想學習FFmpeg 庫,可是工欲善其事必先利其器,因此,這里先從基礎做起,編譯FFmpeg,并集成到ios項目中.

這里從github上找地址(https://github.com/kewlbear/FFmpeg-iOS-build-script) 我測試的環(huán)境是xcode10.1 ffmpeg的版本是4.1 .親自測試好用

該腳本依賴

• gas-preprocessor
• yasm

gas-preprocessor 安裝 可網上查詢
yasm安裝
brew install yams

下載腳本.進入該腳本文件夾
運行命令

./build-ffmpeg.sh
經過一段時間 編譯結束.
當前文件夾的文件有

ffmpeg結果文件夾

到這里很順利編譯結束.

集成新工程

創(chuàng)建新工程

新工程

添加ffmpeg庫

修改搜索頭文件

這里需要注意 要是我們路徑 $(PROJECT_DIR)/TestFFmpeg/include 模式是 non-recursive. 那么我們引用頭文件的格式是#import "libavformat/avformat.h"

添加六個依賴庫

腳本解釋

#!/bin/sh

# directories
FF_VERSION="4.1"
#FF_VERSION="snapshot-git"
if [[ $FFMPEG_VERSION != "" ]]; then
  FF_VERSION=$FFMPEG_VERSION
fi
SOURCE="ffmpeg-$FF_VERSION"
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-build-script-for-iOS/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 --enable-nonfree"
fi

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

ARCHS="arm64 armv7 x86_64 i386"

COMPILE="y"
LIPO="y"

DEPLOYMENT_TARGET="8.0"

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.githubusercontent.com/Homebrew/install/master/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=$DEPLOYMENT_TARGET -fembed-bitcode"
            if [ "$ARCH" = "arm64" ]
            then
                EXPORT="GASPP_FIX_XCODE5=1"
            fi
        fi

        XCRUN_SDK=`echo $PLATFORM | tr '[:upper:]' '[:lower:]'`
        CC="xcrun -sdk $XCRUN_SDK clang"

        # force "configure" to use "gas-preprocessor.pl" (FFmpeg 3.3)
        if [ "$ARCH" = "arm64" ]
        then
            AS="gas-preprocessor.pl -arch aarch64 -- $CC"
        else
            AS="gas-preprocessor.pl -- $CC"
        fi

        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" \
            --as="$AS" \
            $CONFIGURE_FLAGS \
            --extra-cflags="$CFLAGS" \
            --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

以上是完整腳本摘錄,下面依次解釋.

FF_VERSION="4.1"

這個是ffmpeg的realease的版本可以從github地址中查看

image.png

if [[ $FFMPEG_VERSION != "" ]]; then
  FF_VERSION=$FFMPEG_VERSION
fi

判斷是否配置了變量FFMPEG_VERSION,配置就賦值給變量FF_VERSION

SOURCE="ffmpeg-$FF_VERSION"
FAT="FFmpeg-iOS"

聲明兩個變量

SOURCE 源碼指向的tag
FAT 代表的最后輸出的fat文件所在的文件夾名字

SCRATCH="scratch"
THIN=`pwd`/"thin"

也是兩個路徑

#X264=`pwd`/fat-x264

#FDK_AAC=`pwd`/../fdk-aac-build-script-for-iOS/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 --enable-nonfree"
fi

這里的x264 和FDK_AAC 兩個變量默認是注釋掉的.如果需要庫x264 和aac音頻.這里需要打開

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

要是需要配置avresample 可以打開該選項

ARCHS="arm64 armv7 x86_64 i386"

編譯的結構體

COMPILE="y"
LIPO="y"
DEPLOYMENT_TARGET="8.0"

COMPILE 代表編譯
LIPO 代表合并
y 應該是獲取yes的首字母,方便記憶吧
DEPLOYMENT_TARGET 編譯庫的最低版本

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

腳本名稱叫test.sh 入參三個: 1 2 3
運行test.sh 1 2 3后
$為"1 2 3"（一起被引號包状朴纭）
$@為"1" "2" "3"（分別被包住）
$#為3（參數數量）
這里因為我們沒有傳入參數因此,這里$ 是空.不會跳入該函數中
傳入參數lipo,那么就不需要進行編譯
其他的參數就是arch了,要是參數是一個,就不需要lipo命令 了

if [ "$COMPILE" ]
then
  ....
fi

這段是判斷是否需要編譯

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.githubusercontent.com/Homebrew/install/master/install)" \
                || exit 1
        fi
        echo 'Trying to install Yasm...'
        brew install yasm || exit 1
    fi

依賴yasm ,要是沒有安裝yasm,那么安裝yasm.而yasm依賴brew,沒有brew,那么安裝brew命令

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

同理加載gas-preprocessor.pl 命令

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

判斷是否有源碼,沒有那么就需要去github下載源碼.

