save avpack raw data into h264 file, but it can't play,help! about avcpp HOT 4 CLOSED

#include <iostream>

#include "av.h"
#include "format.h"
#include "codeccontext.h"
#include "formatcontext.h"

using namespace std;

int main(int argc, char** argv)
{
    if (argc < 3)
        return 2;

    string input_uri{argv[1]};
    string output_uri{argv[2]};

    av::init();

    //
    // INPUT
    //
    av::FormatContext ictx;

    ictx.openInput(input_uri);
    ictx.findStreamInfo();

    ssize_t video_stream = -1;

    //
    // OUTPUT
    //
    av::OutputFormat oformat("h264");
    av::FormatContext octx;
    octx.setFormat(oformat);

    for (size_t i = 0; i < ictx.streamsCount(); ++i) {
        auto st = ictx.stream(i);
        auto coder = av::GenericCodecContext(st);

        if (!st.isVideo())
            continue;

        if (!octx.outputFormat().codecSupported(coder.codec()))
            continue;

        auto ost = octx.addStream(coder.codec());
        ost.setTimeBase(st.timeBase());
        auto ocoder = av::GenericCodecContext(ost);

        ocoder.copyContextFrom(coder);

        video_stream = i;
        break;
    }

    clog << "VideoStream: " << video_stream << '\n';

    octx.openOutput(output_uri);
    octx.writeHeader();
    octx.dump();

    while (true) {
        auto pkt = ictx.readPacket();
        if (!pkt)
            break;

        if (pkt.streamIndex() != video_stream)
            continue;

        pkt.setStreamIndex(0);
        octx.writePacket(pkt);
    }

    octx.writePacket();
    octx.writeTrailer();

    return 0;
}