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• syncing a video file with audio using ffmpeg is returning a video without audio

  31 juillet 2019, par abbood

  When I attempt to sync a .mov video with an .m4a audio file using ffmpeg like so

  ffmpeg -ss 00:00:2 -i test.m4a  -i test.mov -c:v copy -c:a aac -strict experimental output.mp4

  it works like a charm. But right now I’ve recorded a usability test video using adobe XD, and it returned an .mp4 (MPEG-4) video and I manually recorded the audio using quicktimre returning a .m4a audio file.

  Trying to merge them using ffmpeg is returning a video without any audio :

  ffmpeg -i video.mp4  -i audio.m4a -c:v copy -c:a aac -strict experimental output.mp4
  
  ffmpeg version 4.1 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/4.1_1 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gpl --enable-libmp3lame --enable-libopus --enable-libsnappy --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-opencl --enable-videotoolbox
  
    libavutil      56. 22.100 / 56. 22.100
  
    libavcodec     58. 35.100 / 58. 35.100
  
    libavformat    58. 20.100 / 58. 20.100
  
    libavdevice    58.  5.100 / 58.  5.100
  
    libavfilter     7. 40.101 /  7. 40.101
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  3.100 /  5.  3.100
  
    libswresample   3.  3.100 /  3.  3.100
  
    libpostproc    55.  3.100 / 55.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4':
  
    Metadata:
  
      major_brand     : qt
  
      minor_version   : 0
  
      compatible_brands: qt
  
      creation_time   : 2019-07-31T14:43:18.000000Z
  
      com.apple.quicktime.make: Apple
  
      com.apple.quicktime.model: MacBookPro15,1
  
      com.apple.quicktime.software: Mac OS X 10.14.5 (18F203)
  
      com.apple.quicktime.creationdate: 2019-07-31T17:43:17+0300
  
    Duration: 00:03:46.05, start: 0.000000, bitrate: 498 kb/s
  
      Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 374x812 [SAR 1:1 DAR 187:406], 390 kb/s, 60 fps, 60 tbr, 6k tbn, 12k tbc (default)
  
      Metadata:
  
        creation_time   : 2019-07-31T14:43:18.000000Z
  
        handler_name    : Core Media Video
  
        encoder         : H.264
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 8000 Hz, stereo, fltp, 0 kb/s (default)
  
      Metadata:
  
        creation_time   : 2019-07-31T14:43:18.000000Z
  
        handler_name    : Core Media Audio
  
  Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'audio.m4a':
  
    Metadata:
  
      major_brand     : M4A
  
      minor_version   : 0
  
      compatible_brands: M4A mp42isom
  
      creation_time   : 2019-07-31T14:47:26.000000Z
  
      iTunSMPB        :  00000000 00000840 00000000 00000000009DFBC0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
  
    Duration: 00:03:54.78, start: 0.047891, bitrate: 225 kb/s
  
      Stream #1:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 224 kb/s (default)
  
      Metadata:
  
        creation_time   : 2019-07-31T14:47:26.000000Z
  
        handler_name    : Core Media Audio
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (aac (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  [aac @ 0x7fb5a4806a00] Too many bits 16384.000000 > 12288 per frame requested, clamping to max
  
  Output #0, mp4, to 'output.mp4':
  
    Metadata:
  
      major_brand     : qt
  
      minor_version   : 0
  
      compatible_brands: qt
  
      com.apple.quicktime.creationdate: 2019-07-31T17:43:17+0300
  
      com.apple.quicktime.make: Apple
  
      com.apple.quicktime.model: MacBookPro15,1
  
      com.apple.quicktime.software: Mac OS X 10.14.5 (18F203)
  
      encoder         : Lavf58.20.100
  
      Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 374x812 [SAR 1:1 DAR 187:406], q=2-31, 390 kb/s, 60 fps, 60 tbr, 12k tbn, 6k tbc (default)
  
      Metadata:
  
        creation_time   : 2019-07-31T14:43:18.000000Z
  
        handler_name    : Core Media Video
  
        encoder         : H.264
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 8000 Hz, stereo, fltp, 96 kb/s (default)
  
      Metadata:
  
        creation_time   : 2019-07-31T14:43:18.000000Z
  
        handler_name    : Core Media Audio
  
        encoder         : Lavc58.35.100 aac
  
  frame=13563 fps=0.0 q=-1.0 Lsize=   10903kB time=00:03:46.08 bitrate= 395.1kbits/s speed= 916x
  
  video:10699kB audio:10kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.805767%

  How can I get around this limitation ?

