bug.c

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>

int process_pkt(struct AVPacket *pkt) {
    if (pkt->priv)
        return 20;
    return 40;;
}

int main() {
    const char *filename = "test.mp4";
    int numstreams;
    int vidx;
    int i;
    AVFormatContext *avfctx;
    AVCodec *codec;
    AVPacket pkt = { 0 };
    int ret;

    av_register_all();

    avfctx = avformat_alloc_context();
    if (!avfctx) {
        printf("Could not allocate format context.\n");
        return 1;
    }

    if ((ret = avformat_open_input(&avfctx, filename, NULL, NULL)) != 0) {
        printf("Could not open context: %d\n", ret);
        return 1;
    }

    if (avformat_find_stream_info(avfctx, NULL) < 0) {
        printf("No streams?\n");
        return 1;
    }

    numstreams = avfctx->nb_streams;
    vidx = -1;

    for (i = 0; i < numstreams; i++) {
        if (avfctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
            vidx = i;
            break;
        }
    }

    if (vidx == -1) {
        printf("No V stream.\n");
        return 1;
    }

    codec = avcodec_find_decoder(avfctx->streams[i]->codec->codec_id);
    if (!codec) {
        printf("No codec.\n");
        return 1;
    }

    if (avcodec_open2(avfctx->streams[vidx]->codec, codec, NULL) < 0) {
        printf("Can't open codec.\n");
        return 1;
    }

    if (avformat_seek_file(avfctx, vidx, 0, 0, 0, AVSEEK_FLAG_FRAME) < 0) {
        printf("Can't seek.\n");
        return 1;
    }

    avcodec_flush_buffers(avfctx->streams[vidx]->codec);

    while (av_read_frame(avfctx, &pkt) == 0) {
        if (process_pkt(&pkt) == 40) {
            printf("WTF\n");
            return 1;
        }
        av_free_packet(&pkt);
    }
    return 0;
}