[Transcode h265] Use ffmpeg to transcode a video to h.265 / hvc1 which will play natively on a Mac (and Linux). #tags: video, python, ffmpeg

readme.md

Transcode Video to h.265

Links

• How to generate an MP4 with H.265 codec using FFmpeg?
• H.265 HEVC support in High Sierra
• Converting WebM to MP4 Using FFmpeg

What seems to work

ffmpeg -i <input.???> -c:v libx265 -c:a aac -crf 25 -tag:v hvc1 <output.h265.mp4>

Note the need for the -tag:v hvc1 (see H.265 HEVC support in High Sierra for details). Without the tag, VLC opens the video with out issue, but QuickTime Player does not. The tag fixes the issue with QuickTime.

Probe codecs used

• Is there a way to use ffmpeg to determine the encoding of a file before transcoding?

Get audio encoder

ffprobe -v error -select_streams a:0 -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 input.mp4

Get video encoder

ffprobe -v error -select_streams v:0 -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 input.mp4

Copy audio

ffmpeg -i <infile> -c:v libx265 -crf 28 -c:a copy -tag:v hvc1 -preset slow <outfile>

Transcode audio

ffmpeg -i <infile> -c:v libx265 -crf 28 -c:a aac -b:a 128k -tag:v hvc1 -preset slow <outfile>

Example

Transcode a folder of AVI files:

for filename in *.avi; do
	ffmpeg -i $filename -c:v libx265 -crf 28 -c:a aac -b:a 128k -tag:v hvc1 -preset slow "${filename%.*}.hvc1.mp4"
done

Smart conversion

Avoid converting videos already encoded as HVC1.

for filename in *.{avi,mpeg,mp4,webm}; do
  # Get codecs
  video_codec=$(ffprobe -v error -select_streams 'v:0' -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 "${filename}")
  audio_codec=$(ffprobe -v error -select_streams 'a:0' -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 "${filename}")

  if [ "$video_codec" = "hevc" ]; then
      echo "Skipping (already HVC1): ${filename}"
  else
      #video_opts="-c:v libx265 -crf 28 -tag:v hvc1 -preset slow"
      if [ "$audio_codec" = "aac" ]; then
          #audio_opts="-c:a copy"
          ffmpeg -i "${filename}" -c:v libx265 -crf 28 -tag:v hvc1 -preset slow -c:a copy "${filename%.*}.hvc1.mp4"
      else
          #audio_opts="-c:a aac -b:a 128k"
          ffmpeg -i "${filename}" -c:v libx265 -crf 28 -tag:v hvc1 -preset slow -c:a aac -b:a 128k "${filename%.*}.hvc1.mp4"
      fi
  fi
done

Links

• FFmpeg and H.265 Encoding Guide

transcode_h265.py

'''
Transcode videos to H265 / hvc1.  Skip any file which is already h265 encoded.

https://trac.ffmpeg.org/wiki/Encode/H.265
'''

import os
import sys
import json
from subprocess import call, check_output

def get_codec(filepath, channel='v:0'):
    ''' Return the codec and codec-tag for a given channel '''

    output = check_output(['ffprobe', '-v', 'error', '-select_streams', channel,
                            '-show_entries', 'stream=codec_name,codec_tag_string', '-of', 
                            'default=nokey=1:noprint_wrappers=1', filepath])

    return output.decode('utf-8').split()

for filepath in sys.argv[1:]:

    basefilepath, extension = os.path.splitext(filepath)

    output_filepath = basefilepath + '.hvc1' + '.mp4'

    assert(output_filepath != filepath)

    if os.path.isfile(output_filepath):
        print('Skipping "{}": file already exists'.format(output_filepath))
        continue
    
    print(filepath)

    # Get the video channel codec
    video_codec = get_codec(filepath, channel='v:0')

    if video_codec == []:
        print('Skipping: no video codec reported')
        continue

    # Video transcode options
    if video_codec[0] == 'hevc':
        if video_codec[1] == 'hvc1':
            print('Skipping: already h265 / hvc1')
            continue
        else:
            # Copy stream to hvc1
            video_opts = '-c:v copy -tag:v hvc1'
    else:
        # Transcode to h265 / hvc1
        video_opts = '-c:v libx265 -crf 28 -tag:v hvc1 -preset slow -threads 8'

    # Get the audio channel codec
    audio_codec = get_codec(filepath, channel='a:0')

    if audio_codec == []:
        audio_opts = ''
    elif audio_codec[0] == 'aac':
        audio_opts = '-c:a copy'
    else:
        audio_opts = '-c:a aac -b:a 128k'

    call(['ffmpeg', '-i', filepath] + video_opts.split() + audio_opts.split() + [output_filepath])