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• Create a demultiplexer for MPEG 2 TS in android

  17 novembre 2014, par anz

  I have a requirement where I need to extract ID3 tags from a MPEG2 TS(HLS STREAM). MPEG2 has a limited support in android in regards to playing the file. But my concern is to extract the ID3 tags(playing the file is not necessary). Hence I am not concerned with the codecs(encoding and decoding).

  I have explored the following options :

  libstagefright and OpenMax : A playback engine implemented by Google from Android 2.0.
  It has a MediaExtractor is responsible for retrieving track data and the corresponding meta data from the underlying file system or http stream. But according to this post Adding video codec to Android I need to build my own firmware or my own media player.I am hoping I don’t have to go down that path. More info on stagefright and openMax can be found here :

  An overview of Stagefright player

  Android’s Stagefright Media Player Architecture

  Custom Wrapper Codec Integration into Android

  How to integrate a decoder to multimedia framework

  Compiling and using FFMPEG : A complete, cross-platform solution to record, convert and stream audio and video. We can demultiplex ts files with this library as mentioned here :

  FFmpeg - Extracting video and audio from transport stream file (.ts).

  But I am not sure if I will be able to extract the ID3 tags from the HLS Stream. libavformat might be able to do this but I still need to come up with a mechanism for signaling the read metadata to my application.

  Compiling vlc for android : I have compiled vlc for android and made some modifications inside the transport module in demux component for extracting the tags, but it is not able to play all the streams that I am supplying to it.

  After looking through these options , I am still at a fix in how to achieve this. I don’t want to create a media player as I will not be playing the files nor do I want to build my own firmware. Using ffmpeg seems to be the most viable option, but I want to try this without using any third-party or open source library. My questions are :

  Is it even possible to create a demultiplexer from scratch that will work on android ?

  If possible then ,how to go about it ?

  Any options that I have missed ?

  I am new to this. Any help would be greatly appreciated..Thanks

• How to record audio with ffmpeg on linux ?

  7 décembre 2014, par Conor Patrick

  I’d like to record audio from my microphone. My OS is ubuntu. I’ve tried the following and got errors

  $ ffmpeg -f alsa -ac 2 -i hw:1,0 -itsoffset 00:00:00.5 -f video4linux2 -s 320x240 -r 25 /dev/video0 out.mpg
  
  
  
  ffmpeg version 0.8.8-4:0.8.8-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav
  
  developers
  
    built on Oct 22 2013 12:31:55 with gcc 4.6.3
  
  *** THIS PROGRAM IS DEPRECATED ***
  
  This program is only provided for compatibility and will be removed in a future release.
  
  Please use avconv instead.
  
  ALSA lib conf.c:3314:(snd_config_hooks_call) Cannot open shared library
  
  libasound_module_conf_pulse.so
  
  ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM hw:1,0
  
  [alsa @ 0xbda7a0] cannot open audio device hw:1,0 (No such file or directory)
  
  hw:1,0: Input/output error

  Then I tried

  $ ffmpeg -f oss -i /dev/dsp audio.mp3
  
  
  
  ffmpeg version 0.8.8-4:0.8.8-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav
  
  developers
  
  built on Oct 22 2013 12:31:55 with gcc 4.6.3
  
  *** THIS PROGRAM IS DEPRECATED ***
  
  This program is only provided for compatibility and will be removed in a future release.
  
  Please use avconv instead.
  
  [oss @ 0x1ba57a0] /dev/dsp: No such file or directory
  
  /dev/dsp: Input/output error

  I haven’t been able to get ffmpeg to find my microphone. How can I tell ffmpeg to record from my microphone ?
  It seems the ’Deprecated’ message can be ignored because of this topic

• Unrecognized option 'preset' with ubuntu 12.04 and ffmpeg

  5 novembre 2013, par hyperrjas

  I have compiled ffmpeg with the guide How To Compile FFmpeg and x264 on Ubuntu.

  Now I'm trying upload a .mp4 file to encode. However I get this error now :

  ffmpeg version git-2013-11-05-934e489 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Nov  5 2013 13:58:43 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  
    configuration: --enable-gpl --enable-libass --enable-libfaac --enable-libfdk-aac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librtmp --enable-libtheora --enable-libvorbis --enable-libvpx --enable-x11grab --enable-nonfree --enable-version3
  
    libavutil      52. 51.100 / 52. 51.100
  
    libavcodec     55. 41.100 / 55. 41.100
  
    libavformat    55. 21.100 / 55. 21.100
  
    libavdevice    55.  5.100 / 55.  5.100
  
    libavfilter     3. 90.101 /  3. 90.101
  
    libswscale      2.  5.101 /  2.  5.101
  
    libswresample   0. 17.104 /  0. 17.104
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Unrecognized option 'preset'.
  
  Error splitting the argument list: Option not found
  
  
  
  Errors: no output file created.

  This is the ruby methods to encode :

  case format
  
    when 'mp4'
  
     h[:video_codec] = 'libx264'
  
     h[:audio_codec] = 'libfaac'
  
     h[:custom] = '-qscale 0 -preset slow -g 30'
  
    when 'ogv'
  
     h[:video_codec] = 'libtheora'
  
     h[:audio_codec] = 'libvorbis'
  
     h[:custom] = '-b 1500k -ab 160000 -g 30'
  
    when 'webm'
  
     h[:video_codec] = 'libvpx'
  
     h[:audio_codec] = 'libvorbis'
  
     h[:custom] = '-b 1500k -ab 160000 -f webm -g 30'
  
  end