Recherche avancée

Sur d’autres sites (3814)

• Combining 2 FFMPEG Commands

  11 juillet 2020, par John Doe

  I'm trying to combine 2 ffmpeg commands, one which creates the video, and another which adds a simple fade to the beginning of the created video. Here's what I have :

  


  ffmpeg -y -stream_loop -1 -i "video.mp4" -stream_loop -1 -i "music.mp3" -i "audio.mp3" -filter_complex "[1:a]volume=0.1[a1];[2:a]adelay=5000|5000,apad=pad_dur=10[a2];[a1][a2]amerge=inputs=2,afade=in:st=0:d=5[audio]" -map "0:v" -map "[audio]" -c:v libx264 -c:a aac -ac 2 -ar 22050 -preset veryfast -shortest "output.mp4"

ffmpeg -y -i "output.mp4" -filter_complex "[0:v]fade=in:0:d=5" -c:a copy -preset veryfast -movflags faststart -fflags genpts "done.mp4"


  


  The two commands work perfectly fine, however the second one takes about the same amount of time to process as the first, and I feel it should be relatively easy to do the fade-in during the first encode. For my skillset atleast, I was wrong. Please could someone with more experience lend a helping hand ?

  


  Thanks.

  


• I have downloaded a static built of a linux program. Where should I put the man pages ?

  29 novembre 2015, par Mephisto

  I have downloaded a static built of a linux program (ffmpeg) I want to use in my Ubuntu 14.04

  I just copy the executable (ffmpeg) into /usr/local/bin and the program works. I have been doing so for long now with this program. The author of the static built updates it very often.

  But I have no man pages. Inside the directory where the static built comes, there is a directory called manpages. I think I might copy the files inside that directory (or the directory itself) to some location in my hard drive and from that moment I would be able to type in a console :
  man ffmpeg

  Where should I put those files ?

  Remark : I don’t want to delve into the complexities of compiling the program on my own (gathering information about the components I should include in the compilation, etc) and I don’t want to use the fork (avconv) of ffmpeg that unluckily comes with my ubuntu because of the multiple bugs I have experience with it, and because of its lack of some ffmpeg features (video de-shaking !). Thanks.

• libav : where to get a reference to AV_PIX_FMT_NV12 when using cuda/cuvid ?

  29 mars 2019, par Simon Labrecque

  Say I’m using av_hwdevice_find_type_by_name("cuda"), as in here. I need to convert the decoded frames to RGB using a SwsContext. I know, by experience, that when using the cuda/cuvid decoder I get frames in the AV_PIX_FMT_NV12 format, even though every struct I look at says either AV_PIX_FMT_NONE or AV_PIX_FMT_YUV420P.

  On what field of what struct can I get the AV_PIX_FMT_NV12 value so I can remove my hardcoded source format on my call to SwsContext.sws_scale ? Thanks !

  Update :

  Looks like I can get it by :

  AVCodecContext* avctx;
  
  ...
  
  frames_ctx = (AVHWFramesContext*)avctx->hw_frames_ctx->data;
  
  AVPixelFormat pixel_fmt = frames_ctx->sw_format;

  ...once at least one frame has been decoded. Not sure if it’s the correct way though.