ffmpeg/libavformat/utils.c

/*
 * various utility functions for use within FFmpeg
 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <stdint.h>

#include "config.h"

#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/bprint.h"
#include "libavutil/internal.h"
#include "libavutil/thread.h"
#include "libavutil/time.h"

#include "libavcodec/internal.h"

#include "avformat.h"
#include "avio_internal.h"
#include "internal.h"
#if CONFIG_NETWORK
#include "network.h"
#endif

static AVMutex avformat_mutex = AV_MUTEX_INITIALIZER;

/**
 * @file
 * various utility functions for use within FFmpeg
 */

int ff_lock_avformat(void)
{
    return ff_mutex_lock(&avformat_mutex) ? -1 : 0;
}

int ff_unlock_avformat(void)
{
    return ff_mutex_unlock(&avformat_mutex) ? -1 : 0;
}

int ff_copy_whiteblacklists(AVFormatContext *dst, const AVFormatContext *src)
{
    av_assert0(!dst->codec_whitelist &&
               !dst->format_whitelist &&
               !dst->protocol_whitelist &&
               !dst->protocol_blacklist);
    dst-> codec_whitelist = av_strdup(src->codec_whitelist);
    dst->format_whitelist = av_strdup(src->format_whitelist);
    dst->protocol_whitelist = av_strdup(src->protocol_whitelist);
    dst->protocol_blacklist = av_strdup(src->protocol_blacklist);
    if (   (src-> codec_whitelist && !dst-> codec_whitelist)
        || (src->  format_whitelist && !dst->  format_whitelist)
        || (src->protocol_whitelist && !dst->protocol_whitelist)
        || (src->protocol_blacklist && !dst->protocol_blacklist)) {
        av_log(dst, AV_LOG_ERROR, "Failed to duplicate black/whitelist\n");
        return AVERROR(ENOMEM);
    }
    return 0;
}

const AVCodec *ff_find_decoder(AVFormatContext *s, const AVStream *st,
                               enum AVCodecID codec_id)
{
    switch (st->codecpar->codec_type) {
    case AVMEDIA_TYPE_VIDEO:
        if (s->video_codec)    return s->video_codec;
        break;
    case AVMEDIA_TYPE_AUDIO:
        if (s->audio_codec)    return s->audio_codec;
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        if (s->subtitle_codec) return s->subtitle_codec;
        break;
    }

    return avcodec_find_decoder(codec_id);
}

/* an arbitrarily chosen "sane" max packet size -- 50M */
#define SANE_CHUNK_SIZE (50000000)

/* Read the data in sane-sized chunks and append to pkt.
 * Return the number of bytes read or an error. */
static int append_packet_chunked(AVIOContext *s, AVPacket *pkt, int size)
{
    int orig_size      = pkt->size;
    int ret;

    do {
        int prev_size = pkt->size;
        int read_size;

        /* When the caller requests a lot of data, limit it to the amount
         * left in file or SANE_CHUNK_SIZE when it is not known. */
        read_size = size;
        if (read_size > SANE_CHUNK_SIZE/10) {
            read_size = ffio_limit(s, read_size);
            // If filesize/maxsize is unknown, limit to SANE_CHUNK_SIZE
            if (ffiocontext(s)->maxsize < 0)
                read_size = FFMIN(read_size, SANE_CHUNK_SIZE);
        }

        ret = av_grow_packet(pkt, read_size);
        if (ret < 0)
            break;

        ret = avio_read(s, pkt->data + prev_size, read_size);
        if (ret != read_size) {
            av_shrink_packet(pkt, prev_size + FFMAX(ret, 0));
            break;
        }

        size -= read_size;
    } while (size > 0);
    if (size > 0)
        pkt->flags |= AV_PKT_FLAG_CORRUPT;

    if (!pkt->size)
        av_packet_unref(pkt);
    return pkt->size > orig_size ? pkt->size - orig_size : ret;
}

int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
{
#if FF_API_INIT_PACKET
FF_DISABLE_DEPRECATION_WARNINGS
    av_init_packet(pkt);
    pkt->data = NULL;
    pkt->size = 0;
FF_ENABLE_DEPRECATION_WARNINGS
#else
    av_packet_unref(pkt);
#endif
    pkt->pos  = avio_tell(s);

    return append_packet_chunked(s, pkt, size);
}

int av_append_packet(AVIOContext *s, AVPacket *pkt, int size)
{
    if (!pkt->size)
        return av_get_packet(s, pkt, size);
    return append_packet_chunked(s, pkt, size);
}

int av_filename_number_test(const char *filename)
{
    char buf[1024];
    return filename &&
           (av_get_frame_filename(buf, sizeof(buf), filename, 1) >= 0);
}

/**********************************************************/

int ff_is_intra_only(enum AVCodecID id)
{
    const AVCodecDescriptor *d = avcodec_descriptor_get(id);
    if (!d)
        return 0;
    if ((d->type == AVMEDIA_TYPE_VIDEO || d->type == AVMEDIA_TYPE_AUDIO) &&
        !(d->props & AV_CODEC_PROP_INTRA_ONLY))
        return 0;
    return 1;
}

