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• PHP - Read and write the same file hangs

  2 février 2016, par Adracat

  I’m trying to use FFMPEG to make some works with video on the server, and something I need to do is to get the progress of the process.

  I searched a little and I found this solution which tells to write the log into a file and then reading and parsing it.

  The problem

  What is driving me crazy is that I tell FFMPEG - with exec - (process A) to write the log into a file, but when I try to read it - with file_get_contents() - (process B) it does not show the contents until process A is finished (or interrupted the PHP script).

  So, when process A finishes or it says "PHP script timeout", then I can read the file as times as I want, refreshing the page (process B) and showing the contents at the time.

  What I’ve tried

  I’ve tried to use fopen() to create the file with w, w+ and a parameters, using - and without using - fclose(). I’ve tried to use also flock() just in case it gets faster to read to process B if it knows it’s already locked and does not have to wait, but then FFMPEG is not able to write into the file.

  I’ve searched for multithreading too, but I think there must be an easier and simpler way.

  I’ve used also CURL and HTTP context, as this link suggests, but no luck.

  I’ve tried, too, to use PHP-FFMPEG but it’s not supporting the last FFMPEG version, so I cannot use it.

  When I said before "(or interrupted the PHP script)" is because I tried to wait and, when PHP got a timeout, process B worked alright and the file was still updating.

  The code

  Process A (fileA.php)

  exec('ffmpeg -y -i input_file.mp4 output_file.avi 2> C:\Full\Path\To\File\log.txt 1>&2');

  Process B (fileB.php)

  $content = file_get_contents($file);
  
  
  
  if($content){
  
      //get duration of source
  
      preg_match("/Duration: (.*?), start:/", $content, $matches);
  
  
  
      $rawDuration = $matches[1];
  
  
  
      //rawDuration is in 00:00:00.00 format. This converts it to seconds.
  
      $ar = array_reverse(explode(":", $rawDuration));
  
      $duration = floatval($ar[0]);
  
      if (!empty($ar[1])) $duration += intval($ar[1]) * 60;
  
      if (!empty($ar[2])) $duration += intval($ar[2]) * 60 * 60;
  
  
  
      //get the time in the file that is already encoded
  
      preg_match_all("/time=(.*?) bitrate/", $content, $matches);
  
  
  
      $rawTime = array_pop($matches);
  
  
  
      //this is needed if there is more than one match
  
      if (is_array($rawTime)){$rawTime = array_pop($rawTime);}
  
  
  
      //rawTime is in 00:00:00.00 format. This converts it to seconds.
  
      $ar = array_reverse(explode(":", $rawTime));
  
      $time = floatval($ar[0]);
  
      if (!empty($ar[1])) $time += intval($ar[1]) * 60;
  
      if (!empty($ar[2])) $time += intval($ar[2]) * 60 * 60;
  
  
  
      //calculate the progress
  
      $progress = round(($time/$duration) * 100);
  
  
  
      echo "Duration: " . $duration . "<br />";
  
      echo "Current Time: " . $time . "<br />";
  
      echo "Progress: " . $progress . "%";
  
  
  
  }

  The process

  I just open fileA.php on a Chrome tab and, after a few seconds, I open fileB.php on another Chrome tab (and it stays as loading).

  What I need

  I need to be able to load the file and show the information I want to show while the file is being written (by exec and FFMPEG or other PHP scripts), so I can update the progress percentage with some AJAX calls.

  Extra information

  At this point, I’m using PHP 5.4 on a IIS 7.5 with Windows 7 Professional.

  Thank you everyone for your time, help and patience !

  Best regards.

• Why my ffmpeg video encode codes does not work on other computer ?

  10 avril 2022, par Object Unknown

  I'm writing code to encode some cv::Mat images to a MP4 video. The program can run successfully in my computer which I developed it, but when I copied it (and all dlls it needs) to an other computer, it stopped work.

  


  The function which reporting error : (I got it from StackOverflow, and added some changes)

  


