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• Realtime removal of carriage return in shell

  1er mai 2013, par Seth

  For context, I'm attempting to create a shell script that simplifies the realtime console output of ffmpeg, only displaying the current frame being encoded. My end goal is to use this information in some sort of progress indicator for batch processing.

  For those unfamiliar with ffmpeg's output, it outputs encoded video information to stdout and console information to stderr. Also, when it actually gets to displaying encode information, it uses carriage returns to keep the console screen from filling up. This makes it impossible to simply use grep and awk to capture the appropriate line and frame information.

  The first thing I've tried is replacing the carriage returns using tr :

  $ ffmpeg -i "ScreeningSchedule-1.mov" -y "test.mp4" 2>&1 | tr '\r' '\n'

  This works in that it displays realtime output to the console. However, if I then pipe that information to grep or awk or anything else, tr's output is buffered and is no longer realtime. For example : $ ffmpeg -i "ScreeningSchedule-1.mov" -y "test.mp4" 2>&1 | tr '\r' '\n'>log.txt results in a file that is immediately filled with some information, then 5-10 secs later, more lines get dropped into the log file.

  At first I thought sed would be great for this : $ # ffmpeg -i "ScreeningSchedule-1.mov" -y "test.mp4" 2>&1 | sed 's/\\r/\\n/', but it gets to the line with all the carriage returns and waits until the processing has finished before it attempts to do anything. I assume this is because sed works on a line-by-line basis and needs the whole line to have completed before it does anything else, and then it doesn't replace the carriage returns anyway. I've tried various different regex's for the carriage return and new line, and have yet to find a solution that replaces the carriage return. I'm running OSX 10.6.8, so I am using BSD sed, which might account for that.

  I have also attempted to write the information to a log file and use tail -f to read it back, but I still run into the issue of replacing carriage returns in realtime.

  I have seen that there are solutions for this in python and perl, however, I'm reluctant to go that route immediately. First, I don't know python or perl. Second, I have a completely functional batch processing shell application that I would need to either port or figure out how to integrate with python/perl. Probably not hard, but not what I want to get into unless I absolutely have to. So I'm looking for a shell solution, preferably bash, but any of the OSX shells would be fine.

  And if what I want is simply not doable, well I guess I'll cross that bridge when I get there.

• how to scale server setup with ffmpeg for converting videos on website

  26 mai 2020, par Tom

  I have a website that will offer video conversion service with ffmpeg. Users will select some options and click a button to process and create a video. The site is currently using laravel/php. If there are many requests at the same time, how should I handle the scaling up ? How can it be done with traditional ISP ? How about cloud service, e.g. Amazon, Digital Ocean ?

  


• ffmpeg extract multiple frames from single input

  10 octobre 2023, par Andrew Still

  I'm trying to dynamically extract multiple different frames from single video input. So the command I'm calling looking like this

  


  ffmpeg -loglevel debug -hide_banner -t 13.269541 -y -ss 0 -i "input-s3-url" -ss 13.269541 -i "same-input-s3-url" -map 0:v -vframes 1 /tmp/ca4cd7a3159743938c5362c171ea2cae.0.png -map 1:v -vframes 1 /tmp/ca4cd7a3159743938c5362c171ea2cae.13.269541.png


  


  It works and everything is good, until I deploy it to lambda. Even though I'm using 10gb of RAM it still failing with error. Locally it works like a charm but not on lambda. I'm not sure what the problem here but i'm regularly (not always) getting SIGSEGV

  


  

  


  Double-checked memory usage and it's doesn't look like a reason, but I'm not sure how correct this number

  


  

  


  I'm think maybe it's because it's making requests for each input, at least that's what I saw in debug mode, but still have no idea what's the problem here, would appreciate any suggestions/optimizations/help. Thanks

  


  ffmpeg added on lambda using this layer - https://serverlessrepo.aws.amazon.com/applications/us-east-1/145266761615/ffmpeg-lambda-layer