ffmpeg xcode 中的使用

    最近比较闲,苦于ios设备上没有直接播放torrent 文件的软件,开始折腾了.找了不少资料有了思路.但是其中用到了ffmpeg 这个东西.

　　ffmpeg 是通用的一个视频解决框架,用C语言编写,通用性很强.

  1. 编译ffmpeg.
    1. 下载源码后可以自己手动编译 ,反正是通过各种命令 配置configure 
    2. 通过一个很牛逼的脚本:git@github.com:kewlbear/FFmpeg-iOS-build-script.git     下载之后,检查ffmpeg的版本号,替换成最新的 然后运行脚本就行了
      #!/bin/sh

# directories
SOURCE="ffmpeg-2.5"
FAT="FFmpeg-iOS"

SCRATCH="scratch"
# must be an absolute path
THIN=`pwd`/"thin"

# absolute path to x264 library
#X264=`pwd`/fat-x264

#FDK_AAC=`pwd`/fdk-aac/fdk-aac-ios

CONFIGURE_FLAGS="--enable-cross-compile --disable-debug --disable-programs 
                 --disable-doc --enable-pic"

if [ "$X264" ]
then
	CONFIGURE_FLAGS="$CONFIGURE_FLAGS --enable-gpl --enable-libx264"
fi

if [ "$FDK_AAC" ]
then
	CONFIGURE_FLAGS="$CONFIGURE_FLAGS --enable-libfdk-aac"
fi

# avresample
#CONFIGURE_FLAGS="$CONFIGURE_FLAGS --enable-avresample"

ARCHS="arm64 armv7s armv7 x86_64 i386"

COMPILE="y"
LIPO="y"

DEPLOYMENT_TARGET="6.0"

if [ "$*" ]
then
	if [ "$*" = "lipo" ]
	then
		# skip compile
		COMPILE=
	else
		ARCHS="$*"
		if [ $# -eq 1 ]
		then
			# skip lipo
			LIPO=
		fi
	fi
fi

if [ "$COMPILE" ]
then
	if [ ! `which yasm` ]
	then
		echo 'Yasm not found'
		if [ ! `which brew` ]
		then
			echo 'Homebrew not found. Trying to install...'
			ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)" 
				|| exit 1
		fi
		echo 'Trying to install Yasm...'
		brew install yasm || exit 1
	fi
	if [ ! `which gas-preprocessor.pl` ]
	then
		echo 'gas-preprocessor.pl not found. Trying to install...'
		(curl -L https://github.com/libav/gas-preprocessor/raw/master/gas-preprocessor.pl 
			-o /usr/local/bin/gas-preprocessor.pl 
			&& chmod +x /usr/local/bin/gas-preprocessor.pl) 
			|| exit 1
	fi

	if [ ! -r $SOURCE ]
	then
		echo 'FFmpeg source not found. Trying to download...'
		curl http://www.ffmpeg.org/releases/$SOURCE.tar.bz2 | tar xj 
			|| exit 1
	fi

	CWD=`pwd`
	for ARCH in $ARCHS
	do
		echo "building $ARCH..."
		mkdir -p "$SCRATCH/$ARCH"
		cd "$SCRATCH/$ARCH"

		CFLAGS="-arch $ARCH"
		if [ "$ARCH" = "i386" -o "$ARCH" = "x86_64" ]
		then
		    PLATFORM="iPhoneSimulator"
		    CFLAGS="$CFLAGS -mios-simulator-version-min=$DEPLOYMENT_TARGET"
		else
		    PLATFORM="iPhoneOS"
		    CFLAGS="$CFLAGS -mios-version-min=$DEPLOYMENT_TARGET"
		    if [ "$ARCH" = "arm64" ]
		    then
		        EXPORT="GASPP_FIX_XCODE5=1"
		    fi
		fi

		XCRUN_SDK=`echo $PLATFORM | tr '[:upper:]' '[:lower:]'`
		CC="xcrun -sdk $XCRUN_SDK clang"
		CXXFLAGS="$CFLAGS"
		LDFLAGS="$CFLAGS"
		if [ "$X264" ]
		then
			CFLAGS="$CFLAGS -I$X264/include"
			LDFLAGS="$LDFLAGS -L$X264/lib"
		fi
		if [ "$FDK_AAC" ]
		then
			CFLAGS="$CFLAGS -I$FDK_AAC/include"
			LDFLAGS="$LDFLAGS -L$FDK_AAC/lib"
		fi

