FFmpeg —— 5.windows+eclipse+FFmpeg环境搭建

谁践踏了优雅 2021-09-24 03:32 515阅读 0赞

# 保证在Windows环境下已成功安装eclipse，MinGW #

1. eclipse在Windows的环境搭建（省略）—— 网上有很多教程，这里不做介绍

2. MinGW在Windows的配置，此处也省略 —— 参考网上其他教程

# 新建工程 #

打开eclipse，File -> New -> C/C++ Project

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![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1b3l1bmZlaTEyMw_size_16_color_FFFFFF_t_70 1][]

工程创建之后，编译运行，输出“!!!Hello World!!!”，说明成功

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# 配置FFmpeg的依赖头文件和库文件  #

## 下载FFmpeg的依赖头文件和库文件（我们下载开发版本） ##

[http://ffmpeg.zeranoe.com/builds/][http_ffmpeg.zeranoe.com_builds]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1b3l1bmZlaTEyMw_size_16_color_FFFFFF_t_70 3][]

**注意事项：**

要保证下载的版本和Windows下面的MinGW的GCC版本保持一致。

本人Windows版本的GCC是32位，因此此处下载的是32位的FFmpeg的开发版本。

##  将下载的FFmpeg解压到工程目录 ##

（当然，你可以解压到任何其他地方，只需要在后面的链接路径指向正确即可）

![202004092105117.png][]

## 设置库路径和头文件路径  ##

### 库路径  ###

打开项目属性设置对话框（Alt+Enter）

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此处把所有的库都加进去了，你可以根据自己需要只加载指定库。

### 头文件路径  ###

# ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1b3l1bmZlaTEyMw_size_16_color_FFFFFF_t_70 5][]  #

# 编译 #

修改ffmpeg.cpp文件

/*
     * Copyright (c) 2001 Fabrice Bellard
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
     * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     * THE SOFTWARE.
     */
    
    /**
     * @file
     * audio encoding with libavcodec API example.
     *
     * @example encode_audio.c
     */
    
    #include <stdint.h>
    #include <stdio.h>
    #include <stdlib.h>
    
    extern "C"
    {
    #include "libavcodec/avcodec.h"
    #include "libavformat/avformat.h"
    #include "libswscale/swscale.h"
    };
    
    
    /* check that a given sample format is supported by the encoder */
    static int check_sample_fmt(const AVCodec *codec, enum AVSampleFormat sample_fmt)
    {
        const enum AVSampleFormat *p = codec->sample_fmts;
    
        while (*p != AV_SAMPLE_FMT_NONE) {
            if (*p == sample_fmt)
                return 1;
            p++;
        }
        return 0;
    }
    
    /* just pick the highest supported samplerate */
    static int select_sample_rate(const AVCodec *codec)
    {
        const int *p;
        int best_samplerate = 0;
    
        if (!codec->supported_samplerates)
            return 44100;
    
        p = codec->supported_samplerates;
        while (*p) {
            if (!best_samplerate || abs(44100 - *p) < abs(44100 - best_samplerate))
                best_samplerate = *p;
            p++;
        }
        return best_samplerate;
    }
    
    /* select layout with the highest channel count */
    static int select_channel_layout(const AVCodec *codec)
    {
        const uint64_t *p;
        uint64_t best_ch_layout = 0;
        int best_nb_channels   = 0;
    
        if (!codec->channel_layouts)
            return AV_CH_LAYOUT_STEREO;
    
        p = codec->channel_layouts;
        while (*p) {
            int nb_channels = av_get_channel_layout_nb_channels(*p);
    
            if (nb_channels > best_nb_channels) {
                best_ch_layout    = *p;
                best_nb_channels = nb_channels;
            }
            p++;
        }
        return best_ch_layout;
    }
    
    static void encode(AVCodecContext *ctx, AVFrame *frame, AVPacket *pkt,
                       FILE *output)
    {
        int ret;
    
        /* send the frame for encoding */
        ret = avcodec_send_frame(ctx, frame);
        if (ret < 0) {
            fprintf(stderr, "Error sending the frame to the encoder\n");
            exit(1);
        }
    
        /* read all the available output packets (in general there may be any
         * number of them */
        while (ret >= 0) {
            ret = avcodec_receive_packet(ctx, pkt);
            if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
                return;
            else if (ret < 0) {
                fprintf(stderr, "Error encoding audio frame\n");
                exit(1);
            }
    
            fwrite(pkt->data, 1, pkt->size, output);
            av_packet_unref(pkt);
        }
    }
    
    int main(int argc, char **argv)
    {
        const char *filename;
        const AVCodec *codec;
        AVCodecContext *c= NULL;
        AVFrame *frame;
        AVPacket *pkt;
        int i, j, k, ret;
        FILE *f;
        uint16_t *samples;
        float t, tincr;
    
        if (argc <= 1) {
            fprintf(stderr, "Usage: %s <output file>\n", argv[0]);
            return 0;
        }
        filename = argv[1];
    
