If you want to re-encode, see FFmpeg Wiki: H.264 Encoding Guide. With -c copy the streams will be stream copied, not re-encoded, so there will be no quality loss.To copy the video from in0.mp4 and audio from in1.mp4: ffmpeg -i in0.mp4 -i in1.mp4 -c copy -map 0:0 -map 1:1 -shortest out.mp4 For high quality video and audio, read the x264 Encoding Guide and the AAC Encoding Guide, respectively.įor example: ffmpeg -ss -i in.mp4 -t -c:v libx264 -c:a aac -strict If you leave out the -c copy option, ffmpeg will automatically re-encode the output video and audio according to the format you chose. This won't harm the quality and make the command run within seconds. -c copy copies the first video, audio, and subtitle bitstream from the input to the output file without re-encoding them.Recent ffmpeg also has a flag to supply the end time with -to.-t specifies the duration of the clip (same format).Without re-encoding: ffmpeg -ss -i in.mp4 -t -c copy out.mp4 Additional info: ffmpeg -i in.mp4 -preset slower -crf 18 out.mp4 Use the preset parameter to control the speed of the compression process. The default value is 23, and visually lossless compression corresponds to -crf 18.
The lower crf, the higher the quality (range: 0-51). Use the crf (Constant Rate Factor) parameter to control the output quality. Remux an MKV file into MP4 ffmpeg -i in.mkv -c:v copy -c:a copy out.mp4 A list of useful commands for the ffmpeg command line tool.įull documentation: Basic conversion ffmpeg -i in.mp4 out.avi
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