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• Parsing avconv/ffmpeg rawvideo output ?

  23 avril 2013, par DigitalMan

  I'm about to begin a project that will involve working with the output of avconv/ffmpeg, pixel-by-pixel, in rgb32 format. I intend to work with a raw byte stream, such as from the pipe protocol. Basic pointer arithmetic (C/C++) will be used to iterate over these pixels, and modify them in arbitrary manners in real-time.

  I've created a very small file using rawvideo format and codec, and opened it up in a hex editor. As expected, it's just a series of pixels, read right to left, top to bottom. No distinguishing between lines - no problem, if you know how wide the video is beforehand. No distinguishing between frames - no problem, if you also know how tall the video is. No file header for frame rate, or even what the encoding (rgb32, rgb24, yuv, etc.) is - again, as long as you already know, it can be worked with.

  The problem occurs when - for one reason or another - some bytes are missing. Maybe the stream isn't being examined from the beginning, which is likely be the case in my project, or maybe something just got lost. All the pre-existing knowledge in the world (besides maybe a byte count of what's been missed, not gonna happen) won't prevent it from happily chugging along, with an incorrect offset of line and frame.

  So, what I'm looking for is an option for rawvideo, or possibly some other format/codec, that will allow me to work with the resulting stream at the pixel level, in RGB, yet still have a clear definition of where a new frame begins, even if it happens to start "looking" in the middle of a frame. (Width, height, and framerate will indeed be known.)

• Can we declare a variable in ffmpeg ffprobe

  16 avril 2020, par ilham zacky

  I am new to ffmpeg.

  



  I want to get a video duration through ffmpeg and declare it to a variable. where I can use the value for a different function. I am using power shell.

  



  This is my code :

  



  ffmpeg -i 1aef53e6-92ac-4d28-89f8-4cce28fa0f58.mp4 2>&1 | sed -n 's/Duration: \(.*\), start/\1/gp'


  


• Multiple outputs from same source

  28 septembre 2021, par Christian R

  How do I modify this ffmpeg string to generate multiple outputs with different video bitrates ?
This to save time when yadif=1 take a lot of power. Also, can't get it to accept yadif_cuda in windows.

  


  ffmpeg -y -f lavfi -i anullsrc=cl=mono:sample_rate=48000 -i "test.mxf" -vf yadif=1 -s 1920:1080 -c:v h264_nvenc -force_key_frames "expr:gte(t,n_forced*10)" -pix_fmt yuv420p -preset slow -rc vbr_hq -b:v 4.5M -map 1:v -map 0:a -c:a aac -b:a 192k -shortest "test.mp4"