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• 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 !

• FFmpeg static keyframe rate

  7 novembre 2011, par 2di

  I have a question about ffmpeg usage. Every time when I trying to convert video files into
  some different format, output file getting static keyframe sequence.

  What I mean is that keyframes appear at the distance of 12 frames. I know that its controllerd by parameter -g that you can change to any other number.

  ffmpeg -i 1.avi -vcodec mpeg4 -b 2000000  out.avi

  I believe there should be some way to make keyframes appear on uneven intervals. These interval should be calculated by codec, and it should be based on image changes in the video file. So keyframes should be inserted only when they needed, but not consistently after N frames.

  Can somebody please explain to me how this "smart" encoding can be done with ffmpeg ?
  Thank you

  SOLUTION : ok what I'ev been looking for has very simple solution. If you set -g to zero, ffmpeg will choose keyframes based on the video shots and bitrate

• The First Problem

  19 janvier 2011, par Multimedia Mike — HTML5

  A few years ago, The Linux Hater made the following poignant observation regarding Linux driver support :

  Drivers are only just the beginning... But for some reason y’all like to focus on the drivers. You know why lusers do that ? Because it just happens to be the problem that people notice first.

  And so it is with the HTML5 video codec debate, re-invigorated in the past week by Google’s announcement of dropping native H.264 support in their own HTML5 video tag implementation. As I read up on the fiery debate, I kept wondering why people are so obsessed with this issue. Then I remembered the Linux Hater’s post and realized that the video codec issue is simply the first problem that most people notice regarding HTML5 video.

  I appreciate that the video codec debate has prompted Niedermayer to post on his blog once more. Otherwise, I’m just munching popcorn on the sidelines, amused and mildly relieved that the various factions are vociferously attacking each other rather than that little project I help with at work.

  Getting back to the "first problem" aspect— there’s so much emphasis on the video codec ; I wonder why no one ever, ever mentions word one about an audio codec. AAC is typically the codec that pairs with H.264 in the MPEG stack. Dark Shikari once mentioned that "AAC’s licensing terms are exponentially more onerous than H.264′s. If Google didn’t want to use H.264, they would sure as hell not want to use AAC." Most people are probably using "H.264" to refer to the entire MPEG/H.264/AAC stack, even if they probably don’t understand what all of those pieces mean.

  Anyway, The Linux Hater’s driver piece continues :

  Once y’all have drivers, the fight will move to the next layer up. And like I said, it’s a lot harder at that layer.

  A few months ago, when I wanted to post the WebM output of my new VP8 encoder and thought it would be a nice touch to deliver it via a video tag, I ignored the video codec problem (just encoded a VP8/WebM file) only to immediately discover a problem at a different layer— specifically, embedding a file using a video tag triggers a full file download when the page is loaded, which is unacceptable from end user and web hosting perspectives. This is a known issue but doesn’t get as much attention, I guess because there are bigger problems to solve first (c.f. video codec issue).

  For other issues, check out the YouTube blog’s HTML5 post or Hulu’s post that also commented on HTML5. Issues such as video streaming flexibility, content protection, fullscreen video, webcam/microphone input, and numerous others are rarely mentioned in the debates. Only "video codec" is of paramount importance.

  But I’m lending too much weight to the cacophony of a largely uninformed internet debate. Realistically, I know there are many talented engineers down in the trenches working to solve at least some of these problems. To tie this in with the Linux driver example, I’m consistently stunned these days regarding how simple it is to get Linux working on a new computer— most commodity consumer hardware really does just work right out of the box. Maybe one day, we’ll wake up and find that HTML5 video has advanced to the point that it solves all of the relevant problems to make it the simple and obvious choice for delivering web video in nearly all situations.

  It won’t be this year.