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• Anomalie #4357 (Fermé): page ’contact.html’ différente ?

  27 June 2019, by Anonyme

  Appliqué par commit r115799.

• Anomalie #4268: Désélectionner un article choisi préalablement par le sélecteur d’article

  10 January 2019, by chan kalan

  Par exemple dans le squelette Editorial, le paramétrage propose de choisir un article "héro" pour le mettre en avant sur l’accueil en utilisant le sélecteur d’article :
  [(#SAISIEselecteur_article, hero,
  label=<:html5up:hero:>,
  explication=<:html5up:hero_explications:>)]

  Ce qui appelle le fichier cité ci-dessus...

• How to save video data in a vector using ffmpeg? (C++)

  25 October 2022, by nokla

  I'm new to ffmpeg and I am trying to write a program for video editing.

  &#xA;

  I want to import a video file and save it somehow in a vector so I could edit its frames later.&#xA;When I saved all the decoded AVFrames in a vector I saw it takes a lot of memory and that I need to find a better way to do so.

  &#xA;

  The function I used for reading a video:

  &#xA;

  ** the function is in a class that representing video, source type is std::vector<avframe></avframe>

  &#xA;

  void VideoSource::ReadSource(std::string path)
{
    // Open the file using libavformat
    AVFormatContext* av_format_ctx = avformat_alloc_context();
    if (!av_format_ctx) {
        printf("Couldn't create AVFormatContext\n");
        return; 
    }
    if (avformat_open_input(&av_format_ctx, path.c_str(), NULL, NULL) != 0) {
        printf("Couldn't open video file\n");
        return;
    }

    // Find the first valid video stream inside the file
    int video_stream_index = -1;
    AVCodecParameters* av_codec_params = NULL;
    const AVCodec* av_codec = NULL;
    for (int i = 0; i < av_format_ctx->nb_streams; i)
    {
        av_codec_params = av_format_ctx->streams[i]->codecpar;
        av_codec = avcodec_find_decoder(av_codec_params->codec_id);

        if (!av_codec) {
            continue;
        }
        if (av_codec_params->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_stream_index = i;
            break;
        }
    }

    if (video_stream_index == -1) {
        printf("Couldn't find valid video stream inside file\n");
        return;
    }

    // Set up a codec context for the decoder
    AVCodecContext* av_codec_ctx = avcodec_alloc_context3(av_codec);
    if (!av_codec_ctx) {
        printf("Couldn't create AVCpdecContext\n");
        return;
    }

    if (avcodec_parameters_to_context(av_codec_ctx, av_codec_params) < 0)
    {
        printf("Couldn't initialize AVCodecContext\n");
        return;
    }
    if (avcodec_open2(av_codec_ctx, av_codec, NULL) < 0) {
        printf("Couldn't open codec\n");
        return;
    }

    AVFrame* av_frame = av_frame_alloc();
    if (!av_frame) {
        printf("Couldn't allocate AVFrame\n");
        return;
    }
    AVPacket* av_packet = av_packet_alloc();
    if (!av_packet) {
        printf("Couldn't allocate AVPacket\n");
        return;
    }
    int response;

    while (av_read_frame(av_format_ctx, av_packet) >= 0) {
        if (av_packet->stream_index != video_stream_index) {
            av_packet_unref(av_packet);
            continue;
        }
        response = avcodec_send_packet(av_codec_ctx, av_packet);
        if (response < 0) {
            printf("Failed to decode packet: %s\n", av_err2str(response));
            return;
        }
        response = avcodec_receive_frame(av_codec_ctx, av_frame);
        if (response == AVERROR(EAGAIN) || response == AVERROR_EOF) {
            av_packet_unref(av_packet);
            continue;
        }
        else if (response < 0) {
            printf("Failed to decode frame: %s\n", av_err2str(response));
            return;
        }
        av_packet_unref(av_packet);

        av_packet = av_packet_alloc();

        // response = avcodec_send_frame(av_codec_ctx, av_frame);

        source.push_back(*new AVFrame);
        source.back() = *av_frame_clone(av_frame);

        av_frame_unref(av_frame);
    }
    

    avformat_close_input(&av_format_ctx);
    avformat_free_context(av_format_ctx);
    av_frame_free(&av_frame);
    av_packet_free(&av_packet);
    avcodec_free_context(&av_codec_ctx);
}


  &#xA;

  I thought maybe I should save it as a vector of encoded AVFrames or as a vector of encoded packet that contains some frames in it.

  &#xA;

  When I tried to encode a single AVFrame, I added this line&#xA;response = avcodec_send_frame(av_codec_ctx, av_frame); before pushing the frame into the vector (You can see it marked as a comment in the code above).
  &#xA;It returned invalid argument (-22) and I am not sure why.

  &#xA;

  Questions:

  &#xA;

  &#xA;
  1. Why did I get that error (-22)?

  &#xA;

  2. How to save an encoded packet with multiple AVFrame in it?

  &#xA;

  3. Is there a better way of working on a video that won't take as much memory?

  &#xA;

  &#xA;