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• FFMPEG DirectShow AJAX Audio capture

  1er septembre 2019, par NiCO

  I have an AJA board with an SDI input cable connected to it.
  The input signal has video and audio embeded.

  The video is accesible through the "Vid" Pin and the audio is accesible through the "Aud 1-2" pin.

  Well running DirectShow filter graphs :

  

  

  "No Direct Show Audio Devices" :

  

  I cannot get FFMPEG to correctly map the audio part.

  This is what I tried without success to record the audio :

  ffmpeg -y -rtbufsize 2048M -f dshow -i audio="AJA S-Capture KonaLHi- 0"  -acodec pcm_s24le -ar 48000 output.wav
  
  
  
  ffmpeg -y -rtbufsize 2048M -f dshow -audio_pin_name "Aud 1-2" -i audio="AJA S-Capture KonaLHi- 0"  -acodec pcm_s24le -ar 48000 output.wav

  this is the return error I get
  return error :

  

  The filter is NOT being used by any other software.
  I have no problems recording the video.

• avformat/mpegts : parse large PMTs with multiple tables

  11 juin 2018, par Aman Gupta

  avformat/mpegts : parse large PMTs with multiple tables
  In 9152c1e4955, the mpegts parser was taught how to parse
  
  PMT sections which contained multiple tables. That commit
  
  fixed parsing of PMT packets from some cable providers,
  
  which included a special SCTE table (0xc0) before the
  
  standard program map table (0x2).
  Sometimes, however, the combined 0xc0 and 0x2 tables are
  
  larger than a single TS packet (188 bytes). The mpegts parser
  
  already attempts to parse sections which span multiple packets,
  
  but still assumed that the split section only contained one
  
  table.
  This patch fixes parsing of such a sample[1].
  Before :
      Input #0, mpegts, from 'combined-pmt-tids-split.ts' :
  
        Duration : 00:00:01.26, start : 39188.931756, bitrate : 597 kb/s
  
        Program 1
  
        No Program
  
          Stream #0:0[0xeff] : Audio : ac3, 48000 Hz, mono, fltp, 64 kb/s
  
          Stream #0:1[0xefd] : Audio : mp3, 0 channels, fltp
  
          Stream #0:2[0xefe] : Unknown : none
  After :
      Input #0, mpegts, from 'combined-pmt-tids-split.ts' :
  
        Duration : 00:00:01.27, start : 39188.931756, bitrate : 589 kb/s
  
        Program 1
  
          Stream #0:0[0xefd] : Video : h264 ([27][0][0][0] / 0x001B), none, 59.94 fps, 59.94 tbr, 90k tbn, 180k tbc
  
          Stream #0:1[0xefe](eng) : Audio : ac3 ([129][0][0][0] / 0x0081), 48000 Hz, stereo, fltp, 384 kb/s
  
          Stream #0:2[0xeff](spa) : Audio : ac3 ([129][0][0][0] / 0x0081), 48000 Hz, mono, fltp, 64 kb/s
  
          Stream #0:3[0xf00] : Data : scte_35
  
          Stream #0:4[0xf01] : Unknown : none (ETV1 / 0x31565445)
  
          Stream #0:5[0xf02] : Unknown : none (ETV1 / 0x31565445)
  
          Stream #0:6[0xf03] : Unknown : none ([192][0][0][0] / 0x00C0)
  With the patch, the PMT is parsed correctly so the streams are
  
  created in the correct order, are associated with "Program 1",
  
  and their codecs are set correctly.
  [1] https://s3.amazonaws.com/tmm1/combined-pmt-tids-split.ts
  Signed-off-by : Aman Gupta <aman@tmm1.net>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/mpegts.c

• FFMPEG output to append to a text file without overwriting the content

  5 juin 2018, par ST94

  I am sending a UDP stream to the destination and saving the contents of the FFMPEG output to a text file. I run the ffmpeg command in a loop as follows,

  while : 
  
  do
  
        echo `ffmpeg -hide_banner -f v4l2 -i /dev/video0 -c:v libx264 -f mpegts tcp://ip:port -c:v libx264 /path/to/.mp4 2> out.txt -y`
  
  done

  When I disconnect the cable connected the destination, the above ffmpeg process stops and a new one starts oevrwriting the content of the output that has been saved. And when I reconnect the cable, a new ffmpeg process starts and its output is what is displayed in the out.txt file.

  I need the output of each ffmpeg process that runs to an output file. Can anyone please suggest me a way to do it ?