opt.c

/*
 * AVOptions
 * Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * AVOptions
 * @author Michael Niedermayer <michaelni@gmx.at>
 */

#include "avstring.h"
#include "avutil.h"
#include "common.h"
#include "dict.h"
#include "eval.h"
#include "log.h"
#include "mathematics.h"
#include "opt.h"

const AVOption *av_opt_next(const void *obj, const AVOption *last)
{
    AVClass *class = *(AVClass **)obj;
    if (!last && class->option && class->option[0].name)
        return class->option;
    if (last && last[1].name)
        return ++last;
    return NULL;
}

static int read_number(const AVOption *o, const void *dst, double *num, int *den, int64_t *intnum)
{
    switch (o->type) {
    case AV_OPT_TYPE_FLAGS:
        *intnum = *(unsigned int *)dst;
        return 0;
    case AV_OPT_TYPE_INT:
        *intnum = *(int *)dst;
        return 0;
    case AV_OPT_TYPE_INT64:
        *intnum = *(int64_t *)dst;
        return 0;
    case AV_OPT_TYPE_FLOAT:
        *num = *(float *)dst;
        return 0;
    case AV_OPT_TYPE_DOUBLE:
        *num = *(double *)dst;
        return 0;
    case AV_OPT_TYPE_RATIONAL:
        *intnum = ((AVRational *)dst)->num;
        *den    = ((AVRational *)dst)->den;
        return 0;
    }
    return AVERROR(EINVAL);
}

static int write_number(void *obj, const AVOption *o, void *dst, double num, int den, int64_t intnum)
{
    if (o->type != AV_OPT_TYPE_FLAGS &&
        (o->max * den < num * intnum || o->min * den > num * intnum)) {
        av_log(obj, AV_LOG_ERROR, "Value %f for parameter '%s' out of range\n",
               num * intnum / den, o->name);
        return AVERROR(ERANGE);
    }

    switch (o->type) {
    case AV_OPT_TYPE_FLAGS:
    case AV_OPT_TYPE_INT:
        *(int *)dst = llrint(num / den) * intnum;
        break;
    case AV_OPT_TYPE_INT64:
        *(int64_t *)dst = llrint(num / den) * intnum;
        break;
    case AV_OPT_TYPE_FLOAT:
        *(float *)dst = num * intnum / den;
        break;
    case AV_OPT_TYPE_DOUBLE:
        *(double *)dst = num * intnum / den;
        break;
    case AV_OPT_TYPE_RATIONAL:
        if ((int) num == num)
            *(AVRational *)dst = (AVRational) { num *intnum, den };
        else
            *(AVRational *)dst = av_d2q(num * intnum / den, 1 << 24);
        break;
    default:
        return AVERROR(EINVAL);
    }
    return 0;
}

static const double const_values[] = {
    M_PI,
    M_E,
    FF_QP2LAMBDA,
    0
};

static const char *const const_names[] = {
    "PI",
    "E",
    "QP2LAMBDA",
    0
};

static int hexchar2int(char c)
{
    if (c >= '0' && c <= '9')
        return c - '0';
    if (c >= 'a' && c <= 'f')
        return c - 'a' + 10;
    if (c >= 'A' && c <= 'F')
        return c - 'A' + 10;
    return -1;
}

static int set_string_binary(void *obj, const AVOption *o, const char *val, uint8_t **dst)
{
    int *lendst = (int *)(dst + 1);
    uint8_t *bin, *ptr;
    int len = strlen(val);

    av_freep(dst);
    *lendst = 0;

    if (len & 1)
        return AVERROR(EINVAL);
    len /= 2;

    ptr = bin = av_malloc(len);
    if (!ptr)
        return AVERROR(ENOMEM);
    while (*val) {
        int a = hexchar2int(*val++);
        int b = hexchar2int(*val++);
        if (a < 0 || b < 0) {
            av_free(bin);
            return AVERROR(EINVAL);
        }
        *ptr++ = (a << 4) | b;
    }
    *dst    = bin;
    *lendst = len;

    return 0;
}

static int set_string(void *obj, const AVOption *o, const char *val, uint8_t **dst)
{
    av_freep(dst);
    *dst = av_strdup(val);
    return *dst ? 0 : AVERROR(ENOMEM);
}