• Having trouble obtaining the time from RTP Timestamps obtained through OpenCV

  24 août 2019, par Fr0sty

  I am finding it a bit difficult trying to understand whether or not the hack around with FFmpeg and OpenCV really provided a RTP timestamp. My last post helped a little bit but got me stuck in trying to validate the timestamps obtained through this work around by modifying ffmpeg and opencv.

  FFmpeg version : 4.1.0
  OpenCV version : 3.4.1

  import cv2
  
  import time
  
  from datetime import datetime, date
  
  
  
  uri = 'rtsp://admin:password@192.168.1.66:554/Streaming/Channels/101'
  
  cap = cv2.VideoCapture(uri)
  
  '''One is the offset between the two epochs. Unix uses an epoch located at 1/1/1970-00:00h (UTC) and NTP uses 1/1/1900-00:00h.
  
  This leads to an offset equivalent to 70 years in seconds (there are 17 leap years between the two dates so the offset is'''
  
  time_offset = 2208988800 # (70*365 + 17)*86400 = 2208988800 (in seconds)
  
  # offset = 3775484294
  
  days = 43697
  
  pdat = "1900-01-01 00:00:00:00"
  
  mdat = "2019-08-23 22:02:44:00" # str(datetime.now()) + str(datetime.now().time())
  
  pdate = datetime.strptime(pdat, "%Y-%m-%d %H:%M:%S:%f").date()
  
  mdate = datetime.strptime(mdat, "%Y-%m-%d %H:%M:%S:%f").date()
  
  delta = (mdate - pdate).days
  
  offset = delta * 86400
  
  def time_delta(s):
  
      return (s - time_offset)
  
  
  
  while True:
  
      frame_exists, curr_frame = cap.read()
  
      if frame_exists:
  
          seconds = cap.getRTPTimeStampSeconds()
  
          fraction = cap.getRTPTimeStampFraction()
  
          timestamp = cap.getRTPTimeStampTs()
  
          unix_offset = seconds - time_offset
  
          msec = int((int(fraction) / 0xFFFFFFFF) * 1000.0)
  
          ts = float(str(unix_offset) + "." + str(msec))
  
          # print("Timestamp per Frame:%i" % timestamp)
  
          print((datetime.fromtimestamp(float(ts) + offset)))
  
  cap.release()

  My Output :

  On August 23, 2019 at 22:02

  ...
  
  2019-08-23 13:59:52.781000
  
  2019-08-23 13:59:52.726000
  
  2019-08-23 13:59:52.671000
  
  2019-08-23 13:59:52.616000
  
  2019-08-23 13:59:52.561000
  
  2019-08-23 13:59:52.506000
  
  2019-08-23 13:59:52.451000
  
  2019-08-23 13:59:52.396000
  
  2019-08-23 13:59:52.342000
  
  2019-08-23 13:59:52.287000
  
  2019-08-23 13:59:52.232000
  
  2019-08-23 13:59:52.177000
  
  2019-08-23 13:59:52.122000
  
  2019-08-23 13:59:52.067000
  
  2019-08-23 13:59:52.012000
  
  2019-08-23 13:59:53.570000
  
  2019-08-23 13:59:53.020000
  
  2019-08-23 13:59:53.847000
  
  2019-08-23 13:59:53.792000

  I’ve noticed how the time increments weirdly (that’s not suppose to happen in the real, current time), such as the last two lines and a few others in between in the output. A bit flabbergasted as to what went wrong. Also trying this out on multiple IP cameras, with each showing a different timestamp probably related to when they were turned on.

• 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