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--- ffmpeg:conversions:convert_h265_to_h264 [2023/06/13 10:47] – created peter
+++ ffmpeg:conversions:convert_h265_to_h264 [2023/06/13 10:56] (current) – peter
@@ Line 1: / Line 1: @@
 ====== ffmpeg - Conversions - Convert H265 to H264 ======
+===== Software Encoding =====
+==== Using ffmpeg ====
+<code bash>
+ffmpeg -i input.mkv -c copy output.mp4
+</code>
+----
+===== Matroska output =====
+<code bash>
+mkdir h264vids
+for f in *.mp4; do ffmpeg -i "$f" -map 0 -c copy -c:v libx264 -crf 23 -preset medium h264vids/"${f%.*}.mkv"; done
+</code>
+  * Will output to a directory named h264vids.
+  * Assumes your inputs are .mp4.  If not, change the .mp4 instance in the example to your input file type, or just use the greedy * by itself.
+  * Adjust -crf for quality and -preset for encoding speed/efficiency.  Or just remove these options and use the defaults which are fairly good and should suffice for most (the example is using the default values for these options).
+See [[https://trac.ffmpeg.org/wiki/Encode/H.264|FFmpeg Wiki: H.264]] for more info on these options.
+----
+===== MP4 output =====
+This example is a little more complicated.
+This will perform conditional encoding depending if the input audio is AAC or not.
+If the input audio is AAC then the audio will be stream copied (re-muxed) as is and needless re-encoding is avoided.
+If the input audio is not AAC then it will be re-encoded to AAC.
+<code bash>
+#!/bin/bash
+mkdir h264vids
+for f in *.mkv
+do
+  audioformat=$(ffprobe -loglevel error -select_streams a:0 -show_entries stream=codec_name -of default=nw=1:nk=1 "$f")
+  if [ "$audioformat" = "aac" ]; then
+    ffmpeg -i "$f" -c:v libx264 -crf 23 -preset medium -c:a copy -movflags +faststart h264vids/"${f%.*}.mp4"
+  else
+    ffmpeg -i "$f" -c:v libx264 -crf 23 -preset medium -c:a aac -movflags +faststart h264vids/"${f%.*}.mp4"
+  fi
+done
+</code>
+  * Will output to a directory named h264vids.
+  * Assumes your inputs are .mkv.  If not, change the .mkv instance in the example to your input file type, or just use the greedy * by itself.
+  * See note above regarding -crf and -preset.
+  * You can pause the encoding with ctrl+z and resume with fg.
+----
+===== Using ffmpeg =====
+<code bash>
+for file in *265.mkv; do nice -n19 ffmpeg -i $file -c copy -c:v libx264 ${file/%265.mkv/264.mkv}; done
+</code>
+  * Assumes that the files have always a name ending in 265.mkv.
+  * This ending will be replaced with 264.mkv.
+----
+===== Using libav =====
+<code bash>
+sudo apt-get install libav-tools
+avconv -i oldvideo.mkv -ar 22050 convertedvideo.mp4
+</code>