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• UWP C# and Windows Runtime Component C++ Permission Denied error when opening file

  29 décembre 2020, par Surya Solanki

  I have developed a UWP app in C# which contains a Windows Runtime Component C++ project. the app allows the user to choose an mp4 file and passes this file to the c++ code, which then utilizes ffmpeg libraries to retrieve the presentation time stamps of a video file and output them to a file.

  


  the issue i'm facing is that the c++ code is not able to open the mp4 file when using the avformat_open_input function :

  


  int PTSExtraction::parse_file(Platform::String^ filename)
{
    int ret = 0;
    AVPacket pkt = { 0 };


    std::wstring fileNameW(filename->Begin());
    std::string fileNameA(fileNameW.begin(), fileNameW.end());
    const wchar_t* w_chars = fileNameW.c_str();
    src_filename = fileNameA.c_str(); 

    if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
        fprintf(stderr, "Could not open source file %s\n", src_filename);
        return 1; 
    }
    // rest of code 
}


  


  the error received by avformat_open_input is Permission Denied. I cannot even open a random text file in this function by doing :

  


  ofstream output; 
output.open("output.txt");


  


  I realize there are file system permissions that are blocking the C++ component of my uwp app from opening files. here are the things i have tried so far :

  


  

  • i have enabled broadFileSystemAccess in the Package.appxmanifest (https://blogs.windows.com/windowsdeveloper/2018/05/18/console-uwp-applications-and-file-system-access/) - in the Capabilities section of the Package.appxmanifest file I've allowed access to Location, Pictures Library, and Videos Library.

  


  • I've checked the File System Privacy Settings on my computer and enabled my app to access the File System.

  


  • I've tried moving the mp4 file to various locations (Documents, Pictures Library, Videos Library) to see if the C++ component has access to these locations.

  


  • I've tried the solution from this post : Qt WinRT App cannot access file permission denied.

  


  


  None of these allow the C++ component to open any files. i would really appreciate if anyone has a solution for this problem.

  


• hls fails to play m3u8 playlist with videojs

  9 novembre 2020, par charlie

  I created an hls stream from yuv frames with ffmpeg which appears to work just fine. It creates a playlist and updates that, and all .ts files as expected. However even videojs refuses to play it, and I really run out of ideas, probably missing the obvious ?

  


  First, the m3u8 list which is continuously updated :

  


  #EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:2
#EXT-X-MEDIA-SEQUENCE:190
#EXTINF:2.000000,
test190.ts
#EXTINF:2.000000,
test191.ts
#EXTINF:2.000000,
test192.ts
#EXTINF:2.000000,
test193.ts
#EXTINF:2.000000,
test194.ts


  


  Those .ts files exist and have sizes of approx 250 kBytes.
Then, I open this standard videojs html file (residing in the same directory) :

  


  &#xA;&#xA;&#xA;&#xA;&#xA;&#xA;  &#xA;&#xA;&#xA;  <h1>VSTream</h1>&#xA;&#xA;  &#xA;    <source src="test.m3u8" type="application/x-mpegURL">&#xA;  &#xA;  &#xA;  <code class="echappe-js">&lt;script src='http://stackoverflow.com/feeds/tag/video.min.js'&gt;&lt;/script&gt;&#xA;  &lt;script src='http://stackoverflow.com/feeds/tag/videojs-http-streaming.min.js'&gt;&lt;/script&gt;&#xA;  &#xA;  &lt;script&gt;&amp;#xA;    var player = videojs(&amp;#x27;my_video_1&amp;#x27;);&amp;#xA;  &lt;/script&gt;&#xA;  &#xA;&#xA;&#xA;

  


  I open this in Firefox (or Chrome, or Edge, none works) and use its debugger which in the console shows :

  


  


