Recherche avancée

Sur d’autres sites (4328)

• Installing faad library for ffmpeg through Homebrew on mac OS X Lion

  14 décembre 2011, par alex

  Following up with my previous question, I decided to give Ffmpeg a try and installed it on my Mac with Homebrew.

  I am now trying to follow this tutorial and use the linked script. But can't make/install the script. I first corrected a small bug (replaced CODEC_TYPE_AUDIO, CODEC_TYPE_VIDEO and PKT_FLAG_KEY with AVMEDIA_TYPE_AUDIO, AVMEDIA_TYPE_VIDEO, and AV_PKT_FLAG_KEY respectively in live_segmenter.c). But now, when I run make in the unzipped folder, I get the following warning and error messages :

  gcc -Wall -g live_segmenter.c -o live_segmenter -lavformat -lavcodec -lavutil -lbz2 -lm -lz -lfaac -lmp3lame -lx264 -lfaad -lpthread
  
  live_segmenter.c: In function ‘main’:
  
  live_segmenter.c:149: warning: ‘av_open_input_file’ is deprecated (declared at /usr/local/include/libavformat/avformat.h:1093)
  
  live_segmenter.c:165: warning: implicit declaration of function ‘guess_format’
  
  live_segmenter.c:165: warning: initialization makes pointer from integer without a cast
  
  live_segmenter.c:208: warning: ‘av_set_parameters’ is deprecated (declared at /usr/local/include/libavformat/avformat.h:1407)
  
  live_segmenter.c:214: warning: ‘dump_format’ is deprecated (declared at /usr/local/include/libavformat/avformat.h:1535)
  
  live_segmenter.c:232: warning: ‘url_fopen’ is deprecated (declared at /usr/local/include/libavformat/avio.h:279)
  
  live_segmenter.c:238: warning: ‘av_write_header’ is deprecated (declared at /usr/local/include/libavformat/avformat.h:1465)
  
  live_segmenter.c:283: warning: ‘put_flush_packet’ is deprecated (declared at /usr/local/include/libavformat/avio.h:293)
  
  live_segmenter.c:284: warning: ‘url_fclose’ is deprecated (declared at /usr/local/include/libavformat/avio.h:280)
  
  live_segmenter.c:289: warning: ‘url_fopen’ is deprecated (declared at /usr/local/include/libavformat/avio.h:279)
  
  live_segmenter.c:326: warning: ‘url_fclose’ is deprecated (declared at /usr/local/include/libavformat/avio.h:280)
  
  ld: library not found for -lfaad
  
  collect2: ld returned 1 exit status
  
  make: *** [all] Error 1

  I also downloaded the faac/faad libraries from here. When I run make in faac, it says I have nothing to install, but I can't find out how to install faad...

  Would love any help you can offer !

• Getting video metadata in ruby script using ffmpeg, ffprobe or rvideo

  24 janvier 2013, par alex

  I want to get metadata of videos referenced by a URL using Ruby. At this point, I found many related posts, but could not find out how to solve my problem.

  I tried to use RVideo, but when I do :

  file = RVideo::Inspector.new(:file => 'http://www.agreatsite.com/avideo.mp4' ;)

  It throws

  'ArgumentError : File not found (http://www.agreatsite.com/avideo.mp4)...

  So I can't get the information using RVideo (but it works well when I have the file hosted on my local computer).

  I then tried to use ffprobe, but I don't know how to read the output.
  So far, I have the following method, which "shows" the information I want when I run it in the console, but it actually returns "true" and I can't find out how to capture the output I need...

    def media_info
  
      source = self
  
      command = <<-end_command
  
        ffprobe -v quiet -print_format json -show_format -show_streams  #{source}
  
      end_command
  
      command.gsub!(/\s+/, " ")
  
      system(command)
  
    end

  Would love some help, to make this work with either ffprobe or RVideo !

  UPDATE :
  I found a way to get what I needed. Not sure this is the best way to do it :

  def get_media_duration

  source = self.media[0][:url]    
  
  
  
  command = <<-end_command
  
    ffprobe -v quiet  -show_streams  #{source}
  
  end_command
  
  command.gsub!(/\s+/, " ")
  
  
  
  duration = ""
  
  IO.popen(command) { |io| while (line = io.gets) do
  
                          puts "++ "+line.inspect
  
                          duration = line.split("duration=")[1].gsub("\n", "") if line.split("duration=").length > 1
  
                        end
  
                    }
  
  duration   

  end

  I guess I could make it work that way, but doesn't seem very elegant to me. Better suggestions would be greatly appreciated !

• encapsulating H.264 streams variable framerate in MPEG2 transport stream

  2 mai 2012, par user1058600

  Imagine I have H.264 AnxB frames coming in from a real-time conversation. What is the best way to encapsulate in MPEG2 transport stream while maintaining the timing information for subsequent playback ?

  I am using libavcodec and libavformat libraries. When I obtain pointer to object (*pcc) of type AVCodecContext, I set the foll.

  pcc->codec_id = CODEC_ID_H264;
  
  pcc->bit_rate = br;
  
  pcc->width = 640;
  
  pcc->height = 480;
  
  pcc->time_base.num = 1;
  
  pcc->time_base.den = fps;

  When I receive NAL units, I create a AVPacket and call av_interleaved_write_frame().

  AVPacket pkt;
  
  av_init_packet( &pkt );
  
  pkt.flags |= AV_PKT_FLAG_KEY;   
  
  pkt.stream_index = pst->index;
  
  pkt.data = (uint8_t*)p_NALunit;
  
  pkt.size = len;
  
  
  
  pkt.dts = AV_NOPTS_VALUE;
  
  pkt.pts = AV_NOPTS_VALUE;
  
  
  
  av_interleaved_write_frame( fc, &pkt );

  I basically have two questions :

  1) For variable framerate, is there a way to not specify the foll.
  pcc->time_base.num = 1 ;
  pcc->time_base.den = fps ;
  and replace it with something to indicate variable framerate ?

  2) While submitting packets, what "timestamps" should I assign to
  pkt.dts and pkt.pts ?

  Right now, when I play the output using ffplay it is playing at constant framerate (fps) which I use in the above code.

  I also would love to know how to accommodate varying spatial resolution. In the stream that I receive, each keyframe is preceded by SPS and PPS. I know whenever the spatial resolution changes.
  IS there a way to not have to specify
  pcc->width = 640 ;
  pcc->height = 480 ;
  upfront ? In other words, indicate that the spatial resolution can change mid-stream.

  Thanks a lot,
  Eddie