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• Cut AVI video via FFMPEG results in black screen video, but audio is OK

  25 décembre 2017, par mipi

  I want to trim a AVI video (H264 codec) via ffmpeg. The time interval for the result is available as START_TIME_ORIG and DURATION_ORIG (both in microseconds). To make sure that the resulting video starts with an IDR frame, I determine START_TIME and DURATION via ffprobe by executing

  ffprobe -show_frames -pretty -read_intervals [TIME_FROM%TIME_TO] input.avi

  twice to get the IDR frames which are (1st call) closest to START_TIME_ORIG and (2nd call) closest to START_TIME_ORIG+DURATION_ORIG. TIME_FROM and TIME_TO is an interval of 5 seconds plus/minus around (1st call) START_TIME_ORIG and (2nd call) START_TIME_ORIG+DURATION_ORIG. To identify a frame as IDR frame I verify that key_frame=1 and pict_type=I. START_TIME is then set to pkt_dts_time of that frame. In a similar way I calculate DURATION.

  Then ffmpeg is called :

  ffmpeg -ss [START_TIME] -i input.avi -t [DURATION] -codec copy -reset_timestamps 1 -async 1 -map 0 -y output.avi

  Unfortunately the resulting video has a black screen only, audio is OK. What is wrong with my approach ?
  Thanks, mipi

• Video trim get size before triming video

  30 octobre 2015, par user3514786

  I want file size of video before trim. For example I have video length of five Mins and I am triming it to two Mins then how would i get size of video whose length is two mins before any trim process done

• Split a video in two and burn subtitles into each output video

  11 février, par Kairei

  I want to split a single input video "input.mp4" into two separate videos "out1.mp4" and "out2.mp4." I also want to burn hard subtitles into each of the output files. The subtitles come from two pre-existing subtitle files "subtitles1.ass" and "subtitles2.ass." I tried just adding -vf "ass=subtitles1.ass" and -vf "ass=subtitles2.ass" before each of the output files. Subtitles from subtitles1.ass were added to out1.mp4 but out2.mp4 had no subtitles. I spent hours reading docs and trying things and realized I probably need a complex filter and mapping so came up with this :

  


  ffmpeg.exe -i "input.mp4" -filter_complex "[0:v]split=2[in1][in2];[in1]ass=subtitles1.ass[out1];[in2]ass=subtitles2.ass[out2]" -map "[out1]" -map 0:a -ss 0:00:00.00 -to 0:01:00.00 "C:\out1.mp4" -map "[out2]" -map 0:a -ss 0:01:00.00 -to 0:02:00.00 "C:\out2.mp4"

  


  ... which I think means "Take the input file, split it into two "input pads," send input pad 1 through the subtitle filter with parameter subtitles1.ass and send input pad 2 through the subtitle filter with parameter subtitles2.ass. The two then come out to output pads out1 and out2. I then map out1 (which has the video with burned in subtitles) and also map the audio from the input file, and send the first hour of the video to out1.mp4. I do the same thing for output pad out2 and try to get the second hour of video with subtitles from subtitiles2.ass.

  


  I do get out1.mp4 with the first hour of video and audio and properly burned in subtitles. Unfortunately, out2.mp4 has the correct second hour of video and audio but no subtitles. Am I missing something to get subtitles2.ass burned into out2.mp4 ?