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--- utils_video_encoding [2020/06/14 18:34]
xavier created
+++ utils_video_encoding [2020/06/18 16:19] (current)
xavier
@@ Line 1: / Line 1: @@
-====== Video compression commands and explanations ======
+====== Video encoding (ffmpeg) commands and explanations ======
+===== Compress video stream =====
 Compression without important video quality loss (tested with relatively low quality full HD source):\\
 ''$ ffmpeg -i input -vcodec libx265 -crf 24 output''\\
-==> crf is the compression factor. Lower is better, 24 is about as low as is useful for libx265\\
+=> -crf is the compression factor. Lower is better, 24 is about as low as is useful for libx265\\
+=> -map 0 to keep all streams (audio, subtitles, but also video)\\
+=> Use -vf scale=-1:720 to resize to 720p (keeping aspect ratio with -1, resulting in calculation of width)\\
+===== Select language streams =====
+Do not re-encode streams, keep all subtitles and select English and French audio languages:\\
+''$ ffmpeg -i input -map 0:v -map 0:s -map 0:m:language:eng -map 0:m:language:fre? -c copy output''\\
+=> -c copy to avoid re-encoding streams\\
+=> -map:0:v to keep all video streams\\
+=> -map 0:s to keel all subtitle streams\\
+=> -map 0:m:language:eng to keep streams with english metadata defined (all types of streams but impacting only audio (a) since we're keeping all subtitles in this case)\\
+=> the ? at the end of -map instruction avoids failure if the matching input is missing\\
+===== Script examples =====

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