Android使用FFmpeg播放視頻（二）編寫代碼

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1、播放視頻

1.1、新建Android項目

筆者用的AndroidStudio 3.6.1版本，新建項目選Native C++，其他版本可能不太一樣，語言這裏選擇的是Kotlin

1.2、配置項目

這裏我們只需要armeabi-v7架構的FFmpeg，如需要其他架構，自行編譯，將編譯好的armv7/lib下的so複製到app/libs/armeabi-v7a，筆者一般都習慣把第三方so庫放到module/libs下面，這裏需要注意在module的build.gradle加入配置

	sourceSets {
        main {
            jniLibs.srcDirs = ['libs']
        }
    }

然後複製include文件夾到cpp文件夾下，複製到哪裏都無所謂，只要在CMakeLists.txt配置對就行。

1.3、編寫CMakeLists.txt

如果AndroidStudio創建項目沒有自動生成的需要手動新建

# For more information about using CMake with Android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html

# Sets the minimum version of CMake required to build the native library.

cmake_minimum_required(VERSION 3.4.1)


# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.
#設置生成的動態庫目錄 生成的so在當前項目不需要手動拷貝到libs或jniLibs，生成apk會自動引入，這裏生成的可以供其他項目使用
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/libs/${ANDROID_ABI})
#設置jni庫目錄
set(JNI_LIBS_DIR ${CMAKE_SOURCE_DIR}/../../../libs)


add_library( video
        SHARED
        video.cpp)

find_library( log-lib
        log )


add_library( avcodec SHARED IMPORTED)
set_target_properties(
        avcodec
        PROPERTIES IMPORTED_LOCATION
        ${JNI_LIBS_DIR}/${ANDROID_ABI}/libavcodec.so)

add_library(avdevice SHARED IMPORTED)
set_target_properties(
        avdevice
        PROPERTIES IMPORTED_LOCATION
        ${JNI_LIBS_DIR}/${ANDROID_ABI}/libavdevice.so)

add_library(avfilter SHARED IMPORTED)
set_target_properties(
        avfilter
        PROPERTIES IMPORTED_LOCATION
        ${JNI_LIBS_DIR}/${ANDROID_ABI}/libavfilter.so)

add_library(avformat SHARED IMPORTED)
set_target_properties(
        avformat
        PROPERTIES IMPORTED_LOCATION
        ${JNI_LIBS_DIR}/${ANDROID_ABI}/libavformat.so)

add_library(avutil SHARED IMPORTED)
set_target_properties(
        avutil
        PROPERTIES IMPORTED_LOCATION
        ${JNI_LIBS_DIR}/${ANDROID_ABI}/libavutil.so)

add_library(postproc SHARED IMPORTED)
set_target_properties(
        postproc
        PROPERTIES IMPORTED_LOCATION
        ${JNI_LIBS_DIR}/${ANDROID_ABI}/libpostproc.so)

add_library(swresample SHARED IMPORTED)
set_target_properties(
        swresample
        PROPERTIES IMPORTED_LOCATION
        ${JNI_LIBS_DIR}/${ANDROID_ABI}/libswresample.so)

add_library(swscale SHARED IMPORTED)
set_target_properties(
        swscale
        PROPERTIES IMPORTED_LOCATION
        ${JNI_LIBS_DIR}/${ANDROID_ABI}/libswscale.so)
#添加頭文件
include_directories(${CMAKE_SOURCE_DIR}/include)

target_link_libraries(
        video
        avcodec
        avdevice
        avfilter
        avformat
        avutil
        postproc
        swresample
        swscale
        android
        ${log-lib} )

1.4 配置build.gradle

android {
	...
	defaultConfig {
        ...
        externalNativeBuild {
            cmake {
                cppFlags ""
            }
            ndk {
                abiFilters "armeabi-v7a"
            }
        }
    }
    externalNativeBuild {
        cmake {
            path "src/main/cpp/CMakeLists.txt"//CMakeLists.txt文件路徑
        }
    }
    sourceSets {
        main {
            jniLibs.srcDirs = ['libs']
        }
    }
}

1.5、編寫C代碼

在src/main/cpp新建video.cpp
參考文章https://blog.csdn.net/johanman/article/details/83091706

