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• HEVC/H.265 interlaced format support in ffmpeg or VLC

  30 décembre 2020, par Ernestas Gruodis

  "Music Box Russia" channel over satellite transmits in HEVC 1920x1080 25fps interlaced - and after recording VLC recognizes file as 50 fps, and resolution 1920x540 - half a height. But on satellite tuner the player works fine - it plays a file as 1920x1080 25fps... When we can expect support for HEVC/H.265 interlaced ? Here is recorded file (Garry Grey & Eva Miller - wtf). Also - a lot of lost frames in VLC player statistics..

  


  EDIT :

  


  I found some interesting info how in HEVC the interlace video content can be indicated here :

  


  


  Unlike to H.264/AVC, interlace-dedicated coding in HEVC is not exist :

  


  

  • No mixed frame-field interaction (like PAFF in H.264/AVC)

  


  • No interlace scanning of transform coefficients

  


  • No correction MVX[1] (or y-component of MV) if current and reference pictures are in different polarity (top-bottom or
bottom-top).

  


  


  However, in HEVC the interlace video content can be indicated
(signaled in VPS/SPS and pic_timing SEI messages the latter are
transmitted for every picture in the sequence). Interlace-related
setting :

  


  


  • in VPS/SPS set general_interlaced_source_flag=1 and general_progressive_source_flag=0. Indeed, the HEVC standard says :

    


    if general_progressive_source_flag is equal to 0 and
general_interlaced_source_flag is equal to 1, the source scan type of
the pictures in the CVS should be interpreted as interlaced only.

    


  


  • in VPS/SPS set general_frame_only_constraint_flag=0

    


  


  • in SPS VUI set field_seq_flag=1 and frame_field_info_present_flag=1. Notice that if these flags are ON
then picture timing SEIs shall be present for each picture.

    


  


  • transmission of Picture Timing SEI per picture with the following parameters :

    


    source_scan_type = 0 to indicate interlace mode
for top field picture signal pict_struct=1 and for bottom field picture pict_struct=2

    


  


  


  


  Perhaps it is possible to pass these parameters to ffmpeg/vlc before playing a file ?

  


• Array Getting Lost While Passing From C++ to C Using Callback [duplicate]

  23 décembre 2020, par Abhishek Sharma

  I am trying to write Video Using FFmpeg by generating frame at run time using direct3d and the frames are generated using sharp dx at c# and I use window runtime to callback to c# to generate Frame And return Platform::Array of Byte ;

  


  so for writing video using FFmpeg, I used C code that writes video, and to ask for generating frame I implemented a callback to generate a frame and all that in StaticLib

  


  uint8_t*(*genrate_frame_callback)(int) = NULL;   


  


  now in C-File, I call fill_image to get the frame and write to the video

  


  static void fill_image(int frame_index, int width, int height)
{
    int x, y, i;

    i = frame_index;
    auto result = genrate_frame_callback(frame_index);// after passing this point while using debugger reults single element not even array
    .
    .
    .
    code to write video
    
}


  


  now when I call to Write Video before that pass this function to the callback that is in the c++ file in a Window Runtime Component that reference to static lib

  


  uint8_t* genrate_frame(int args)&#xA;{&#xA;    auto frame = FireGenrateFramet(args); // returns Platform::Array<byte>&#xA;    vector v(frame->begin(), frame->end());&#xA;    return v.data();// data is abilabe to this point &#xA;}&#xA;</byte>

  


  now the result variable contains a single element
I am new to c++ and c and unable to understand why is data not passed to the function using call back

  


  Edit :

  


  then can you help me with how to pass Data I tried using the global Scope Variable c++ file too but still,
it gets lost,
but after introducing another call back to read data stored in global Variable it read the whole data correctly

  


  vector frame_v;
uint8_t* genrate_frame(int args)
{
    auto frame = FireGenrateFrame(args);
     vector v(frame->begin(), frame->end());
    frame_v = v;
    return v.data();// this loose the Same 
}

uint8_t read_pixal(int args)
{
    return frame_v[args];// where as it read out correctly
}


  


  but I don't want to store and add new call back an read from their just pass the array

  


• Piping FFmpeg output to Unity texture

  1er février 2021, par Sincress

  I'm working on a networking component where the server provides a Texture and sends it to FFmpeg to be encoded (h264_qsv), and sends it over the network. The client receives the stream (mp4 presumably), decodes it using FFmpeg again and displays it on a Texture.

  



  Currently this works very slowly since I am saving the texture to the disk before encoding it to a mp4 file (also saved to disk), and on the client side I am saving the .png texture to disk after decoding it so that I could use it in Unity.

  



  Server side FFmpeg process is started with process.StartInfo.Arguments = @" -y -i testimg.png -c:v h264_qsv -q 5 -look_ahead 0 -preset:v faster -crf 0 test.qsv.mp4"; currently and client side with process.StartInfo.Arguments = @" -y -i test.qsv.mp4 output.png";

  



  Since this needs to be very fast (30 fps at least) and real time, I need to pipe the Texture directly to the FFmpeg process. On the client side, I need to pipe the decoded data to the displayed Texture directly as well (opposed to saving it and then reading from disk).

  



  A few days of researching showed me that FFmpeg supports various pipelining options, including using data formats such as bmp_pipe (piped bmp sequence), bin(binary text), data (raw data) and image2pipe (piped image2 sequence) however documentation and examples on how to use these options are very scarce.

  



  Please help me : which format should I use (and how should it be used) ?