outputOptions('-c:v libx264') // Change these options to whatever suits your needs
  
      .outputOptions('-c:a copy')
  
      .outputOptions('-vf "scale=4800:2400"')
  
      .outputOptions('-b:a 160k')
  
      .outputOptions('-b:a 160k')
  
      .outputOptions('-x264-params mvrange=511')
  
      .outputOptions('-f mp4')
  
      .outputOptions('-preset slow')
  
      .outputOptions('-movflags frag_keyframe+empty_moov')
  
      .outputOptions('-crf 18')
  
      // https://github.com/fluent-ffmpeg/node-fluent-ffmpeg/issues/346#issuecomment-67299526 
  
      .on('start', (cmdLine) => {
  
        console.log('Started ffmpeg with command:', cmdLine);
  
      })
  
      .on('end', () => {
  
        console.log('Successfully re-encoded video.');
  
        callback();
  
      })
  
      .on('error', (err, stdout, stderr) => {
  
        console.error('An error occured during encoding', err.message);
  
        console.error('stdout:', stdout);
  
        console.error('stderr:', stderr);
  
        callback(err);
  
      })
  
      .pipe(remoteWriteStream, { end: true }); // end: true, emit end event when readable stream ends
  
  };