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• faster way to downmix 5.1 videos to stereo ?

  22 octobre 2020, par alex hansen

  I have a hand full of movies that are all in 5.1 audio, i need there to be one audio track that is only in stereo. i have found a few suggestions as to how to do this but some dont work for me and others are way too slow.

  


  the one i found that works the fastest is this :

  


  ffmpeg -y -i "input" -map 0:v -c:v copy -map 0:a:0? -c:a:0 copy -map 0:a:0? -c:a:1 aac -ac 2 -metadata:s:a:1 title="Eng 2.0 Stereo" -map 0:a:1? -c:a:2 copy -map 0:a:2? -c:a:3 copy -map 0:a:3? -c:a:4 copy -map 0:a:4? -c:a:5 copy -map 0:a:5? -c:a:6 copy -map 0:a:6? -c:a:7 copy -map 0:s? -c:s copy "output"   


  


  sadly i do not remember where it came from.

  


  the problem with this being that it creates a separate audio track, and for my purposes this does not work.

  


  doing just the standard -ac 2 works but is way to slow, i estimated to take over 40 hours to go through all my movies.

  


  edit :
a bit of extra information to throw in here

  


  

  • all the movies are mp4's

  


  • all except 2 movies are 5.1 audio (there is 1 7.1 and 1 mono. i dont really care about them tho)

  


  • the command i posted runs at about a 40x speed while just doing -ac 4 runs at 2x speed

  


  


• MXF To dash conversion using FFMPEG

  17 septembre 2020, par user726720

  I'm trying to convert a mxf to dash using FFMPEG. But when i do so the dash file doesnt play in VLC. I have a working dash file (got sample from some website), so i'm sure my VLC seems to work fine and can read dash.

  


  ffmpeg -re -i "XXX-05763.mxf" -pix_fmt yuv420p -map 1:v -map 0:v -map 0:a  -c:a aac -c:v libx264 -use_template 1 -use_timeline 1 -init_seg_name "init-stream$RepresentationID$-$Bandwidth$.mp4" -adaptation_sets "id=0,streams=v id=1,streams=a" -dash_segment_type mp4 -f dash XXX-05763.mpd


  


  Is there something I'm missing in the above.

  


• playback of ffmpeg converted video on LDPI device (Samsung S5300 240 x 320)

  25 décembre 2013, par user737486

  I have Full HD video taken by Samsung Galaxy S4 camera.
  video stream info as follows :

  {"index":0,"codec_name":"h264","codec_long_name":"H.264 \/ AVC \/ MPEG-4 AVC \/ MPEG-4 part 10","profile":"High","codec_type":"video","codec_time_base":"1\/180000","codec_tag_string":"avc1","codec_tag":"0x31637661","width":1920,"height":1080,"has_b_frames":0,"sample_aspect_ratio":"0:1","display_aspect_ratio":"0:1","pix_fmt":"yuv420p","level":40,"r_frame_rate":"30\/1","avg_frame_rate":"21240000\/707831","time_base":"1\/90000","start_pts":0,"start_time":"0.000000","duration_ts":1415662,"duration":"15.729578","bit_rate":"16553536","nb_frames":"472","disposition":{"default":1,"dub":0,"original":0,"comment":0,"lyrics":0,"karaoke":0,"forced":0,"hearing_impaired":0,"visual_impaired":0,"clean_effects":0,"attached_pic":0},"tags":{"rotate":"90","creation_time":"2013-12-24 10:19:18","language":"eng","handler_name":"VideoHandle"}}

  in short it is 1920x1080, 16KK bitrate, rotation : 90.
  I'm converting it using ffmpeg by the following command :

  ffmpeg -y -threads 8 -i input.mp4 -vcodec libx264 -vpre ipod640 -s 324x576 -strict -2 -b:v 512k -acodec aac -ac 1 -ar 16000 -ab 32000 -vf "transpose=1" -metadata:s:v:0 rotate=0  output.mp4

  The output video stream info :

   {"index":0,"codec_name":"h264","codec_long_name":"H.264 \/ AVC \/ MPEG-4 AVC \/ MPEG-4 part 10","profile":"Constrained Baseline","codec_type":"video","codec_time_base":"1\/48","codec_tag_string":"avc1","codec_tag":"0x31637661","width":324,"height":576,"has_b_frames":0,"sample_aspect_ratio":"0:1","display_aspect_ratio":"0:1","pix_fmt":"yuv420p","level":30,"r_frame_rate":"24\/1","avg_frame_rate":"24\/1","time_base":"1\/12288","start_pts":0,"start_time":"0.000000","duration_ts":72192,"duration":"5.875000","bit_rate":"521597","nb_frames":"141","disposition":{"default":1,"dub":0,"original":0,"comment":0,"lyrics":0,"karaoke":0,"forced":0,"hearing_impaired":0,"visual_impaired":0,"clean_effects":0,"attached_pic":0},"tags":{"language":"eng","handler_name":"VideoHandler"}}

  The output video being played without any problem, on many different devices and OSes including different iOs and androids, but Samsung S5300 doesn't play it. From the device log I can see the following exception :

  E/AwesomePlayer( 1349): This resolution [324X576] Not Supported

  But, when I change the width and height to 576x324 the video can be played on S5300, but in wrong rotation.
  What should I add in ffmpeg parameters to make it play in correct orientation ?

  ffmpeg version :

  ffmpeg version git-2013-12-22-911676c Copyright (c) 2000-2013 the FFmpeg developers built on Dec 22 2013 22:55:31 with gcc 4.4.5 (Debian 4.4.5-8)

  Thanks