        /* find the MP2 encoder */
        codec = avcodec_find_encoder(AV_CODEC_ID_MP2);
        if (!codec) {
            fprintf(stderr, "Codec not found\n");
            exit(1);
        }
    
        c = avcodec_alloc_context3(codec);
        if (!c) {
            fprintf(stderr, "Could not allocate audio codec context\n");
            exit(1);
        }
    
        /* put sample parameters */
        c->bit_rate = 64000;
    
        /* check that the encoder supports s16 pcm input */
        c->sample_fmt = AV_SAMPLE_FMT_S16;
        if (!check_sample_fmt(codec, c->sample_fmt)) {
            fprintf(stderr, "Encoder does not support sample format %s",
                    av_get_sample_fmt_name(c->sample_fmt));
            exit(1);
        }
    
        /* select other audio parameters supported by the encoder */
        c->sample_rate    = select_sample_rate(codec);
        c->channel_layout = select_channel_layout(codec);
        c->channels       = av_get_channel_layout_nb_channels(c->channel_layout);
    
        /* open it */
        if (avcodec_open2(c, codec, NULL) < 0) {
            fprintf(stderr, "Could not open codec\n");
            exit(1);
        }
    
        f = fopen(filename, "wb");
        if (!f) {
            fprintf(stderr, "Could not open %s\n", filename);
            exit(1);
        }
    
        /* packet for holding encoded output */
        pkt = av_packet_alloc();
        if (!pkt) {
            fprintf(stderr, "could not allocate the packet\n");
            exit(1);
        }
    
        /* frame containing input raw audio */
        frame = av_frame_alloc();
        if (!frame) {
            fprintf(stderr, "Could not allocate audio frame\n");
            exit(1);
        }
    
        frame->nb_samples     = c->frame_size;
        frame->format         = c->sample_fmt;
        frame->channel_layout = c->channel_layout;
    
        /* allocate the data buffers */
        ret = av_frame_get_buffer(frame, 0);
        if (ret < 0) {
            fprintf(stderr, "Could not allocate audio data buffers\n");
            exit(1);
        }
    
        /* encode a single tone sound */
        t = 0;
        tincr = 2 * M_PI * 440.0 / c->sample_rate;
        for (i = 0; i < 200; i++) {
            /* make sure the frame is writable -- makes a copy if the encoder
             * kept a reference internally */
            ret = av_frame_make_writable(frame);
            if (ret < 0)
                exit(1);
            samples = (uint16_t*)frame->data[0];
    
            for (j = 0; j < c->frame_size; j++) {
                samples[2*j] = (int)(sin(t) * 10000);
    
                for (k = 1; k < c->channels; k++)
                    samples[2*j + k] = samples[2*j];
                t += tincr;
            }
            encode(c, frame, pkt, f);
        }
    
        /* flush the encoder */
        encode(c, NULL, pkt, f);
    
        fclose(f);
    
        av_frame_free(&frame);
        av_packet_free(&pkt);
        avcodec_free_context(&c);
    
        return 0;
    }

编译通过，证明各种环境变量及参数配置正确。

# 运行  #

由于找不到 avformat-56.dll，无法继续执行代码。重新安装应用程序可能会解决此问题

![20200411223114477.png][]

**为什么报错呢？？？ **

代码中用到了FFmpeg库，那么编译的时候需要该库相应的头文件，链接的时候需要静态lib文件，而**运行的时候需要相应的dll文件**。

原因是，你虽然引用了LIB文件，但这并不是真正的静态库文件，而是对DLL的引用，所以当你调用ffmpeg库函数时，需要DLL文件在场。

参考：[https://www.cnblogs.com/jerry-chou/archive/2011/03/31/2000761.html][https_www.cnblogs.com_jerry-chou_archive_2011_03_31_2000761.html]

**解决办法：**

[http://ffmpeg.zeranoe.com/builds/][http_ffmpeg.zeranoe.com_builds]

下载shared版本

![20200411223607440.png][]

将解压之后的dll文件拷贝到FFmpeg的安装目录：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1b3l1bmZlaTEyMw_size_16_color_FFFFFF_t_70 6][]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1b3l1bmZlaTEyMw_size_16_color_FFFFFF_t_70 1]: /images/20210923/d9ddd03c3e8f473ea43f5c56b5076f98.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1b3l1bmZlaTEyMw_size_16_color_FFFFFF_t_70 2]: /images/20210923/945f514a00f74c7da0d865d80698e182.png
[http_ffmpeg.zeranoe.com_builds]: http://ffmpeg.zeranoe.com/builds/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1b3l1bmZlaTEyMw_size_16_color_FFFFFF_t_70 3]: /images/20210923/1d09f3e650c1455cbffed385777721d8.png
[202004092105117.png]: /images/20210923/cd7db4aba18e4c97a1e72196a08d1f8f.png
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[20200411223114477.png]: /images/20210923/64f66cb98ae64c2591d1acb3e949f147.png
[https_www.cnblogs.com_jerry-chou_archive_2011_03_31_2000761.html]: https://www.cnblogs.com/jerry-chou/archive/2011/03/31/2000761.html
[20200411223607440.png]: /images/20210923/dac16ca518714ddda6da014f7c847d35.png
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