  VIDEOJS : WARN : A plugin named "reloadSourceOnError" already exists.
You may want to avoid re-registering plugins ! video.min.js:12:977
Specified “type” attribute of “application/x-mpegURL” is not
supported. Load of media resource test.m3u8 failed. vstream.html All
candidate resources failed to load. Media load paused. vstream.html
XML Parsing Error : syntax error Location : file :///C :/test/test.m3u8
Line Number 1, Column 1 : 2 test.m3u8:1:1 MouseEvent.mozPressure is
deprecated. Use PointerEvent.pressure instead. video.min.js:12:9031
VIDEOJS : ERROR : (CODE:3 MEDIA_ERR_DECODE) Playback cannot continue. No
available working or supported playlists. Object code : 3, message :
"Playback cannot continue. No available working or supported
playlists." video.min.js:12:977

  


  


  This doesn't make much sense to me. Why would it throw an XML parsing error for an m3u8 file ? Of course, the MEDIA_ERR_DECODE points in some direction, but the same problem persists with fMP4 files.

  


  The relevant ffmpeg c++ code (format is "hls" and formatContext works well in other scenarios, gop is 2) :

  


      AVDictionary* options = 0;
    if (fragmented)
    {
        // type
        if (codecID == AV_CODEC_ID_H264)
            av_dict_set (&options, "hls_segment_type", "fmp4", 0);
        else
            av_dict_set (&options, "hls_segment_type", "mpegts", 0);

        av_dict_set (&options, "hls_time", "2.0", 0);
        av_dict_set_int (&options, "hls_list_size", 5, 0);
        av_dict_set (&options, "hls_flags", "delete_segments", 0);
    }

    int ret = avformat_write_header (formatContext, &options);


  


  ...which returns success. Then writing frames

  


      int ret = avcodec_send_frame (videoStream->codecContext, frame);
    av_init_packet (avPacket);
    AVRational timeBase = videoStream->getTimeBase ();
    avPacket->stream_index = streams.indexOf (videoStream);
    ret = avcodec_receive_packet (videoStream->codecContext, avPacket);
    avPacket->duration = av_rescale_q (1, videoStream->codecContext->time_base, videoStream->getTimeBase ());
    pts += avPacket->duration;
    avPacket->pts = pts;
    avPacket->dts = pts;    //  AV_NOPTS_VALUE;
    ret = av_interleaved_write_frame (formatContext, avPacket);


  


  (videoStream here is an internal object representing the avstream).
I've omitted error checks for clarity. All return values show success.
Thanks for any help on this !

  


• Running ffmpeg via PHP

  11 mars 2020, par FionaF

  So the end goal is to have a php script that, given a list of images, will automatically create a slideshow video with transitions and text overlays and maybe an audio track as well.

  I’m competent in coding PHP but not experienced in command line stuff.

  We have a dedicated server and I got hosting company to install ffmpeg for me.

  So I thought I’d start simple and slowly build up to ultimate goal. But I’m really struggling. I’ve spent a couple of days trying all sorts of things with very little success.

  I found this post with some excellent examples https://superuser.com/questions/833232/create-video-with-5-images-with-fadein-out-effect-in-ffmpeg but I can’t get any of them to work. Which makes me think that I’m doing something fundamentally wrong.

  So this does work for me - I get a nice little 30 sec video slideshow of 6 images displaying for 5 secs each :

  $ffmpeg="/usr/bin/ffmpeg";
  
  exec($ffmpeg.' -f concat -safe 0 -i input.txt -c:v libx264 -r 30 -pix_fmt yuv420p -y out.mp4 2>&1', $output);
  
  var_dump($output);

  and this is input.txt

  file /home/webvivre/public_html/videos/test/i1.jpg
  
  duration 5
  
  file /home/webvivre/public_html/videos/test/i2.jpg
  
  duration 5
  
  file /home/webvivre/public_html/videos/test/i3.jpg
  
  duration 5
  
  file /home/webvivre/public_html/videos/test/i4.jpg
  
  duration 5
  
  file /home/webvivre/public_html/videos/test/i5.jpg
  
  duration 5
  
  file /home/webvivre/public_html/videos/test/i6.jpg
  
  duration 5

  But this (basically taken from example in link above - have only changed image names and ffmpeg location) doesn’t work for me :

