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• ffmpeg php some video output with zero byte

  30 janvier 2017, par medo

  i use this code for change video frame size

  if($this->height > 1440)
  
  exec('ffmpeg -i upload/default/'.$file.' -vf scale=-1:1440 -b 64k upload/1440/'.$file.'');
  
  
  
  
  
  if($this->height > 1080)
  
  exec('ffmpeg -i upload/default/'.$file.' -vf scale=-1:1080 -b 64k  upload/1080/'.$file.'');
  
  
  
  
  
  if($this->height > 720)
  
  exec('ffmpeg -i upload/default/'.$file.' -vf scale=-1:720 -b 64k  upload/720/'.$file.'');
  
  
  
  
  
  if($this->height > 480)
  
  exec('ffmpeg -i upload/default/'.$file.' -vf scale=-1:480 -b 64k  upload/480/'.$file.'');
  
  
  
  
  
  if($this->height > 360)
  
  exec('ffmpeg -i upload/default/'.$file.' -vf scale=-1:360 -b 64k  upload/360/'.$file.'');

  some time 240 frame size give zero byte or 360 some of them like 50% of my converted video with zero byte

• FFMPEG encode audio and forced subtitles at same time ?

  8 janvier 2017, par Nick Bell

  I’m using latest static build of ffmpeg windows.

  My input file (.mkv) is :

  [video] - 1080, V_MPEG4/ISO/AVC, 14.6 Mbps, ID#0
  
  [audio] - DTS 5.1, 1510 Kbps, ID#1
  
  [subtitles] - S_TEXT/ASS Lossless English, ID#14

  My problem is this : I convert the audio, so that my target player, a XB1 console (media support faq), is able to play audio/video. However sometimes its rather difficult to hear or parts may be in foreign language, so I want to force the english subtitles into the mix at the same time I convert the audio.

  Currently for the audio, I use the following command

  ffmpeg -i input.mkv -codec copy -acodec ac3 output.mkv

  Can I somehow tie in the forced subtitles (onto the video) in order to save an extra process of taking the output.mkv and trying to force subtitles on ?

  Edit : I’ve tried using the following command to extract subtitles to be able to edit them

  ffmpeg -i Movie.mkv -map 0:s:14 subs.srt

  However i get the error : Stream map '0:s:14' matches no streams

  Edit2 : attempted to extract subtitles and succeeded with

  ffmpeg -i input.mkv -map 0:14 -c copy subtitles.ass

  but still looking to force the subtitles, nonetheless !

  Also - a little bonus to this question - can I somehow extract the .ass file and edit it to only produce subtitles for foreign parts - so english audio doesn’t have subtitles during the movie but foreign audio does have subtitles ?

  Cheers

  Edit3 :

  When I try to use both of the commands at once (my earlier mentioned audio converter & one from the ffmpeg wiki)

  ffmpeg -i input.mkv -codec copy -acodec ac3 -vf "ass=subs.ass" output.mkv

  I get the following error from ffmpeg,

  Filtergraph 'ass=subs.ass' was defined for video output stream 0:0 but codec copy was selected.
  
  Filtering and streamcopy cannot be used together.

• FFmpeg api : combine Camera Stream and Screen Capture or Video File stream to one stream (C/C++)

  31 décembre 2016, par lostin2010

  I have one big question which spent me 2 total days to solve , but fail .

  I want to combine Camera Stream with another stream (.flv,.mpg) to one stream . Just like the picture below. camera is a part of the Live , background is another stream.

  

  My camera device is

  [dshow @ 000373e0]  "TTQ HD Camera"
  
  [dshow @ 000373e0]     Alternative name "@device_pnp_\\?\usb#vid_114d&pid_8455&mi_00#6&1e9bcf33&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"

  I decode my Camera Stream , its format is YUYV422, and decode another flv file its format is ’YUV420p’.
  I use each decoder of oneself to build its own avfilter , camera is in0, flv file is in1 . and use this filter_spec

  color=c=black@1:s=1920x1080[x0];[in0]null[ine0];[ine0]scale=w=960:h=540[inn0];[x0][inn0]overlay=1920*0/2:1080*0/2[x1];[in1]null[ine1];[ine1]scale=w=1160:h=740[inn1];[x1][inn1]overlay=1920*1/2:1080*0/2[x2];[x2]null[out]

  i build a filter_graph.then I read packet out separately and add_frame to filter.

  for (i = 0; i < video_num; i++)//i=0 camera packet , i=1 flv file packet 
  
  {
  
      while ((read_frame_done = av_read_frame(ifmt_ctx[i], &packet)) >= 0)
  
      {
  
         ret = av_buffersrc_add_frame(filter_ctx[stream_index].buffersrc_ctx[i],     frame[i]);
  
      }
  
  }

  then i get frame out into picref

  while (1) {
  
      ret = av_buffersink_get_frame_flags(filter_ctx[stream_index].buffersink_ctx, picref, 0);
  
  }

  I encode picref or display it with SDL , I find there is only the flv stream , no camera stream on showing. i don’t know why.
  but if I change the source stream from camera stream to another flv file, means two flv file as source streams, then it is correct like demo picture above. this confuses me a lot .
  who can help me, I will really thank you.