How to use FFmpeg to convert flv files to mp4 format

ffmpeg -i input.flv -c:v libx264 -c:a aac -strict -2 output.mp4

explain:

• -i input.flv : Specifies the input file.
• -c:v libx264: The video codec uses the x264 library.
• -c:a aac: The audio codec uses the AAC encoder.
• -strict -2: Make sure the AAC encoder uses low-latency mode.
• output.mp4: The name and format of the output file.

If you need to change the size or quality of the output file, you can use  -b:v the and  -crf flags. Here is an example:

ffmpeg -i input.flv -c:v libx264 -b:v 500k -crf 23 -c:a aac -strict -2 output.mp4

• -b:v 500k: The video bit rate is 500Kbps.
• -crf 23: Video compression quality, 23 is medium quality. Higher numbers mean worse quality but smaller file size, lower numbers mean better quality but larger file size.