Recherche avancée

Sur d’autres sites (4517)

• How to use sexagesimal syntax in arguments of FFmpeg or if impossible how to convert it in Windows CMD shell

  6 décembre 2020, par Link-akro

  Question updated 2020-12-06 to enlarge the scope without discarding the prior answer which applies to both prior and larger cases.

  


  I had trouble to provide a sexagesimal time (HH:MM:SS.mm) to a filter option that was not an expression. For instance trim filter.
It happens there is an escaping rule i did not know yet when i first asked, and was addressed in the first comment by @Gyan.

  


  The problem is universal, but the solution may depend on the shell if we go the scripting route... and i am currently stuck with Windows's CMD.exe.

  


  For instance the following skips one minute and 4 tenths of seconds in all streams as accurately as it can seek each, then invokes the trim filter to keep the segment between one and two minutes of the remaining duration, and do so with two different syntaxes. This example happens to be compatible with both CMD and BASH shells so no escaping hell.

  


  ffmpeg -ss "1:00.4" -i INPUT -vf "trim=start='1\:00':end='120'" OUTPUT


  


  Then how do we achieve the same in the expressions within the filters ?
If we cannot avoid using the scripting of the shell, i am looking for a Windows CMD solution.
I had posted one answer with a piece of script to convert a textual sexagesimal time to a textual decimal fractional time in seconds, which was not useful for the original case, but may apply to more generic cases and in particular to the expressions.

  


  Example of failed attempt with one expression in the select filter.

  


  ffmpeg -ss "1:00.4" -i INPUT -vf "select='between(t,1\:00',120)'" OUTPUT


  


  The sexagesimal notation seems to not be supported by ffmpeg filter expressions as i found no reference of it in the documentation nor in SO/web.

  


  I browsed through the list of functions defined in ffmpeg expression library but did not find any way to parse the sexagesimal input there yet, nor any way to use text in its semantics.

  


  However i found some unrelated example that hard-coded some arithmetical expression to provide the numerical decimal amount of seconds equivalent to what was intended, such as 2*60+2 to mean 2:02.

  


  The polynome used above to compute seconds may use preprocessing of shell variable, whichever shell it is, but we need to parse the components of HH:MM:SS.mm to put them in those variable first. You know, using bash $var or cmd %var%/%~1 styles. Otherwise we may compute the polynome completely in the shell instead of the expression but it is so much trouble for little gain.

  


  So while CMD still exists like an undead and becomes really dead , and while i do not have the opportunity yet to replace it, i wish for an answer that either :

  


  

  • does not need the shell/script at all, OR

  


  • provide a solution in Windows CMD, although relying on it as little as possible.

  


  


  Reminder and clarification, the use case assumes that we are given a textual sexagesimal time as input and intend to use it in an expression of ffmpeg filter with as little shell dependency as possible or otherwise satisfy Windows CMD.

  


• Developers and vendors : Want a Matomo Hoodie ? Add a tag to the Matomo Open Source Tag Manager and this could be yours !

  7 juin 2018, par Matomo Core Team — Community, Development

  The Free Open Source Tag Manager is now available as a public beta on the Matomo Marketplace. Don’t know what a Tag Manager is ? Learn more here. In Short : It lets you easily manage all your third party JavaScript and HTML snippets (analytics, ads, social media, remarketing, affiliates, etc) through a single interface.

  Over the last few months we have worked on building the core for the Matomo Tag Manager which comes with a great set of features and a large set of pre-configured triggers and variables. However, we currently lack tags.

  This is where we need your help ! Together we can build a complete and industry leading open source tag manager.

  Tag examples include Google AdWords Conversion Tracking, Facebook Buttons, Facebook Pixels, Twitter Universal Website Tags, LinkedIn Insights.

  Are you a developer who is familiar with JavaScript and keen on adding a tag ? Or are you a vendor ? Don’t be shy, we appreciate any tags, even analytics related :) We have documented how to develop a new tag here, which is quite easy and straightforward. You may also need to understand a tiny bit of PHP but you’ll likely be fine even if you don’t (here is an example PHP file and the related JS file).

  As we want to ship the Matomo Tag Manager with as many tags as possible out of the box, we appreciate any new tag additions as a pull request on https://github.com/matomo-org/tag-manager.

  We will send out “Matomo Contributor” stickers that cannot be purchased anywhere for every contributor who contributes a tag within the next 3 months. As for the top 3 contributors… you’ll receive a Matomo hoodie ! Simply send us an email at hello@matomo.org after your tag has been merged. If needed, a draw will decide who gets the hoodies.

