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• Use ffmpeg to downscale, tonemap, downmix and re encode mkv

  1er février 2021, par nikartz

  I try to use ffmpeg to downscale a 4k and tonemap a 4k HDR mkv to a 1080p SDR mkv with this code :

  


  ffmpeg -i "Input.mkv" -vf zscale=t=linear:npl=100,format=gbrpf32le,zscale=p=bt709,tonemap=tonemap=hable:desat=0,zscale=t=bt709:m=bt709:r=tv,format=yuv420p -c:v hevc_nvenc -b:v 12M -preset slow "Output.mkv"


  


  The problem is, that only the first audio track (of four) is copied to the new mkv and the subtitle tracks are missing :

  


  Input :

  


  Stream #0:0: Video: hevc (Main 10), yuv420p10le(tv, bt2020nc/bt2020/smpte2084), 3840x2160 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 23.98 tbc (default)
Stream #0:1(ger): Audio: eac3, 48000 Hz, 7.1, fltp (default)
Stream #0:2(ger): Audio: dts (DTS-HD MA), 48000 Hz, 7.1, s16p
Stream #0:3(eng): Audio: truehd, 48000 Hz, 7.1, s32 (24 bit)
Stream #0:4(eng): Audio: ac3, 48000 Hz, 5.1(side), fltp, 640 kb/s
Stream #0:5(ger): Subtitle: subrip (default) (forced)
Stream #0:6(ger): Subtitle: dvd_subtitle, 1920x1080 (forced)
Stream #0:7(ger): Subtitle: hdmv_pgs_subtitle, 1920x1080 (forced)
Stream #0:8(ger): Subtitle: dvd_subtitle, 1920x1080
Stream #0:9(ger): Subtitle: hdmv_pgs_subtitle
Stream #0:10(eng): Subtitle: dvd_subtitle, 1920x1080
Stream #0:11(eng): Subtitle: hdmv_pgs_subtitle


  


  Output :

  


  Stream #0:0: Video: hevc (Main), yuv420p(tv), 3840x2160 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 23.98 tbc (default)
Stream #0:1(ger): Audio: vorbis, 48000 Hz, 7.1, fltp (default)
Stream #0:2(ger): Subtitle: ass (default) (forced)


  


  I would like to have an mkv as output converts all the audio tracks to aac Stereo (but keeps all four of them), copies the subtitle tracks and tonemaps/downscales the video track.

  


  I have tried to use the -map 0 or -map 0:a:0 -map 0:a:1 ... commands (and some similiar to those, however I seemingly end up with either one audio track, no video track or a video track that is just copied.

  


  I possible, I would also like to use nvenc with a high quality preset, which is the reason for -c:v hevc_nvenc -b:v 12M -preset slow in my command, however I have no idea, if this is done right, since the ouput mkv also as a 4k video track instead of a 1080p. Maybe this is caused by the -c:v because it overrides -vf ? Sorry, I am feeling dumb and am just getting started with ffmpeg.

  


  There is so much information about ffmpeg out there, but it is either too complicated for me, or not answering my questions.

  


  Thanks for your help !

  


• sbc : do not set sample format in parser

  5 janvier 2021, par Arnaud Vrac

  sbc : do not set sample format in parser
  Commit bdd31feec934 changed the SBC decoder to only set the output
  
  sample format on init, instead of setting it explicitly on each frame,
  
  which is correct. But the SBC parser overrides the sample format to S16,
  
  which triggers a crash when combining the parser and the decoder.
  Fix the issue by not setting the sample format anymore in the parser,
  
  which is wrong.
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/sbc_parser.c

• avcodec/[e]ac3enc : Make encoders init-threadsafe, fix race

  3 décembre 2020, par Andreas Rheinhardt

  avcodec/[e]ac3enc : Make encoders init-threadsafe, fix race
  ff_eac3_exponent_init() set values twice when initializing a static
  
  table ; ergo the initialization code must not run concurrently with
  
  a running EAC-3 encoder. Yet this code is executed every time an EAC-3
  
  encoder is initialized. So use ff_thread_once() for this and also for a
  
  similar initialization performed for all AC-3 encoders to make them all
  
  init-threadsafe.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/ac3enc.c
  • [DH] libavcodec/ac3enc_fixed.c
  • [DH] libavcodec/ac3enc_float.c
  • [DH] libavcodec/eac3enc.c