02ffmpeg多媒体文件处理

一、日志系统

常用日志级别(由高到低排序)

• AV_LOG_ERROR

• AV_LOG_WARNING

• AV_LOG_INFO

• AV_LOG_DEBUG

// ffmpeg_log.cpp
extern "C" {
#include <libavutil/log.h>
}

#pragma comment(lib,"avutil.lib")

int main(int argc, char *argv[])
{
    av_log_set_level(AV_LOG_DEBUG);

    // 除去前面两个参数，av_log跟C语言printf差不多
    av_log(NULL, AV_LOG_DEBUG, "hello world!%s\n", "123");

    return 0;
}

二、文件删除与重命名

extern "C" {
#include <libavutil/log.h>
#include <libavformat/avformat.h>
}

int main(int argc, char** argv)
{
    int ret = 0;
    // 重命名
    ret = avpriv_io_move("./1.txt", "2.txt");
    if (ret < 0)
    {
        av_log(NULL, AV_LOG_ERROR, "Failed to rename\n");
        return -1;
    } 
    av_log(NULL, AV_LOG_INFO, "Rename successfully.\n");

    // 删除文件
    ret = avpriv_io_delete("./3.txt");
    if (ret < 0)
    {
        av_log(NULL, AV_LOG_ERROR, "Failed to delete.\n");
        return -1;
    }
    av_log(NULL, AV_LOG_INFO, "Delete successfully.\n");

    return 0;
}

三、抽取音频数据

#include <iostream>
using namespace std;

extern "C" {
#include <libavutil/log.h>
#include <libavutil/avutil.h>
#include <libavformat/avformat.h>
}

#pragma comment(lib,"avcodec.lib")
#pragma comment(lib,"avutil.lib")
#pragma comment(lib,"avformat.lib")

int main(int argc, char* argv[]) {

    int ret = -1;
    int idx = -1;

    //1. 处理一些参数；将1.mp4中的音频提取出来保存为1.acc
    char src[] = "1.mp4";
    char dst[] = "1.aac";
    
    AVFormatContext* pFmtCtx = NULL;
    AVFormatContext* oFmtCtx = NULL;

    AVOutputFormat* outFmt = NULL;
    AVStream* outStream = NULL;
    AVStream* inStream = NULL;

    AVPacket pkt;

    //2. 打开多媒体文件
    if ((ret = avformat_open_input(&pFmtCtx, src, NULL, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "打开多媒体文件错误\n");
        exit(-1);
    }

    //3. 从多媒体文件中找到音频流
    idx = av_find_best_stream(pFmtCtx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0);
    if (idx < 0) {
        av_log(pFmtCtx, AV_LOG_ERROR, "Does not include audio stream!\n");
        goto _ERROR;
    }

    //4. 打开目的文件的上下文
    oFmtCtx = avformat_alloc_context();
    if (!oFmtCtx) {
        av_log(NULL, AV_LOG_ERROR, "NO Memory!\n");
        goto _ERROR;
    }
    outFmt = av_guess_format(NULL, dst, NULL);
    oFmtCtx->oformat = outFmt;

    //5. 为目的文件，创建一个新的音频流
    outStream = avformat_new_stream(oFmtCtx, NULL);
    //6. 设置输出音频参数
    inStream = pFmtCtx->streams[idx];
    avcodec_parameters_copy(outStream->codecpar, inStream->codecpar);
    outStream->codecpar->codec_tag = 0;

    //绑定
    ret = avio_open2(&oFmtCtx->pb, dst, AVIO_FLAG_WRITE, NULL, NULL);
    if (ret < 0) {
        av_log(oFmtCtx, AV_LOG_ERROR, "绑定失败");
        goto _ERROR;
    }

    //7. 写多媒体文件头到目的文件
    ret = avformat_write_header(oFmtCtx, NULL);
    if (ret < 0) {
        cout << "写多媒体文件头到目的文件错误" << endl;
        av_log(oFmtCtx, AV_LOG_ERROR, "写多媒体文件头到目的文件错误");
        goto _ERROR;
    }
    
