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• ffmpeg wasm - how to take client-side created mp4 and upload it to the same server hosting the index/js files being used

  29 juillet 2022, par John Farrell

  Ok, so Im an IT guy and kind of a noob on the dev side of the fence. But I've been able to create this ffmpeg wasm page that takes a canvas and converts it to webm / and .mp4 — what i WANT to do is take the resulting .mp4 file and upload it to the server where the page/js are being served from. is this possible ? I will include my source code which is fairly simple and straight forward, I just don't know how to manipulate the resulting mp4 file that ffmpeg spits out (i realize it is happening client side) to be able to push it up to the server (maybe with aupload.php type situation ?) the solution can be html/java/php whatever, so long as it takes the mp4 output and gets it onto the server. I'd VERY MUCH appreciate a hand here.

  


  Going to try my best to properly insert the html and js. please bear with me if i've done something wrong, i've never had to -ask- a question on here, usually just look up existing answers.

  


  


  


  const { createFFmpeg } = FFmpeg;
const ffmpeg = createFFmpeg({
  log: true
});

const transcode = async (webcamData) => {
  const message = document.getElementById('message');
  const name = 'record.webm';
  await ffmpeg.load();
  message.innerHTML = 'Start transcoding';
  await ffmpeg.write(name, webcamData);
  await ffmpeg.transcode(name,  'output.mp4');
  message.innerHTML = 'Complete transcoding';
  const data = ffmpeg.read('output.mp4');

  const video = document.getElementById('output-video');
  video.src = URL.createObjectURL(new Blob([data.buffer], { type: 'video/mp4' }));
  dl.href = video.src;
  dl.innerHTML = "download mp4"
}

fn().then(async ({url, blob})=>{
    transcode(new Uint8Array(await (blob).arrayBuffer()));
})

function fn() {
var recordedChunks = [];

var time = 0;
var canvas = document.getElementById("canvas");

return new Promise(function (res, rej) {
    var stream = canvas.captureStream(60);

    mediaRecorder = new MediaRecorder(stream, {
        mimeType: "video/webm; codecs=vp9"
    });

    mediaRecorder.start(time);

    mediaRecorder.ondataavailable = function (e) {
        recordedChunks.push(event.data);
        // for demo, removed stop() call to capture more than one frame
    }

    mediaRecorder.onstop = function (event) {
        var blob = new Blob(recordedChunks, {
            "type": "video/webm"
        });
        var url = URL.createObjectURL(blob);
        res({url, blob}); // resolve both blob and url in an object

        myVideo.src = url;
        // removed data url conversion for brevity
    }

// for demo, draw random lines and then stop recording
var i = 0,
tid = setInterval(()=>{
  if(i++ > 20) { // draw 20 lines
    clearInterval(tid);
    mediaRecorder.stop();
  }
  let canvas = document.querySelector("canvas");
  let cx = canvas.getContext("2d");
  cx.beginPath();
  cx.strokeStyle = 'green';
  cx.moveTo(Math.random()*100, Math.random()*100);
  cx.lineTo(Math.random()*100, Math.random()*100);
  cx.stroke();
},200)

});
}

  


  &#xA;&#xA;&#xA;<code class="echappe-js">&lt;script src=&quot;https://unpkg.com/@ffmpeg/ffmpeg@0.8.1/dist/ffmpeg.min.js&quot; defer&gt;&lt;/script&gt;&#xA;&lt;script src='http://stackoverflow.com/feeds/tag/canvas2mp4.js' defer&gt;&lt;/script&gt;&#xA;&#xA;&#xA;&#xA;here is a canvas
  &#xA;
  &#xA;&#xA;here is a recorded video of the canvas in webM format
  &#xA;
  &#xA;&#xA;&#xA;here is a transcoded mp4 from the webm above CLIENT SIDE using ffmpeg
  &#xA;
  &#xA;&#xA;
  
  &#xA;&#xA;
  

  


  


  



• FFMPEG decoding artifacts between keyframes

  13 avril 2015, par OddlyOrdinary

  I’m currently experiencing artifacts when decoding video using ffmpegs api. On what I would assume to be intermediate frames, artifacts build slowly only from active movement in the frame. These artifacts build for 50-100 frames until I assume a keyframe resets them. Frames are then decoded correctly and the artifacts proceed to build again.

