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• Saving frames from a network camera (RTSP) to a mp4 file

  24 novembre 2015, par Dídac Pérez

  I am quite confused about how to save a video stream into a mp4 file. I am using ffmpeg. Let me explain the problem :

  1. I connect to a network camera via RTSP (H.264 stream) with avformat_open_input(), avformat_find_stream_info(), av_read_play(), and I get frames with av_read_frame().
  2. Each time I get a frame with av_read_frame(), I store the corresponding AVPacket in a circular buffer.
  3. In some points in my application, a range of this circular buffer is selected. I find a key frame used to start from.
  4. Once I have a list of AVPacket’s starting from a key frame, I write header, frames, and tail, as I described below in the code.

  The problem is that the resulting mp4 video has artifacts if I try to watch it using VLC, Windows Media Player, or another one.

  I have also realized that the pts of that packets are not continuous, while dts are continuous. I know about B frames, but is this a problem in my case ?

  // Prepare the output
  
  AVFormatContext* oc = avformat_alloc_context();
  
  oc->oformat = av_guess_format(NULL, "video.mp4", NULL);
  
  
  
  // Must write header, packets, and trailing
  
  avio_open2(&oc->pb, "video.mp4", AVIO_FLAG_WRITE, NULL, NULL);
  
  
  
  // Write header
  
  AVStream* stream = avformat_new_stream(oc, (AVCodec*) context->streams[video_stream_index]->codec->codec);
  
  avcodec_copy_context(stream->codec, context->streams[video_stream_index]->codec);
  
  stream->sample_aspect_ratio = context->streams[video_stream_index]->codec->sample_aspect_ratio;
  
  avformat_write_header(oc, NULL);
  
  
  
  // FOR EACH FRAME...
  
  ... av_write_frame(oc, circular[k]); ...
  
  
  
  // Write trailer and close the file
  
  av_write_trailer(oc);
  
  avcodec_close(stream->codec);
  
  avio_close(oc->pb);
  
  avformat_free_context(oc);

  Thank you so much,

• Fastest way to convert video to frames wihout saving the frames locally

  24 février 2020, par Abhik Sarkar

  I want to apply batch prediction on Videos using Pytorch.

  The Problem is I am having many videos to process and don’t want to save additional frames.
  Is there a way I can save ’n frames’ in 1FPS and apply deep learning at the same time ?

  In other words, I am having VIDEODATASET is there any VIDEODATALOADER ?

• Convert file without saving it using fluent-ffmpeg in nodejs

  17 avril 2020, par Scherer

  What I am trying to do is create a node application that receives a mkv file, converts it to mp4, hardburning the subtitles, and sends it back so the user can download it. In the command line this works perfectly

  



  ffmpeg -i input.mkv -threads 1 -vf subtitles=input.mkv -acodec copy output.mp4

  



  Then, I tried to translate this into a node route using fluent-ffmpeg

  



  var ffmpeg = require('fluent-ffmpeg');

routes.post('/process', (req, res) => {
    //file sent
    const file = req.files.file
    const path = __dirname + '/public/data/'

    //saves file in server
    file.mv(path + file.name, err => {
        if (err) return res.sendStatus(500).send(err)
        console.log('upload successful')
    })

    //convert the file to mp4 with the hardburned subtitle
    ffmpeg(path + file.name).toFormat('mp4')
    .addOutputOption(["-threads 1"])
    .addOutputOption(["-acodec copy"])
    .addOutputOption(['-vf subtitles=' + path + file.name])
    .on('end', () => {
        console.log('done')
        res.sendStatus(200)
    })
    .on('error', console.log)
    .saveToFile(path + 'output.mp4') //saves file in server
})


  



  Unfortunately, this didn't work and the code returned the following error message

  



  Error: ffmpeg exited with code 1: Error reinitializing filters!&#xA;Failed to inject frame into filter network: Invalid argument&#xA;Error while processing the decoded data for stream #0:0&#xA;Conversion failed!&#xA;&#xA;    at ChildProcess.<anonymous> (C:\Users\fsvic\Desktop\ffmpeg_teste_node\node_modules\fluent-ffmpeg\lib\processor.js:182:22)&#xA;    at ChildProcess.emit (events.js:182:13)&#xA;    at Process.ChildProcess._handle.onexit (internal/child_process.js:240:12) &#x27;&#x27; &#x27;ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers\n  built with gcc 9.1.1 (GCC) 20190807\n  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt\n  libavutil      56. 31.100 / 56. 31.100\n  libavcodec     58. 54.100 / 58. 54.100\n  libavformat    58. 29.100 / 58. 29.100\n  libavdevice    58.  8.100 / 58.  8.100\n  libavfilter     7. 57.100 /  7. 57.100\n  libswscale      5.  5.100 /  5.  5.100\n  libswresample   3.  5.100 /  3.  5.100\n  libpostproc    55.  5.100 / 55.  5.100\nInput #0, matroska,webm, from \&#x27;C:\\Users\\fsvic\\Desktop\\ffmpeg_teste_node/public/data/star_trails.mkv\&#x27;:\n  Metadata:\n    COMPATIBLE_BRANDS: mp42mp41\n    MAJOR_BRAND     : mp42\n    MINOR_VERSION   : 0\n    ENCODER         : Lavf57.66.105\n  Duration: 00:00:21.25, start: 0.000000, bitrate: 1893 kb/s\n    Stream #0:0(eng): Video: h264 (High), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 1k tbn, 50 tbc (default)\n    Metadata:\n      HANDLER_NAME    : ?Mainconcept Video Media Handler\n      ENCODER         : Lavc57.83.101 libx264\n      DURATION        : 00:00:21.163000000\n    Stream #0:1(eng): Audio: vorbis, 48000 Hz, stereo, fltp (default)\n    Metadata:\n      HANDLER_NAME    : #Mainconcept MP4 Sound Media Handler\n      ENCODER         : Lavc57.83.101 libvorbis\n      DURATION        : 00:00:21.251000000\nStream mapping:\n  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))\n  Stream #0:1 -> #0:1 (copy)\nPress [q] to stop, [?] for help\n[subtitles @ 000001cc091dbb80] Unable to parse option value "UsersfsvicDesktopffmpeg_teste_node/public/data/star_trails.mkv" as image size\n    Last message repeated 1 times\n[subtitles @ 000001cc091dbb80] Error setting option original_size to value UsersfsvicDesktopffmpeg_teste_node/public/data/star_trails.mkv.\n[Parsed_subtitles_0 @ 000001cc0910a8c0] Error applying options to the filter.\n[AVFilterGraph @ 000001cc0912ba80] Error initializing filter \&#x27;subtitles\&#x27; with args \&#x27;C:UsersfsvicDesktopffmpeg_teste_node/public/data/star_trails.mkv\&#x27;\nError reinitializing filters!\nFailed to inject frame into filter network: Invalid argument\nError while processing the decoded data for stream #0:0\nConversion failed!\n&#x27;&#xA;</anonymous>

  



  Besides that, I cannot save anything in the server side due to memory limitations, so I need a way to use the FFmpeg commands without an actual file in the folder. I discovered that the pipe feature might do the job, but I have no idea on how I could implement it in the current code.