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• rtmp Videos encoded with FFmpeg play too fast

  30 janvier 2016, par 江嘉荣

  play back too fast and loading Every once in a while

  here is the code ... please help...

  pFormatCtx = avformat_alloc_context();
  
  out_filename = "rtmp://192.168.1.105:1935/jc";
  
   avformat_alloc_output_context2(&pFormatCtx, ofmt, "flv", out_filename);    
  
   ofmt = pFormatCtx->oformat;
  
  if (avio_open(&pFormatCtx->pb,out_filename, AVIO_FLAG_WRITE) < 0){
      printf("Failed to open output file! \n");
      return -1;
  }
  
  video_st = avformat_new_stream(pFormatCtx, 0);
  video_st->time_base.num = 1;
  video_st->time_base.den = 30;
  
  
  br = 400 * 1000;
  pCodecCtx = video_st->codec;
  pCodecCtx->codec_id = AV_CODEC_ID_H264;
  pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
  pCodecCtx->pix_fmt = PIX_FMT_YUV420P;
  
  pCodecCtx->gop_size = 12;
   pCodecCtx->max_qdiff = 4;
  
  pCodecCtx->qmin = 0;
  pCodecCtx->qmax = 51;
  
  pCodecCtx->bit_rate = br;
  pCodecCtx->rc_min_rate =br;
  pCodecCtx->rc_max_rate = br;
  pCodecCtx->bit_rate_tolerance = br;
  pCodecCtx->rc_buffer_size=br;
  
  pCodecCtx->rc_initial_buffer_occupancy = pCodecCtx->rc_buffer_size*3/4;
  
  pCodecCtx->time_base.num = 1;
  pCodecCtx->time_base.den = 30;
  
  start_time = 0;
  
  pCodecCtx->max_b_frames = 3;
  
  AVDictionary *param = 0;
  
  if(pCodecCtx->codec_id == AV_CODEC_ID_H264) {
  
      av_dict_set(&param, "preset", "ultrafast", 0);
      av_dict_set(&param, "tune", "zerolatency", 0);
      av_dict_set(&param, "max_delay", "500", 0);
  }
  
  av_dump_format(pFormatCtx, 0, out_filename, AVIO_FLAG_WRITE);
  
  pCodec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  avformat_write_header(pFormatCtx, NULL);
  
  y_size = pCodecCtx->width * pCodecCtx->height;
  
  return 0;
  

  get pFrame

      pFrame->width = encoder_h264_frame_width;
      pFrame->height = encoder_h264_frame_height;
      pFrame->format = PIX_FMT_YUV420P;
  

  I don't know if it's right way to set the pFrame->pts here...

      pFrame->pts = av_rescale_q(framecnt, pCodecCtx->time_base, video_st-    >codec->time_base);
      avpicture_fill((AVPicture *)pFrame, picture_buf, pCodecCtx->pix_fmt, pCodecCtx->width,    pCodecCtx->height);
      pkt.data = NULL; 
      pkt.size = 0;
  
      int got_picture = 0;
  
      int ret = avcodec_encode_video2(pCodecCtx, &pkt, pFrame, &got_picture);
      framecnt++;
      if(ret < 0) {
      }
      if (got_picture=) {
          pkt.stream_index = video_st->index;
  

  is it right ?

          pkt.pts = av_rescale_q(pkt.pts, video_st->codec->time_base, video_st->time_base);
          pkt.dts = av_rescale_q(pkt.dts, video_st->codec->time_base, video_st->time_base); 
  
          ret = av_interleaved_write_frame(pFormatCtx, &pkt);
  
      }
      av_frame_free(&pFrame);
      av_free_packet(&pkt);
      free(yuv420_data);
  

  This problem has troubled me for a lot of days....

• Installing ffmpeg on CentOS 6.6

  30 janvier 2016, par Kristaps Drozdovskis

  Im trying to install ffmpeg,.. When I write comand:

  git clone --depth 1 http://source.ffmpeg.org/git/ffmpeg.git
  

  I got this error.. why??

  Initialized empty Git repository in /root/ffmpeg_sources/ffmpeg/ffmpeg/.git/ fatal: dumb http transport does not support --depth

  Installing from this source.. https://trac.ffmpeg.org/wiki/CompilationGuide/Centos

• How to convert the MP4 video file from images without audio using FFMPEG ?

  30 janvier 2016, par Rama Lingam

  I am converting the MP4 video file $output from some images and one audio file. But now I want to convert the same MP4 video file without audio. How to do it?

