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• PHP - 500 error every second time after using exec() on ffmpeg

  23 août 2020, par Eduard Unruh

  I get an 500 error every second time executing this code :

  


  exec('"ffmpeg/bin/ffmpeg.exe" -y -i ' . $infile . ' -movflags faststart -pix_fmt yuv420p -maxrate 500k -bufsize 250k -vf scale=trunc(iw/2)*2:trunc(ih/2)*2 ' . $outfile . ' 2>&1', $output, $return_var);


  


  I've seen this answer :

  


  PHP Exec (ffmpeg) fails on IIS every other request

  


  But before I try to find out what changing the FastCGI protocol is and how to do it : is there a way in the code to avoid this ?

  


• Get frame time in ffmpeg

  30 mai 2013, par Srv19

  I am trying to make a little video player that has seek bar (with ffmpeg, of course). For that i need function that will, using data from frame and/or packet, get me current time in the video that should be set in seek slider.

  It should work like this :

  my_time = get_cur_time()
  
  seek(my_time + 10)
  
  assert(my_time+10 == get_cur_time())
  
  seek(my_time - 10)
  
  assert(my_time-10 == get_cur_time())

  I do understand thatffmpeg does not support precise seeking, so equality here means "something reasonably cloae).

  What code have i used for this thus far :

  frame_time = frame->pts*av_q2d(video_dec_ctx->time_base) * 1000;

  where frame is AVFrame and video_dec_ctx is AVCodecContext.

  And for seeking :

     int fn = ffmpeg::av_rescale(tsms,fmt_ctx->streams[video_stream->index]->time_base.den,
  
                                 fmt_ctx->streams[video_stream->index]->time_base.num);
  
     int frame = fn/1000;
  
  
  
     printf("\t avformat_seek_file to %d\n",frame);
  
     int flags = AVSEEK_FLAG_FRAME;
  
     if (frame < this->frame->pts)
  
         flags |= AVSEEK_FLAG_BACKWARD;
  
     if(ffmpeg::av_seek_frame(fmt_ctx,video_stream->index,frame,flags))
  
     {
  
         printf("\nFailed to seek for time %d",frame);
  
        return false;
  
     }
  
  
  
     avcodec_flush_buffers(video_dec_ctx);
  
     int got_frame = 0;
  
     do
  
     if (av_read_frame(fmt_ctx, &pkt) >= 0) {
  
         decode_packet_ro(&got_frame, 0);
  
         av_free_packet(&pkt);
  
     }
  
     else
  
     {
  
         read_cache = true;
  
         pkt.data = NULL;
  
         pkt.size = 0;
  
         break;
  
     }
  
     while(!(got_frame && this->frame->pts >= frame));

  The code does forward seeking passably, but after any attempt of backward seeking my second assertion fails. After seeking to previous position, my method of getting time does not return position less that one before seeking. That causes my seek slider to work grossly incorrectly.

• avformat/hls : Fixes overwriting existing #EXT-X-PROGRAM-DATE-TIME value in HLS playlist

  1er décembre 2020, par Vignesh Ravichandran

  avformat/hls : Fixes overwriting existing #EXT-X-PROGRAM-DATE-TIME value in HLS playlist
  fix ticket : 8989
  This is is due to the following behavior in the current code :
  
  1. The initial_prog_date_time gets set to the current local time
  
  2. The existing playlist (.m3u8) file gets parsed and the segments
  
     present are added to the variant stream
  
  3. The new segment is created and added
  
  4. The existing segments and the new segment are written to the
  
     playlist file. The initial_prog_date_time from point 1 is used
  
     for calculating "#EXT-X-PROGRAM-DATE-TIME" for the segments,
  
     which results in incorrect "#EXT-X-PROGRAM-DATE-TIME" values
  
     for existing segments
  
  The following approach fixes this bug :
  
  1. Add a new variable "discont_program_date_time" of type double
  
     to HLSSegment struct
  
  2. Store the "EXT-X-PROGRAM-DATE-TIME" value from the existing
  
     segments in this variable
  
  3. When writing to playlist file if "discont_program_date_time"
  
     is set, then use that value for "EXT-X-PROGRAM-DATE-TIME" else
  
     use the value present in vs->initial_prog_date_time
  Signed-off-by : Vignesh Ravichandran <vignesh.ravichandran02@gmail.com>
  
  Signed-off-by : liuqi05 <liuqi05@kuaishou.com>
  

  • [DH] libavformat/hlsenc.c