FFmpeg视频编码 ---- YUV转H264

/**
* @projectName   08-02-encode_video
* @brief         视频编码，从本地读取YUV数据进行H264编码
* @author        Liao Qingfu
* @date          2020-04-16
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <libavcodec/avcodec.h>
#include <libavutil/time.h>
#include <libavutil/opt.h>
#include <libavutil/imgutils.h>

int64_t get_time()
{
    return av_gettime_relative() / 1000;  // 换算成毫秒
}
static int encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
                  FILE *outfile)
{
    int ret;

    /* send the frame to the encoder */
    if (frame)
        printf("Send frame %3"PRId64"\n", frame->pts);
    /* 通过查阅代码，使用x264进行编码时，具体缓存帧是在x264源码进行，
     * 不会增加avframe对应buffer的reference*/
    ret = avcodec_send_frame(enc_ctx, frame);
    if (ret < 0)
    {
        fprintf(stderr, "Error sending a frame for encoding\n");
        return -1;
    }

    while (ret >= 0)
    {
        ret = avcodec_receive_packet(enc_ctx, pkt);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
            return 0;
        } else if (ret < 0) {
            fprintf(stderr, "Error encoding audio frame\n");
            return -1;
        }

        if(pkt->flags & AV_PKT_FLAG_KEY)
            printf("Write packet flags:%d pts:%3"PRId64" dts:%3"PRId64" (size:%5d)\n",
               pkt->flags, pkt->pts, pkt->dts, pkt->size);
        if(!pkt->flags)
            printf("Write packet flags:%d pts:%3"PRId64" dts:%3"PRId64" (size:%5d)\n",
               pkt->flags, pkt->pts, pkt->dts, pkt->size);
        fwrite(pkt->data, 1, pkt->size, outfile);
    }
    return 0;
}
/**
 * @brief 提取测试文件：ffmpeg -i test_1280x720.flv -t 5 -r 25 -pix_fmt yuv420p yuv420p_1280x720.yuv
 *           参数输入: yuv420p_1280x720.yuv yuv420p_1280x720.h264 libx264
 * @param argc
 * @param argv
 * @return
 */
int main(int argc, char **argv)
{
    int ret = 0;
    const char *in_yuv_file = "yuv420p_1280x720.yuv";      // 输入YUV文件
    const char *out_h264_file = "yuv420p_1280x720.h264";
    const char *codec_name = "libx264";

    // 1.查找编码器
    const AVCodec *codec = avcodec_find_encoder_by_name(codec_name);
    if (!codec) {
        fprintf(stderr, "Codec ‘%s‘ not found\n", codec_name);
        exit(1);
    }

    // 2.分配内存
    AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
    if (!codec_ctx) {
        fprintf(stderr, "Could not allocate video codec context\n");
        exit(1);
    }

    // 3.设置编码参数
    /* 设置分辨率*/
    codec_ctx->width = 1280;
    codec_ctx->height = 720;
    /* 设置time base */
    codec_ctx->time_base = (AVRational){1, 25};
    codec_ctx->framerate = (AVRational){25, 1};
    /* 设置I帧间隔
     * 如果frame->pict_type设置为AV_PICTURE_TYPE_I, 则忽略gop_size的设置，一直当做I帧进行编码
     */
    codec_ctx->gop_size = 25;   // I帧间隔
    codec_ctx->max_b_frames = 2; // 如果不想包含B帧则设置为0
    codec_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
    //
    if (codec->id == AV_CODEC_ID_H264) {
        // 相关的参数可以参考libx264.c的 AVOption options
        ret = av_opt_set(codec_ctx->priv_data, "preset", "medium", 0);
        if(ret != 0) {
            printf("av_opt_set preset failed\n");
        }
        ret = av_opt_set(codec_ctx->priv_data, "profile", "main", 0); // 默认是high
        if(ret != 0) {
            printf("av_opt_set profile failed\n");
        }
        ret = av_opt_set(codec_ctx->priv_data, "tune","zerolatency",0); // 直播是才使用该设置
//        ret = av_opt_set(codec_ctx->priv_data, "tune","film",0); //  画质film
        if(ret != 0) {
            printf("av_opt_set tune failed\n");
        }
    }

    /* 设置bitrate */
    codec_ctx->bit_rate = 3000000;
//    codec_ctx->rc_max_rate = 3000000;
//    codec_ctx->rc_min_rate = 3000000;
//    codec_ctx->rc_buffer_size = 2000000;
//    codec_ctx->thread_count = 4;  // 开了多线程后也会导致帧输出延迟, 需要缓存thread_count帧后再编程。
//    codec_ctx->thread_type = FF_THREAD_FRAME; // 并 设置为FF_THREAD_FRAME

    //对于H264 AV_CODEC_FLAG_GLOBAL_HEADER  设置则只包含I帧，此时sps pps需要从codec_ctx->extradata读取 不设置则每个I帧都带 sps pps sei
    //codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER; // 存本地文件时不要去设置