#define DEFAULT_NUMVAL(opt) ((opt->type == AV_OPT_TYPE_INT64 || \
                              opt->type == AV_OPT_TYPE_CONST || \
                              opt->type == AV_OPT_TYPE_FLAGS || \
                              opt->type == AV_OPT_TYPE_INT)     \
                             ? opt->default_val.i64             \
                             : opt->default_val.dbl)

static int set_string_number(void *obj, void *target_obj, const AVOption *o, const char *val, void *dst)
{
    int ret = 0, notfirst = 0;
    for (;;) {
        int i, den = 1;
        char buf[256];
        int cmd = 0;
        double d, num = 1;
        int64_t intnum = 1;

        i = 0;
        if (*val == '+' || *val == '-') {
            if (o->type == AV_OPT_TYPE_FLAGS)
                cmd = *(val++);
            else if (!notfirst)
                buf[i++] = *val;
        }

        for (; i < sizeof(buf) - 1 && val[i] && val[i] != '+' && val[i] != '-'; i++)
            buf[i] = val[i];
        buf[i] = 0;

        {
            const AVOption *o_named = av_opt_find(target_obj, buf, o->unit, 0, 0);
            if (o_named && o_named->type == AV_OPT_TYPE_CONST)
                d = DEFAULT_NUMVAL(o_named);
            else if (!strcmp(buf, "default"))
                d = DEFAULT_NUMVAL(o);
            else if (!strcmp(buf, "max"))
                d = o->max;
            else if (!strcmp(buf, "min"))
                d = o->min;
            else if (!strcmp(buf, "none"))
                d = 0;
            else if (!strcmp(buf, "all"))
                d = ~0;
            else {
                int res = av_expr_parse_and_eval(&d, buf, const_names, const_values, NULL, NULL, NULL, NULL, NULL, 0, obj);
                if (res < 0) {
                    av_log(obj, AV_LOG_ERROR, "Unable to parse option value \"%s\"\n", val);
                    return res;
                }
            }
        }
        if (o->type == AV_OPT_TYPE_FLAGS) {
            read_number(o, dst, NULL, NULL, &intnum);
            if (cmd == '+')
                d = intnum | (int64_t)d;
            else if (cmd == '-')
                d = intnum & ~(int64_t)d;
        } else {
            read_number(o, dst, &num, &den, &intnum);
            if (cmd == '+')
                d = notfirst * num * intnum / den + d;
            else if (cmd == '-')
                d = notfirst * num * intnum / den - d;
        }

        if ((ret = write_number(obj, o, dst, d, 1, 1)) < 0)
            return ret;
        val += i;
        if (!*val)
            return 0;
        notfirst = 1;
    }
}

int av_opt_set(void *obj, const char *name, const char *val, int search_flags)
{
    void *dst, *target_obj;
    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);
    if (!o || !target_obj)
        return AVERROR_OPTION_NOT_FOUND;
    if (!val || o->flags & AV_OPT_FLAG_READONLY)
        return AVERROR(EINVAL);

    dst = ((uint8_t *)target_obj) + o->offset;
    switch (o->type) {
    case AV_OPT_TYPE_STRING:
        return set_string(obj, o, val, dst);
    case AV_OPT_TYPE_BINARY:
        return set_string_binary(obj, o, val, dst);
    case AV_OPT_TYPE_FLAGS:
    case AV_OPT_TYPE_INT:
    case AV_OPT_TYPE_INT64:
    case AV_OPT_TYPE_FLOAT:
    case AV_OPT_TYPE_DOUBLE:
    case AV_OPT_TYPE_RATIONAL:
        return set_string_number(obj, target_obj, o, val, dst);
    }

    av_log(obj, AV_LOG_ERROR, "Invalid option type.\n");
    return AVERROR(EINVAL);
}

#define OPT_EVAL_NUMBER(name, opttype, vartype)                         \
int av_opt_eval_ ## name(void *obj, const AVOption *o,                  \
                         const char *val, vartype *name ## _out)        \
{                                                                       \
    if (!o || o->type != opttype || o->flags & AV_OPT_FLAG_READONLY)    \
        return AVERROR(EINVAL);                                         \
    return set_string_number(obj, obj, o, val, name ## _out);           \
}