/*******************************************************/

unsigned int ff_codec_get_tag(const AVCodecTag *tags, enum AVCodecID id)
{
    while (tags->id != AV_CODEC_ID_NONE) {
        if (tags->id == id)
            return tags->tag;
        tags++;
    }
    return 0;
}

enum AVCodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag)
{
    for (int i = 0; tags[i].id != AV_CODEC_ID_NONE; i++)
        if (tag == tags[i].tag)
            return tags[i].id;
    for (int i = 0; tags[i].id != AV_CODEC_ID_NONE; i++)
        if (ff_toupper4(tag) == ff_toupper4(tags[i].tag))
            return tags[i].id;
    return AV_CODEC_ID_NONE;
}

enum AVCodecID ff_get_pcm_codec_id(int bps, int flt, int be, int sflags)
{
    if (bps <= 0 || bps > 64)
        return AV_CODEC_ID_NONE;

    if (flt) {
        switch (bps) {
        case 32:
            return be ? AV_CODEC_ID_PCM_F32BE : AV_CODEC_ID_PCM_F32LE;
        case 64:
            return be ? AV_CODEC_ID_PCM_F64BE : AV_CODEC_ID_PCM_F64LE;
        default:
            return AV_CODEC_ID_NONE;
        }
    } else {
        bps  += 7;
        bps >>= 3;
        if (sflags & (1 << (bps - 1))) {
            switch (bps) {
            case 1:
                return AV_CODEC_ID_PCM_S8;
            case 2:
                return be ? AV_CODEC_ID_PCM_S16BE : AV_CODEC_ID_PCM_S16LE;
            case 3:
                return be ? AV_CODEC_ID_PCM_S24BE : AV_CODEC_ID_PCM_S24LE;
            case 4:
                return be ? AV_CODEC_ID_PCM_S32BE : AV_CODEC_ID_PCM_S32LE;
            case 8:
                return be ? AV_CODEC_ID_PCM_S64BE : AV_CODEC_ID_PCM_S64LE;
            default:
                return AV_CODEC_ID_NONE;
            }
        } else {
            switch (bps) {
            case 1:
                return AV_CODEC_ID_PCM_U8;
            case 2:
                return be ? AV_CODEC_ID_PCM_U16BE : AV_CODEC_ID_PCM_U16LE;
            case 3:
                return be ? AV_CODEC_ID_PCM_U24BE : AV_CODEC_ID_PCM_U24LE;
            case 4:
                return be ? AV_CODEC_ID_PCM_U32BE : AV_CODEC_ID_PCM_U32LE;
            default:
                return AV_CODEC_ID_NONE;
            }
        }
    }
}

unsigned int av_codec_get_tag(const AVCodecTag *const *tags, enum AVCodecID id)
{
    unsigned int tag;
    if (!av_codec_get_tag2(tags, id, &tag))
        return 0;
    return tag;
}

int av_codec_get_tag2(const AVCodecTag * const *tags, enum AVCodecID id,
                      unsigned int *tag)
{
    for (int i = 0; tags && tags[i]; i++) {
        const AVCodecTag *codec_tags = tags[i];
        while (codec_tags->id != AV_CODEC_ID_NONE) {
            if (codec_tags->id == id) {
                *tag = codec_tags->tag;
                return 1;
            }
            codec_tags++;
        }
    }
    return 0;
}

enum AVCodecID av_codec_get_id(const AVCodecTag *const *tags, unsigned int tag)
{
    for (int i = 0; tags && tags[i]; i++) {
        enum AVCodecID id = ff_codec_get_id(tags[i], tag);
        if (id != AV_CODEC_ID_NONE)
            return id;
    }
    return AV_CODEC_ID_NONE;
}

int ff_alloc_extradata(AVCodecParameters *par, int size)
{
    av_freep(&par->extradata);
    par->extradata_size = 0;

    if (size < 0 || size >= INT32_MAX - AV_INPUT_BUFFER_PADDING_SIZE)
        return AVERROR(EINVAL);

    par->extradata = av_malloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
    if (!par->extradata)
        return AVERROR(ENOMEM);

    memset(par->extradata + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
    par->extradata_size = size;

    return 0;
}

int av_find_best_stream(AVFormatContext *ic, enum AVMediaType type,
                        int wanted_stream_nb, int related_stream,
                        const AVCodec **decoder_ret, int flags)
{
    int nb_streams = ic->nb_streams;
    int ret = AVERROR_STREAM_NOT_FOUND;
    int best_count = -1, best_multiframe = -1, best_disposition = -1;
    int count, multiframe, disposition;
    int64_t best_bitrate = -1;
    int64_t bitrate;
    unsigned *program = NULL;
    const AVCodec *decoder = NULL, *best_decoder = NULL;

