How to build + include FFMPEG into an existing Android project

Question

I've found multiple questions and tutorials regarding FFMPEG, but I don't seem to understand most of them. All of the guides I have read, miss out large gaps and don't tend to explain things.

I have an existing Android app that streams audio using a third party library called AAC Decoder. For various reasons, I need to switch to use FFMPEG, but cannot figure out how. I have managed to follow guides to build FFMPEG, but then I don't understand what I am supposed to do with the output.

My app needs to stream audio only, from a remote URL. The streams can be in a variety of formats.

If anyone could link me to some comprehensive, detailed guides, or provide me with instructions, it would be great.

Thanks.

Answer 1

I created scripts to build FFmpeg, see my answer here:

arm-linux-androideabi-gcc is unable to create an executable - compile ffmpeg for android armeabi devices

One you have FFmpeg compiled create a "jni" folder in the root of your project. In the jni folder create Android.mk with these contents:

include $(call all-subdir-makefiles)

Then create Application.mk with these contents:

APP_ABI := armeabi armeabi-v7a x86

Next, in the jni folder create the following folder structure:

ffmpeg/ffmpeg/

In the first ffmpeg folder create another Android.mk:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE := libavcodec
LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavformat
LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavutil
LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

LOCAL_PATH:= $(call my-dir)

Finally, move the contents of the build folder (from the build script) to /jni/ffmpeg/ffmpeg/

From the project root run:

ndk-build clean

Then run:

ndk-build 

If you are feeling lazy you can simply download the jni folder from my project here and delete the "metadata" and "player" folders:

http://svn.code.sf.net/p/servestream/code/trunk/jni/

Let me know if you have any additional questions.

Answer 2

You need to cross Compile FFMPEG for android support. create jni folder inside your project and put FFMPEG folder inside jni. setup android NDK.

Here is a copy of Config.sh which i have used to cross compile ffmpeg for android.

Config.sh


#!/bin/sh
PLATFORM=/home/nishant/Desktop/android/android-ndk-r5b/platforms/android-8/arch-arm
PREBUILT=/home/nishant/Desktop/android/android-ndk-r5b/toolchains/arm-eabi-4.4.0/prebuilt/linux-x86
LIBX264=/home/nishant/Desktop/android/workspace/DemoProject/jni/x264
LIB=/home/nishant/Desktop/android/workspace/DemoProject/jni
EXTRA_LIBS="-lgcc -lm -ldl -lz -lc"
#EXTRA_EXE_LDFLAGS="$PLATFORM/usr/lib/crtbegin_dynamic.o $PLATFORM/usr/lib/crtend_android.o"

./configure --target-os=linux \
    --arch=arm \
    --enable-version3 \
    --enable-gpl \
    --enable-nonfree \
    --disable-stripping \
    --disable-ffmpeg \
    --disable-ffplay \
    --disable-ffserver \
    --disable-ffprobe \
    --enable-encoders \
    --enable-libfaac \
    --disable-muxers \
    --disable-devices \
    --disable-protocols \
    --enable-protocol=file \
    --enable-avfilter \
    --disable-network \
    --disable-mpegaudio-hp \
    --disable-avdevice \
    --enable-cross-compile \
    --cc=$PREBUILT/bin/arm-eabi-gcc \
    --nm=$PREBUILT/bin/arm-eabi-nm \
    --prefix=/home/nishant/Desktop/android/workspace/DemoProject/jni \
    --cross-prefix=$PREBUILT/bin/arm-eabi- \
    --enable-postproc \
    --extra-libs="$EXTRA_LIBS" \
    --extra-cflags="-I$PLATFORM/usr/include/ -I$LIB/include/ -I/home/admin1/x264 -std=gnu99 -fPIC -DANDROID -fpic -mthumb-interwork -ffunction-sections -funwind-tables -fstack-protector -fno-short-enums -D__ARM_ARCH_5__ -D__ARM_ARCH_5T__ -D__ARM_ARCH_5E__ -D__ARM_ARCH_5TE__  -Wno-psabi -march=armv5te -mtune=xscale -msoft-float -mthumb -Os -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64 -DANDROID -Wa,--noexecstack -MMD -MP" \
    --disable-asm \
    --enable-neon \
    --enable-armv5te \
    --enable-static \
    --disable-shared \
    --extra-ldflags="-Wl,-rpath-link=$LIB/lib -L$LIB/lib -nostdlib -Bdynamic  -Wl,--no-undefined -Wl,-z,noexecstack  -Wl,-z,nocopyreloc -Wl,-soname,/system/lib/libz.so -Wl,-rpath-link=$PLATFORM/usr/lib,-dynamic-linker=/system/bin/linker -L/usr/lib -L$PLATFORM/usr/lib -nostdlib $PLATFORM/usr/lib/crtbegin_dynamic.o $PLATFORM/usr/lib/crtend_android.o"

You can use this Config file to cross compile ffmpeg with some modifications in it.

Compile config.sh using the ndk-build command.

EDIT :

FFMPEG is Bundled with all Audio Encoders and Decoders. For AAC Encoding and Decoding use libfaac and libfaad. You can find Audio Decoding example in libavcodecs api-example.c file. You need to create a JNI Wrapper Class to manipulate the codecs. One of the decoding example from that file i am posting here.

static void audio_decode_example(const char *outfilename, const char *filename)
{
    AVCodec *codec;
    AVCodecContext *c= NULL;
    int out_size, len;
    FILE *f, *outfile;
    uint8_t *outbuf;
    uint8_t inbuf[AUDIO_INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
    AVPacket avpkt;

    av_init_packet(&avpkt);

    printf("Audio decoding\n");

    /* find the mpeg audio decoder */
    codec = avcodec_find_decoder(CODEC_ID_MP2);
    if (!codec) {
        fprintf(stderr, "codec not found\n");
        exit(1);
    }

    c= avcodec_alloc_context();

    /* open it */
    if (avcodec_open(c, codec) < 0) {
        fprintf(stderr, "could not open codec\n");
        exit(1);
    }

    outbuf = malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);

    f = fopen(filename, "rb");
    if (!f) {
        fprintf(stderr, "could not open %s\n", filename);
        exit(1);
    }
    outfile = fopen(outfilename, "wb");
    if (!outfile) {
        av_free(c);
        exit(1);
    }

    /* decode until eof */
    avpkt.data = inbuf;
    avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);

    while (avpkt.size > 0) {
        out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE;
        len = avcodec_decode_audio3(c, (short *)outbuf, &out_size, &avpkt);
        if (len < 0) {
            fprintf(stderr, "Error while decoding\n");
            exit(1);
        }
        if (out_size > 0) {
            /* if a frame has been decoded, output it */
            fwrite(outbuf, 1, out_size, outfile);
        }
        avpkt.size -= len;
        avpkt.data += len;
        if (avpkt.size < AUDIO_REFILL_THRESH) {
            /* Refill the input buffer, to avoid trying to decode
             * incomplete frames. Instead of this, one could also use
             * a parser, or use a proper container format through
             * libavformat. */
            memmove(inbuf, avpkt.data, avpkt.size);
            avpkt.data = inbuf;
            len = fread(avpkt.data + avpkt.size, 1,
                        AUDIO_INBUF_SIZE - avpkt.size, f);
            if (len > 0)
                avpkt.size += len;
        }
    }

    fclose(outfile);
    fclose(f);
    free(outbuf);

    avcodec_close(c);
    av_free(c);
}

Hope it will help you.