android ffmpeg mediacodec 硬解码

ffmpeg 3.1以后 ffmpeg加入了硬解。
用法其实很简单，首先编译一个带硬解码的ffmpeg 库文件。

#!/bin/bash
PLATFORM=/Users/lake/test/android-ndk-r14b/platforms/android-19/arch-arm/
TOOLCHAIN=/Users/lake/test/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64
PREFIX=./android
function build_one
{
./configure \
--prefix=$PREFIX \
--target-os=android \
--cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
--arch=arm \
--sysroot=$PLATFORM \
--extra-cflags="-I$PLATFORM/usr/include" \
--cc=$TOOLCHAIN/bin/arm-linux-androideabi-gcc \
--nm=$TOOLCHAIN/bin/arm-linux-androideabi-nm \
--disable-shared \
--disable-ffmpeg \
--disable-ffplay \
--disable-ffprobe \
--disable-ffserver \
--disable-doc \
--disable-symver \
--enable-small \
--enable-gpl \
--enable-asm \
--enable-jni \
--enable-mediacodec \
--enable-decoder=h264_mediacodec \
--enable-hwaccel=h264_mediacodec \
--enable-decoder=hevc_mediacodec \
--enable-decoder=mpeg4_mediacodec \
--enable-decoder=vp8_mediacodec \
--enable-decoder=vp9_mediacodec \
--enable-nonfree \
--enable-version3 \
--extra-cflags="-Os -fpic $ADDI_CFLAGS" \
--extra-ldflags="$ADDI_LDFLAGS" \
$ADDITIONAL_CONFIGURE_FLAG


    make clean
    make j8
    make install


$TOOLCHAIN/bin/arm-linux-androideabi-ld \
-rpath-link=$PLATFORM/usr/lib \
-L$PLATFORM/usr/lib \
-L$PREFIX/lib \
-soname libffmpeg.so -shared -nostdlib -Bsymbolic --whole-archive --no-undefined -o \
$PREFIX/libffmpeg.so \
libavcodec/libavcodec.a \
libavfilter/libavfilter.a \
libswresample/libswresample.a \
libavformat/libavformat.a \
libavutil/libavutil.a \
libswscale/libswscale.a \
libavdevice/libavdevice.a \
libpostproc/libpostproc.a \
-lc -lm -lz -ldl -llog --dynamic-linker=/system/bin/linker \
$TOOLCHAIN/lib/gcc/arm-linux-androideabi/4.9.x/libgcc.a
}
# arm v7vfp
CPU=arm
OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=vfp -marm -march=$CPU "
ADDI_CFLAGS="-marm"
build_one

PLATFORM和TOOLCHAIN请用自己电脑的路径
温馨提示，请不要用as自带的ndk-bundle，因为这个自带的ndk版本是不完全的，编译会出错哦。

这个编出来是单独一个ffmpeg这个so文件 有点大哈5，60mb样子

然后硬解码的代码

#include <jni.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

extern "C" {
#include <libavformat/avformat.h>
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>
#include <libavcodec/jni.h>
}

#ifdef ANDROID

#include <android/log.h>
#include <android/native_window.h>
#include <android/native_window_jni.h>

#define LOGE(format, ...)  __android_log_print(ANDROID_LOG_ERROR, "(>_<)", format, ##__VA_ARGS__)
#define LOGI(format, ...)  __android_log_print(ANDROID_LOG_INFO,  "(^_^)", format, ##__VA_ARGS__)
#else
#define LOGE(format, ...)  printf("(>_<) " format "\n", ##__VA_ARGS__)
#define LOGI(format, ...)  printf("(^_^) " format "\n", ##__VA_ARGS__)
#endif

extern "C"
JNIEXPORT jint JNICALL Java_com_lake_ndktest_FFmpeg_play
        (JNIEnv *env, jobject obj, jstring input_jstr, jobject surface) {
    LOGI("play");
    // sd卡中的视频文件地址,可自行修改或者通过jni传入
    const char *file_name = env->GetStringUTFChars(input_jstr, NULL);
    LOGI("file_name:%s\n", file_name);
    av_register_all();

    AVFormatContext *pFormatCtx = avformat_alloc_context();

