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• How to configure FFMPEG to generate position independent code on IOS

  8 juillet 2013, par madadi

  I am developing an app on iOS which makes use of FFMPEG for video decoding. I want to get 'position independent code' of FFMPEG working on my app. --enable-pic option in the FFMPEG configuration generates position independent code only if I set --disable-asm. I concluded this when I ran the otool on my app(otool -hv 'appname'). Below are the details :

  If I set --enable-pic alone, below is the output with otool :

  magic     cputype  cpusubtype  caps  filetype  ncmds  sizeofcmds  flags
  
  MH_MAGIC  ARM      V7          0x00  EXECUTE   29     3724        NOUNDEFS DYLDLINK TWOLEVEL WEAK_DEFINES BINDS_TO_WEAK

  If I set --enable-pic and --disable-asm below is the output with otool,

  magic     cputype  cpusubtype  caps  filetype  ncmds  sizeofcmds  flags
  
  MH_MAGIC  ARM      V7          0x00  EXECUTE   51     5520        NOUNDEFS DYLDLINK TWOLEVEL WEAK_DEFINES BINDS_TO_WEAK **PIE** 

  Below are my configuration settings for FFMPEG(build-ffmpeg-ios.sh) :

  if [  `uname` =  "Darwin" ]; then
  
    SEDCMD="sed -i '' "
  
  else
  
    SEDCMD="sed -i "
  
  fi
  
  
  
  
  
  make clean
  
  ./configure \
  
      --prefix=$PREFIX \
  
      --enable-version3 \
  
      --enable-static \
  
      --disable-shared \
  
      --disable-doc \
  
      --disable-ffmpeg \
  
      --disable-ffplay \
  
      --disable-ffprobe \
  
      --disable-ffserver \
  
      --disable-avdevice \
  
      --disable-avfilter \
  
      --disable-postproc \
  
      --enable-small \
  
      --cross-prefix="$DEVROOT/usr/bin/" \
  
      --enable-cross-compile \
  
      --target-os=darwin \
  
      --arch=$ARCH \
  
      --cpu=$CPU \
  
      --cc="$CC" \
  
      --as="$AS" \
  
      --extra-cflags="$CFLAGS" \
  
      --extra-ldflags="$CFLAGS" \
  
      --disable-symver \
  
      --disable-debug \
  
      --disable-indevs \
  
      --disable-encoders \
  
      --disable-bsfs \
  
      --enable-pic \
  
      --disable-filters \
  
      $CONFIGURE_FLAGS || exit 1;
  
  $SEDCMD 's/HAVE_INLINE_ASM 1/HAVE_INLINE_ASM 0/g' config.h
  
  make install || exit 1;

  And below is the make file I use(iOS.mk) :

  FFMPEG_LIBS := libavcodec.a libavformat.a libavutil.a libswscale.a
  
  
  
  IOS_ARMV7_FFMPEG_LIB := $(addprefix build/ios/armv7/lib/, $(FFMPEG_LIBS))
  
  
  
  IOS_UNI_FFMPEG_LIB := $(addprefix build/ios/universal/lib/, $(FFMPEG_LIBS))
  
  
  
  
  
  
  
  IPHONE_SDK_VERSION := "5.0"
  
  IPHONE_DEPLOY_SDK := "3.2"
  
  
  
  ALL_IOS_LIBS := $(IOS_UNI_FFMPEG_LIB) 
  
  
  
  build/ios/universal/lib/%.a : build/ios/armv7/lib/%.a
  
      mkdir -p build/ios/universal/lib
  
      lipo -create -output $@ $^
  
  
  
  
  
  
  
  $(IOS_ARMV7_FFMPEG_LIB): 
  
      export PREFIX="`$(ABSPATH) build/ios/armv7`" && \
  
      export ARCH="arm" && \
  
      export CPU="cortex-a8" && \
  
      export IOS_BASE_SDK="$(IPHONE_SDK_VERSION)" && \
  
      export IOS_DEPLOY_TGT="$(IPHONE_DEPLOY_SDK)" && \
  
      export CONFIGURE_FLAGS="--enable-neon" && \
  
      export PATH="`$(ABSPATH) venders`:$$PATH" && \
  
      cd venders/ffmpeg && bash ../iphone-compile.sh arm7 ../build-ffmpeg-ios.sh

  Can someone please help me with getting the FFMPEG up and running with both 'pic' and assembly optimization enabled. Without assembly optimizastion, FFMPEG would not be helpful to me as the video decoding is extremely slow.