  int uns::VideoWriter::Remux()
{
    AVFormatContext* ifmt_ctx = NULL, * ofmt_ctx = NULL;
    int err = 0, ret = 0;
    int64_t ts = 0;
    AVStream* inVideoStream = NULL;
    AVStream* outVideoStream = NULL;
    if ((err = avformat_open_input(&ifmt_ctx, VIDEO_TMP_FILE.c_str(), 0, 0)) < 0)
    {
        if(callback != nullptr) 
            callback("[uns::VideoWriter/Remux] Failed to open input file for remuxing", err);
        ret = -1;
        goto end;
    }
    if ((err = avformat_find_stream_info(ifmt_ctx, 0)) < 0) 
    {
        if(callback != nullptr) 
            callback("[uns::VideoWriter/Remux] Failed to retrieve input stream information", err);
        ret = -2;
        goto end;
    }
    if ((err = avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, FINAL_FILE_NAME.c_str())))
    {
        if(callback != nullptr) 
            callback("[uns::VideoWriter/Remux] Failed to allocate output context", err);
        ret = -3;
        goto end;
    }
    inVideoStream = ifmt_ctx->streams[0];
    outVideoStream = avformat_new_stream(ofmt_ctx, NULL);
    if (!outVideoStream) 
    {
        if(callback != nullptr) 
            callback("[uns::VideoWriter/Remux] Failed to allocate output video stream", 0);
        ret = -4;
        goto end;
    }
    outVideoStream->time_base = { 1, fps };
    if ((err = avcodec_parameters_copy(outVideoStream->codecpar, inVideoStream->codecpar)) < 0)
    {
        if (callback != nullptr)
            callback("[uns::VideoWriter/Remux] Failed to copy stream information", err);
        return -4;
        goto end;
    }
    outVideoStream->codecpar->codec_tag = 0;
    if (!(ofmt_ctx->oformat->flags & AVFMT_NOFILE)) 
    {
        if ((err = avio_open(&ofmt_ctx->pb, FINAL_FILE_NAME.c_str(), AVIO_FLAG_WRITE)) < 0)
        {
            if(callback != nullptr) 
                callback("[uns::VideoWriter/Remux] Failed to open output file", err);
            ret = -5;
            goto end;
        }
    }
    ofmt_ctx->streams[0]->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
    ofmt_ctx->streams[0]->time_base.num = 1;
    ofmt_ctx->streams[0]->time_base.den = fps;
    if ((err = avformat_write_header(ofmt_ctx, 0)) < 0) 
    {
        if(callback != nullptr) 
            callback("[uns::VideoWriter/Remux] Failed to write header to output file", err);
        ret = -6;
        goto end;
    }
    AVPacket videoPkt;
    while (true) 
    {
        if ((err = av_read_frame(ifmt_ctx, &videoPkt)) < 0) 
        {
            break;
        }
        videoPkt.stream_index = outVideoStream->index;
        videoPkt.pts = ts;
        videoPkt.dts = ts;
        videoPkt.duration = av_rescale_q(videoPkt.duration, inVideoStream->time_base, outVideoStream->time_base);
        ts += videoPkt.duration;
        videoPkt.pos = -1;
        if ((err = av_interleaved_write_frame(ofmt_ctx, &videoPkt)) < 0) 
        {
            if(callback != nullptr) 
                callback("[uns::VideoWriter/Remux] Failed to mux packet", err);
            av_packet_unref(&videoPkt);
            break;
        }
        av_packet_unref(&videoPkt);
    }
    av_write_trailer(ofmt_ctx);
end:
    if (ifmt_ctx) 
    {
        avformat_close_input(&ifmt_ctx);
    }
    if (ofmt_ctx && !(ofmt_ctx->oformat->flags & AVFMT_NOFILE)) 
    {
        avio_closep(&ofmt_ctx->pb);
    }
    if (ofmt_ctx) 
    {
        avformat_free_context(ofmt_ctx);
    }
    return ret;
}


  


  Notes :

  


  


  callback is a function which prints error messsage and error code.

  
The error I recived is [uns::VideoWriter/Remux] Failed to write header to output file, error code: -22

  


  


  I want to know what is causing this and how to resolve it please.

  


  Other Informations :

  


  


  Developing Env :

  


  


  OS : Windows 11 Professional Workstation build 22593.ni_release
  
IDE : Visual Studio 2022
  
ffmpeg : 4.4.1
  
Installed ffmpeg library :
ffmpeg[avcodec],ffmpeg[avdevice],ffmpeg[avfilter],ffmpeg[avfilter],ffmpeg[avformat],ffmpeg[openh264],ffmpeg[swresample],ffmpeg[swscale]
  
Compile Settings : x64 Release
  

  


  


  


  


  Running Env which causing error :

  


  


  OS : Windows Server 2019 DataCenter
  
With all dlls VS2022 copied to release folder

  


  


  


• Non-monotonous DTS in output stream 0:1

  4 mai 2018, par sana

  I’m using ffmpeg to get a video file on network .I get the sound live but I it get the video too late. The code I use on the receiver side is :

   ffmpeg -i rtsp://10.0.0.1:8554/test1.sdp -acodec copy -vcodec copy /home/sana/lab/mrp/test1.avi

  The code I use On the sender side is :

  cvlc -vvv /home/sana/lab/video-server1/1.avi --sout '#transcode{vcodec=h264,vb=3000,scale=Auto,acodec=mp3,ab=128,channels=2,samplerate=8000}:rtp{dst=10.0.0.2,port=1234,sdp=rtsp://10.0.0.1:8554/test1.sdp}'

  the error in the output of the ffmpeg command(on the receiver) is :

   [avi @ 0x521ba80] Non-monotonous DTS in output stream 0:1; previous: 196, current: 162; changing to 197. This may result in incorrect timestamps in the output file

  the errors in the input of the vlc command(on the sender) is :

      [0x7f6070000f58] x264 encoder warning: invalid DTS: PTS is less than DTS
  
  
  
      [0x7f608c0009b8] main input error: ES_OUT_SET_(GROUP_)PCR  is called too late (pts_delay increased to 532 ms)
  
      [0x7f608c0009b8] main input error: ES_OUT_RESET_PCR called
  
      .
  
      .
  
      [mpeg4 @ 0x7f60700075a0] header damaged
  
      [0x7f6070000b08] avcodec generic warning: cannot decode one frame (4105 bytes)
  
      [mpeg4 @ 0x7f60700075a0] header damaged
  
      [0x7f6070000b08] avcodec generic warning: cannot decode one frame (4078 bytes
  
  
  
  )

  What does this actually mean and what can I do to prevent it from happening ?

  the ffmpeg version is 4.0-static and vlc version is VLC media player 2.1.6 Rincewind (revision 2.1.6-0-gea01d28) and ubuntu version is 14.04.