    // Open video file
    if (avformat_open_input(&pFormatCtx, file_name, NULL, NULL) != 0) {

        LOGE("Couldn't open file:%s\n", file_name);
        return -1; // Couldn't open file
    }

    // Retrieve stream information
    if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
        LOGE("Couldn't find stream information.");
        return -1;
    }
    // Find the first video stream
    //找到第一个视频流，因为里面的流还有可能是音频流或者其他的，我们摄像头只关心视频流
    int videoStream = -1, i;
    for (i = 0; i < pFormatCtx->nb_streams; i++) {
        if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO
            && videoStream < 0) {
            videoStream = i;
            break;
        }
    }
    if (videoStream == -1) {
        LOGE("Didn't find a video stream or audio steam.");
        return -1; // Didn't find a video stream
    }
    LOGI("找到视频流");
    AVCodecParameters *pCodecPar = pFormatCtx->streams[videoStream]->codecpar;
    //查找解码器
    //获取一个合适的编码器pCodec find a decoder for the video stream
    //AVCodec *pCodec = avcodec_find_decoder(pCodecPar->codec_id);
    AVCodec *pCodec;
    switch (pCodecPar->codec_id){
        case AV_CODEC_ID_H264:
            pCodec = avcodec_find_decoder_by_name("h264_mediacodec");//硬解码264
            if (pCodec == NULL) {
                LOGE("Couldn't find Codec.\n");
                return -1;
            }
            break;
        case AV_CODEC_ID_MPEG4:
            pCodec = avcodec_find_decoder_by_name("mpeg4_mediacodec");//硬解码mpeg4
            if (pCodec == NULL) {
                LOGE("Couldn't find Codec.\n");
                return -1;
            }
            break;
        case AV_CODEC_ID_HEVC:
            pCodec = avcodec_find_decoder_by_name("hevc_mediacodec");//硬解码265
            if (pCodec == NULL) {
                LOGE("Couldn't find Codec.\n");
                return -1;
            }
            break;
        default:
            pCodec = avcodec_find_decoder(pCodecPar->codec_id);//软解
            if (pCodec == NULL) {
                LOGE("Couldn't find Codec.\n");
                return -1;
            }
            break;
    }

    LOGI("获取解码器");
    //打开这个编码器，pCodecCtx表示编码器上下文，里面有流数据的信息
    // Get a pointer to the codec context for the video stream
    AVCodecContext *pCodecCtx = avcodec_alloc_context3(pCodec);

    // Copy context
    if (avcodec_parameters_to_context(pCodecCtx, pCodecPar) != 0) {
        fprintf(stderr, "Couldn't copy codec context");
        return -1; // Error copying codec context
    }

    LOGI("视频流帧率：%d fps\n", pFormatCtx->streams[videoStream]->r_frame_rate.num /
                           pFormatCtx->streams[videoStream]->r_frame_rate.den);

    int iTotalSeconds = (int) pFormatCtx->duration / 1000000;
    int iHour = iTotalSeconds / 3600;//小时
    int iMinute = iTotalSeconds % 3600 / 60;//分钟
    int iSecond = iTotalSeconds % 60;//秒
    LOGI("持续时间：%02d:%02d:%02d\n", iHour, iMinute, iSecond);

