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• iPhone slow motion video transcode

  25 mai 2016, par coverboy

  I’m developing upload video (taken from iPhone) to my server.

  However, I have no idea how to implement.

  Any source code objective-c or swift will be welcomed.

  I have 120fps or 240fps video (It’s a slo-mo).
  When I playback these video on my iPhone6. I can see slo-mo effect.
  (I know playback frame rate is 30fps.)

  I want to convert that video before upload to my server, from 120/240 fps to 30fps video. (I mean not adjusting playback frame rate, it means video transcode to 30fps.)
  Additionally, I want to check slo-mo effect start-point and end-point.
  (Maybe iPhone record this information to video binary(it might be reside in file’s header.)

  Well, I guess if I use ffmpeg library, it should be easy(?).

  So any suggestions will be welcomed.

• “Hook” libMMS to FFmpeg for iPhone Streaming

  8 novembre 2011, par Xie Xingwei

  These days, I was researching the software architechture for iPhone Streaming (Base on MMS protocol).

  As we know, in order to playback MMS audio stream, we should call libMMS to read wma stream data from remote media server, and then call FFmpeg to decode the stream data from wma format into PCM data buffer, and finally, enqueue the PCM data buffer into iPhone’s audioqueue to generate real sound.

  The introduction above just describe the working process of iPhone streaming. If we only need to implement this simple functionality, that is not difficult. Just follow the introduction above to call libMMS, FFMpeg and audioqueue step by step, we can achieve the streaming function. Actually, I have implemented the code last week.

  But, what I need is not only a simple streaming function ! I need a software architechture makes FFmpeg accessing libMMS just like accessing local filesystem !

  Does anybody know how to hook the libMMS interfaces like mms_read/mms_seek onto FFmpeg filesystem interfaces like av_read_frame/av_seek_frame ?

• Suggestion query : Someone should add 'percent-complete' to ffmpeg's status line

  19 février 2018, par Dave

  I use the PC-platform’s ffmpeg (on Windows and Linux). I’ve always
  wondered why, down on that bottom dynamic status line, it does NOT
  show a ’percent-complete’ value.

  e.g. There’s already a line showing what time-line value is being worked
  on, so I’d expect it would be straight-forward to grab total duration, compute percent-complete, and show it, right after the running time value. Or,
  if based on frames, then show it in parentheses after the frame value.

  The reason I think it would be straight-forward is because I see it
  discussed in detail, for ffmpeg on Android, here :
  How to add progress bar to FFMPEG android
  and it talks about time-values and frame-count based calculations.

  Any volunteers to tackle this ? ^ ;)