Question

所以我对此有点新鲜，我正在编写一个将视频录制到.AVI的WIN32应用程序，然后我计划使用ffmpeg编码为.MP4。根据我发现的样本，我得到了这个。它编译并说它编码并编写了文件但输出文件无法打开和播放。我尝试使用MPEG1编码，就像原始样本一样，但它只给我几秒钟的奇怪颜色。

我是否遗漏了应该使用该文件的内容？

任何有编码/ ffmpeg经验的人，一些指示，建议或帮助都会让我感激不尽。提前谢谢！

int _tmain(int argc, _TCHAR* argv[])
{

    AVFormatContext *pFormatCtx;
    int codec_id = CODEC_ID_MPEG4;
    char filename [] ="C:\\wav\\test2.flv";
// Open video file
     AVCodec *codec;
     AVCodecContext *c= NULL;
     int i, out_size, x, y, outbuf_size;
    FILE *f;
     AVFrame *picture;
    uint8_t *outbuf;
     int had_output=0;

    av_register_all();
   printf("Encode video file %s\n", filename);

    codec = avcodec_find_encoder(CODEC_ID_H264);
    if (!codec) {
         fprintf(stderr, "codec not found\n");
        exit(1);
    }

    c = avcodec_alloc_context3(codec);
    picture= avcodec_alloc_frame();

   /* put sample parameters */
   c->bit_rate = 40000;
   //c->bit_rate_tolerance=30;
     /* resolution must be a multiple of two */
    c->width = 352;
    c->height = 288;
    /* frames per second */

    c->time_base.den=  25;
    c->time_base.num= 1;
     c->gop_size = 10; /* emit one intra frame every ten frames */
   c->max_b_frames=1;
     c->pix_fmt = PIX_FMT_YUV420P;

    if(codec_id == CODEC_ID_H264)
        av_opt_set(c->priv_data, "preset", "slow", 0);
/* 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);
     }

    /* alloc image and output buffer */
    outbuf_size = 100000 + 12*c->width*c->height;
     outbuf = (uint8_t*)malloc(outbuf_size); //CHANGED

     /* the image can be allocated by any means and av_image_alloc() is
      * just the most convenient way if av_malloc() is to be used */
    av_image_alloc(picture->data, picture->linesize,
                   c->width, c->height, c->pix_fmt, 1);

     /* encode 1 second of video */
     for(i=0;i<25;i++) {
         fflush(stdout);
         /* prepare a dummy image */
        /* Y */
         for(y=0;y<c->height;y++) {
            for(x=0;x<c->width;x++) {
                picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
            }
         }

        /* Cb and Cr */
        for(y=0;y<c->height/2;y++) {
            for(x=0;x<c->width/2;x++) {
                picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
                picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
            }
        }

         /* encode the image */
        out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
         had_output |= out_size;
        printf("encoding frame %3d (size=%5d)\n", i, out_size);
        fwrite(outbuf, 1, out_size, f);
     }

     /* get the delayed frames */
     for(; out_size || !had_output; i++) {
         fflush(stdout);

        out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
        had_output |= out_size;
         printf("write frame %3d (size=%5d)\n", i, out_size);
       fwrite(outbuf, 1, out_size, f);
     }

     /* add sequence end code to have a real mpeg file */
     outbuf[0] = 0x00;
     outbuf[1] = 0x00;
     outbuf[2] = 0x01;
   outbuf[3] = 0xb7;
     fwrite(outbuf, 1, 4, f);
     fclose(f);
        fclose(p);
    free(outbuf);

     avcodec_close(c);
     av_free(c);
     av_free(picture->data[0]);
    av_free(picture);
     printf("\n");

    return 0;
}

Answer 1

您没有撰写.MP4，.flv或AVI文件。您正在编写没有任何容器的原始H.264视频流。大多数玩家都无法玩它，但它可以与ffplay和mplayer一起使用。

它似乎按预期工作。它编码25帧奇怪的色彩渐变。但是，由于比特率较低，它可能看起来像垃圾。

您需要做的就是使用libavformat将此流放入某个容器中。并且，提供一些真实的视频帧进行编码。

使用ffmpeg编码到.MP4的问题

1 个答案: