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• C++/C FFmpeg artifact build up across video frames

  6 mars 2017, par ChiragRaman

  Context :
  I am building a recorder for capturing video and audio in separate threads (using Boost thread groups) using FFmpeg 2.8.6 on Ubuntu 16.04. I followed the demuxing_decoding example here : https://www.ffmpeg.org/doxygen/2.8/demuxing_decoding_8c-example.html

  Video capture specifics :
  I am reading H264 off a Logitech C920 webcam and writing the video to a raw file. The issue I notice with the video is that there seems to be a build-up of artifacts across frames until a particular frame resets. Here is my frame grabbing, and decoding functions :

  // Used for injecting decoding functions for different media types, allowing
  
  // for a generic decode loop
  
  typedef std::function PacketDecoder;
  
  
  
  /**
  
   * Decodes a video packet.
  
   * If the decoding operation is successful, returns the number of bytes decoded,
  
   * else returns the result of the decoding process from ffmpeg
  
   */
  
  int decode_video_packet(AVPacket *packet,
  
                          int *got_frame,
  
                          int cached){
  
      int ret = 0;
  
      int decoded = packet->size;
  
  
  
      *got_frame = 0;
  
  
  
      //Decode video frame
  
      ret = avcodec_decode_video2(video_decode_context,
  
                                  video_frame, got_frame, packet);
  
      if (ret < 0) {
  
          //FFmpeg users should use av_err2str
  
          char errbuf[128];
  
          av_strerror(ret, errbuf, sizeof(errbuf));
  
          std::cerr << "Error decoding video frame " << errbuf << std::endl;
  
          decoded = ret;
  
      } else {
  
          if (*got_frame) {
  
              video_frame->pts = av_frame_get_best_effort_timestamp(video_frame);
  
  
  
              //Write to log file
  
              AVRational *time_base = &video_decode_context->time_base;
  
              log_frame(video_frame, time_base,
  
                        video_frame->coded_picture_number, video_log_stream);
  
  
  
  #if( DEBUG )
  
              std::cout << "Video frame " << ( cached ? "(cached)" : "" )
  
                        << " coded:" <<  video_frame->coded_picture_number
  
                        << " pts:" << pts << std::endl;
  
  #endif
  
  
  
              /*Copy decoded frame to destination buffer:
  
               *This is required since rawvideo expects non aligned data*/
  
              av_image_copy(video_dest_attr.video_destination_data,
  
                            video_dest_attr.video_destination_linesize,
  
                            (const uint8_t **)(video_frame->data),
  
                            video_frame->linesize,
  
                            video_decode_context->pix_fmt,
  
                            video_decode_context->width,
  
                            video_decode_context->height);
  
  
  
              //Write to rawvideo file
  
              fwrite(video_dest_attr.video_destination_data[0],
  
                     1,
  
                     video_dest_attr.video_destination_bufsize,
  
                     video_out_file);
  
  
  
              //Unref the refcounted frame
  
              av_frame_unref(video_frame);
  
          }
  
      }
  
  
  
      return decoded;
  
  }
  
  
  
  /**
  
   * Grabs frames in a loop and decodes them using the specified decoding function
  
   */
  
  int process_frames(AVFormatContext *context,
  
                     PacketDecoder packet_decoder) {
  
      int ret = 0;
  
      int got_frame;
  
      AVPacket packet;
  
  
  
      //Initialize packet, set data to NULL, let the demuxer fill it
  
      av_init_packet(&packet);
  
      packet.data = NULL;
  
      packet.size = 0;
  
  
  
      // read frames from the file
  
      for (;;) {
  
          ret = av_read_frame(context, &packet);
  
          if (ret < 0) {
  
              if  (ret == AVERROR(EAGAIN)) {
  
                  continue;
  
              } else {
  
                  break;
  
              }
  
          }
  
  
  
          //Convert timing fields to the decoder timebase
  
          unsigned int stream_index = packet.stream_index;
  
          av_packet_rescale_ts(&packet,
  
                               context->streams[stream_index]->time_base,
  
                               context->streams[stream_index]->codec->time_base);
  
  
  
          AVPacket orig_packet = packet;
  
          do {
  
              ret = packet_decoder(&packet, &got_frame, 0);
  
              if (ret < 0) {
  
                  break;
  
              }
  
              packet.data += ret;
  
              packet.size -= ret;
  
          } while (packet.size > 0);
  
          av_free_packet(&orig_packet);
  
  
  
          if(stop_recording == true) {
  
              break;
  
          }
  
      }
  
  
  
      //Flush cached frames
  
      std::cout << "Flushing frames" << std::endl;
  
      packet.data = NULL;
  
      packet.size = 0;
  
      do {
  
          packet_decoder(&packet, &got_frame, 1);
  
      } while (got_frame);
  
  
  
      av_log(0, AV_LOG_INFO, "Done processing frames\n");
  
      return ret;
  
  }

  Questions :
  

  1. How do I go about debugging the underlying issue ?
     
  2. Is it possible that running the decoding code in a thread other than the one in which the decoding context was opened is causing the problem ?
     