  FYI : The Matomo Tag Manager is already prepared to be handled in different contexts and we may possibly generate containers for Android and iOS. If you are keen on building the official Matomo SDKs for any of these mobile platforms, please get in touch.

  

• How to silent the MP3 decoding process

  3 août 2019, par Golu

  I am learning ffmpeg and I made a MP3 decoder but when I am executing it , some kind of information is printing on my terminal but I don’t want it. So how to silent it ?

  Here is code (full code)

  /* FFmpeg Usage Example
  
   * Date : 28 July 2019
  
   */
  
  #include 
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavutil></libavutil>avutil.h>
  
  #include 
  
  
  
  int decode_packet(AVCodecContext*, AVPacket*, AVFrame*);
  
  
  
  int main(void) {
  
          AVFormatContext *pFormatContext = avformat_alloc_context();
  
          AVCodecParameters *pCodecParameters = NULL;
  
          if(avformat_open_input(&amp;pFormatContext,"song.mp3",NULL,NULL)!=0) {
  
                  fprintf(stderr,"Could not open file\n");
  
                  return -1;
  
          }
  
          if(avformat_find_stream_info(pFormatContext,NULL)&lt;0) {
  
                  fprintf(stderr,"Could not find stream\n");
  
                  return -1;
  
          }
  
  
  
          size_t stream_index = 0;
  
          for(;stream_indexnb_streams;stream_index++) {
  
                  if(pFormatContext->streams[stream_index]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
  
                          pCodecParameters = pFormatContext->streams[stream_index]->codecpar;
  
                  }
  
                          break;
  
          }
  
  
  
          if(stream_index == -1) {
  
                  fprintf(stderr,"could not retrive stream info from file\n");
  
                  return -1;
  
          }
  
          AVStream *stream = pFormatContext->streams[stream_index];
  
          pCodecParameters = stream->codecpar;
  
          AVCodec *cdc = avcodec_find_decoder(pCodecParameters->codec_id);
  
          AVCodecContext *cdc_ctx = avcodec_alloc_context3(cdc);
  
          assert(pCodecParameters);
  
  
  
          if(avcodec_parameters_to_context(cdc_ctx,pCodecParameters) &lt; 0) {
  
                  fprintf(stderr,"Can't copy params to codec context\n");
  
                  return -1;
  
          }
  
  
  
          if(avcodec_open2(cdc_ctx,cdc,NULL) &lt; 0) {
  
                  fprintf(stderr,"Failed to open decoder for stream\n");
  
                  return -1;
  
          }
  
  
  
          AVFrame *frame = av_frame_alloc();
  
          if(!frame) {
  
                  fprintf(stderr,"could not allocate memory for frame\n");
  
                  return -1;
  
          }
  
  
  
          AVPacket *packet = av_packet_alloc();
  
  //      av_init_packet(&amp;packet);
  
          if(!packet) {
  
                  fprintf(stderr,"could not allocate memory for packet");
  
                  return -1;
  
          }
  
  
  
          packet->data=NULL;
  
          packet->size=0;
  
          // lets read the packets
  
          while(av_read_frame(pFormatContext,packet) >= 0) {
  
                  if(packet->stream_index==stream_index) {
  
                          int response = 0 ;
  
              response = decode_packet(cdc_ctx,packet,frame);
  
  
  
                          if(response &lt; 0)
  
                                  continue;
  
                  }
  
          av_packet_unref(packet);
  
          }
  
  
  
          return 0;
  
  }
  
  
  
  int decode_packet(AVCodecContext *cdc_ctx , AVPacket *pkt, AVFrame *frm) {
  
      int response = avcodec_send_packet(cdc_ctx,pkt);
  
      if(response &lt; 0)
  
          return response;
  
      while(response >= 0) {
  
          response = avcodec_receive_frame(cdc_ctx,frm);
  
          if(response == AVERROR(EAGAIN) || response == AVERROR_EOF)
  
              return -1;
  
          else if(response &lt; 0)
  
              return response;
  
      }
  
      return 0;
  
  }

  Expected behaviour : nothing should be printed on screen

  Actual behaviour : some kind of logs are printing automatically

  Here is output logs ( some of them )

  [mp3float @ 0x75172e7400] overread, skip -6 enddists: -5 -5         
  
  [mp3float @ 0x75172e7400] overread, skip -7 enddists: -6 -6
  
  [mp3float @ 0x75172e7400] overread, skip -6 enddists: -5 -5
  
  [mp3float @ 0x75172e7400] overread, skip -6 enddists: -4 -4