OPT_EVAL_NUMBER(flags,  AV_OPT_TYPE_FLAGS,    int)
OPT_EVAL_NUMBER(int,    AV_OPT_TYPE_INT,      int)
OPT_EVAL_NUMBER(int64,  AV_OPT_TYPE_INT64,    int64_t)
OPT_EVAL_NUMBER(float,  AV_OPT_TYPE_FLOAT,    float)
OPT_EVAL_NUMBER(double, AV_OPT_TYPE_DOUBLE,   double)
OPT_EVAL_NUMBER(q,      AV_OPT_TYPE_RATIONAL, AVRational)

static int set_number(void *obj, const char *name, double num, int den, int64_t intnum,
                      int search_flags)
{
    void *dst, *target_obj;
    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);

    if (!o || !target_obj)
        return AVERROR_OPTION_NOT_FOUND;

    if (o->flags & AV_OPT_FLAG_READONLY)
        return AVERROR(EINVAL);

    dst = ((uint8_t *)target_obj) + o->offset;
    return write_number(obj, o, dst, num, den, intnum);
}

int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
{
    return set_number(obj, name, 1, 1, val, search_flags);
}

int av_opt_set_double(void *obj, const char *name, double val, int search_flags)
{
    return set_number(obj, name, val, 1, 1, search_flags);
}

int av_opt_set_q(void *obj, const char *name, AVRational val, int search_flags)
{
    return set_number(obj, name, val.num, val.den, 1, search_flags);
}

int av_opt_set_bin(void *obj, const char *name, const uint8_t *val, int len, int search_flags)
{
    void *target_obj;
    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);
    uint8_t *ptr;
    uint8_t **dst;
    int *lendst;

    if (!o || !target_obj)
        return AVERROR_OPTION_NOT_FOUND;

    if (o->type != AV_OPT_TYPE_BINARY || o->flags & AV_OPT_FLAG_READONLY)
        return AVERROR(EINVAL);

    ptr = av_malloc(len);
    if (!ptr)
        return AVERROR(ENOMEM);

    dst    = (uint8_t **)(((uint8_t *)target_obj) + o->offset);
    lendst = (int *)(dst + 1);

    av_free(*dst);
    *dst    = ptr;
    *lendst = len;
    memcpy(ptr, val, len);

    return 0;
}

int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val,
                        int search_flags)
{
    void *target_obj;
    AVDictionary **dst;
    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);

    if (!o || !target_obj)
        return AVERROR_OPTION_NOT_FOUND;
    if (o->flags & AV_OPT_FLAG_READONLY)
        return AVERROR(EINVAL);

    dst = (AVDictionary **)(((uint8_t *)target_obj) + o->offset);
    av_dict_free(dst);
    av_dict_copy(dst, val, 0);

    return 0;
}

int av_opt_get(void *obj, const char *name, int search_flags, uint8_t **out_val)
{
    void *dst, *target_obj;
    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);
    uint8_t *bin, buf[128];
    int len, i, ret;

    if (!o || !target_obj)
        return AVERROR_OPTION_NOT_FOUND;

    dst = (uint8_t *)target_obj + o->offset;