    //8. 从源多媒体文件中读到音频数据到目的文件中
    while (av_read_frame(pFmtCtx, &pkt) >= 0) {
        if (pkt.stream_index == idx) {
            pkt.pts = av_rescale_q_rnd(pkt.pts, inStream->time_base, outStream->time_base, (enum AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
            pkt.dts = pkt.pts;
            pkt.duration = av_rescale_q(pkt.duration, inStream->time_base, outStream->time_base);
            pkt.stream_index = 0;
            pkt.pos = -1;
            av_interleaved_write_frame(oFmtCtx, &pkt);
            av_packet_unref(&pkt);
        }
    }
    //9. 写多媒体文件尾到文件中
    av_write_trailer(oFmtCtx);

    //10. 将申请的资源释放掉
_ERROR:
    if (pFmtCtx) {
        avformat_close_input(&pFmtCtx);
        pFmtCtx = NULL;
    }
    if (oFmtCtx->pb) {
        avio_close(oFmtCtx->pb);
    }

    if (oFmtCtx) {
        avformat_free_context(oFmtCtx);
        oFmtCtx = NULL;
    }

    cout << "提取音频数据成功" << endl;
    return 0;
}

四、抽取视频数据

#include <iostream>
using namespace std;

extern "C" {
#include <libavutil/log.h>
#include <libavutil/avutil.h>
#include <libavformat/avformat.h>
}

#pragma comment(lib,"avcodec.lib")
#pragma comment(lib,"avutil.lib")
#pragma comment(lib,"avformat.lib")

int main(int argc, char* argv[]) {

    int ret = -1;
    int idx = -1;

    //1. 处理一些参数；抽取1.mp4中的视频保存到2.mp4
    char src[] = "1.mp4";
    char dst[] = "2.mp4";

    AVFormatContext* pFmtCtx = NULL;
    AVFormatContext* oFmtCtx = NULL;

    AVOutputFormat* outFmt = NULL;
    AVStream* outStream = NULL;
    AVStream* inStream = NULL;

    AVPacket pkt;

    av_log_set_level(AV_LOG_DEBUG);

    //2. 打开多媒体文件
    if ((ret = avformat_open_input(&pFmtCtx, src, NULL, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "打开多媒体文件失败\n");
        exit(-1);
    }

    //3. 从多媒体文件中找到视频流
    idx = av_find_best_stream(pFmtCtx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);
    if (idx < 0) {
        av_log(pFmtCtx, AV_LOG_ERROR, "Does not include audio stream!\n");
        goto _ERROR;
    }

    //4. 打开目的文件的上下文
    oFmtCtx = avformat_alloc_context();
    if (!oFmtCtx) {
        av_log(NULL, AV_LOG_ERROR, "NO Memory!\n");
        goto _ERROR;
    }
    outFmt = av_guess_format(NULL, dst, NULL);
    oFmtCtx->oformat = outFmt;

    //5. 为目的文件，创建一个新的视频流
    outStream = avformat_new_stream(oFmtCtx, NULL);
    //6. 设置输出视频参数
    inStream = pFmtCtx->streams[idx];
    avcodec_parameters_copy(outStream->codecpar, inStream->codecpar);
    outStream->codecpar->codec_tag = 0;

    //绑定
    ret = avio_open2(&oFmtCtx->pb, dst, AVIO_FLAG_WRITE, NULL, NULL);
    if (ret < 0) {
        av_log(oFmtCtx, AV_LOG_ERROR, "绑定失败");
        goto _ERROR;
    }

    //7. 写多媒体文件头到目的文件
    ret = avformat_write_header(oFmtCtx, NULL);
    if (ret < 0) {
        av_log(oFmtCtx, AV_LOG_ERROR, "写多媒体文件头到目的文件失败");
        goto _ERROR;
    }
    //8. 从源多媒体文件中读到视频数据到目的文件中
    while (av_read_frame(pFmtCtx, &pkt) >= 0) {
        if (pkt.stream_index == idx) {
            pkt.pts = av_rescale_q_rnd(pkt.pts, inStream->time_base, outStream->time_base, (enum AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
            pkt.dts = av_rescale_q_rnd(pkt.dts, inStream->time_base, outStream->time_base, (enum AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
            pkt.duration = av_rescale_q(pkt.duration, inStream->time_base, outStream->time_base);
            pkt.stream_index = 0;
            pkt.pos = -1;
            av_interleaved_write_frame(oFmtCtx, &pkt);
            av_packet_unref(&pkt);
        }
    }
    //9. 写多媒体文件尾到文件中
    av_write_trailer(oFmtCtx);

