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• Video to image sequence export (preserving color range)

  20 août 2017, par Floating Point

  When I convert the material which is in legal range (tv) to prores, legal range is preserved, but when I export it to image sequence (tiff), I get files which are already in full range, although I try to preserver the original values with -vf "zscale=rin=limited:r=limited".

  Is ffmpeg automatically changes color range when exporting to images ?

• How to add escape characters to a filename to be consumed later by a shell command ?

  9 mars 2023, par nhershy

  I am trying to find out which of my video files are corrupted. I loop through a directory, grab each video file, and check if it is corrupt/healthy. If the filename has no spaces nor special characters, it will work. Unfortunately, many of my files have spaces or parenthesis in the name, and this causes my shell command ffmpeg within my python script to fail. How can I retrieve the filenames in abs_file_path with the escape characters preceding the special characters ?

  


  Example filename : Movie Name (1080p)

  


  Goal : Movie\ Name\ \(1080p\)

  


  for filename in os.listdir(directory):
    if filename.endswith(tuple(VIDEO_EXTENSIONS)):
        print(f'PROCESSING: {filename}...')

        abs_file_path = os.path.join(directory, filename)

        proc = subprocess.Popen(f'./ffmpeg -v error -i {abs_file_path} -f null - 2>&1', shell=True, stdout=subprocess.PIPE)
        output = proc.communicate()[0]

        row = ''
        if not output:
            # Healthy
            print("\033[92m{0}\033[00m".format("HEALTHY -> {}".format(filename)), end='\n')  # red
            row = [filename, 0]
        else:
            # Corrupt
            print("\033[31m{0}\033[00m".format("CORRUPTED -> {}".format(filename)), end='\n')  # red
            row = [filename, 1]

        results_file_writer.writerow(row)
        results_file.flush()

results_file.flush()
results_file.close()


  


• 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.