    buf[0] = 0;
    switch (o->type) {
    case AV_OPT_TYPE_FLAGS:
        ret = snprintf(buf, sizeof(buf), "0x%08X", *(int *)dst);
        break;
    case AV_OPT_TYPE_INT:
        ret = snprintf(buf, sizeof(buf), "%d", *(int *)dst);
        break;
    case AV_OPT_TYPE_INT64:
        ret = snprintf(buf, sizeof(buf), "%" PRId64, *(int64_t *)dst);
        break;
    case AV_OPT_TYPE_FLOAT:
        ret = snprintf(buf, sizeof(buf), "%f", *(float *)dst);
        break;
    case AV_OPT_TYPE_DOUBLE:
        ret = snprintf(buf, sizeof(buf), "%f", *(double *)dst);
        break;
    case AV_OPT_TYPE_RATIONAL:
        ret = snprintf(buf, sizeof(buf), "%d/%d", ((AVRational *)dst)->num,
                       ((AVRational *)dst)->den);
        break;
    case AV_OPT_TYPE_STRING:
        if (*(uint8_t **)dst)
            *out_val = av_strdup(*(uint8_t **)dst);
        else
            *out_val = av_strdup("");
        return *out_val ? 0 : AVERROR(ENOMEM);
    case AV_OPT_TYPE_BINARY:
        len = *(int *)(((uint8_t *)dst) + sizeof(uint8_t *));
        if ((uint64_t)len * 2 + 1 > INT_MAX)
            return AVERROR(EINVAL);
        if (!(*out_val = av_malloc(len * 2 + 1)))
            return AVERROR(ENOMEM);
        bin = *(uint8_t **)dst;
        for (i = 0; i < len; i++)
            snprintf(*out_val + i * 2, 3, "%02X", bin[i]);
        return 0;
    default:
        return AVERROR(EINVAL);
    }

    if (ret >= sizeof(buf))
        return AVERROR(EINVAL);
    *out_val = av_strdup(buf);
    return *out_val ? 0 : AVERROR(ENOMEM);
}

static int get_number(void *obj, const char *name, double *num, int *den, int64_t *intnum,
                      int search_flags)
{
    void *dst, *target_obj;
    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);
    if (!o || !target_obj)
        goto error;

    dst = ((uint8_t *)target_obj) + o->offset;

    return read_number(o, dst, num, den, intnum);

error:
    *den    =
    *intnum = 0;
    return -1;
}

int av_opt_get_int(void *obj, const char *name, int search_flags, int64_t *out_val)
{
    int64_t intnum = 1;
    double num = 1;
    int ret, den = 1;

    if ((ret = get_number(obj, name, &num, &den, &intnum, search_flags)) < 0)
        return ret;
    *out_val = num * intnum / den;
    return 0;
}

int av_opt_get_double(void *obj, const char *name, int search_flags, double *out_val)
{
    int64_t intnum = 1;
    double num = 1;
    int ret, den = 1;

    if ((ret = get_number(obj, name, &num, &den, &intnum, search_flags)) < 0)
        return ret;
    *out_val = num * intnum / den;
    return 0;
}

int av_opt_get_q(void *obj, const char *name, int search_flags, AVRational *out_val)
{
    int64_t intnum = 1;
    double num = 1;
    int ret, den = 1;

    if ((ret = get_number(obj, name, &num, &den, &intnum, search_flags)) < 0)
        return ret;

    if (num == 1.0 && (int)intnum == intnum)
        *out_val = (AVRational) { intnum, den };
    else
        *out_val = av_d2q(num * intnum / den, 1 << 24);
    return 0;
}

int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val)
{
    void *target_obj;
    AVDictionary *src;
    const AVOption *o = av_opt_find2(obj, name, NULL, 0, search_flags, &target_obj);

    if (!o || !target_obj)
        return AVERROR_OPTION_NOT_FOUND;
    if (o->type != AV_OPT_TYPE_DICT)
        return AVERROR(EINVAL);

    src = *(AVDictionary **)(((uint8_t *)target_obj) + o->offset);
    av_dict_copy(out_val, src, 0);

    return 0;
}

int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name)
{
    const AVOption *field = av_opt_find(obj, field_name, NULL, 0, 0);
    const AVOption *flag  = av_opt_find(obj, flag_name,
                                        field ? field->unit : NULL, 0, 0);
    int64_t res;

    if (!field || !flag || flag->type != AV_OPT_TYPE_CONST ||
        av_opt_get_int(obj, field_name, 0, &res) < 0)
        return 0;
    return res & flag->default_val.i64;
}

static void opt_list(void *obj, void *av_log_obj, const char *unit,
                     int req_flags, int rej_flags)
{
    const AVOption *opt = NULL;

    while ((opt = av_opt_next(obj, opt))) {
        if (!(opt->flags & req_flags) || (opt->flags & rej_flags))
            continue;