    //10. 将申请的资源释放掉
_ERROR:
    if (pFmtCtx) {
        avformat_close_input(&pFmtCtx);
        pFmtCtx = NULL;
    }
    if (oFmtCtx->pb) {
        avio_close(oFmtCtx->pb);
    }

    if (oFmtCtx) {
        avformat_free_context(oFmtCtx);
        oFmtCtx = NULL;
    }

    cout << "抽取视频数据成功" << endl;
    return 0;
}

五、多媒体格式转封装

#include <iostream>
using namespace std;

extern "C" {
#include <libavutil/log.h>
#include <libavutil/avutil.h>
#include <libavformat/avformat.h>
}

#pragma comment(lib,"avcodec.lib")
#pragma comment(lib,"avutil.lib")
#pragma comment(lib,"avformat.lib")

int main(int argc, char* argv[]) {

    int ret = -1;
    int idx = -1;
    int stream_idx = 0;
    int i = 0;

    //1. 处理一些参数；
    char src[] = "1.mp4";
    char dst[] = "1.wmv";

    int* stream_map = NULL;

    AVFormatContext* pFmtCtx = NULL;
    AVFormatContext* oFmtCtx = NULL;

    const AVOutputFormat* outFmt = NULL;

    AVPacket pkt;

    av_log_set_level(AV_LOG_DEBUG);

    //2. 打开多媒体文件
    if ((ret = avformat_open_input(&pFmtCtx, src, NULL, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "error");
        return -1;
    }

    //4. 打开目的文件的上下文
    avformat_alloc_output_context2(&oFmtCtx, NULL, NULL, dst);
    if (!oFmtCtx) {
        av_log(NULL, AV_LOG_ERROR, "NO MEMORY!\n");
        goto _ERROR;
    }

    stream_map = (int *)av_calloc(pFmtCtx->nb_streams, sizeof(int));
    if (!stream_map) {
        av_log(NULL, AV_LOG_ERROR, "NO MEMORY!\n");
        goto _ERROR;
    }

    for (i = 0; i < pFmtCtx->nb_streams; i++) {
        AVStream* outStream = NULL;
        AVStream* inStream = pFmtCtx->streams[i];
        AVCodecParameters* inCodecPar = inStream->codecpar;
        if (inCodecPar->codec_type != AVMEDIA_TYPE_AUDIO &&
            inCodecPar->codec_type != AVMEDIA_TYPE_VIDEO &&
            inCodecPar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
            stream_map[i] = -1;
            continue;
        }
        stream_map[i] = stream_idx++;

        //5. 为目的文件，创建一个新的视频流
        outStream = avformat_new_stream(oFmtCtx, NULL);
        if (!outStream) {
            av_log(oFmtCtx, AV_LOG_ERROR, "NO MEMORY!\n");
            goto _ERROR;
        }

        avcodec_parameters_copy(outStream->codecpar, inStream->codecpar);
        outStream->codecpar->codec_tag = 0;
    }

    //绑定
    ret = avio_open2(&oFmtCtx->pb, dst, AVIO_FLAG_WRITE, NULL, NULL);
    if (ret < 0) {
        av_log(oFmtCtx, AV_LOG_ERROR, "绑定失败");
        goto _ERROR;
    }

    //7. 写多媒体文件头到目的文件
    ret = avformat_write_header(oFmtCtx, NULL);
    if (ret < 0) {
        av_log(oFmtCtx, AV_LOG_ERROR, "写多媒体文件头到目的文件失败");
        goto _ERROR;
    }
    //8. 从源多媒体文件中读取音频/视频/字幕数据到目的文件中
    while (av_read_frame(pFmtCtx, &pkt) >= 0) {
        AVStream* inStream, * outStream;

        inStream = pFmtCtx->streams[pkt.stream_index];
        if (stream_map[pkt.stream_index] < 0) {
            av_packet_unref(&pkt);
            continue;
        }
        pkt.stream_index = stream_map[pkt.stream_index];

        outStream = oFmtCtx->streams[pkt.stream_index];
        av_packet_rescale_ts(&pkt, inStream->time_base, outStream->time_base);
        pkt.pos = -1;
        av_interleaved_write_frame(oFmtCtx, &pkt);
        av_packet_unref(&pkt);

