Recherche avancée

Sur d’autres sites (13168)

• ffmpeg Proper Command to Upscale Video

  19 mai 2014, par user3651716

  We have a problem with the watermark upon ffmpeg conversion to .mp4.

  We use a PHP KVS tube script, running CentOS & hopefully the latest ffmpeg version.

  If input video is in smaller resolution then watermark appearing in the output is too big, so video won’t properly re-size (upscale).

  Looking for a proper command that will upscale video resolution if this is smaller than 720px (width). Re sizing bigger videos work fine, but not smaller.

  So, we would always like 720px-1(dynamic height), no matter what is the input video resolution.

  Here is one of the command we have tried to use but it didnt work can you please provide the correct command to upscale videos 720px (width).

  ---

  This is the below command which we used but it has not worked
  _______________________________________________________-

  -vf "resize=720:trunc(ow/a/2)*2" -vcodec libx264 -threads 0 -acodec libfaac -ar 44100 -ab 128k -f mp4

• ffmpeg - dts/pts values for mpegts relative to the input

  22 juin 2015, par Ivo

  I’m trying to use ffmpeg to split an input video into mpegts segments.

  Currently what I’m using to generate a segment (this case - 2nd segment) is :

  ffmpeg -y -t 15 -ss 15 -i INPUT -c:v libx264 -c:a aac -strict -2 -vbsf h264_mp4toannexb -preset veryfast -f mpegts pipe:1

  This works perfectly, except on the output mpegts result, dts/pts values start from zero and they’re not relative to the input. Which breaks HLS continuity.

  The setpts filter could be a great option, but I cannot figure out how to use it.

  Please do not suggest the segment or the hls muxers, since I need to generate every segment only on-demand.

  Thanks in advance.

• Implementing a multiple input filter graph with the Libavfilter library in Android NDK

  4 avril 2014, par gookman

  I am trying to use the overlay filter with multiple input sources, for an Android app. Basically, I want to overlay multiple video sources on top of a static image.
  I have looked at the sample that comes with ffmpeg and implemented my code based on that, but things don't seem to be working as expected.

  In the ffmpeg filtering sample there seems to be a single video input. I have to handle multiple video inputs and I am not sure that my solution is the correct one. I have tried to find other examples, but looks like this is the only one.

  Here is my code :

  AVFilterContext **inputContexts;
  
  AVFilterContext *outputContext;
  
  AVFilterGraph *graph;
  
  
  
  int initFilters(AVFrame *bgFrame, int inputCount, AVCodecContext **codecContexts, char *filters)
  
  {
  
      int i;
  
      int returnCode;
  
      char args[512];
  
      char name[9];
  
      AVFilterInOut **graphInputs = NULL;
  
      AVFilterInOut *graphOutput = NULL;
  
  
  
      AVFilter *bufferSrc  = avfilter_get_by_name("buffer");
  
      AVFilter *bufferSink = avfilter_get_by_name("buffersink");
  
  
  
      graph = avfilter_graph_alloc();
  
      if(graph == NULL)
  
          return -1;
  
  
  
      //allocate inputs
  
      graphInputs = av_calloc(inputCount + 1, sizeof(AVFilterInOut *));
  
      for(i = 0; i <= inputCount; i++)
  
      {
  
          graphInputs[i] = avfilter_inout_alloc();
  
          if(graphInputs[i] == NULL)
  
              return -1;
  
      }
  
  
  
      //allocate input contexts
  
      inputContexts = av_calloc(inputCount + 1, sizeof(AVFilterContext *));
  
      //first is the background
  
      snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=1/1:pixel_aspect=0", bgFrame->width, bgFrame->height, bgFrame->format);
  
      returnCode = avfilter_graph_create_filter(&inputContexts[0], bufferSrc, "background", args, NULL, graph);
  
      if(returnCode < 0)
  
          return returnCode;
  
      graphInputs[0]->filter_ctx = inputContexts[0];
  
      graphInputs[0]->name = av_strdup("background");
  
      graphInputs[0]->next = graphInputs[1];
  
  
  
      //allocate the rest
  
      for(i = 1; i <= inputCount; i++)
  
      {
  
          AVCodecContext *codecCtx = codecContexts[i - 1];
  
          snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
                      codecCtx->width, codecCtx->height, codecCtx->pix_fmt,
  
                      codecCtx->time_base.num, codecCtx->time_base.den,
  
                      codecCtx->sample_aspect_ratio.num, codecCtx->sample_aspect_ratio.den);
  
          snprintf(name, sizeof(name), "video_%d", i);
  
  
  
          returnCode = avfilter_graph_create_filter(&inputContexts[i], bufferSrc, name, args, NULL, graph);
  
          if(returnCode < 0)
  
              return returnCode;
  
  
  
          graphInputs[i]->filter_ctx = inputContexts[i];
  
          graphInputs[i]->name = av_strdup(name);
  
          graphInputs[i]->pad_idx = 0;
  
          if(i < inputCount)
  
          {
  
              graphInputs[i]->next = graphInputs[i + 1];
  
          }
  
          else
  
          {
  
              graphInputs[i]->next = NULL;
  
          }
  
      }
  
  
  
      //allocate outputs
  
      graphOutput = avfilter_inout_alloc();   
  
      returnCode = avfilter_graph_create_filter(&outputContext, bufferSink, "out", NULL, NULL, graph);
  
      if(returnCode < 0)
  
          return returnCode;
  
      graphOutput->filter_ctx = outputContext;
  
      graphOutput->name = av_strdup("out");
  
      graphOutput->next = NULL;
  
      graphOutput->pad_idx = 0;
  
  
  
      returnCode = avfilter_graph_parse_ptr(graph, filters, graphInputs, &graphOutput, NULL);
  
      if(returnCode < 0)
  
          return returnCode;
  
  
  
      returnCode = avfilter_graph_config(graph, NULL);
  
          return returnCode;
  
  
  
      return 0;
  
  }

  The filters argument of the function is passed on to avfilter_graph_parse_ptr and it can looks like this : [background] scale=512x512 [base]; [video_1] scale=256x256 [tmp_1]; [base][tmp_1] overlay=0:0 [out]

  The call breaks after the call to avfilter_graph_config with the warning :
  Output pad "default" with type video of the filter instance "background" of buffer not connected to any destination and the error Invalid argument.

  What is it that I am not doing correctly ?

  EDIT : The are two issues that I have discovered :

  1. Looks like the description of avfilter_graph_parse_ptr is a bit vague. The ouputs parameter represents a list of the current outputs of the graph, in my case that being the graphInputs variable, because these are the outputs from the buffer filter. The inputs parameter represents a list of the current inputs of the graph, in this case this is the graphOutput variable, because it represents the input to the buffersink filter.

  2. I did some testing with a scale filter and a single input. It seems that the name of the AVFilterInOut structure required by avfilter_graph_parse_ptr needs to be in. I have tried with different versions : in_1, in_link_1. None of them work and I have not been able to find any documentation related to this.

  So the issue still remains. How do I implement a filter graph with multiple inputs ?