  3. Am I doing something wrong in the decoding code ?

  Things I have tried/found :
  

  1. I found this thread that is about the same problem here : FFMPEG decoding artifacts between keyframes
     (I cannot post samples of my corrupted frames due to privacy issues, but the image linked to in that question depicts the same issue I have)
     However, the answer to the question is posted by the OP without specific details about how the issue was fixed. The OP only mentions that he wasn’t ’preserving the packets correctly’, but nothing about what was wrong or how to fix it. I do not have enough reputation to post a comment seeking clarification.

  2. I was initially passing the packet into the decoding function by value, but switched to passing by pointer on the off chance that the packet freeing was being done incorrectly.

  3. I found another question about debugging decoding issues, but couldn’t find anything conclusive : How is video decoding corruption debugged ?

  I’d appreciate any insight. Thanks a lot !

  [EDIT] In response to Ronald’s answer, I am adding a little more information that wouldn’t fit in a comment :

  1. I am only calling decode_video_packet() from the thread processing video frames ; the other thread processing audio frames calls a similar decode_audio_packet() function. So only one thread calls the function. I should mention that I have set the thread_count in the decoding context to 1, failing which I would get a segfault in malloc.c while flushing the cached frames.

  2. I can see this being a problem if the process_frames and the frame decoder function were run on separate threads, which is not the case. Is there a specific reason why it would matter if the freeing is done within the function, or after it returns ? I believe the freeing function is passed a copy of the original packet because multiple decode calls would be required for audio packet in case the decoder doesnt decode the entire audio packet.

  3. A general problem is that the corruption does not occur all the time. I can debug better if it is deterministic. Otherwise, I can’t even say if a solution works or not.

• FFmpeg text is not displayed in my streamed video

  18 février 2017, par Ferguson

  on orangepi PC (armbian os) have installed Ffmpeg. I have followed the example in one previous post on how to add text into the stream but I don’t get any text in my video..

  ffserver.conf

  HTTPPort 8090
  
  HTTPBindAddress 0.0.0.0
  
  MaxHTTPConnections 2000
  
  MaxClients 1000
  
  MaxBandwidth 10000
  
  CustomLog -
  
  
  
  <feed>
  
  File /tmp/monitoring1.ffm
  
  FileMaxSize 50M
  
  ACL allow 127.0.0.1
  
  ACL allow 192.168.0.0 192.168.255.255
  
  </feed>
  
  
  
  <stream>
  
  Feed monitoring1.ffm
  
  Format mpjpeg
  
  VideoCodec mjpeg
  
  VideoFrameRate 22
  
  VideoBufferSize 80
  
  VideoSize 720x264
  
  NoAudio
  
  </stream>
  
  
  
  
  
  # Redirect index.html to the appropriate site
  
  
  
  <redirect>
  
  URL http://www.ffmpeg.org/
  
  </redirect>

  I start a ffmpeg as :

  #!/bin/bash
  
  # My first script
  
  ffmpeg -i rtsp://mpv.cdn3.bigCDN.com:554/bigCDN/definst/mp4:bigbuckbunnyiphone_400.mp4 -vf drawtext="fontfile=/home/projekt/StreamTest/DejaVuSans.ttf: \
  
  text='Stack Overflow': fontcolor=white: fontsize=36: box=1: boxcolor=black@0.5: \
  
  boxborderw=5: x=(w-text_w)/2: y=(h-text_h)/2" -codec:a copy http://localhost:8090/monitoring1.ffm

  

  this is the result but the text is missing

  

  thank you

• In Android how to add text as watermark on already recorded video with ffmpeg ?

  23 juillet 2016, par jullie

  I am trying to set text as a watermark on already recorded video but it is not working. As I tried image.png as a water mark and it works by following this url http://androidwarzone.blogspot.in/2011/12/ffmpeg4android.html

  Command for apply image as watermark on already recorded video :

  String[] complexCommand = {"ffmpeg","-y" ,"-i", videoPathHere,"-strict",
  
  "experimental", "-vf", "movie=" 
  
  + Environment.getExternalStorageDirectory().getAbsolutePath() 
  
  + "/watermarkImg.png [watermark]; [in][watermark] overlay=main_w-overlay_w-10:10 [out]",
  
  "-s", "160x120","-r", "30", "-b", "15496k", "-vcodec", "mpeg4","-ab", "48000", 
  
  "-ac", "2", "-ar", "22050", 
  
  Environment.getExternalStorageDirectory().getAbsolutePath()+"/watermark.mp4"}; 

  but when I tried to implement text as watermark its not working :

  String[] complexCommand = {"ffmpeg", "-y" , "-i", videoPathHere, "-strict", "experimental", 
  
  "-vf", "drawtext=fontfile=" + file + ":text=TestText", "-s", "160x120", "-r", "30", 
  
  "-b", "15496k", "-vcodec", "mpeg4", "-ab", "48000", "-ac", "2", "-ar", "22050", 
  
  Environment.getExternalStorageDirectory().getAbsolutePath()+"/watermark.mp4"}; 

  Even I tried this also
  http://video.stackexchange.com/questions/15551/ffmpeg-drawtext-filter-create-transparent-background-with-text

  but it is also not working in my case.