    }
    //9. 写多媒体文件尾到文件中
    av_write_trailer(oFmtCtx);

    //10. 将申请的资源释放掉
_ERROR:
    if (pFmtCtx) {
        avformat_close_input(&pFmtCtx);
        pFmtCtx = NULL;
    }
    if (oFmtCtx->pb) {
        avio_close(oFmtCtx->pb);
    }

    if (oFmtCtx) {
        avformat_free_context(oFmtCtx);
        oFmtCtx = NULL;
    }

    if (stream_map) {
        av_free(stream_map);
    }
    
    return 0;
}

六、视频裁剪

#include <iostream>
using namespace std;

extern "C" {
#include <libavutil/log.h>
#include <libavutil/avutil.h>
#include <libavutil/timestamp.h>
#include <libavformat/avformat.h>
}

#pragma comment(lib,"avcodec.lib")
#pragma comment(lib,"avutil.lib")
#pragma comment(lib,"avformat.lib")

static void log_packet(AVFormatContext* fmtCtx, const AVPacket* pkt, int64_t pts_start, int64_t dts_start) {
    // = &fmtCtx->streams[pkt->stream_index]->time_base;
    av_log(fmtCtx,
        AV_LOG_INFO,
        "pts:%s dts:%s pts_diff:%lld dts_diff:%lld stream_idx:%d pts_start:%lld dts_start:%lld\n",
        av_ts2str(pkt->pts),
        av_ts2str(pkt->dts),
        pkt->pts - pts_start,
        pkt->dts - dts_start,
        pkt->stream_index,
        pts_start,
        dts_start);
}

int main(int argc, char* argv[]) {

    int ret = -1;
    int idx = -1;
    int stream_idx = 0;
    int i = 0;

    //1. 处理一些参数；从视频的30秒裁剪到视频的50秒
    char src[] = "1.mp4";
    char dst[] = "cut.mp4";

    double starttime = 30;
    double endtime = 50;

    int* stream_map = NULL;
    int64_t* dts_start_time = NULL;
    int64_t* pts_start_time = NULL;


    AVFormatContext* pFmtCtx = NULL;
    AVFormatContext* oFmtCtx = NULL;

    const AVOutputFormat* outFmt = NULL;

    AVPacket pkt;

    av_log_set_level(AV_LOG_DEBUG);


    //2. 打开多媒体文件
    if ((ret = avformat_open_input(&pFmtCtx, src, NULL, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "%s\n", av_err2str(ret));
        exit(-1);
    }

    //4. 打开目的文件的上下文
    avformat_alloc_output_context2(&oFmtCtx, NULL, NULL, dst);
    if (!oFmtCtx) {
        av_log(NULL, AV_LOG_ERROR, "NO MEMORY!\n");
        goto _ERROR;
    }

    stream_map = (int *)av_calloc(pFmtCtx->nb_streams, sizeof(int));
    if (!stream_map) {
        av_log(NULL, AV_LOG_ERROR, "NO MEMORY!\n");
        goto _ERROR;
    }

    for (i = 0; i < pFmtCtx->nb_streams; i++) {
        AVStream* outStream = NULL;
        AVStream* inStream = pFmtCtx->streams[i];
        AVCodecParameters* inCodecPar = inStream->codecpar;
        if (inCodecPar->codec_type != AVMEDIA_TYPE_AUDIO &&
            inCodecPar->codec_type != AVMEDIA_TYPE_VIDEO &&
            inCodecPar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
            stream_map[i] = -1;
            continue;
        }
        stream_map[i] = stream_idx++;

