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• Output file not specified [closed]

  16 mai 2024, par Rich Madrid

  I have been messing around with ffmpeg working on basic mkv to mp4 conversions the last couple of days on my Mac and Windows computers. Mac was easier buy my windows desktop has a much faster OS so I wanted to do some conversions on it tonight. Got ffmpeg installed and working.

  


  After having some issues with the command prompt not finding the directory, I solved that with the following basic code to convert an mkv file to an mp4 for me :

  


  ffmpeg -i "C:\Users\Computer\videos\decade.mkv" "C:\Users\Computer\Videos\RJ videos\Complete\decade.mp4"


  


  I moved on to wanting to scale up an mkv to 1080p and use a yadif filter. I couldn’t find an adequate way to do this so I used a portion of the command that worked on my Mac last night, and stuffed it into the command for windows and I got an error code “at least one output file must be specified” after using the following command :

  


  ffmpeg -i "C:\Users\Computer\videos\decade.mkv" -vf "yadif=1,scale=1440x1080:flags=lanczos,setsar=1" -c:v libx264 -crf 21
-c:a aac -b:a 128k -ar 48k "C:\Users\Computer\Videos\RJ videos\Complete\decade.mp4"


  


  What am I doing wrong ?

  


• How to stream an image during specific seconds with ffmpeg ?

  14 juillet 2021, par Alex Rypun

  I need to stream an image to RTMP destination for 20 seconds.
I use AWS medialive + mediapackage for streaming.
I'm trying to do it using different framerates (-r) by command :

  


  ffmpeg -loop 1 -r 30 -t 20 -i ./stream_stub.jpg -vcodec libx264 -f flv rtmp://mystream


  


  but the real stream time is from 8 to 14 seconds (depending on framerate).

  


  If I create a video file the duration is 20 seconds (as expected) regardless of framerate :

  


  ffmpeg -loop 1 -r 30 -t 20 -i ./stream_stub.jpg -vcodec libx264 -f flv out.mp4


  


  But for live streaming, I can't reach the expected behavior.

  


  What I'm doing wrong ? And what framerate should I use for a single still image (as I understand 1 fps should be ok) ?

  


• 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.)