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How does FFmpeg change the aspect ratio of a video?
For reasons not completely understood, FFMPEG monkeys around with the Sample/Pixel Aspect Ratio to turn the video back to the original aspect ratio. For instance, if you stretch the video out twice as wide, it will make the aspect ratio 1:2, or something similar (2:1?)
How to concatenate multiple videos while using FFmpeg?
Example for 1280×720: If you would rather crop instead of pad and/or avoid upscaling see examples in Resizing videos with ffmpeg to fit specific size. As for “original quality” you would have to use a lossless encoder, not a lossy encoder. Add -crf 0 to enable lossless when encoding with libx264, but note the files will be huge.
How to concatenate multiple videos while maintaining original aspect ratio?
How to concatenate multiple videos while maintaining original aspect ratio? Is it possible to concatenate many videos with different aspect ratio? So in the end every video segment maintains the original aspect ratio. I’m using unsafe=1 which works almost perfect. The only issue is that some videos stretch.
What happens if you use unsafe mode in FFmpeg?
Without unsafe it will fail if segments have a different format or vary in some attributes, but with unsafe it will not fail but the resulting output may not be compatible or playable with your player or device. Thanks for contributing an answer to Video Production Stack Exchange!
What should the parameter size be for FFmpeg?
The parameter -s [size] is the size of the output video, in pixels, for the HD file you probably want something around 1280×720, if your material is 5:4 ratio (as 360×288 is) you’ll want to try 1280×1024, 960×768 or 900×720.
How to do 2 pass encode in FFmpeg?
Do a 2-pass encode, link. If you don’t want to read all the documentation for ffmpeg and the codec parameters that you need I suggest you look at this cheat sheet, although the command line switches have changed over the different versions of ffmpeg so the examples might not work.
How to set the audio bitrate in FFmpeg?
Bitrate is specified in bits/s (unless you are using a very old ffmpeg), and 200 bps is not usable for anything, add k to get kilobits/s. You have not specified an audio codec, but you have specified an audio bitrate, ffmpeg will try to guess the audio codec for you but I don’t know what codec is the default for .flv-files.
Can you change the SAR without reencoding in FFmpeg?
To do this, try: Changing the SAR without reencoding also works with ffmpeg on .mp4 using the h264_metadata as Gyan pointed out here: Delgado’s answer is correct that MP4Box can do this, but the -par option doesn’t work quite as described.
How do I change frame size, preserving width ( using FFmpeg?
It ends up at 608×406 or thereabouts. I’ve been playing with various GUI versions of FFmpeg today, and they seem to do the same thing. What would be the proper options/parameters to pass in (assuming I’ll have more control via the command line) to achieve the desired frame size? using the scale filter will do it, but there is a bit more to it.
How to scale overlay image in FFmpeg Stack Overflow?
For example, PAL SD broadcast (stored in 720×576 pixels, SAR=5:4) is usually displayed using 16:9 DAR, thus would be resized upon playback to 1024×576 to keep DAR. So if you overlay 320×240 image on such video, its display size would then be 455×240 and it would look stretched.