    // 4.将codec_ctx和codec进行绑定
    ret = avcodec_open2(codec_ctx, codec, NULL);
    if (ret < 0) {
        fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
        exit(1);
    }
    printf("thread_count: %d, thread_type:%d\n", codec_ctx->thread_count, codec_ctx->thread_type);

    // 5.打开输入和输出文件
    FILE *infile = fopen(in_yuv_file, "rb");
    if (!infile) {
        fprintf(stderr, "Could not open %s\n", in_yuv_file);
        exit(1);
    }
    FILE *outfile = fopen(out_h264_file, "wb");
    if (!outfile) {
        fprintf(stderr, "Could not open %s\n", out_h264_file);
        exit(1);
    }

    // 6.分配pkt和frame
    AVPacket *pkt = av_packet_alloc();
    if (!pkt) {
        fprintf(stderr, "Could not allocate video frame\n");
        exit(1);
    }
    AVFrame *frame = av_frame_alloc();
    if (!frame) {
        fprintf(stderr, "Could not allocate video frame\n");
        exit(1);
    }

    // 7.为frame分配buffer
    frame->format = codec_ctx->pix_fmt;
    frame->width  = codec_ctx->width;
    frame->height = codec_ctx->height;
    ret = av_frame_get_buffer(frame, 0);
    if (ret < 0) {
        fprintf(stderr, "Could not allocate the video frame data\n");
        exit(1);
    }
    // 计算出每一帧的数据 像素格式 * 宽 * 高
    // 1382400
    int frame_bytes = av_image_get_buffer_size(frame->format, frame->width,
                                               frame->height, 1);
    printf("frame_bytes %d\n", frame_bytes);
    uint8_t *yuv_buf = (uint8_t *)malloc(frame_bytes);
    if(!yuv_buf) {
        printf("yuv_buf malloc failed\n");
        return 1;
    }
    int64_t begin_time = get_time();
    int64_t end_time = begin_time;
    int64_t all_begin_time = get_time();
    int64_t all_end_time = all_begin_time;
    int64_t pts = 0;

    // 8.循环读取数据
    printf("start enode\n");
    for (;;) {
        memset(yuv_buf, 0, frame_bytes);
        size_t read_bytes = fread(yuv_buf, 1, frame_bytes, infile);
        if(read_bytes <= 0) {
            printf("read file finish\n");
            break;
        }
        /* 确保该frame可写, 如果编码器内部保持了内存参考计数，则需要重新拷贝一个备份
            目的是新写入的数据和编码器保存的数据不能产生冲突
        */
        int frame_is_writable = 1;
        if(av_frame_is_writable(frame) == 0) { // 这里只是用来测试
            printf("the frame can‘t write, buf:%p\n", frame->buf[0]);
            if(frame->buf && frame->buf[0])        // 打印referenc-counted，必须保证传入的是有效指针
                printf("ref_count1(frame) = %d\n", av_buffer_get_ref_count(frame->buf[0]));
            frame_is_writable = 0;
        }
        ret = av_frame_make_writable(frame);
        if(frame_is_writable == 0) {  // 这里只是用来测试
            printf("av_frame_make_writable, buf:%p\n", frame->buf[0]);
            if(frame->buf && frame->buf[0])        // 打印referenc-counted，必须保证传入的是有效指针
                printf("ref_count2(frame) = %d\n", av_buffer_get_ref_count(frame->buf[0]));
        }
        if(ret != 0) {
            printf("av_frame_make_writable failed, ret = %d\n", ret);
            break;
        }
        int need_size = av_image_fill_arrays(frame->data, frame->linesize, yuv_buf,
                                             frame->format,
                                             frame->width, frame->height, 1);
        if(need_size != frame_bytes) {
            printf("av_image_fill_arrays failed, need_size:%d, frame_bytes:%d\n",
                   need_size, frame_bytes);
            break;
        }
         pts += 40;
        // 设置pts
        frame->pts = pts;       // 使用采样率作为pts的单位，具体换算成秒 pts*1/采样率
        begin_time = get_time();
        ret = encode(codec_ctx, frame, pkt, outfile);
        end_time = get_time();
        printf("encode time:%lldms\n", end_time - begin_time);
        if(ret < 0) {
            printf("encode failed\n");
            break;
        }
    }

    // 9.冲刷编码器
    encode(codec_ctx, NULL, pkt, outfile);
    all_end_time = get_time();
    printf("all encode time:%lldms\n", all_end_time - all_begin_time);

    // 10.结束
    fclose(infile);
    fclose(outfile);

    // 释放内存
    if(yuv_buf) {
        free(yuv_buf);
    }

    av_frame_free(&frame);
    av_packet_free(&pkt);
    avcodec_free_context(&codec_ctx);

    printf("main finish, please enter Enter and exit\n");
    getchar();
    return 0;
}