ffmpeg混合内存中yuv数据

要将内存中的YUV数据混合成一个视频，可以使用FFmpeg库进行处理。以下是一个基本的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <math.h>

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

#define WIDTH 640
#define HEIGHT 480
#define FPS 25

int main(int argc, char *argv[])
{
    int ret;
    AVCodec *codec;
    AVCodecContext *codec_context;
    AVFrame *frame;
    AVPacket packet;
    uint8_t *buffer;
    int buffer_size;
    int frame_count = 0;

    /* Allocate frame */
    frame = av_frame_alloc();
    if (!frame) {
        fprintf(stderr, "Error allocating frame\n");
        exit(1);
    }

    /* Set frame properties */
    frame->format = AV_PIX_FMT_YUV420P;
    frame->width = WIDTH;
    frame->height = HEIGHT;

    /* Allocate buffer for frame */
    buffer_size = av_image_get_buffer_size(frame->format, frame->width, frame->height, 1);
    buffer = av_malloc(buffer_size);
    av_image_fill_arrays(frame->data, frame->linesize, buffer, frame->format, frame->width, frame->height, 1);

    /* Open codec */
    codec = avcodec_find_encoder(AV_CODEC_ID_H264);
    if (!codec) {
        fprintf(stderr, "Codec not found\n");
        exit(1);
    }

    codec_context = avcodec_alloc_context3(codec);
    if (!codec_context) {
        fprintf(stderr, "Error allocating codec context\n");
        exit(1);
    }

    /* Set codec properties */
    codec_context->width = WIDTH;
    codec_context->height = HEIGHT;
    codec_context->pix_fmt = AV_PIX_FMT_YUV420P;
    codec_context->time_base = (AVRational){1, FPS};
    codec_context->bit_rate = 400000;

    /* Open codec */
    ret = avcodec_open2(codec_context, codec, NULL);
    if (ret < 0) {
        fprintf(stderr, "Error opening codec: %s\n", av_err2str(ret));
        exit(1);
    }

    /* Encode frames */
    while (frame_count < FPS * 10) {
        /* Generate YUV data */
        uint8_t *y_data = malloc(WIDTH * HEIGHT);
        uint8_t *u_data = malloc(WIDTH * HEIGHT / 4);
        uint8_t *v_data = malloc(WIDTH * HEIGHT / 4);
        // fill y_data, u_data, v_data with your desired YUV data

        /* Convert YUV data to frame */
        int y_size = WIDTH * HEIGHT;
        int u_size = y_size / 4;
        int v_size = y_size / 4;
        memcpy(frame->data[0], y_data, y_size);
        memcpy(frame->data[1], u_data, u_size);
        memcpy(frame->data[2], v_data, v_size);

        /* Set frame properties */
        frame->pts = frame_count++;

        /* Encode frame */
        ret = avcodec_send_frame(codec_context, frame);
        if (ret < 0) {
            fprintf(stderr, "Error sending frame to codec: %s\n", av_err2str(ret));
            exit(1);
        }

        while (ret >= 0) {
            ret = avcodec_receive_packet(codec_context, &packet);
            if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
                break;
            else if (ret < 0) {
                fprintf(stderr, "Error receiving packet from codec: %s\n", av_err2str(ret));
                exit(1);
            }

            /* Write packet to file or stream */
            // fwrite(packet.data, 1, packet.size, outfile);
            av_packet_unref(&packet);
        }

        free(y_data);
        free(u_data);
        free(v_data);
    }

    /* Flush encoder */
    ret = avcodec_send_frame(codec_context, NULL);
    if (ret < 0) {
        fprintf(stderr, "Error sending flush frame to codec: %s\n", av_err2str(ret));
        exit(1);
    }

    while (ret >= 0) {
        ret = avcodec_receive_packet(codec_context, &packet);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
            break;
        else if (ret < 0) {
            fprintf(stderr, "Error receiving packet from codec: %s\n", av_err2str(ret));
            exit(1);
        }

        /* Write packet to file or stream */
        // fwrite(packet.data, 1, packet.size, outfile);
        av_packet_unref(&packet);
    }

    /* Free resources */
    avcodec_free_context(&codec_context);
    av_frame_free(&frame);
    av_free(buffer);

    return 0;
}

在此示例中，我们使用`av_image_fill_arrays()`函数分配了一个YUV420P格式的AVFrame，并将其用作编码器的输入。我们使用`avcodec_send_frame()`函数将帧发送到编码器进行编码，然后使用`avcodec_receive_packet()`函数从编码器接收编码数据包。最后，我们使用`av_packet_unref()`函数释放数据包并清除任何剩余的缓存数据。

要生成要混合的YUV数据，您可以从文件中读取数据，也可以在内存中生成数据。无论哪种方法，您都需要将其复制到AVFrame的data数组中。请注意，AVFrame中的YUV数据顺序是YUV420P，即先是所有的Y分量，然后是U和V分量交错。因此，在将YUV数据复制到AVFrame之前，请确保按正确的顺序复制它们。

希望这可以帮助您开始使用FFmpeg处理内存中的YUV数据。