    LOGI("视频时长：%lld微秒\n", pFormatCtx->streams[videoStream]->duration);
    LOGI("持续时间：%lld微秒\n", pFormatCtx->duration);
    LOGI("获取解码器SUCESS");
    if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
        LOGE("Could not open codec.");
        return -1; // Could not open codec
    }
    LOGI("获取native window");
    // 获取native window
    ANativeWindow *nativeWindow = ANativeWindow_fromSurface(env, surface);
    LOGI("获取视频宽高");
    // 获取视频宽高
    int videoWidth = pCodecCtx->width;
    int videoHeight = pCodecCtx->height;
    LOGI("设置native window的buffer大小,可自动拉伸");
    // 设置native window的buffer大小,可自动拉伸
    ANativeWindow_setBuffersGeometry(nativeWindow, videoWidth, videoHeight,
                                     WINDOW_FORMAT_RGBA_8888);
    ANativeWindow_Buffer windowBuffer;
    LOGI("Allocate video frame");
    // Allocate video frame
    AVFrame *pFrame = av_frame_alloc();
    LOGI("用于渲染");
    // 用于渲染
    AVFrame *pFrameRGBA = av_frame_alloc();
    if (pFrameRGBA == NULL || pFrame == NULL) {
        LOGE("Could not allocate video frame.");
        return -1;
    }
    LOGI("Determine required buffer size and allocate buffer");
    // Determine required buffer size and allocate buffer
    int numBytes = av_image_get_buffer_size(AV_PIX_FMT_RGBA, pCodecCtx->width, pCodecCtx->height,
                                            1);
    uint8_t *buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
    av_image_fill_arrays(pFrameRGBA->data, pFrameRGBA->linesize, buffer, AV_PIX_FMT_RGBA,
                         pCodecCtx->width, pCodecCtx->height, 1);
    LOGI("由于解码出来的帧格式不是RGBA的,在渲染之前需要进行格式转换");
    // 由于解码出来的帧格式不是RGBA的,在渲染之前需要进行格式转换
    struct SwsContext *sws_ctx = sws_getContext(pCodecCtx->width/*视频宽度*/, pCodecCtx->height/*视频高度*/,
                                                pCodecCtx->pix_fmt/*像素格式*/,
                                                pCodecCtx->width/*目标宽度*/,
                                                pCodecCtx->height/*目标高度*/, AV_PIX_FMT_RGBA/*目标格式*/,
                                                SWS_BICUBIC/*图像转换的一些算法*/, NULL, NULL, NULL);
    if (sws_ctx == NULL) {
        LOGE("Cannot initialize the conversion context!\n");
        return -1;
    }
    LOGI("格式转换成功");
    LOGE("开始播放");
    int ret;
    AVPacket packet;
    while (av_read_frame(pFormatCtx, &packet) >= 0) {
        // Is this a packet from the video stream?
        if (packet.stream_index == videoStream) {
            //该楨位置
            float timestamp = packet.pts * av_q2d(pFormatCtx->streams[videoStream]->time_base);
            LOGI("timestamp=%f", timestamp);
            // 解码
            ret = avcodec_send_packet(pCodecCtx, &packet);
            if (ret < 0) {
                break;
            }
            while (avcodec_receive_frame(pCodecCtx, pFrame) == 0) {
   //绘图
                // lock native window buffer
                ANativeWindow_lock(nativeWindow, &windowBuffer, 0);
                // 格式转换
                sws_scale(sws_ctx, (uint8_t const *const *) pFrame->data,
                          pFrame->linesize, 0, pCodecCtx->height,
                          pFrameRGBA->data, pFrameRGBA->linesize);
                // 获取stride
                uint8_t *dst = (uint8_t *) windowBuffer.bits;
                int dstStride = windowBuffer.stride * 4;
                uint8_t *src = pFrameRGBA->data[0];
                int srcStride = pFrameRGBA->linesize[0];

                // 由于window的stride和帧的stride不同,因此需要逐行复制
                int h;
                for (h = 0; h < videoHeight; h++) {
                    memcpy(dst + h * dstStride, src + h * srcStride, srcStride);
                }
                ANativeWindow_unlockAndPost(nativeWindow);
            }
        }
        av_packet_unref(&packet);
    }
    LOGE("播放完成");
    av_free(buffer);
    av_free(pFrameRGBA);

    // Free the YUV frame
    av_free(pFrame);

    // Close the codecs
    avcodec_close(pCodecCtx);

    // Close the video file
    avformat_close_input(&pFormatCtx);
    return 0;
}

jint JNI_OnLoad(JavaVM* vm, void* reserved)//这个类似android的生命周期，加载jni的时候会自己调用
{
    LOGI("ffmpeg JNI_OnLoad");
    av_jni_set_java_vm(vm, reserved);
    return JNI_VERSION_1_6;
}

软解和硬解区别太大了，尤其1080p的视频，软解很慢，硬解速度非常快，质的提升啊。所以理论上手机支持硬解的视频优先硬解，不支持再调用ffmpeg的软解。

demo例子 https://github.com/lakehubo/NDKtest/tree/ffmpeg-meidacodec