		TMPDIR=${TMPDIR/%/} $CWD/$SOURCE/configure 
		    --target-os=darwin 
		    --arch=$ARCH 
		    --cc="$CC" 
		    $CONFIGURE_FLAGS 
		    --extra-cflags="$CFLAGS" 
		    --extra-cxxflags="$CXXFLAGS" 
		    --extra-ldflags="$LDFLAGS" 
		    --prefix="$THIN/$ARCH" 
		|| exit 1

		make -j3 install $EXPORT || exit 1
		cd $CWD
	done
fi

if [ "$LIPO" ]
then
	echo "building fat binaries..."
	mkdir -p $FAT/lib
	set - $ARCHS
	CWD=`pwd`
	cd $THIN/$1/lib
	for LIB in *.a
	do
		cd $CWD
		echo lipo -create `find $THIN -name $LIB` -output $FAT/lib/$LIB 1>&2
		lipo -create `find $THIN -name $LIB` -output $FAT/lib/$LIB || exit 1
	done

	cd $CWD
	cp -rf $THIN/$1/include $FAT
fi

echo Done
  2. 导入项目,有静态包经验的就就不用看了,这个对于我这个半路出家的和尚还是处理了老半天才解决.
    .a文件直接导入 .h文件要导入文件夹结构   配置header search 环境变量  使用的时候导入文件 结构:#import "文件夹/文件.h"
  3. 编译.
    1. 首次编译.
      Undefined symbols for architecture armv7:
  "_deflateInit2_", referenced from:
      _encode_frame in libavcodec.a(pngenc.o)
  "_crc32", referenced from:
      _encode_frame in libavcodec.a(pngenc.o)
  "_deflateReset", referenced from:
      _encode_frame in libavcodec.a(lclenc.o)
      _encode_frame in libavcodec.a(zmbvenc.o)
  "_compress", referenced from:
      _encode_strip in libavcodec.a(tiffenc.o)
  "_deflateBound", referenced from:
      _flashsv_decode_frame in libavcodec.a(flashsv.o)
      _encode_frame in libavcodec.a(pngenc.o)
      _encode_frame in libavcodec.a(lclenc.o)
  "_inflateSync", referenced from:
      _flashsv_decode_frame in libavcodec.a(flashsv.o)
  "_inflateReset", referenced from:
      _flashsv_decode_frame in libavcodec.a(flashsv.o)
      _zlib_decomp in libavcodec.a(lcldec.o)
      _decode_frame in libavcodec.a(tscc.o)
      _zerocodec_decode_frame in libavcodec.a(zerocodec.o)
      _decode_frame in libavcodec.a(zmbv.o)
  "_iconv_open", referenced from:
      _avcodec_open2 in libavcodec.a(utils.o)
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
  "_BZ2_bzDecompress", referenced from:
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
  "_inflate", referenced from:
      _http_read_stream in libavformat.a(http.o)
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
      _rtmp_open in libavformat.a(rtmpproto.o)
      _zlib_refill in libavformat.a(swfdec.o)
      _decode_frame_common in libavcodec.a(pngdec.o)
      _decode_text_chunk in libavcodec.a(pngdec.o)
      _flashsv_decode_frame in libavcodec.a(flashsv.o)
      ...
  "_inflateInit_", referenced from:
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
      _rtmp_open in libavformat.a(rtmpproto.o)
      _swf_read_header in libavformat.a(swfdec.o)
      _decode_frame_apng in libavcodec.a(pngdec.o)
      _decode_frame_png in libavcodec.a(pngdec.o)
      _decode_text_chunk in libavcodec.a(pngdec.o)
      _flashsv_decode_init in libavcodec.a(flashsv.o)
      ...
  "_iconv", referenced from:
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
  "_BZ2_bzDecompressEnd", referenced from:
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
  "_inflateInit2_", referenced from:
      _http_read_header in libavformat.a(http.o)
  "_deflateEnd", referenced from:
      _flashsv_decode_frame in libavcodec.a(flashsv.o)
      _flashsv2_encode_frame in libavcodec.a(flashsv2enc.o)
      _flashsv_encode_init in libavcodec.a(flashsvenc.o)
      _flashsv_encode_end in libavcodec.a(flashsvenc.o)
      _encode_frame in libavcodec.a(pngenc.o)
      _encode_end in libavcodec.a(lclenc.o)
      _encode_init in libavcodec.a(zmbvenc.o)
      ...
  "_BZ2_bzDecompressInit", referenced from:
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
  "_deflateInit_", referenced from:
      _flashsv_decode_frame in libavcodec.a(flashsv.o)
      _flashsv2_encode_frame in libavcodec.a(flashsv2enc.o)
      _encode_init in libavcodec.a(lclenc.o)
      _encode_init in libavcodec.a(zmbvenc.o)
  "_zlibCompileFlags", referenced from:
      _http_read_header in libavformat.a(http.o)
  "_compress2", referenced from:
      _flashsv2_encode_frame in libavcodec.a(flashsv2enc.o)
      _flashsv_encode_frame in libavcodec.a(flashsvenc.o)
  "_deflate", referenced from:
      _flashsv_decode_frame in libavcodec.a(flashsv.o)
      _flashsv2_encode_frame in libavcodec.a(flashsv2enc.o)
      _encode_frame in libavcodec.a(pngenc.o)
      _encode_frame in libavcodec.a(lclenc.o)
      _encode_frame in libavcodec.a(zmbvenc.o)
  "_inflateEnd", referenced from:
      _http_close in libavformat.a(http.o)
      _http_read_header in libavformat.a(http.o)
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
      _rtmp_open in libavformat.a(rtmpproto.o)
      _swf_read_close in libavformat.a(swfdec.o)
      _decode_frame_apng in libavcodec.a(pngdec.o)
      _decode_frame_png in libavcodec.a(pngdec.o)
      ...
  "_uncompress", referenced from:
      _id3v2_read_internal in libavformat.a(id3v2.o)
      _mov_read_cmov in libavformat.a(mov.o)
      _swf_read_packet in libavformat.a(swfdec.o)
      _decode_frame in libavcodec.a(cscd.o)
      _decode_frame in libavcodec.a(dxa.o)
      _decode_block in libavcodec.a(exr.o)
      _g2m_decode_frame in libavcodec.a(g2meet.o)
      ...
  "_iconv_close", referenced from:
      _avcodec_open2 in libavcodec.a(utils.o)
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)