//
// Created by k on 2020-05-13.
//

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

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

// Android 打印 Log
#define LOGE(FORMAT,...) __android_log_print(ANDROID_LOG_ERROR, "FFmpeg_log", FORMAT, ##__VA_ARGS__);

extern "C"
JNIEXPORT void JNICALL
Java_com_mrkzs_android_ffmpegplayvideo_MainActivity_playVideo(JNIEnv *env, jobject instance, jstring source, jobject surface) {
    // 記錄結果
    int result;
    // R1 Java String -> C String
    const char *path = env->GetStringUTFChars(source, 0);
    // 註冊 FFmpeg 組件
    av_register_all();
    // R2 初始化 AVFormatContext 上下文
    AVFormatContext *format_context = avformat_alloc_context();
    // 打開視頻文件
    result = avformat_open_input(&format_context, path, NULL, NULL);
    if (result < 0) {
        LOGE("Player Error : Can not open video file");
        return;
    }
    // 查找視頻文件的流信息
    result = avformat_find_stream_info(format_context, NULL);
    if (result < 0) {
        LOGE("Player Error : Can not find video file stream info");
        return;
    }
    // 查找視頻編碼器
    int video_stream_index = -1;
    for (int i = 0; i < format_context->nb_streams; i++) {
        // 匹配視頻流
        if (format_context->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_stream_index = i;
        }
    }
    // 沒找到視頻流
    if (video_stream_index == -1) {
        LOGE("Player Error : Can not find video stream");
        return;
    }
    // 初始化視頻編碼器上下文
    AVCodecContext *video_codec_context = avcodec_alloc_context3(NULL);
    avcodec_parameters_to_context(video_codec_context, format_context->streams[video_stream_index]->codecpar);
    // 初始化視頻編碼器
    AVCodec *video_codec = avcodec_find_decoder(video_codec_context->codec_id);
    if (video_codec == NULL) {
        LOGE("Player Error : Can not find video codec");
        return;
    }
    // R3 打開視頻解碼器
    result  = avcodec_open2(video_codec_context, video_codec, NULL);
    if (result < 0) {
        LOGE("Player Error : Can not find video stream");
        return;
    }
    // 獲取視頻的寬高
    int videoWidth = video_codec_context->width;
    int videoHeight = video_codec_context->height;
    // R4 初始化 Native Window 用於播放視頻
    ANativeWindow *native_window = ANativeWindow_fromSurface(env, surface);
    if (native_window == NULL) {
        LOGE("Player Error : Can not create native window");
        return;
    }
    // 通過設置寬高限制緩衝區中的像素數量，而非屏幕的物理顯示尺寸。
    // 如果緩衝區與物理屏幕的顯示尺寸不相符，則實際顯示可能會是拉伸，或者被壓縮的圖像
    result = ANativeWindow_setBuffersGeometry(native_window, videoWidth, videoHeight,WINDOW_FORMAT_RGBA_8888);
    if (result < 0){
        LOGE("Player Error : Can not set native window buffer");
        ANativeWindow_release(native_window);
        return;
    }
    // 定義繪圖緩衝區
    ANativeWindow_Buffer window_buffer;
    // 聲明數據容器 有3個
    // R5 解碼前數據容器 Packet 編碼數據
    AVPacket *packet = av_packet_alloc();
    // R6 解碼後數據容器 Frame 像素數據 不能直接播放像素數據 還要轉換
    AVFrame *frame = av_frame_alloc();
    // R7 轉換後數據容器 這裏面的數據可以用於播放
    AVFrame *rgba_frame = av_frame_alloc();
    // 數據格式轉換準備
    // 輸出 Buffer
    int buffer_size = av_image_get_buffer_size(AV_PIX_FMT_RGBA, videoWidth, videoHeight, 1);
    // R8 申請 Buffer 內存
    uint8_t *out_buffer = (uint8_t *) av_malloc(buffer_size * sizeof(uint8_t));
    av_image_fill_arrays(rgba_frame->data, rgba_frame->linesize, out_buffer, AV_PIX_FMT_RGBA, videoWidth, videoHeight, 1);
    // R9 數據格式轉換上下文
    struct SwsContext *data_convert_context = sws_getContext(
            videoWidth, videoHeight, video_codec_context->pix_fmt,
            videoWidth, videoHeight, AV_PIX_FMT_RGBA,
            SWS_BICUBIC, NULL, NULL, NULL);
    // 開始讀取幀
    while (av_read_frame(format_context, packet) >= 0) {
        // 匹配視頻流
        if (packet->stream_index == video_stream_index) {
            // 解碼
            result = avcodec_send_packet(video_codec_context, packet);
            if (result < 0 && result != AVERROR(EAGAIN) && result != AVERROR_EOF) {
                LOGE("Player Error : codec step 1 fail");
                return;
            }
            result = avcodec_receive_frame(video_codec_context, frame);
            if (result < 0 && result != AVERROR_EOF) {
                LOGE("Player Error : codec step 2 fail");
                return;
            }
            // 數據格式轉換
            result = sws_scale(
                    data_convert_context,
                    (const uint8_t* const*) frame->data, frame->linesize,
                    0, videoHeight,
                    rgba_frame->data, rgba_frame->linesize);
            if (result <= 0) {
                LOGE("Player Error : data convert fail");
                return;
            }
            // 播放
            result = ANativeWindow_lock(native_window, &window_buffer, NULL);
            if (result < 0) {
                LOGE("Player Error : Can not lock native window");
            } else {
                // 將圖像繪製到界面上
                // 注意 : 這裏 rgba_frame 一行的像素和 window_buffer 一行的像素長度可能不一致
                // 需要轉換好 否則可能花屏
                uint8_t *bits = (uint8_t *) window_buffer.bits;
                for (int h = 0; h < videoHeight; h++) {
                    memcpy(bits + h * window_buffer.stride * 4,
                           out_buffer + h * rgba_frame->linesize[0],
                           rgba_frame->linesize[0]);
                }
                ANativeWindow_unlockAndPost(native_window);
            }
        }
        // 釋放 packet 引用
        av_packet_unref(packet);
    }
    // 釋放 R9
    sws_freeContext(data_convert_context);
    // 釋放 R8
    av_free(out_buffer);
    // 釋放 R7
    av_frame_free(&rgba_frame);
    // 釋放 R6
    av_frame_free(&frame);
    // 釋放 R5
    av_packet_free(&packet);
    // 釋放 R4
    ANativeWindow_release(native_window);
    // 關閉 R3
    avcodec_close(video_codec_context);
    // 釋放 R2
    avformat_close_input(&format_context);
    // 釋放 R1
    env->ReleaseStringUTFChars(source, path);
}

