Calling ffmpeg.c's main twice causes app crash

问题:

Using FFmpeg 4.0.2 and call its ffmpeg.c's main function twice causes Android app crash (using FFmpeg shared libs and JNI)

A/libc: Fatal signal 11 (SIGSEGV), code 1, fault addr 0x0 in tid 20153

Though it works ok for FFmpeg 3.2.5

FFmpeg 4.0.2 main

int main(int argc, char **argv) {
    int i, ret;
    int64_t ti;

    init_dynload();

    register_exit(ffmpeg_cleanup);

    setvbuf(stderr,NULL,_IONBF,0); /* win32 runtime needs this */

    av_log_set_flags(AV_LOG_SKIP_REPEATED);
    parse_loglevel(argc, argv, options);

    if(argc>1 && !strcmp(argv[1], "-d")){
        run_as_daemon=1;
        av_log_set_callback(log_callback_null);
        argc--;
        argv++;
    }

#if CONFIG_AVDEVICE
    avdevice_register_all();
#endif
    avformat_network_init();

    show_banner(argc, argv, options);

    /* parse options and open all input/output files */
    ret = ffmpeg_parse_options(argc, argv);
    if (ret < 0)
        exit_program(1);

    if (nb_output_files <= 0 && nb_input_files == 0) {
        show_usage();
        av_log(NULL, AV_LOG_WARNING, "Use -h to get full help or, even better, run 'man %s'\n", program_name);
        exit_program(1);
    }

    /* file converter / grab */
    if (nb_output_files <= 0) {
        av_log(NULL, AV_LOG_FATAL, "At least one output file must be specified\n");
        exit_program(1);
    }

//     if (nb_input_files == 0) {
//         av_log(NULL, AV_LOG_FATAL, "At least one input file must be specified\n");
//         exit_program(1);
//     }

    for (i = 0; i < nb_output_files; i++) {
        if (strcmp(output_files[i]->ctx->oformat->name, "rtp"))
            want_sdp = 0;
    }

    current_time = ti = getutime();
    if (transcode() < 0)
        exit_program(1);
    ti = getutime() - ti;
    if (do_benchmark) {
        av_log(NULL, AV_LOG_INFO, "bench: utime=%0.3fs\n", ti / 1000000.0);
    }
    av_log(NULL, AV_LOG_DEBUG, "%"PRIu64" frames successfully decoded, %"PRIu64" decoding errors\n",
           decode_error_stat[0], decode_error_stat[1]);
    if ((decode_error_stat[0] + decode_error_stat[1]) * max_error_rate < decode_error_stat[1])
        exit_program(69);

    ffmpeg_cleanup(received_nb_signals ? 255 : main_return_code);
    return main_return_code;
}

FFmpeg 3.2.5 main

int main(int argc, char **argv) {
    av_log(NULL, AV_LOG_WARNING, " Command start");

    int i, ret;
    int64_t ti;
    init_dynload();

    register_exit(ffmpeg_cleanup);

    setvbuf(stderr, NULL, _IONBF, 0); /* win32 runtime needs this */

    av_log_set_flags(AV_LOG_SKIP_REPEATED);
    parse_loglevel(argc, argv, options);

    if (argc > 1 && !strcmp(argv[1], "-d")) {
        run_as_daemon = 1;
        av_log_set_callback(log_callback_null);
        argc--;
        argv++;
    }

    avcodec_register_all();
#if CONFIG_AVDEVICE
    avdevice_register_all();
#endif
    avfilter_register_all();
    av_register_all();
    avformat_network_init();

    av_log(NULL, AV_LOG_WARNING, " Register to complete the codec");

    show_banner(argc, argv, options);

    /* parse options and open all input/output files */
    ret = ffmpeg_parse_options(argc, argv);
    if (ret < 0)
        exit_program(1);

    if (nb_output_files <= 0 && nb_input_files == 0) {
        show_usage();
        av_log(NULL, AV_LOG_WARNING, "Use -h to get full help or, even better, run 'man %s'\n",
               program_name);
        exit_program(1);
    }

    /* file converter / grab */
    if (nb_output_files <= 0) {
        av_log(NULL, AV_LOG_FATAL, "At least one output file must be specified\n");
        exit_program(1);
    }

//     if (nb_input_files == 0) {
//         av_log(NULL, AV_LOG_FATAL, "At least one input file must be specified\n");
//         exit_program(1);
//     }

    for (i = 0; i < nb_output_files; i++) {
        if (strcmp(output_files[i]->ctx->oformat->name, "rtp"))
            want_sdp = 0;
    }

    current_time = ti = getutime();
    if (transcode() < 0)
        exit_program(1);
    ti = getutime() - ti;
    if (do_benchmark) {
        av_log(NULL, AV_LOG_INFO, "bench: utime=%0.3fs\n", ti / 1000000.0);
    }
    av_log(NULL, AV_LOG_DEBUG, "%"PRIu64" frames successfully decoded, %"PRIu64" decoding errors\n",
           decode_error_stat[0], decode_error_stat[1]);
    if ((decode_error_stat[0] + decode_error_stat[1]) * max_error_rate < decode_error_stat[1])
        exit_program(69);

    exit_program(received_nb_signals ? 255 : main_return_code);

    nb_filtergraphs = 0;
    nb_input_streams = 0;
    nb_input_files = 0;
    progress_avio = NULL;


    input_streams = NULL;
    nb_input_streams = 0;
    input_files = NULL;
    nb_input_files = 0;

    output_streams = NULL;
    nb_output_streams = 0;
    output_files = NULL;
    nb_output_files = 0;

    return main_return_code;
}

So what could be issue? It seems FFmpeg 4.0.2 doesn't release something (resources or its static variables to initial values after the first command)

回答1:

Adding next lines from FFmpeg 3.2.5 to FFmpeg 4.0.2 to the end of main function solved the problem (I downloaded FFmpeg 3.2.5 as someone's Android project so that user added those lines)

nb_filtergraphs = 0;
nb_input_streams = 0;
nb_input_files = 0;
progress_avio = NULL;

input_streams = NULL;
nb_input_streams = 0;
input_files = NULL;
nb_input_files = 0;

output_streams = NULL;
nb_output_streams = 0;
output_files = NULL;
nb_output_files = 0;