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• Run PHP exec() asynchronously, but check for completion ?

  1er septembre 2015, par PeregrineStudios

  I’m coding up a website back-end that will include user-uploaded video. In order to ensure maximum accessibility, I’m compressing the uploaded videos and re-saving them as .mp4 and .webm format to cover all browsers (or as many as possible anyway). To do this, I’m running an avconv command in the PHP exec() function.

  I don’t want to make the user wait for the script to finish before the page loads, so I’m running the code asynchronously. My code so far is below.

  exec('bash -c "exec nohup setsid avconv -i ' . $tempPath . ' -c:v libx264 ' . $transpose . ' ' . $newPath . 'mp4 > /dev/null 2>/dev/null &"');
  
  exec('bash -c "exec nohup setsid avconv -i ' . $tempPath . ' -c:v libvpx ' . $transpose . ' ' . $newPath . 'webm > /dev/null 2>/dev/null &"');

  In addition to running the exec functions, I also save the video to a database and send the user an email thanking them for uploading their video.

  Here’s the rub : I want the server to WAIT until the video conversion is finished, and THEN add it to the database and send the user an email. Basically, the program flow would be :

  User uploads video.
  Video is placed in a temp folder.
  User is taken to a thank you page indicating their video will be up shortly.
  The server executes two avconv commands to convert and compress the video for web use.
  Once BOTH conversions are finished, the video info is added to a MySQL database, an email is sent to the user, and the original uploaded video is deleted.

  It may just be my ignorance of the command line (in fact it almost definitely is), but how could I ’queue up’ these commands ? First do both conversions, then call a PHP script to add to the database, then delete the original video, all while being asynchronous with the original PHP script ?

  EDIT : I’ve tried queuing them up with an ’&&’ operator, like below :

  exec('bash -c "exec nohup setsid avconv -i ' . $tempPath . ' -c:v libx264 ' . $transpose . ' ' . $newPath . 'mp4 && avconv -i ' . $tempPath . ' -c:v libvpx ' . $transpose . ' ' . $newPath . 'webm > /dev/null 2>/dev/null &"');

  However, that seems to cancel out the fact that I’m running it asynchronously, since the page now seems to wait for the command to finish.

• Broadcasting video from the camera to YouTube

  17 octobre 2022, par vernise

  I want to stream video on YouTube. But there are a lot of restrictions. Firstly, I want to do it via an intermediate server. If there is no connection, the broadcast will not complete. Instead, an error will be displayed on the broadcast. This is due to the fact that the camera is close to the battle line. A blackout is not an uncommon occurrence. Also due to the limitations of YouTube (maximum 12 hours of broadcasting time to save), the broadcast has to start twice a day. I tried to implement transmission via FFmpeg and UDP to an intermediary server (I'm using a simple webcam), but the latency at this stage is more than 30 seconds. Any suggestions would be appreciated.

  


• ffmpeg creating video with 1 minute empty space at the end of the video

  13 octobre 2022, par David Ruan

  I am using this command to generate a video with a cover page and an audio.

  


  ffmpeg -loop 1 -r 1 -i c :/temp/coverImage.jpeg -i C :/temp/out/input.mp3 -vf "pad=ceil(iw/2)*2:ceil(ih/2)*2" -c:a copy -shortest -c:v libx264 C :/temp/VideoOut/output.mp4

  


  But the generated mp4 file has 1 minute's of empty space after the audio finished.

  


  Actually I have multiple audio files, and after the conversion, every video has that 1 minute empty space.

  


  Any idea how to solve this ? Thanks a lot.