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• Use FFMPEG to export audios with gaps filled

  17 octobre 2018, par jcea

  I have a MKV file with gaps in the audio. That is, there are gaps in the MKV audio track timestamps. According to "ffmpeg", the AC3 audio length is 802 seconds, but when exporting the audio to WAV, the resulting file length is 801’53 seconds. That is, the "exported" audio is shorter.

  Triaging the issue with

  ffmpeg -i INPUT.mkv -af ashowinfo -map 0:2 -y -frames:a XXXX -f alaw /dev/null

  I can confirm that the length difference is consistent with gaps in the timestamps of the original audio frames. There are a handful of missing audio frames. I guess those are replaced by silence in the player.

  The command I use to export the audio is :

  ffmpeg -i INPUT.mkv -map 0:1 -ac 2 OUTPUT.wav

  My question is : How can I instruct FFMPEG to preserve the gaps in the original audio, zero (silence) filled ?. The WAV file duration should be the same than the original AC3 audio.

  Given my current workflow, I would rather prefer to not keep the original timestamps in the output file but generate a WAV with (tiny) silences instead. I could consider keeping timestamps if there is no other choice, but this could be quite a pain in my workflow.

  Advice ? Help ?

  Thanks a lot in advance !

• Recording video and creation like Talking Tom on Android

  23 octobre 2013, par coder000001

  How can I ( video within the own app, not screen-cast) record video like "Talking Tom" does on android ?

  Stitching video from Images with the help of FFMPEG is too much CPU intensive and doesn't take help of hardware acceleration.

• Using explicit casting to solve invalid conversion from ‘int’ to ‘AVRounding’

  29 juillet 2020, par C4RN4GE

  I'm trying to follow the "learn ffmpeg the hard way" guide on github (https://github.com/leandromoreira/ffmpeg-libav-tutorial#chapter-2---remuxing) and when I try to run the remuxing code for myself using a C++ compiler I always get the error

  


  invalid conversion from ‘int’ to ‘AVRounding’[-fpermissive]


  


  The only real difference between my code and the github original is that I take the input filename and output filename as parameters instead. Doing some resarch I have found that AVRounding is a enum ? I think ? Thus I need to explicitly cast somehow. However I'm failing to understand how explicit casting works and how I would use it to solve my issue. Where would I cast it ?
Here's the line that causes the issue :

  


  packet.pts =  av_rescale_q_rnd(packet.pts, in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
packet.dts =  av_rescale_q_rnd(packet.dts, in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);


  


  Could anyone explain how to solve the issue ? Sorry if it's a beginners mistake. Thanks in advance for any help.