  One thing that is bothering me is I have a few video samples that are 30fps(h264) that work correctly, but all of my 60fps videos(h264) experience the problem.

  I don’t currently have enough reputation to post an image, so hopefully this link will work.
  http://i.imgur.com/PPXXkJc.jpg

  int numBytes;
  
  int frameFinished;
  
  AVFrame* decodedRawFrame;
  
  AVFrame* rgbFrame;
  
  
  
      //Enum class for decoding results, used to break decode loop when a frame is gathered
  
  DecodeResult retResult = DecodeResult::Fail;
  
  
  
  decodedRawFrame = av_frame_alloc();
  
  rgbFrame = av_frame_alloc();
  
  if (!decodedRawFrame) {
  
      fprintf(stderr, "Could not allocate video frame\n");
  
      return DecodeResult::Fail;
  
  }
  
  
  
  numBytes = avpicture_get_size(PIX_FMT_RGBA, mCodecCtx->width,mCodecCtx->height);
  
  uint8_t* buffer = (uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  
  
  avpicture_fill((AVPicture *) rgbFrame, buffer, PIX_FMT_RGBA, mCodecCtx->width, mCodecCtx->height);
  
  
  
  AVPacket packet;
  
  
  
  while(av_read_frame(mFormatCtx, &packet) >= 0 && retResult != DecodeResult::Success)
  
  {
  
      // Is this a packet from the video stream?
  
      if (packet.stream_index == mVideoStreamIndex)
  
      {
  
          // Decode video frame
  
          int decodeValue = avcodec_decode_video2(mCodecCtx, decodedRawFrame, &frameFinished, &packet);
  
  
  
          // Did we get a video frame?
  
          if (frameFinished)// && rgbFrame->pict_type != AV_PICTURE_TYPE_NONE )
  
          {
  
              // Convert the image from its native format to RGB
  
              int SwsFlags = SWS_BILINEAR;
  
              // Accurate round clears up a problem where the start
  
                              // of videos have green bars on them
  
              SwsFlags |= SWS_ACCURATE_RND;
  
              struct SwsContext *ctx = sws_getCachedContext(NULL, mCodecCtx->width, mCodecCtx->height, mCodecCtx->pix_fmt, mCodecCtx->width, mCodecCtx->height, 
  
                  PIX_FMT_RGBA, SwsFlags, NULL, NULL, NULL);
  
              sws_scale(ctx, decodedRawFrame->data, decodedRawFrame->linesize, 0, mCodecCtx->height, rgbFrame->data, rgbFrame->linesize);
  
  
  
              //if(count%5 == 0 && count < 105)
  
              //  DebugSavePPMImage(rgbFrame, mCodecCtx->width, mCodecCtx->height, count);
  
  
  
              ++count;
  
              // Viewable frame is a struct to hold buffer and frame together in a queue
  
              ViewableFrame frame;
  
              frame.buffer = buffer;
  
              frame.frame = rgbFrame;
  
              mFrameQueue.push(frame);
  
  
  
  
  
              retResult = DecodeResult::Success;
  
  
  
              sws_freeContext(ctx);
  
          }
  
      }
  
  
  
      // Free the packet that was allocated by av_read_frame
  
      av_free_packet(&packet);
  
  }
  
  
  
  // Check for end of file leftover frames
  
  if(retResult != DecodeResult::Success)
  
  {
  
      int result = av_read_frame(mFormatCtx, &packet);
  
      if(result < 0)
  
          isEoF = true;
  
      av_free_packet(&packet); 
  
  }   
  
  
  
  // Free the YUV frame
  
  av_frame_free(&decodedRawFrame);

  I’m attempting to build a queue of the decoded frames that I then use and free as needed. Is my seperation of the frames causing the intermediate frames to be decoded incorrectly ? I also break the decoding loop once I’ve successfully gathered a frame(Decode::Success, most examples I’ve seen tend to loop through the whole video.