-r 是讀取當前目錄文件
! 取反
tar xj 就是解壓文件

CWD=`pwd`

代表當前路徑

for ARCH in $ARCHS
    do
.....
done

循環(huán)生成所需要的結構體.這中間的內容就是生成結構體

echo "building $ARCH..."
        mkdir -p "$SCRATCH/$ARCH"
        cd "$SCRATCH/$ARCH"

• 打印當前build的結構體
• 生成文件夾,路徑是$SCRATCH/$ARCH 其實就是scratch/arm64等
• 進入該路徑

    CFLAGS="-arch $ARCH"

編譯參數,選擇生成的結構體類型

        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 -fembed-bitcode"
            if [ "$ARCH" = "arm64" ]
            then
                EXPORT="GASPP_FIX_XCODE5=1"
            fi
        fi

這里是根據結構體類型選擇PLATFORM 和 編譯參數

i386 和x86_64 是模擬器結構體
arm64 armv7 是真機結構體
-fembed-bitcode bitcode指令

        XCRUN_SDK=`echo $PLATFORM | tr '[:upper:]' '[:lower:]'`
        CC="xcrun -sdk $XCRUN_SDK clang"

XCRUN_SDK 是編譯所需的sdk連接地址 結果是iphonesimulator 和 iphoneos
CC 參數是編譯命令

if [ "$ARCH" = "arm64" ]
        then
            AS="gas-preprocessor.pl -arch aarch64 -- $CC"
        else
            AS="gas-preprocessor.pl -- $CC"
        fi

聲明一個變量AS

    CXXFLAGS="$CFLAGS"
        LDFLAGS="$CFLAGS"

兩個變量

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

是否需要變量這兩個庫

到目前為止.

CC = "xcrun -sdk iphonesimulator clang"
AS = "gas-preprocessor.pl -- $CC"
CXXFLAGS = -arch x86_64 -mios-simulator-version-min=8.0
CFLAGS = -arch x86_64 -mios-simulator-version-min=8.0
LDFLAGS = -arch x86_64 -mios-simulator-version-min=8.0
TMPDIR = /var/folders/xz/ndlv58rj50q3v260h8lnyngh0000gn/T/
CONFIGURE_FLAGS = --enable-cross-compile --disable-debug --disable-programs --disable-doc --enable-pic

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

${TMPDIR/%/} 臨時路徑 這里其實就是執(zhí)行ffmpeg的 configure命令

這里我們看看configure的最終結果是啥
configure --target-os=darwin --arch=x86_64 --cc=xcrun -sdk iphonesimulator clang --as=gas-preprocessor.pl -- $CC --enable-cross-compile --disable-debug --disable-programs --disable-doc --enable-pic --extra-cflags= -arch x86_64 -mios-simulator-version-min=8.0 --extra-ldflags= -arch x86_64 -mios-simulator-version-min=8.0 --prefix=./thin/x86_64

make -j3 install $EXPORT || exit 1

安裝
cd $CWD
退出到根目錄

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

這里就是lipo命令的簡單使用

1.首先創(chuàng)建文件夾FFmpeg-iOS/lib
2 設置參數
3.進入 目錄thin/x86_64/lib

4. 依次尋找該目錄下的.a 文件

1.跳轉到 根目錄

2. 打印lipo 需要執(zhí)行的命令
   3.lipo 命令執(zhí)行.(從thin文件夾中找 .a文件,輸出到FFmpeg-iOS/lib/中,命名查找的.a文件)
   5.進入根目錄
   6.將thin/x86_64/include 的文件拷貝到FFmpeg-iOS/lib/include

編譯參數選擇

1 生成參數

2 交叉參數

3 性能參數
以下參數使用--enable-foo啟用或使用--disable-foo禁用時使用--e/d-代替班缰。

其他的可更改優(yōu)化方案：AltiVec安寺、3DNow! 嫁盲、MMX、MMX2、SSE喳挑、SSE3、armv5te滔悉、armv6伊诵、armv6t2、ARM VFP回官、iwmmxt曹宴、MMI、neon歉提、VIS

4 功能選項
使用--enable-foo啟用或使用--disable-foo禁用需要的功能插件笛坦，使用--e/d-代替区转。某些部件（如decoder）enable時需要明確指明，例：--enable-decoder=libdavs2版扩。

注：打開與啟用非等同
其他默認開啟但可以關閉的部分：ffmpeg废离、ffprobe、ffplay礁芦、ffserver蜻韭、avdevice、avcodec柿扣、avcore肖方、avformat、swscale未状、特定部件（如某個編解碼器等）
可選擇禁用的編碼：AAN DCT俯画、DCT、Golomb司草、FFT艰垂、Golomb、LPC埋虹、MDCT材泄、RDFT、VAAPI吨岭、VDPAU拉宗、DXVA2

查看./configure 的參數,我們可以通過 ./configure --help 查看

參數編譯
ffmpeg-github
kxmovie
官方文檔
腳本地址