  So, what is going wrong with adding text as watermark ?

  I make changes in commenad from ;text=TestText to :text=TestText then it shows given error.

  07-23 10:58:07.595 : I/Videokit(28832) : libvideokit.so loaded
  07-23 10:58:07.595 : I/Videokit(28832) : args is not NULL
  07-23 10:58:07.595 : I/Videokit(28832) : more then one arg
  07-23 10:58:07.595 : I/Videokit(28832) : function symbol found
  07-23 10:58:07.595 : D/Videokit(28832) : Calling videokit run via loader
  07-23 10:58:07.595 : I/Videokit(28832) : vk ffmpeg sdcardPath : /data/user/0/valamovie.com/files/
  07-23 10:58:07.595 : D/Videokit(28832) : call licenseCheckComplex
  07-23 10:58:07.595 : I/Videokit(28832) : licenseCheck in path : /data/user/0/valamovie.com/files/
  07-23 10:58:07.595 : I/Videokit(28832) : isLicExistsComplex...
  07-23 10:58:07.595 : I/Videokit(28832) : trying to open /data/user/0/valamovie.com/files//ffmpeglicense.lic
  07-23 10:58:07.595 : I/Videokit(28832) : license file found...
  07-23 10:58:07.596 : I/Videokit(28832) : You used 0 of your 15 trial days.
  07-23 10:58:07.596 : D/Videokit(28832) : license check rc : 0
  07-23 10:58:07.596 : D/Videokit(28832) : run() called
  07-23 10:58:07.670 : A/libc(28832) : Fatal signal 11 (SIGSEGV), code 1, fault addr 0x10 in tid 28832 (valamovie.com)
  07-23 10:58:07.771 : A/DEBUG(152) : * *
  07-23 10:58:07.771 : A/DEBUG(152) : Build fingerprint : ’Lava/PixelV1/PixelV1_sprout:6.0/MRA58V/eng.admin.20160419.120644:user/release-keys’
  07-23 10:58:07.771 : A/DEBUG(152) : Revision : ’0’
  07-23 10:58:07.771 : A/DEBUG(152) : ABI : ’arm’
  07-23 10:58:07.771 : A/DEBUG(152) : pid : 28832, tid : 28832, name : valamovie.com >>> valamovie.com <<<
  07-23 10:58:07.772 : A/DEBUG(152) : signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x10
  07-23 10:58:07.789 : A/DEBUG(152) : r0 00000000 r1 00000001 r2 0000001e r3 00000000
  07-23 10:58:07.789 : A/DEBUG(152) : r4 b8ae87c0 r5 b8ae7fb0 r6 00000000 r7 b8b22500
  07-23 10:58:07.789 : A/DEBUG(152) : r8 9ee64cc4 r9 b8a1fad0 sl b8b625d0 fp 00000000
  07-23 10:58:07.789 : A/DEBUG(152) : ip b6d875dc sp bea3e340 lr 9e3969ac pc 9e395bb8 cpsr 600f0010
  07-23 10:58:07.791 : A/DEBUG(152) : backtrace :
  07-23 10:58:07.791 : A/DEBUG(152) : #00 pc 0007cbb8 /data/app/valamovie.com-1/lib/arm/libvideokit.so
  07-23 10:58:08.503 : W/ActivityManager(557) : Force finishing activity valamovie.com/.Ui.addNewProject
  07-23 10:58:08.504 : A/DEBUG(152) : Tombstone written to : /data/tombstones/tombstone_00
  07-23 10:58:08.504 : E/DEBUG(152) : AM write failed : Broken pipe
  07-23 10:58:08.505 : I/BootReceiver(557) : Copying /data/tombstones/tombstone_00 to DropBox (SYSTEM_TOMBSTONE)
  07-23 10:58:08.527 : W/InputDispatcher(557) : channel ’86e38ae valamovie.com/valamovie.com.Ui.MainActivity (server)’ Consumer closed input channel or an error occurred. events=0x9
  07-23 10:58:08.528 : E/InputDispatcher(557) : channel ’86e38ae valamovie.com/valamovie.com.Ui.MainActivity (server)’ Channel is unrecoverably broken and will be disposed !
  07-23 10:58:08.529 : W/InputDispatcher(557) : channel ’e50713f valamovie.com/valamovie.com.Ui.addNewProject (server)’ Consumer closed input channel or an error occurred. events=0x9
  07-23 10:58:08.529 : E/InputDispatcher(557) : channel ’e50713f valamovie.com/valamovie.com.Ui.addNewProject (server)’ Channel is unrecoverably broken and will be disposed !
  07-23 10:58:08.531 : W/ActivityManager(557) : Exception thrown during pause