        /* Don't print CONST's on level one.
         * Don't print anything but CONST's on level two.
         * Only print items from the requested unit.
         */
        if (!unit && opt->type == AV_OPT_TYPE_CONST)
            continue;
        else if (unit && opt->type != AV_OPT_TYPE_CONST)
            continue;
        else if (unit && opt->type == AV_OPT_TYPE_CONST && strcmp(unit, opt->unit))
            continue;
        else if (unit && opt->type == AV_OPT_TYPE_CONST)
            av_log(av_log_obj, AV_LOG_INFO, "   %-15s ", opt->name);
        else
            av_log(av_log_obj, AV_LOG_INFO, "-%-17s ", opt->name);

        switch (opt->type) {
        case AV_OPT_TYPE_FLAGS:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "<flags>");
            break;
        case AV_OPT_TYPE_INT:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "<int>");
            break;
        case AV_OPT_TYPE_INT64:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "<int64>");
            break;
        case AV_OPT_TYPE_DOUBLE:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "<double>");
            break;
        case AV_OPT_TYPE_FLOAT:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "<float>");
            break;
        case AV_OPT_TYPE_STRING:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "<string>");
            break;
        case AV_OPT_TYPE_RATIONAL:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "<rational>");
            break;
        case AV_OPT_TYPE_BINARY:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "<binary>");
            break;
        case AV_OPT_TYPE_CONST:
        default:
            av_log(av_log_obj, AV_LOG_INFO, "%-7s ", "");
            break;
        }
        av_log(av_log_obj, AV_LOG_INFO, "%c", (opt->flags & AV_OPT_FLAG_ENCODING_PARAM) ? 'E' : '.');
        av_log(av_log_obj, AV_LOG_INFO, "%c", (opt->flags & AV_OPT_FLAG_DECODING_PARAM) ? 'D' : '.');
        av_log(av_log_obj, AV_LOG_INFO, "%c", (opt->flags & AV_OPT_FLAG_VIDEO_PARAM)    ? 'V' : '.');
        av_log(av_log_obj, AV_LOG_INFO, "%c", (opt->flags & AV_OPT_FLAG_AUDIO_PARAM)    ? 'A' : '.');
        av_log(av_log_obj, AV_LOG_INFO, "%c", (opt->flags & AV_OPT_FLAG_SUBTITLE_PARAM) ? 'S' : '.');
        av_log(av_log_obj, AV_LOG_INFO, "%c", (opt->flags & AV_OPT_FLAG_EXPORT)         ? 'X' : '.');
        av_log(av_log_obj, AV_LOG_INFO, "%c", (opt->flags & AV_OPT_FLAG_READONLY)       ? 'R' : '.');

        if (opt->help)
            av_log(av_log_obj, AV_LOG_INFO, " %s", opt->help);
        av_log(av_log_obj, AV_LOG_INFO, "\n");
        if (opt->unit && opt->type != AV_OPT_TYPE_CONST)
            opt_list(obj, av_log_obj, opt->unit, req_flags, rej_flags);
    }
}

int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags)
{
    if (!obj)
        return -1;

    av_log(av_log_obj, AV_LOG_INFO, "%s AVOptions:\n", (*(AVClass **)obj)->class_name);

    opt_list(obj, av_log_obj, NULL, req_flags, rej_flags);

    return 0;
}

void av_opt_set_defaults(void *s)
{
    const AVOption *opt = NULL;
    while ((opt = av_opt_next(s, opt))) {
        if (opt->flags & AV_OPT_FLAG_READONLY)
            continue;

        switch (opt->type) {
        case AV_OPT_TYPE_CONST:
            /* Nothing to be done here */
            break;
        case AV_OPT_TYPE_FLAGS:
        case AV_OPT_TYPE_INT:
        case AV_OPT_TYPE_INT64:
            av_opt_set_int(s, opt->name, opt->default_val.i64, 0);
            break;
        case AV_OPT_TYPE_DOUBLE:
        case AV_OPT_TYPE_FLOAT:
        {
            double val;
            val = opt->default_val.dbl;
            av_opt_set_double(s, opt->name, val, 0);
        }
        break;
        case AV_OPT_TYPE_RATIONAL:
        {
            AVRational val;
            val = av_d2q(opt->default_val.dbl, INT_MAX);
            av_opt_set_q(s, opt->name, val, 0);
        }
        break;
        case AV_OPT_TYPE_STRING:
            av_opt_set(s, opt->name, opt->default_val.str, 0);
            break;
        case AV_OPT_TYPE_BINARY:
        case AV_OPT_TYPE_DICT:
            /* Cannot set defaults for these types */
            break;
        default:
            av_log(s, AV_LOG_DEBUG, "AVOption type %d of option %s not implemented yet\n",
                   opt->type, opt->name);
        }
    }
}

