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• Can FFMPEG library send the live H264 iOS Camera stream to Wowza using RTSP

  7 janvier 2015, par Vishal Lohia

  My requirement is to get iphone camera feed, encode it into H264 format and send it to server.
  In search, I found encoding part is possible with ffmpeg lib with x264 (libx264). But now the next task is to send the encoded data to Wowza server using rtsp.

  Please share some code or useful document if anyone is aware about this.

  There is one another library for encoding purpose live555. But I am not sure it can send the data to server using rtsp.

• How to write out a MOV video into a raw, uncompressed format ?

  8 juin 2015, par feroze

  I have a video in a MOV file format, shot using an IPhone. I have to convert it into an uncompressed raw format, with multiple frames laid out one after the other. This has to be written to a file for post processing.

  Is there a stock format out there that I can convert this video to, using ffmpeg ? If not, I will have to write a C program to open the MOV file and write out the video. I have never worked in video land before, so I am confused about the options.

  I took a look at ffmpeg documentation, and did a web search, but all of them are talking about using ffmpeg as a command line tool, and not about how to write out a file format that I want.

• Fast accurate video trim like Instagram using FFmpeg Android

  11 août 2016, par dan87

  I know it’s been asked before but I couldn’t find a fast and accurate solution yet, I want to trim videos with a maximum lenght of 15 seconds. Here is what I’ve tried so far, I’m working with this video as example :http://www.sample-videos.com/video/mp4/720/big_buck_bunny_720p_30mb.mp4

  The fastest way

  This is by far the fastest way because it doesn’t need to re-encode the video but it’s very innacurate in this video because the key frames are every 5-10 seconds :

  ffmpeg -i SampleVideo_1280x720_30mb.mp4 -ss 30 -to 50 -c copy -y out.mp4

  Here is how I check the key frames in this video :

  ffprobe -select_streams v -show_frames -show_entries frame=pict_type -of csv SampleVideo_1280x720_30mb.mp4 | grep -n I | cut -d ':' -f 1

  With this command I found out that the second key frame it’s in the 211th frame which means 210 frames between the first key frame and the second, knowing that it’s a 25fps video it would be around 8 seconds between the key frames, so any cut between 1-8 seconds would fall in one of this frames which is a huge difference for a 15 seconds video.

  The accurate way

  This way it’s accurate but it requires to re-encode the video :

  ffmpeg -i SampleVideo_1280x720_30mb.mp4 -ss 30 -to 50 -preset ultrafast -y out.mp4

  The problem is this command takes more than 20 seconds to finish using the ultrafast preset, in a samsung galaxy s6 edge plus which probably would be much more in other devices.

  Nevertheless, if I open the SampleVideo_1280x720_30mb.mp4 in Instagram and trim it they get an accurate trim in less than 2 seconds.

  I also tried to force the keyframes every second, but it also requires to re-encode the video and it affects the video quality :

  ffmpeg -i SampleVideo_1280x720_30mb.mp4 -force_key_frames "expr:gte(t,n_forced*1)" out.mp4

  Does anybody know how Instagram trim the videos or a way to get a fast and accurate trim with FFMpeg ?