ffmpeg remux from https://github.com/krieger-od

simplest_ffmpeg_remux.c

#include <assert.h>
#include <stdio.h>
#include <libavformat/avformat.h>
#include <libavutil/log.h>
int main(int argc, char *argv[]) {
    int r;
    assert(argc == 3);
    av_register_all();
    avformat_network_init();
    //av_log_set_level(AV_LOG_DEBUG);
    AVFormatContext *in = NULL;
    r = avformat_open_input(&in, argv[1], NULL, NULL);
    printf("err %d\n", r);
    assert(!r);
    r = avformat_find_stream_info(in, NULL);
    printf("err %d\n", r);
    assert(r >= 0);

    AVFormatContext *out = avformat_alloc_context();
    assert(out);
    out->oformat = av_guess_format(NULL, argv[2], NULL);
    assert(out->oformat);
    r = avio_open2(&out->pb, argv[2], AVIO_FLAG_WRITE, NULL, NULL);
    assert(!r);
    int i;
    for (i = 0; i < in->nb_streams; i++) {
        AVStream *inputStream = in->streams[i];
        AVStream *newStream = avformat_new_stream(out, inputStream->codec->codec);
        assert(newStream);
        r = avcodec_copy_context(newStream->codec, inputStream->codec);
        assert(!r);
        newStream->codec->codec_id = inputStream->codec->codec_id;
        if (newStream->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
            newStream->sample_aspect_ratio = (AVRational){1, 1};
        }
    }
    r = avformat_write_header(out, NULL);

    
    AVPacket pkt;
    int64_t frames_in = 0;
    while (1) {
        av_init_packet(&pkt);
        r = av_read_frame(in, &pkt);
        if (r) {
            printf("read error %d\n", r);
            break;
        }
        printf("stream %d, pts %"PRId64", dts %"PRId64"\n",
                pkt.stream_index, pkt.pts, pkt.dts);
        frames_in++;
        r = av_write_frame(out, &pkt);
        if (r && (r != AVERROR(EINVAL))) {
            printf("write error %d\n", r);
            break;
        }
    }
    return 0;
}