        //5. 为目的文件，创建一个新的视频流
        outStream = avformat_new_stream(oFmtCtx, NULL);
        if (!outStream) {
            av_log(oFmtCtx, AV_LOG_ERROR, "NO MEMORY!\n");
            goto _ERROR;
        }

        avcodec_parameters_copy(outStream->codecpar, inStream->codecpar);
        outStream->codecpar->codec_tag = 0;
    }

    //绑定
    ret = avio_open2(&oFmtCtx->pb, dst, AVIO_FLAG_WRITE, NULL, NULL);
    if (ret < 0) {
        av_log(oFmtCtx, AV_LOG_ERROR, "绑定失败");
        goto _ERROR;
    }

    //7. 写多媒体文件头到目的文件
    ret = avformat_write_header(oFmtCtx, NULL);
    if (ret < 0) {
        av_log(oFmtCtx, AV_LOG_ERROR, "写多媒体文件头到目的文件失败");
        goto _ERROR;
    }

    //seek
    ret = av_seek_frame(pFmtCtx, -1, starttime * AV_TIME_BASE, AVSEEK_FLAG_BACKWARD);
    if (ret < 0) {
        av_log(oFmtCtx, AV_LOG_ERROR, "seek error");
        goto _ERROR;
    }

    dts_start_time = (int64_t * )av_calloc(pFmtCtx->nb_streams, sizeof(int64_t));
    for (int t = 0; t < pFmtCtx->nb_streams; t++) {
        dts_start_time[t] = -1;
    }
    pts_start_time = (int64_t * )av_calloc(pFmtCtx->nb_streams, sizeof(int64_t));
    for (int t = 0; t < pFmtCtx->nb_streams; t++) {
        pts_start_time[t] = -1;
    }

    //8. 从源多媒体文件中读取音频/视频/字幕数据到目的文件中
    while (av_read_frame(pFmtCtx, &pkt) >= 0) {
        AVStream* inStream, * outStream;

        if (dts_start_time[pkt.stream_index] == -1 && pkt.dts >= 0) {
            dts_start_time[pkt.stream_index] = pkt.dts;
        }

        if (pts_start_time[pkt.stream_index] == -1 && pkt.pts >= 0) {
            pts_start_time[pkt.stream_index] = pkt.pts;
        }

        inStream = pFmtCtx->streams[pkt.stream_index];

        if (av_q2d(inStream->time_base) * pkt.pts > endtime) {
            av_log(oFmtCtx, AV_LOG_INFO, "success!\n");
            break;
        }
        if (stream_map[pkt.stream_index] < 0) {
            av_packet_unref(&pkt);
            continue;
        }
        //printf("pkt.pts=%lld, pkt.dts=%lld\n", pkt.pts, pkt.dts);
        log_packet(pFmtCtx, &pkt, pts_start_time[pkt.stream_index], dts_start_time[pkt.stream_index]);

        pkt.pts = pkt.pts - pts_start_time[pkt.stream_index];
        pkt.dts = pkt.dts - dts_start_time[pkt.stream_index];


        if (pkt.dts > pkt.pts) {
            pkt.pts = pkt.dts;
        }

        pkt.stream_index = stream_map[pkt.stream_index];

        outStream = oFmtCtx->streams[pkt.stream_index];
        av_packet_rescale_ts(&pkt, inStream->time_base, outStream->time_base);

        pkt.pos = -1;
        av_interleaved_write_frame(oFmtCtx, &pkt);
        av_packet_unref(&pkt);

    }
    //9. 写多媒体文件尾到文件中
    av_write_trailer(oFmtCtx);

    //10. 将申请的资源释放掉
_ERROR:
    if (pFmtCtx) {
        avformat_close_input(&pFmtCtx);
        pFmtCtx = NULL;
    }
    if (oFmtCtx->pb) {
        avio_close(oFmtCtx->pb);
    }

    if (oFmtCtx) {
        avformat_free_context(oFmtCtx);
        oFmtCtx = NULL;
    }

    if (stream_map) {
        av_free(stream_map);
    }

    if (dts_start_time) {
        av_free(dts_start_time);
    }

    if (pts_start_time) {
        av_free(pts_start_time);
    }
    
    cout << "裁剪成功" << endl;
    return 0;
}