  $code="/usr/bin/ffmpeg -y -loop 1 -i i1.jpg -loop 1 -i i2.jpg -loop 1 -i i3.jpg -filter_complex \" [0:v]zoompan=z='min(zoom+0.0015,1.5)':d=125,trim=duration=5,blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))',setpts=PTS-STARTPTS[v0]; [1:v]zoompan=z='min(zoom+0.0015,1.5)':d=125,trim=duration=5,blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))',setpts=PTS-STARTPTS[v1]; [2:v]zoompan=z='min(zoom+0.0015,1.5)':d=125,trim=duration=5,blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))',setpts=PTS-STARTPTS[v2]; [v0][v1][v2] concat=n=3:v=1:a=0, format=yuv420p[v]\" -map '[v]' -c:v libx264 -pix_fmt yuvj420p -q:v 1 out.mp4 2>&1";
  
  exec($code,$output);
  
  var_dump($output);

  This is the output :

  array(25) { [0]=> string(67) "ffmpeg version 2.8.15 Copyright (c) 2000-2018 the FFmpeg developers" [1]=> string(56) " built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-36)" [2]=> string(1147) " configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --extra-ldflags='-Wl,-z,relro ' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --disable-crystalhd --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --enable-libfdk-aac --enable-nonfree --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect" [3]=> string(40) " libavutil 54. 31.100 / 54. 31.100" [4]=> string(40) " libavcodec 56. 60.100 / 56. 60.100" [5]=> string(40) " libavformat 56. 40.101 / 56. 40.101" [6]=> string(40) " libavdevice 56. 4.100 / 56. 4.100" [7]=> string(40) " libavfilter 5. 40.101 / 5. 40.101" [8]=> string(40) " libavresample 2. 1. 0 / 2. 1. 0" [9]=> string(40) " libswscale 3. 1.101 / 3. 1.101" [10]=> string(40) " libswresample 1. 2.101 / 1. 2.101" [11]=> string(40) " libpostproc 53. 3.100 / 53. 3.100" [12]=> string(38) "[mjpeg @ 0x183c720] Changeing bps to 8" [13]=> string(32) "Input #0, image2, from 'i1.jpg':" [14]=> string(61) " Duration: 00:00:00.04, start: 0.000000, bitrate: 33777 kb/s" [15]=> string(128) " Stream #0:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1000x750 [SAR 1:1 DAR 4:3], 25 fps, 25 tbr, 25 tbn, 25 tbc" [16]=> string(38) "[mjpeg @ 0x18427c0] Changeing bps to 8" [17]=> string(32) "Input #1, image2, from 'i2.jpg':" [18]=> string(61) " Duration: 00:00:00.04, start: 0.000000, bitrate: 41896 kb/s" [19]=> string(132) " Stream #1:0: Video: mjpeg, yuvj444p(pc, bt470bg/unknown/unknown), 1000x750 [SAR 300:300 DAR 4:3], 25 fps, 25 tbr, 25 tbn, 25 tbc" [20]=> string(38) "[mjpeg @ 0x1849fa0] Changeing bps to 8" [21]=> string(32) "Input #2, image2, from 'i3.jpg':" [22]=> string(61) " Duration: 00:00:00.04, start: 0.000000, bitrate: 34776 kb/s" [23]=> string(132) " Stream #2:0: Video: mjpeg, yuvj444p(pc, bt470bg/unknown/unknown), 1000x750 [SAR 300:300 DAR 4:3], 25 fps, 25 tbr, 25 tbn, 25 tbc" [24]=> string(81) "Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_blend_10" }

  And for reference, this is info provided to me by hosting company after installing ffmpeg for me :

  svr01~ # ffmpeg
  
  ffmpeg version 2.8.15 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-36)
  
    configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --extra-ldflags='-Wl,-z,relro ' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --disable-crystalhd --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --enable-libfdk-aac --enable-nonfree --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
  
    libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Hyper fast Audio and Video encoder

  If someone could just shove me in the right direction to get the above working I’d be very grateful. I just know it’s going to end up being something really simple.