      导入 libz.1.2.5.dylib ,再次编译

      Undefined symbols for architecture armv7:
  "_BZ2_bzDecompressInit", referenced from:
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
  "_iconv", referenced from:
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
  "_BZ2_bzDecompress", referenced from:
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
  "_BZ2_bzDecompressEnd", referenced from:
      _matroska_decode_buffer in libavformat.a(matroskadec.o)
  "_iconv_open", referenced from:
      _avcodec_open2 in libavcodec.a(utils.o)
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
  "_iconv_close", referenced from:
      _avcodec_open2 in libavcodec.a(utils.o)
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)

      导入 libbz2.1.0.dylib ,再次编译

      Undefined symbols for architecture armv7:
  "_iconv", referenced from:
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
  "_iconv_open", referenced from:
      _avcodec_open2 in libavcodec.a(utils.o)
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
  "_iconv_close", referenced from:
      _avcodec_open2 in libavcodec.a(utils.o)
      _avcodec_decode_subtitle2 in libavcodec.a(utils.o)
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)

      导入  libiconv.2.4.0.dylib  编译通过   3.0 后不通过

      Undefined symbols for architecture x86_64:
  "_CMBlockBufferCreateWithMemoryBlock", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_CMSampleBufferCreate", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_CMVideoFormatDescriptionCreate", referenced from:
      _av_videotoolbox_default_init2 in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionCreate", referenced from:
      _av_videotoolbox_default_init2 in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionDecodeFrame", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionInvalidate", referenced from:
      _av_videotoolbox_default_free in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionWaitForAsynchronousFrames", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_kCMFormatDescriptionExtension_SampleDescriptionExtensionAtoms", referenced from:
      _av_videotoolbox_default_init2 in libavcodec.a(videotoolbox.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

      导入 CoreMedia.framework  编译

      Undefined symbols for architecture x86_64:
  "_VTDecompressionSessionCreate", referenced from:
      _av_videotoolbox_default_init2 in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionDecodeFrame", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionInvalidate", referenced from:
      _av_videotoolbox_default_free in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionWaitForAsynchronousFrames", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
ld: symbol(s) not found for architecture x86_64

      导入 VideoToolbox.framework  编译通过

　　到此准备结束

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原文地址：https://www.cnblogs.com/liyufeng2013/p/4286684.html