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• Read and check the duration of small mp4 files in a directory then concatenate into 3 mins each then assign a unique name in BASH

  23 septembre 2020, par super_nooba

  OS : Darwin Kernel Version 19.6.0

  


  Step 1 : Scan all the files until it reaches 3 mins of duration

  


  for f in *.mp4; 
do ffmpeg -i "$f" 2>&1 | grep "Duration" \
   | grep -o " [0-9:.]*, " | head -n1 | tr ',' ' ' \
   | awk -F: '{ print ($1 * 3600) + ($2 * 60) + $3 }')


  


  How do I assign a variable or loop until it reaches the combination of different videos until 3 mins minimum and 4 mins max ?

  


  Step 2 : Concatenate and assign a unique name when 3 mins is reached

  


  ffmpeg -i concat $f


  


  Step 3 : Resize to 1080p and fit to screen (spatial conform to fit)

  


  Step 4 : Continue until all the files have been concatenated

  


• FFMPEG width not divisible by 2 (639x360)

  5 octobre 2020, par yasgur99

  I am using python wrapper command of ffmepeg. I followed the tutorial from here for a "Production ready HLS" : https://docs.peer5.com/guides/production-ready-hls-vod/

  


  This is my code :

  


   subprocess.call(['ffmpeg', '-y', '-i', download_path,
                     '-vf', 'scale=w=640:h=360:force_original_aspect_ratio=decrease', \
                     '-c:a', 'aac', '-ar', '48000', '-c:v', 'h264', \
                     '-profile:v', 'main', '-crf', '20', '-sc_threshold', '0', \
                     '-g', '48', '-keyint_min', '48', '-hls_time', '4', \
                     '-hls_playlist_type', 'vod',  '-b:v', '800k', \
                     '-maxrate', '856k', '-bufsize', '1200k', '-b:a', '96k', \
                     '-hls_segment_filename', upload_path + \
                     '/360p_%03d.ts', upload_path + '/360p.m3u8', \
                     '-vf', 'scale=w=842:h=480:force_original_aspect_ratio=decrease', \
                     '-c:a', 'aac', '-ar', '48000', '-c:v', 'h264', \
                     '-profile:v', 'main', '-crf', '20', '-sc_threshold', '0', \
                     '-g', '48', '-keyint_min', '48', '-hls_time', '4', \
                     '-hls_playlist_type', 'vod', '-b:v', '1400k', \
                     '-maxrate', '1498k', '-bufsize', '2100k', '-b:a', '128k', \
                     '-hls_segment_filename', upload_path + \
                     '/480p_%03d.ts', upload_path + '/480p.m3u8', \
                     '-vf', 'scale=w=1280:h=720:force_original_aspect_ratio=decrease', \
                     '-c:a', 'aac', '-ar', '48000', '-c:v', 'h264', \
                     '-profile:v', 'main', '-crf', '20', '-sc_threshold', '0', \
                     '-g', '48', '-keyint_min', '48', '-hls_time', '4', \
                     '-hls_playlist_type', 'vod', '-b:v', '2800k', \
                     '-maxrate', '2996k', '-bufsize', '4200k', '-b:a', '128k', \
                     '-hls_segment_filename', upload_path + \
                     '/720p_%03d.ts', upload_path + '/720p.m3u8', \
                     '-vf', 'scale=w=1920:h=1080:force_original_aspect_ratio=decrease', \
                     '-c:a', 'aac', '-ar', '48000', '-c:v', 'h264', \
                     '-profile:v', 'main', '-crf', '20', '-sc_threshold', '0', \
                     '-g', '48', '-keyint_min', '48', '-hls_time', '4', \
                     '-hls_playlist_type', 'vod', '-b:v', '5000k', \
                     '-maxrate', '5350k', '-bufsize', '7500k', '-b:a', '192k', \
                     '-hls_segment_filename', upload_path + '/1080p_%03d.ts', upload_path + '/1080p.m3u8'])


  


  And getting this output

  


  [libx264 @ 0x7fb95500c800] width not divisible by 2 (639x360)
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height


  


  Any ideas of whats going wrong ?

  


• What ffmpeg arguments will approximate Zoom recording quality [closed]

  25 octobre 2020, par Stan Ivanov

  I've been recording screen sharing presentations using Quicktime on my Mac and it uses x264 format with 60fps. The produced video file is with type MOV and around 2.2GB for 1 hour of presentation. I want to compress it using ffmpeg and I've been doing so using x264 as well. Here are my arguments :

  


  ffmpeg -i '$inputFile' -vcodec "libx264" -crf 32 -vf 'scale=${width}:-2,fps=24' -c:a aac -b:a 128k -preset veryslow -profile:v high -tune stillimage -f mp4 '$outputFile'


  


  I rescale my video to 1600px width to save on space and I also convert the recording to 24fps as I see no need to have the full 60fps available. It's mostly static images as I talk over my screen. This results in about 100MB file using the -profile:v high argument. Otherwise it is around 160MB.

  


  On the other hand Zoom recording for much larger resolutions (4k etc) are around 80MB per 1 hour. Does anyone know what options we can use to approximate this file size and quality ? I know they are using lower quality audio which might explain some of the difference.

  


  But if I increase the -crf 32 argument it starts to degrade quality too much. I am not sure how Zoom achieves it's video quality with high resolutions such as 1080p and 4k with a file size of 80MB while I can't match it using 1600px width.

  


  Edit : I had an idea that I probably don't need all 24 fps in a screen sharing of static content. So I reduced it to 5 fps and that seems to work well for my use case. I wonder if this is what Zoom does ?