• IframeExtractor don't output sound with rtsp

  9 janvier 2013, par Kamax

  I use IframeExtractor from the git mooncatventure, it play nice the .mov file.
  But when i try to read a rtsp stream, i hear no sound.

  This is the FFMEG dump from the rtsp stream :

  Metadata:
  
  title           : unknown
  
  comment         : unknown
  
  Duration: N/A, start: 49435.000589, bitrate: 258 kb/s
  
  Program 3223 
  
  No Program
  
  Stream #0:0: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 720x576 [SAR 64:45 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
  
  Stream #0:1(fra): Audio: aac ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 142 kb/s
  
  Stream #0:2(fra): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006)
  
  Stream #0:3(qad): Audio: aac ([15][0][0][0] / 0x000F), 48000 Hz, mono, fltp, 47 kb/s
  
  Stream #0:4(qaa): Audio: aac ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 68 kb/s

  And this is the dump from the local .mov file that work :

  Metadata:
  
  major_brand     : qt  
  
  minor_version   : 0
  
  compatible_brands: qt  
  
  creation_time   : 2010-01-17 21:52:33
  
  model           : iPhone 3GS
  
  model-eng       : iPhone 3GS
  
  date            : 2010-01-17T16:52:33-0500
  
  date-eng        : 2010-01-17T16:52:33-0500
  
  encoder         : 3.1.2
  
  encoder-eng     : 3.1.2
  
  make            : Apple
  
  make-eng        : Apple
  
  Duration: 00:00:03.25, start: 0.000000, bitrate: 3836 kb/s
  
  Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 640x480, 3695 kb/s, 30.02 fps, 30 tbr, 600 tbn, 1200 tbc
  
  Metadata:
  
    rotate          : 90
  
    creation_time   : 2010-01-17 21:52:33
  
    handler_name    : Core Media Data Handler
  
  Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s
  
  Metadata:
  
    creation_time   : 2010-01-17 21:52:33
  
    handler_name    : Core Media Data Handler

  The audio class that manage sounds contain a codec detector which say that the codec CODEC_ID_AAC is found for the two input :

  audioStreamBasicDesc_.mFormatFlags = 0;
  
  switch (_audioCodecContext->codec_id) {
  
      case CODEC_ID_MP3:
  
           audioStreamBasicDesc_.mFormatID = kAudioFormatMPEGLayer3;
  
          break;
  
      case CODEC_ID_AAC:
  
           audioStreamBasicDesc_.mFormatID = kAudioFormatMPEG4AAC;
  
           audioStreamBasicDesc_.mFormatFlags = kMPEG4Object_AAC_Main;
  
          NSLog(@"audio format aac %s (%d) is  supported",  _audioCodecContext->codec_name, _audioCodecContext->codec_id);
  
          break;
  
  }

  I see data going into the buffer but i hear nothing. It's maybe audioStreamBasicDesc_ which has wrong settings but i can't find what.

  Is it possible that it's not the same AAC codec ?

  Has someone experienced the same issue ?

  Any help are welcome, i'm on this problem since some days now.

  Edit :
  I have found a error that i had not before, i don't know how to resolve it. If i change audioStreamBasicDesc.mFramesPerPacket to 0 or divided by 2, the error message dissapear.

  AudioConverterNew returned 'fmt?'
  
  Prime failed ('fmt?'); will stop (72000/0 frames)

• Compile ffmpeg with libfaac for armv7

  25 juillet 2013, par user2617213

  how can I compile ffmpeg with libfaac for armv7 ?
  I want to use libfaac.a for iPhone ,but how to compile ffmpeg with libfaac ?