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• Set frame timestamp according to file

  16 octobre 2019, par Draykoon D

  I have a Qt application running, each new frame I hijack the frameBuffer, get the raw bitmap and send it to ffmpeg through a pipe. A new frame is drawn when there change in the scene (no constant framerate).

  Currently i am using the -use_wallclock_as_timestamps 1 to let ffmpeg put the timeStamp in the resulting video.

  ffmpeg -f rawvideo -pix_fmt rgba -s size -use_wallclock_as_timestamps 1 -i - -threads 0 -y -c:v libx264 -pix_fmt yuv420p -b:v rate -vf vflip out.mp4

  It works in most computers, but I think that between the moment i retrieve the video and the moment ffmpeg encode it there is a delay which cause artefact in my final ouput.

  Is there a way to send/note the timestamp in my side of the pipe and send them with the data. Or can I put the different timeStamp in a file and then reencode my firstoutput using thoose new timeStamps.

• ffmpeg not encoding 'container' correctly

  11 août 2012, par Barry Chapman

  I am trying to encode a file that is uploaded to our server using ffmpeg.

  However, when we play the video through any flash based media player (FlowPlayer, JW Player) it plays the audio but no video. When we play it on a desktop application (VLC, QT, WMP) - it works fine.

  Here is my encoding command :

  /usr/local/bin/ffmpeg -y -i {$in} -vcodec libx264 -acodec libfaac -ab 128k -ac 2 -b 300 -threads 4 -flags +loop -cmp +chroma -partitions 0 -subq 1 -trellis 0 -refs 1 -coder 0 -bufsize 10M  -qcomp 0.6 -qmax 22 -qdiff 4 -level 30 {$out}

  {$in} is the input file, {$out} is the output file.

  Our ffmpeg version is N-41485-g1321e6e-syslint

  I am still somewhat new to the video encoding scene, can anyone see anything with my encode string that might be a giveaway ?

• FFmpeg avutil.lib unresolved external symbol

  2 août 2022, par Sere

  i'm trying to use FFmpeg with visual sudio 2022 .NET 6 through an MSVC project.
I followed this tutorial : https://www.youtube.com/watch?v=qMNr1Su-nR8&ab_channel=HakanSoyalp.
I mean I have configureg Include (.h) file, library (.lib) files and dynamic (.dll) file copied into bin folder.
If I call for example the avformat_alloc_context() method inside the avformat.lib all work rightly, if I call for example av_file_map(...) inside the avutil.lib the compiler give me an error :
LNK2019 unresolved external symbol "int __cdecl av_file_map ...
But the avutil.lib is linked !!!
The same happen if I call other methods inside avutil.lib module.

  


  Thanks for help...

  


  Code :

  


  extern "C"&#xA;{&#xA;    #include <libavformat></libavformat>avformat.h>&#xA;    #include <libavutil></libavutil>file.h> // av_file_map&#xA;}&#xA;&#xA;int ConvertJPEGtoNALs(int argc, char* argv[])&#xA;{&#xA;    AVFormatContext* fmt_ctx = NULL;&#xA;    AVIOContext* avio_ctx = NULL;&#xA;    uint8_t* buffer = NULL, * avio_ctx_buffer = NULL;&#xA;    size_t buffer_size, avio_ctx_buffer_size = 4096;&#xA;    char* input_filename = NULL;&#xA;    int ret = 0;&#xA;    struct buffer_data bd = { 0 };&#xA;    if (argc != 2) {&#xA;        fprintf(stderr, "usage: %s input_file\n"&#xA;            "API example program to show how to read from a custom buffer "&#xA;            "accessed through AVIOContext.\n", argv[0]);&#xA;        return 1;&#xA;    }&#xA;    input_filename = argv[1];&#xA;    /* register codecs and formats and other lavf/lavc components*/&#xA;    //av_register_all();    //!deprecated&#xA;    /* slurp file content into buffer */&#xA;    ret = av_file_map(input_filename, &amp;buffer, &amp;buffer_size, 0, NULL);&#xA;    /* fill opaque structure used by the AVIOContext read callback */&#xA;    bd.ptr = buffer;&#xA;    bd.size = buffer_size; ???&#xA;    if (!(fmt_ctx = avformat_alloc_context())) {&#xA;        ret = AVERROR(ENOMEM);&#xA;        goto end;&#xA;    }&#xA;    //... to be continue ...&#xA;}&#xA;