/**
 * Store the value in the field in ctx that is named like key.
 * ctx must be an AVClass context, storing is done using AVOptions.
 *
 * @param buf the string to parse, buf will be updated to point at the
 * separator just after the parsed key/value pair
 * @param key_val_sep a 0-terminated list of characters used to
 * separate key from value
 * @param pairs_sep a 0-terminated list of characters used to separate
 * two pairs from each other
 * @return 0 if the key/value pair has been successfully parsed and
 * set, or a negative value corresponding to an AVERROR code in case
 * of error:
 * AVERROR(EINVAL) if the key/value pair cannot be parsed,
 * the error code issued by av_opt_set() if the key/value pair
 * cannot be set
 */
static int parse_key_value_pair(void *ctx, const char **buf,
                                const char *key_val_sep, const char *pairs_sep)
{
    char *key = av_get_token(buf, key_val_sep);
    char *val;
    int ret;

    if (!key)
        return AVERROR(ENOMEM);

    if (*key && strspn(*buf, key_val_sep)) {
        (*buf)++;
        val = av_get_token(buf, pairs_sep);
        if (!val) {
            av_freep(&key);
            return AVERROR(ENOMEM);
        }
    } else {
        av_log(ctx, AV_LOG_ERROR, "Missing key or no key/value separator found after key '%s'\n", key);
        av_free(key);
        return AVERROR(EINVAL);
    }

    av_log(ctx, AV_LOG_DEBUG, "Setting value '%s' for key '%s'\n", val, key);

    ret = av_opt_set(ctx, key, val, AV_OPT_SEARCH_CHILDREN);
    if (ret == AVERROR_OPTION_NOT_FOUND)
        av_log(ctx, AV_LOG_ERROR, "Key '%s' not found.\n", key);

    av_free(key);
    av_free(val);
    return ret;
}

int av_set_options_string(void *ctx, const char *opts,
                          const char *key_val_sep, const char *pairs_sep)
{
    int ret, count = 0;

    if (!opts)
        return 0;

    while (*opts) {
        if ((ret = parse_key_value_pair(ctx, &opts, key_val_sep, pairs_sep)) < 0)
            return ret;
        count++;

        if (*opts)
            opts++;
    }

    return count;
}

void av_opt_free(void *obj)
{
    const AVOption *o = NULL;
    while ((o = av_opt_next(obj, o))) {
        switch (o->type) {
        case AV_OPT_TYPE_STRING:
        case AV_OPT_TYPE_BINARY:
            av_freep((uint8_t *)obj + o->offset);
            break;

        case AV_OPT_TYPE_DICT:
            av_dict_free((AVDictionary **)(((uint8_t *)obj) + o->offset));
            break;

        default:
            break;
        }
    }
}

int av_opt_set_dict(void *obj, AVDictionary **options)
{
    AVDictionaryEntry *t = NULL;
    AVDictionary    *tmp = NULL;
    int ret = 0;

    while ((t = av_dict_get(*options, "", t, AV_DICT_IGNORE_SUFFIX))) {
        ret = av_opt_set(obj, t->key, t->value, 0);
        if (ret == AVERROR_OPTION_NOT_FOUND)
            av_dict_set(&tmp, t->key, t->value, 0);
        else if (ret < 0) {
            av_log(obj, AV_LOG_ERROR, "Error setting option %s to value %s.\n", t->key, t->value);
            break;
        }
        ret = 0;
    }
    av_dict_free(options);
    *options = tmp;
    return ret;
}

const AVOption *av_opt_find(void *obj, const char *name, const char *unit,
                            int opt_flags, int search_flags)
{
    return av_opt_find2(obj, name, unit, opt_flags, search_flags, NULL);
}

