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• Concat multiple (self-generated) videos using ffmpeg on raspbian linux

  25 février 2016, par Thomas Kekeisen

  I am a very talented sleep talker, so I decided to write a solution that records the things I talk at night to make funny videos with subtitles of it. The project is nearly done, but I got a big problem with concating videos I generated before.

  The video parts are generated from single png frames using this command :

  ffmpeg -y -framerate 15 -i "${images_file_path}" -c:v libx264 -r 30 -pix_fmt yuv420p "${video_file_path}"

  Then the sound is added using this command (got this from #9049970 and #11779490) :

  ffmpeg -y -i "${video_file_path}" -i "${mp3_file_path}" -map 0:v -map 1:a -vcodec copy -acodec copy -shortest "${final_video_file_path}"

  All this is causing no problems so far, but I think it may be relevant to know how the videos are generated. I can watch all this and get valid video and sound - the full source code of this first part can be found here.

  Now I added a feature that is able to generate "full videos" containing a title and a various number of previously generated "video parts" using this command :

  ffmpeg -f concat -i "${video_list_path}" -filter_complex "${filter_string} concat=n=${input_file_counter}:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" "${full_video_path}"

  But something is wrong with it and I get this error :

  Invalid file index 1 in filtergraph description [0:v:0] [1:v:0] [2:v:0] [2:a:0] [3:v:0] [4:v:0] [4:a:0] [5:v:0] [6:v:0] [6:a:0] [7:v:0] concat=n=8:v=1:a=1 [v] [a].

  The full output is :

  ffmpeg version N-77213-g7c1c453 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.9.2 (Raspbian 4.9.2-10)
  
    configuration: --enable-shared --enable-gpl --prefix=/usr --enable-nonfree --enable-libmp3lame --enable-libfaac --enable-libx264 --enable-version3 --disable-mmx
  
    libavutil      55. 10.100 / 55. 10.100
  
    libavcodec     57. 17.100 / 57. 17.100
  
    libavformat    57. 20.100 / 57. 20.100
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 20.100 /  6. 20.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0xc2e900] Auto-inserting h264_mp4toannexb bitstream filter
  
  Input #0, concat, from '/usr/sleeptalk/records-rendered/3enguzpuu2gw0ogk8wkko/videos.txt':
  
    Duration: N/A, start: 0.000000, bitrate: 61 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 58 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 2 kb/s
  
      Metadata:
  
        handler_name    : SoundHandler
  
  Invalid file index 1 in filtergraph description [0:v:0] [1:v:0] [2:v:0] [2:a:0] [3:v:0] [4:v:0] [4:a:0] [5:v:0] [6:v:0] [6:a:0] [7:v:0] concat=n=8:v=1:a=1 [v] [a].

  I also wrote a test case so you can reproduce this on your local machine. Download the files from my dropbox. Also, the full script that renders the "final move" can be found here.

  Would be great to get an Idea, got struggle to fix this the last two days.

• RGB to YUV conversion with libav (ffmpeg) triplicates image

  17 avril 2021, par José Tomás Tocino

  I'm building a small program to capture the screen (using X11 MIT-SHM extension) on video. It works well if I create individual PNG files of the captured frames, but now I'm trying to integrate libav (ffmpeg) to create the video and I'm getting... funny results.

  


  The furthest I've been able to reach is this. The expected result (which is a PNG created directly from the RGB data of the XImage file) is this :

  


  

  


  However, the result I'm getting is this :

  


  

  


  As you can see the colors are funky and the image appears cropped three times. I have a loop where I capture the screen, and first I generate the individual PNG files (currently commented in the code below) and then I try to use libswscale to convert from RGB24 to YUV420 :

  


  while (gRunning) {
        printf("Processing frame framecnt=%i \n", framecnt);

        if (!XShmGetImage(display, RootWindow(display, DefaultScreen(display)), img, 0, 0, AllPlanes)) {
            printf("\n Ooops.. Something is wrong.");
            break;
        }

        // PNG generation
        // snprintf(imageName, sizeof(imageName), "salida_%i.png", framecnt);
        // writePngForImage(img, width, height, imageName);

        unsigned long red_mask = img->red_mask;
        unsigned long green_mask = img->green_mask;
        unsigned long blue_mask = img->blue_mask;

        // Write image data
        for (int y = 0; y < height; y++) {
            for (int x = 0; x < width; x++) {
                unsigned long pixel = XGetPixel(img, x, y);

                unsigned char blue = pixel & blue_mask;
                unsigned char green = (pixel & green_mask) >> 8;
                unsigned char red = (pixel & red_mask) >> 16;

                pixel_rgb_data[y * width + x * 3] = red;
                pixel_rgb_data[y * width + x * 3 + 1] = green;
                pixel_rgb_data[y * width + x * 3 + 2] = blue;
            }
        }

        uint8_t* inData[1] = { pixel_rgb_data };
        int inLinesize[1] = { in_w };

        printf("Scaling frame... \n");
        int sliceHeight = sws_scale(sws_context, inData, inLinesize, 0, height, pFrame->data, pFrame->linesize);

        printf("Obtained slice height: %i \n", sliceHeight);
        pFrame->pts = framecnt * (pVideoStream->time_base.den) / ((pVideoStream->time_base.num) * 25);

        printf("Frame pts: %li \n", pFrame->pts);
        int got_picture = 0;

        printf("Encoding frame... \n");
        int ret = avcodec_encode_video2(pCodecCtx, &pkt, pFrame, &got_picture);

//                int ret = avcodec_send_frame(pCodecCtx, pFrame);

        if (ret != 0) {
            printf("Failed to encode! Error: %i\n", ret);
            return -1;
        }

        printf("Succeed to encode frame: %5d - size: %5d\n", framecnt, pkt.size);

        framecnt++;

        pkt.stream_index = pVideoStream->index;
        ret = av_write_frame(pFormatCtx, &pkt);

        if (ret != 0) {
            printf("Error writing frame! Error: %framecnt \n", ret);
            return -1;
        }

        av_packet_unref(&pkt);
    }


  


  I've placed the entire code at this gist. This question right here looks pretty similar to mine, but not quite, and the solution did not work for me, although I think this has something to do with the way the line stride is calculated.

  


• Anomalie #4438 : Manque Msg :message:lien_reponse_message :

  22 mars 2020

  Ça m’interroge...

  Les chaines de langues sont dans ’forum’, là : https://git.spip.net/spip/forum/src/branch/master/lang/forum_fr.php#L129
  Donc appeler `_T(’message:lien_reponse_message’)` ne donnera rien, quelque soit la version de SPIP.
  Cette chaine (forum:lien_reponse_message) est appelé si le message a un `id_parent`.

  La question semble plutôt :
  - soit `#OBJET` qui vaut ’message’ est erroné (ça devait être autre chose (genre l’objet du parent), mais un bug remplit a rempli ’message’ ?
  - soit on avait jamais eu ce cas simplement ?