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• Join a series of mp4 files using ffmpeg following a pattern in filenames

  26 juin 2015, par Slabo

  I’m trying to join a series of generated mp4 files with the filenames in the following order>>

  Vid1.mp4,Vid1s.mp4,Smiley.mp4,Vid2.mp4,Vid2s.mp4,Smiley.mp4, ..... VidN.mp4,VidNs.mp4,Smiley.mp4

  where the pattern is A1,A1s,C,A2,A2s,C .... AN,ANs,C ... where N is the half the number of files in the folder.. File names are actually in a format similar to AN.mp4 and ANs.mp4

  I know it’s going to be something like : :

  ffmpeg -f concat -i some regex -c copy FinalVid.mp4

  I used to know this stuff 10 years ago... ok, 9 years ago..

  Edit : Ok, so after trying to fix this myself, I can better describe the problem as follows

  if two files Vid-N.mp4 and Vid-Ns.mp4 exist, then should be appended to FinalVid.mp4. How do I solve this ? Just thinking out loud: :

  1. get list of mp4 files
  2. for every two pairs of files, append to
     FinalVid.mp4

  Any help appreciated, thanks.

• How do I encode a series of WebP image files into a WebM video ? [on hold]

  18 mars 2015, par Tony Nardi

  I have looked into tools like ffmpeg, libvpx, and VP8. I have not found any examples that illustrate the exact problem I am attempting to solve.

  My goal is to use a command, like the one found here to encode a series of image files to a video. I would prefer, however, to use WebP as my series of images and encode them to a WebM video.

  I have also looked at using the VP8 encoder directly, but the examples assume using a YUV input file.

  Also, there is an example here to convert PNG files to a WebM video. This is very close to what I want to do !

  I am fairly new to all of these concepts and tools, but it seems like WebP is pretty much a single WebM frame with a different container format. It seems pretty simple in theory to encode many WebP images to a single WebM video.

  Any help, whether a solution or documents for me to read, would be greatly appreciated. Thanks !

• Adding total duration/enable seeking in mp4 AAC audio stream file with FFMPEG

  12 avril 2016, par lex82

  I’m trying to write an AAC audio stream into an mp4 file using the FFMPEG libraries. I am using a custom IO context that writes directly to a socket so I have to set ioContext->seekable = 0. To make this work I had to add the "movflags" empty_moov and frag_keyframe when writing the header.

  After writing the output to a file on the other end of the socket, I can play the file in VLC or Windows Media Player. However, seeking to a specific position in the file is not working properly in both players. WMP also does not show the total duration and VLC only flashes it shortly when reaching the end of the audio.

  Is there a way to add more metadata when muxing so the players are able to treat the file as if it was not written as a stream ? Transfer via the socket is not interrupted abruptly, so I could write metadata at the end of the file. I also know the total duration in advance, so I could add it to the header of the file if it was possible. I cannot use the faststart flag because this would require output to a seekable file before writing to the socket.

  Update : I learned that I can set the duration in AVFormatContext and I can set nb_frames and avg_frame_rate in AVStream. However, it doesn’t solve my problem. When I set the codecContext flag AV_CODEC_FLAG_QSCALE, VLC seems to be able to estimate the total time. However, seeking still doesn’t work.