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• avformat/mpegtsenc: Fix mpegts_write_pes() for private_stream_2 and other types

  25 April 2021, by zheng qian

  avformat/mpegtsenc: Fix mpegts_write_pes() for private_stream_2 and other types
  According to the PES packet definition defined in Table 2-17 of ISO_IEC_13818-1
  
  specification, some fields like PTS/DTS or pes_extension could only appears if
  
  the stream_id meets the condition:
  if (stream_id != 0xBC &&  // program_stream_map
  
      stream_id != 0xBE &&  // padding_stream
  
      stream_id != 0xBF &&  // private_stream_2
  
      stream_id != 0xF0 &&  // ECM
  
      stream_id != 0xF1 &&  // EMM
  
      stream_id != 0xFF &&  // program_stream_directory
  
      stream_id != 0xF2 &&  // DSMCC_stream
  
      stream_id != 0xF8)    // ITU-T Rec. H.222.1 type E stream
  And the following stream_id types don't have fields like PTS/DTS:
  else if ( stream_id == program_stream_map
  
  || stream_id == private_stream_2
  
  || stream_id == ECM
  
  || stream_id == EMM
  
  || stream_id == program_stream_directory
  
  || stream_id == DSMCC_stream
  
  || stream_id == ITU-T Rec. H.222.1 type E stream ) 
  
      for (i = 0; i < PES_packet_length; i++) 
  
          PES_packet_data_byte
  
      
  
  
  Current implementation skipped the check of stream_id causing some kind of
  
  streams like private_stream_2 to be incorrectly written with actually a
  
  private_stream_1-like PES header with PTS/DTS field. For example, Japan DTV
  
  transmits news and alerts through ARIB superimpose that utilizes
  
  private_stream_2 still could not be remuxed correctly for now.
  This patch set fixes the remuxing for private_stream_2 and
  
  other stream_id types.
  Signed-off-by: zheng qian <xqq@xqq.im>
  
  Signed-off-by: Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/mpegtsenc.c

• ffmpeg perspective filter animation error

  17 March 2021, by eeun

  I'm trying to create a pseudo-3d pan effect in ffmpeg using the perspective filter.

  


  Here is a sample for the starting point...

  


  ffmpeg -y -filter-complex "color=black:s=1600x900,trim=0:5,drawgrid=width=100:height=100:thickness=2:color=white,perspective=x0=200:y0=200:x1=1600:y1=0:x2=200:y2=700:x3=1600:y3=900[skew]" -an -map [skew] "skew-start.mp4"


  


  And here is a sample for the end point...

  


  ffmpeg -y -filter-complex "color=black:s=1600x900,trim=0:5,drawgrid=width=100:height=100:thickness=2:color=white,perspective=x0=0:y0=0:x1=1600:y1=0:x2=0:y2=900:x3=1600:y3=900[skew]" -an -map [skew] "skew-end.mp4"


  


  So far so good. Adding the animation would give this...

  


  ffmpeg -y -filter-complex "color=black:s=1600x900,trim=0:5,drawgrid=width=100:height=100:thickness=2:color=white,perspective=eval=frame:x0='200-(200*t/5)':y0='200-(200*t/5)':x1=1600:y1=0:x2='200-(200*t/5)':y2='700+(200*t/5)':x3=1600:y3=900[skew]" -an -map [skew] skew.mp4


  


  This is where the problem occurs. I get an error saying [Eval @ 000000f36ebfebf0] Undefined constant or missing '(' in 't/5)' Error while filtering: Invalid argument

  


  The perspective docs say it should work with an eval=frame option. Anyone got any ideas? Does this look like a bug in ffmpeg? I'm using the latest version, 4.3.2.

  


• Why does the remainder of the video not appear in this FFMPEG complex filter graph?

  10 January 2019, by Jonathan Gilbert

  I have a filter graph where I am trying to shift the first 18 seconds of a long video up by 60 pixels in each frame (the frame size is 1920x1040) without affecting the rest of the video. The graph definition looks like this:

  -filter_complex "[0:v] trim=start=0:duration=18 [pretitle];\
  
                   [0:v] trim=start=18,setpts=PTS-STARTPTS [remainder];\
  
                   color=color=black:size=1920x1040 [blank];\
  
                   [blank][pretitle] overlay=0:-60 [pretitle_shifted];\
  
                   [pretitle_shifted][remainder] concat [t];\
  
                   [t] ass=Subtitles.ass,fade=t=out:st=2608.6:d=2 [output]"
  
  -map [output] -map 0:1

  This filter graph runs without errors, but after the first 18 seconds, the video is just the subtitles on a black background. I can’t figure out why. :-(