Newest 'ffmpeg' Questions - Stack Overflow

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• Quality issue with ffmpeg stream

  17 octobre 2013, par Gregory

  I'm trying to save a YouTube's RSTP stream.

  First of all, I get JSON info about the stream I want to catch. For example, http://gdata.youtube.com/feeds/api/videos/gSTegCPviDQ?alt=json&v=2&prettyprint=true&format=1

  Second, I use ffmpeg to save stream to file:

  ffmpeg -i rtsp://r4---sn-5hn7su7z.c.youtube.com/CiILENy73wIaGQk0iO8jgN4kgRMYESARFEgGUgZ2aWRlb3MM/0/0/0/video.3gp -an -vcodec copy -s 480x360 -y /software/tmp/tmp.avi
  

  Everything works fine but the quality of video is extremely bad.

  Q: How can I download the stream in a better quality?

  JSON says that there is a yt$format variable which defines the quality of stream. Unfortunately, stream links looks same (as you can see in JSON response I mentioned above).

  Thanks in advance!

• How to create an H264 video for specific Libav decoding

  16 octobre 2013, par James491

  I'm creating a program that decodes and displays videos using Libav. I have complete control over the videos the program uses because I make them beforehand. I am able to seek and decode the videos as needed but only after adjusting to a few quirks of x264 encoded videos. For instance, I have to add 8-10 extra frames at the end of my videos to be able to decode and seek to the original last frame. Is it possible to further customize the encoding of an H264 video using ffmpeg or another application, or perhaps some parameters I can initialize in AVFormatContext or AVCodecContext, in order to solve something like decoding the last frames? Also, are there any specifics I can add to the video file or implement in decoding to decrease seek time, since all seek commands and positions are predetermined? My current seeking function is just composed of an avformat_seek_file(...) followed by avcodec_flush_buffers(...). I am already seeking to key frames. I am willing to read and learn if all you have is a recommended page or article to investigate.

• How to link Eclipse Indigo in Ubuntu 11 to FFMPEG 8 for C++

  16 octobre 2013, par AMB0027

  I have tried everything in the book and EVERYTHING I could find on how to do this and reinstalled and reconfigured and rebuilt several times to no avail. This is what I have. I've made FFMPEG on my Ubuntu VM and have the following code written:

  #include "libavcodec/avcodec.h"
  #include "libavformat/avformat.h"
  
  #include 
  #include 
  
  using namespace std;
  
  int main( int argc, char* argv[] ) {
  
      avcodec_register_all();
  
      return 0;
  }
  

  This errors and says:

  /home/adam/workspace/MP4 Tools/Debug/../testDriver.cpp:19: undefined reference to     `avcodec_register_all()'
  collect2: ld returned 1 exit status
  

  I have included the libavcodec.a file. Project->Properties->GCC C++ Linker->Libraries->add "avcodec"

  Can anyone think of something I'm not doing or overlooking? Thanks so much.

• Encode loopback capture data in mp3 using ffmpeg in VC++

  16 octobre 2013, par NetCoder89

  I'm trying to work on loopback capture(What you hear) and record this file in mp3/aac format using VC++. ->I can capture audio and can create a .wav file i.e. not compressed but I want a compressed file so I'm encoding this through ffmpeg to write an mp3 file not a .wav.

  However I'm not getting any way to do it directly? I referred this for loopback capture.

  Please share your experience and opinions.

  Thanks!

• Need explanation of details of ffmpeg and pipes command

  16 octobre 2013, par Donald A Nummer Jr

  Got the following from FFmpeg FAQ:

  mkfifo intermediate1.mpg
  mkfifo intermediate2.mpg
  ffmpeg -i input1.avi -sameq -y intermediate1.mpg < /dev/null &
  ffmpeg -i input2.avi -sameq -y intermediate2.mpg < /dev/null &
  cat intermediate1.mpg intermediate2.mpg |\
  ffmpeg -f mpeg -i - -sameq -vcodec mpeg4 -acodec libmp3lame output.avi
  

  Before i use or modify it I would like to understand it completely.

  What does the < /dev/null & do?

  I understand | is pipe but why |\ ?

  What is the -f mpeg after ffmpeg (Seems, it tells ffmpeg to accept the piped in output from the cat(?) )