1.6、佈局文件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/url"
        android:layout_width="match_parent"
        android:layout_marginEnd="100dp"
        android:layout_height="60dp" />
    <Button
        android:id="@+id/play"
        android:layout_width="100dp"
        android:layout_height="60dp"
        app:layout_constraintLeft_toRightOf="@id/url"/>

    <SurfaceView
        android:id="@+id/surface"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="60dp"
        app:layout_constraintTop_toBottomOf="@+id/url" />


</androidx.constraintlayout.widget.ConstraintLayout>

1.7、MainActivity

kotlin代碼

package com.mrkzs.android.ffmpegplayvideo

import android.os.Bundle
import android.text.TextUtils
import android.view.Surface
import android.view.SurfaceHolder
import android.view.SurfaceView
import android.widget.Button
import android.widget.EditText
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val urlEt = findViewById<EditText>(R.id.url)
        val playBtn = findViewById<Button>(R.id.play)
        val surfaceView = findViewById<SurfaceView>(R.id.surface)
        val holder : SurfaceHolder = surfaceView.holder
        playBtn.setOnClickListener { view ->
            if (view.id == R.id.play) {
                if(!TextUtils.isEmpty(urlEt.text.trim())) {
                    Thread(Runnable {
                        playVideo(urlEt.text.trim().toString(), holder.surface)
                    }).start()

                }
            }
        }
    }

    external fun playVideo(url : String, surface: Surface)

    companion object {
        init {
            System.loadLibrary("video")
        }
    }
}

這只是一個小小demo，後續學習中會不斷深入。

2、總結

github demo：https://github.com/hiongyend/FFmpegPlayVideo
上一篇文章：Android使用FFmpeg播放視頻（一）編譯FFmpeg