const AVOption *av_opt_find2(void *obj, const char *name, const char *unit,
                             int opt_flags, int search_flags, void **target_obj)
{
    const AVClass  *c = *(AVClass **)obj;
    const AVOption *o = NULL;

    if (!c)
        return NULL;

    if (search_flags & AV_OPT_SEARCH_CHILDREN) {
        if (search_flags & AV_OPT_SEARCH_FAKE_OBJ) {
            const AVClass *child = NULL;
            while (child = av_opt_child_class_next(c, child))
                if (o = av_opt_find2(&child, name, unit, opt_flags, search_flags, NULL))
                    return o;
        } else {
            void *child = NULL;
            while (child = av_opt_child_next(obj, child))
                if (o = av_opt_find2(child, name, unit, opt_flags, search_flags, target_obj))
                    return o;
        }
    }

    while (o = av_opt_next(obj, o)) {
        if (!strcmp(o->name, name) && (o->flags & opt_flags) == opt_flags &&
            ((!unit && o->type != AV_OPT_TYPE_CONST) ||
              (unit && o->unit && !strcmp(o->unit, unit)))) {
            if (target_obj) {
                if (!(search_flags & AV_OPT_SEARCH_FAKE_OBJ))
                    *target_obj = obj;
                else
                    *target_obj = NULL;
            }
            return o;
        }
    }
    return NULL;
}

void *av_opt_child_next(void *obj, void *prev)
{
    const AVClass *c = *(AVClass **)obj;
    if (c->child_next)
        return c->child_next(obj, prev);
    return NULL;
}

const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *prev)
{
    if (parent->child_class_next)
        return parent->child_class_next(prev);
    return NULL;
}

static int opt_size(enum AVOptionType type)
{
    switch (type) {
    case AV_OPT_TYPE_INT:
    case AV_OPT_TYPE_FLAGS:
        return sizeof(int);
    case AV_OPT_TYPE_INT64:
        return sizeof(int64_t);
    case AV_OPT_TYPE_DOUBLE:
        return sizeof(double);
    case AV_OPT_TYPE_FLOAT:
        return sizeof(float);
    case AV_OPT_TYPE_STRING:
        return sizeof(uint8_t *);
    case AV_OPT_TYPE_RATIONAL:
        return sizeof(AVRational);
    case AV_OPT_TYPE_BINARY:
        return sizeof(uint8_t *) + sizeof(int);
    }
    return AVERROR(EINVAL);
}

int av_opt_copy(void *dst, const void *src)
{
    const AVOption *o = NULL;
    const AVClass *c;
    int ret = 0;

    if (!src)
        return AVERROR(EINVAL);

    c = *(AVClass **)src;
    if (!c || c != *(AVClass **)dst)
        return AVERROR(EINVAL);

    while ((o = av_opt_next(src, o))) {
        void *field_dst = (uint8_t *)dst + o->offset;
        void *field_src = (uint8_t *)src + o->offset;
        uint8_t **field_dst8 = (uint8_t **)field_dst;
        uint8_t **field_src8 = (uint8_t **)field_src;

        if (o->type == AV_OPT_TYPE_STRING) {
            set_string(dst, o, *field_src8, field_dst8);
            if (*field_src8 && !*field_dst8)
                ret = AVERROR(ENOMEM);
        } else if (o->type == AV_OPT_TYPE_BINARY) {
            int len = *(int *)(field_src8 + 1);
            if (*field_dst8 != *field_src8)
                av_freep(field_dst8);
            if (len) {
                *field_dst8 = av_malloc(len);
                if (!*field_dst8) {
                    ret = AVERROR(ENOMEM);
                    len = 0;
                }
                memcpy(*field_dst8, *field_src8, len);
            } else {
                *field_dst8 = NULL;
            }
            *(int *)(field_dst8 + 1) = len;
        } else if (o->type == AV_OPT_TYPE_CONST) {
            // do nothing
        } else {
            int size = opt_size(o->type);
            if (size < 0)
                ret = size;
            else
                memcpy(field_dst, field_src, size);
        }
    }
    return ret;
}