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• Properly open audio files with libav/ffmpeg

  20 November 2013, by Hyndrix

  I am trying to decode audio samples from various file formats using ffmpeg. Therefore I have started some experimenting based on the code in this discussion: How to decode audio via FFmpeg in Android . I use the latest FFMPEG release (1.0) and compile it using https://github.com/halfninja/android-ffmpeg-x264

  AVFormatContext * pFormatCtx;
  
  
  
  avcodec_register_all();
  
  av_register_all();
  
  
  
  int lError;
  
  if ((lError = avformat_open_input(&pFormatCtx, filename, NULL, 0))
  
          != 0) {
  
      LOGE("Error open source file: %d", lError);
  
      return;
  
  }
  
  if ((lError = avformat_find_stream_info(pFormatCtx, 0)) < 0) {
  
      LOGE("Error find stream information: %d (Streams: %d)", lError, pFormatCtx->nb_streams);
  
      return;
  
  }
  
  LOGE("audio format: %s", pFormatCtx->iformat->name);
  
  LOGE("audio bitrate: %d", pFormatCtx->bit_rate);
  
  audioStreamIndex = av_find_best_stream(pFormatCtx, AVMEDIA_TYPE_AUDIO,
  
          -1, -1, &codec, 0);
  
  
  
  //if (audioStreamIndex < 0 || audioStreamIndex >= pFormatCtx->nb_streams)
  
  //  audioStreamIndex = 0;
  
  
  
  LOGE("Stream: %d (total: %d)", audioStreamIndex, pFormatCtx->nb_streams);
  
  LOGE("audio codec: %s", codec->name);

  FFMPEG is compiled using enable-decoder=mp1/mp2/mp3/ogg/vorbis/wav/aac/theora and without any external libraries (e.g. libmp3lame, libtheora, etc.)

  Opening of mp3 and wav files works without problems producing the following output for instance for mp3:

  audio format: mp3

  audio bitrate: 256121

  stream: 0 (total: 1)

  audio codec: mp3

  But when I try to open an ogg file I get this:

  Error find stream information: -1 (Streams: 1)

  When I manually set audioStreamIndex=0 and comment out the return statement:

  Error find stream information: -1 (Streams: 1)

  audio format: mp3

  audio bitrate: 0

  stream: 0 (total: 1)

  audio codec: mp3

  For m4a (AAC) I get this:

  audio format: mp3

  audio bitrate: 288000

  stream: 0 (total: 1)

  audio codec: mp1

  but later it fails in avcodec_decode_audio3.

  I also tried to manually force a format without success:

  AVInputFormat *pForceFormat= av_find_input_format("ogg");
  
  if ((lError = avformat_open_input(&pFormatCtx, filename, pForceFormat, 0))
  
  // continue

  Is there something wrong with the loading code which makes it only work with mp3 and wav and fails for other formats?

  Regards,

• Couldn't open file with iFrameExtractor

  21 October 2012, by why

  I has built ffmpeg and iFrameExtractor with ios5.1 successful, But when I play the video, the log shows "Couldn't open file"

  // Register all formats and codecs
  
      avcodec_register_all();
  
      av_register_all();
  
  
  
      // Open video file
  
      if(avformat_open_input(&pFormatCtx, [moviePath cStringUsingEncoding:NSASCIIStringEncoding], NULL, NULL) != 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Couldn't open file\n");
  
          goto initError;
  
      }

  This is my configure file for ffmpeg 0.11.1:

  #!/bin/tcsh -f
  
  
  
  rm -rf compiled/*
  
  
  
  ./configure \
  
  --cc=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc \
  
  --as='/usr/local/bin/gas-preprocessor.pl /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc' \
  
  --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk \
  
  --target-os=darwin \
  
  --arch=arm \
  
  --cpu=cortex-a8 \
  
  --extra-cflags='-arch armv7' \
  
  --extra-ldflags='-arch armv7 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk' \
  
  --prefix=compiled/armv7 \
  
  --enable-cross-compile \
  
  --enable-nonfree \
  
  --disable-armv5te \
  
  --disable-swscale-alpha \
  
  --disable-doc \
  
  --disable-ffmpeg \
  
  --disable-ffplay \
  
  --disable-ffprobe \
  
  --disable-ffserver \
  
  --enable-decoder=h264 \
  
  --enable-decoder=svq3 \
  
  --disable-asm \
  
  --disable-bzlib \
  
  --disable-gpl \
  
  --disable-shared \
  
  --enable-static \
  
  --disable-mmx \
  
  --disable-neon \
  
  --disable-decoders \
  
  --disable-muxers \
  
  --disable-demuxers \
  
  --disable-devices \
  
  --disable-parsers \
  
  --disable-encoders \
  
  --enable-protocols \
  
  --disable-filters \
  
  --disable-bsfs \
  
  --disable-postproc \
  
  --disable-debug 

• cannot open video using opencv on linux

  13 May 2014, by user3358147

  I am trying to open a video file (.MOV,.AVI or .MP4) using OpenCV on linux. So that I can extract specific frames as images on the disc and do image processing. I have also installed ffmpeg on linux.

  My code snippet is :

  CvCapture* capture = cvCreateFileCapture("sample.avi");
  
  
  
      if(!capture)  // check if we succeeded
  
          printf("Video failed to open\n");
  
      else
  
          printf("Video opened\n");

  I cannot open an avi file. Can anyone guide me:

  1. Why I cannot open AVI video file using OpenCV?
  2. I was reading somewhere that OpenCV can only handle .avi files. So, what I will do with other movie formats?

  Any help will be really appreciated . .