How to generate an MP4 with H.265 codec using FFmpeg?

Background

FFmpeg supports encoding HEVC/H.265 since 2014-2-12 with libx265. Now you can use ffmpeg directly to encode HEVC or use another encoder then manually mux that into .mp4, .mov, or .mkv using FFmpeg.

Available Encoders

Current H.265/HEVC encoders are:

• MulticoreWare x265
• Chinese x265
• DivX HEVC Encoder
• Kvazaar

Only the MulticoreWare and DivX are suggested because of their development time and reliability.

Two x265's

One confusion is that there are two independent projects both named "x265", one by a Chinese college student and is practically dead, and another by a commercial company called MulticoreWare. Although the former started out first, it is practically dead now, and the latter is under active development and is endorsed by VideoLAN (the developer of x264).

Timeline of FFmpeg HEVC Encoding Support

• 2013-10-12 .mov muxing support added in 53f903b.
• 2014-02-12 libx265 encoding support added in bb6b173.
• 2014-03-09 More complete Matroska muxing support for HEVC added in 38aee64.
• 2014-03-09 More complete .mov and new .mp4 muxing support added in 9563e67.

tl;dr

Anyways, these are a complete set of current possibilities of encoding HEVC in order of my recommendation:

• Directly using MulticoreWare libx265 with FFmpeg. This means with the latest Zeranoe build you can now do this:

  ffmpeg -i INPUT -c:v libx265 -an -x265-params crf=25 OUT.mov
  # With audio
  ffmpeg -i INPUT -c:v libx265 -c:a copy -x265-params crf=25 OUT.mov
  

  Note: FFmpeg builds newer than 2014-03-09 allows you to mux HEVC into .mp4 files now (commit 9563e67):

  ffmpeg -i INPUT -c:v libx265 -an -x265-params crf=25 OUT.mp4
  

  You can also mux it in Matroska (.mkv):

  ffmpeg -i INPUT -c:v libx265 -an -x265-params crf=25 OUT.mkv
  

• Using standalone MulticoreWare x265 and then mux the resulting file with FFmpeg or MP4Box. This will work with older FFmpeg builds that don't have libx265 support.

  # Decode input using FFmpeg and encode using x265 using pipe
  ffmpeg -i INPUT -f yuv4mpegpipe -pix_fmt yuv420p - | \
  x265 --y4m -o encoded.265 -
  
  # Mux the resulting encoded .265 file into an .mp4 or .mov
  
  # Using ffmpeg: only works with newer builds that support muxing HEVC
  # Muxing to .mp4 supported since 03-09-2014
  ffmpeg -i encoded.265 -c copy out.mp4
  # With audio
  ffmpeg -i encoded.265 -i INPUT -map 0 -map 1:a -c copy out.mp4
  
  # Using MP4Box
  MP4Box -add raw.265 out.mp4
  # With audio
  MP4Box -add {INPUT}#audio -add raw.265 out.mp4
  

  Thanks to @Duvrai.

• Using DivX HEVC Encoder and then mux it.

  The way of using it is similar to using standalone x265 (see above).

Update: FFmpeg has HEVC encoding support using MulticoreWare libx265 now.

Update 2: FFmpeg now has support for muxing HEVC into mp4 AND mov now.

ffmpeg added x265 encoding on 12 February 2014, and mp4 container support on 9 March:

ffmpeg -i input -c:v libx265 -c:a copy output.mp4

Note:

• The above command will copy the audio in it's original codec. If that doesn't work, convert the audio to AAC by omitting -c:a copy (or replace copy with aac, libfdk_aac or libfaac — ordered quality-wise)
• when compiling ffmpeg use --enable-libx265 (and --enable-libfdk-aac or --enable-libfaac if needed)