  Here is my sample code:

  // Convert Video from audio and images
  exec("$ffmpeg -framerate 1/5 -i $convImgPath -i $convAudioPath -c:v libx264 -c:a aac -strict experimental -b:a 16k -shortest $output");
  

  Please update my code where I am change.

• Is it possible install only ffprobe ? [on hold]

  30 janvier 2016, par Kristaps Drozdovskis

  i have installed ffmpeg. But missed ffprobe. Is it posible to install only ffprobe? I have looked all around.. but can't find a answer.

• Compile error when using ffmpeg

  30 janvier 2016, par polin

  I've found a strange problem during the compile of an example of ffmpeg in Qt Mac.

  I have installed the ffmpeg library and I have tested the examples of this with cc and gcc compiler on the terminal, and I don't have any problem in the case of compile and run.

  But when I call the library (ffmpeg are C library) in Qt for compile the same code of the example, the g++ compiler give me many error.

  I have used this structure in the main.cpp code:

  #include "mainwindow.h"
  #include "ui_mainwindow.h"
  #include 
  
  extern "C" {
  #include imgutils.h>
  #include samplefmt.h>
  #include timestamp.h>
  #include avformat.h>
  }
  
  #include 
  

  and the Compile Output gives me:

  In file included from ../audvid/main.cpp:7:
  /opt/local/include/libavutil/timestamp.h: In function 'char*
  av_ts_make_string(char*, int64_t)':
  /opt/local/include/libavutil/timestamp.h:48: warning: comparison
  between signed and unsigned integer expressions
  /opt/local/include/libavutil/timestamp.h:49: error: expected `)'
  before 'PRId64' /opt/local/include/libavutil/timestamp.h:49: warning:
  spurious trailing '%' in format
  /opt/local/include/libavutil/timestamp.h:49: warning: too many
  arguments for format /opt/local/include/libavutil/timestamp.h: At
  global scope: /opt/local/include/libavutil/timestamp.h:68: error:
  'AVRational' has not been declared
  /opt/local/include/libavutil/timestamp.h: In function 'char*
  av_ts_make_time_string(char*, int64_t, int*)':
  /opt/local/include/libavutil/timestamp.h:70: warning: comparison
  between signed and unsigned integer expressions
  /opt/local/include/libavutil/timestamp.h:71: error: 'av_q2d' was not
  declared in this scope ../audvid/main.cpp: In function 'int
  decode_packet(int*, int)': ../audvid/main.cpp:50: error: cannot
  convert 'AVRational*' to 'int*' for argument '3' to 'char*
  av_ts_make_time_string(char*, int64_t, int*)' ../audvid/main.cpp:73:
  error: cannot convert 'AVRational*' to 'int*' for argument '3' to
  'char* av_ts_make_time_string(char*, int64_t, int*)'
  ../audvid/main.cpp:75: error: 'struct AVFrame' has no member named
  'channels' ../audvid/main.cpp:84: error: 'struct AVFrame' has no
  member named 'channels' ../audvid/main.cpp:90: error: 'struct AVFrame'
  has no member named 'channels' ../audvid/main.cpp: In function 'int
  open_codec_context(int*, AVFormatContext*, AVMediaType)':
  ../audvid/main.cpp:112: error: 'av_get_media_type_string' was not
  declared in this scope ../audvid/main.cpp:123: error:
  'av_get_media_type_string' was not declared in this scope
  ../audvid/main.cpp:129: error: 'av_get_media_type_string' was not
  declared in this scope ../audvid/main.cpp: In function 'int
  get_format_from_sample_fmt(const char**, AVSampleFormat)':
  ../audvid/main.cpp:152: warning: comparison between signed and
  unsigned integer expressions ../audvid/main.cpp: In function 'int
  main(int, char**)': ../audvid/main.cpp:239: error: invalid conversion
  from 'void*' to 'uint8_t**' make: *** [main.o] Error 1 make: Leaving
  directory
  `/Users/polin/Desktop/audvid/audvid-build-    Qt_4_8_0_qt_everywhere_opensource_src_4_8_0_tp-Release'
  10:44:37: The process "/usr/bin/make" exited with code 2. Error while
  building/deploying project audvid (target: Qt 4.8.0
  (qt-everywhere-opensource-src-4.8.0-tp)) When executing step 'Make'
  

  I don't understand if I make a mistake in the code or if I must change the Qt compiler? (and I don't know how can do this)