  All codec contect, video stream information, and format contexts are setup up exactly as shown in the main function of https://github.com/chelyaev/ffmpeg-tutorial/blob/master/tutorial01.c

  Any suggestions would be greatly appreciated.

• Attempting to concat with FFMpeg but failing

  11 mars 2020, par GloriousRez

  I’ve been trying to create a php app that more or less acts as a video editor. I’d like my users to insert both images and videos and then concat these in a certain order and add music. I’ve decided to utilize ffmpeg for this purpose.

  I’ve succeeded in making mp4s of these images and add music to the mp4s with the following commands

  $ ffmpeg -r 0.1 -i %05d.morph.jpg output.mp4
  
  
  
  $ ffmpeg -i output.mp4 -i audio.mp3 -c:v copy -c:a aac -b:a 128k final.mp4

  This produces decent results. But this is where the issues start.

  I’ve been attempting to concat these created mp4s (WITHOUT music) but cannot seem to do so. Nor can I even concat them with a duplicate of themselves.
  (I’ve been using the concat demuxer as indicated in this link : How to concatenate two MP4 files using FFmpeg ?)

  $ cat mylist.txt
  
  file 'output.mp4'
  
  file 'vid1.mp4'
  
  file 'output2.mp4'
  
  
  
  $ ffmpeg -f concat -safe 0 -i mylist.txt -c copy outputSemi.mp4

  The result is a video (of the appropriate length), however only the first video is played, and repeated over and over, often with green screens mixing between the frames.

  Any help would be helpful.

  ---

  Figure I should include the result of the concat command

  ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with Apple clang version 11.0.0 (clang-1100.0.33.8)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.1_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags='-I/Library/Java/JavaVirtualMachines/adoptopenjdk-13.jdk/Contents/Home/include -I/Library/Java/JavaVirtualMachines/adoptopenjdk-13.jdk/Contents/Home/include/darwin -fno-stack-check' --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  
    libavutil      56. 31.100 / 56. 31.100
  
    libavcodec     58. 54.100 / 58. 54.100
  
    libavformat    58. 29.100 / 58. 29.100
  
    libavdevice    58.  8.100 / 58.  8.100
  
    libavfilter     7. 57.100 /  7. 57.100
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  5.100 /  5.  5.100
  
    libswresample   3.  5.100 /  3.  5.100
  
    libpostproc    55.  5.100 / 55.  5.100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc70f00bc00] Auto-inserting h264_mp4toannexb bitstream filter
  
  Input #0, concat, from 'mylist.txt':
  
    Duration: N/A, start: 0.000000, bitrate: 1507 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc), 4864x3648 [SAR 1:1 DAR 4:3], 1507 kb/s, 0.10 fps, 0.10 tbr, 16384 tbn, 0.20 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
  File 'outputFFMPEG.mp4' already exists. Overwrite ? [y/N] y
  
  Output #0, mp4, to 'outputFFMPEG.mp4':
  
    Metadata:
  
      encoder         : Lavf58.29.100
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc), 4864x3648 [SAR 1:1 DAR 4:3], q=2-31, 1507 kb/s, 0.10 fps, 0.10 tbr, 16384 tbn, 16384 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc70e80b600] Auto-inserting h264_mp4toannexb bitstream filter
  
  frame=    5 fps=0.0 q=-1.0 Lsize=    9543kB time=00:00:40.00 bitrate=1954.4kbits/s speed= 169x    
  
  video:9542kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.009467%