    if (related_stream >= 0 && wanted_stream_nb < 0) {
        AVProgram *p = av_find_program_from_stream(ic, NULL, related_stream);
        if (p) {
            program    = p->stream_index;
            nb_streams = p->nb_stream_indexes;
        }
    }
    for (unsigned i = 0; i < nb_streams; i++) {
        int real_stream_index = program ? program[i] : i;
        AVStream *st          = ic->streams[real_stream_index];
        AVCodecParameters *par = st->codecpar;
        if (par->codec_type != type)
            continue;
        if (wanted_stream_nb >= 0 && real_stream_index != wanted_stream_nb)
            continue;
        if (type == AVMEDIA_TYPE_AUDIO && !(par->ch_layout.nb_channels && par->sample_rate))
            continue;
        if (decoder_ret) {
            decoder = ff_find_decoder(ic, st, par->codec_id);
            if (!decoder) {
                if (ret < 0)
                    ret = AVERROR_DECODER_NOT_FOUND;
                continue;
            }
        }
        disposition = !(st->disposition & (AV_DISPOSITION_HEARING_IMPAIRED | AV_DISPOSITION_VISUAL_IMPAIRED))
                      + !! (st->disposition & AV_DISPOSITION_DEFAULT);
        count = ffstream(st)->codec_info_nb_frames;
        bitrate = par->bit_rate;
        multiframe = FFMIN(5, count);
        if ((best_disposition >  disposition) ||
            (best_disposition == disposition && best_multiframe >  multiframe) ||
            (best_disposition == disposition && best_multiframe == multiframe && best_bitrate >  bitrate) ||
            (best_disposition == disposition && best_multiframe == multiframe && best_bitrate == bitrate && best_count >= count))
            continue;
        best_disposition = disposition;
        best_count   = count;
        best_bitrate = bitrate;
        best_multiframe = multiframe;
        ret          = real_stream_index;
        best_decoder = decoder;
        if (program && i == nb_streams - 1 && ret < 0) {
            program    = NULL;
            nb_streams = ic->nb_streams;
            /* no related stream found, try again with everything */
            i = 0;
        }
    }
    if (decoder_ret)
        *decoder_ret = best_decoder;
    return ret;
}

/*******************************************************/

int ff_stream_side_data_copy(AVStream *dst, const AVStream *src)
{
    /* Free existing side data*/
    for (int i = 0; i < dst->nb_side_data; i++)
        av_free(dst->side_data[i].data);
    av_freep(&dst->side_data);
    dst->nb_side_data = 0;

    /* Copy side data if present */
    if (src->nb_side_data) {
        dst->side_data = av_calloc(src->nb_side_data,
                                   sizeof(*dst->side_data));
        if (!dst->side_data)
            return AVERROR(ENOMEM);
        dst->nb_side_data = src->nb_side_data;

        for (int i = 0; i < src->nb_side_data; i++) {
            uint8_t *data = av_memdup(src->side_data[i].data,
                                      src->side_data[i].size);
            if (!data)
                return AVERROR(ENOMEM);
            dst->side_data[i].type = src->side_data[i].type;
            dst->side_data[i].size = src->side_data[i].size;
            dst->side_data[i].data = data;
        }
    }

    return 0;
}

uint64_t ff_ntp_time(void)
{
    return (av_gettime() / 1000) * 1000 + NTP_OFFSET_US;
}

uint64_t ff_get_formatted_ntp_time(uint64_t ntp_time_us)
{
    uint64_t ntp_ts, frac_part, sec;
    uint32_t usec;

    //current ntp time in seconds and micro seconds
    sec = ntp_time_us / 1000000;
    usec = ntp_time_us % 1000000;

    //encoding in ntp timestamp format
    frac_part = usec * 0xFFFFFFFFULL;
    frac_part /= 1000000;

    if (sec > 0xFFFFFFFFULL)
        av_log(NULL, AV_LOG_WARNING, "NTP time format roll over detected\n");

    ntp_ts = sec << 32;
    ntp_ts |= frac_part;

    return ntp_ts;
}

uint64_t ff_parse_ntp_time(uint64_t ntp_ts)
{
    uint64_t sec = ntp_ts >> 32;
    uint64_t frac_part = ntp_ts & 0xFFFFFFFFULL;
    uint64_t usec = (frac_part * 1000000) / 0xFFFFFFFFULL;

    return (sec * 1000000) + usec;
}

int av_get_frame_filename2(char *buf, int buf_size, const char *path, int number, int flags)
{
    const char *p;
    char *q, buf1[20], c;
    int nd, len, percentd_found;

    q = buf;
    p = path;
    percentd_found = 0;
    for (;;) {
        c = *p++;
        if (c == '\0')
            break;
        if (c == '%') {
            do {
                nd = 0;
                while (av_isdigit(*p)) {
                    if (nd >= INT_MAX / 10 - 255)
                        goto fail;
                    nd = nd * 10 + *p++ - '0';
                }
                c = *p++;
            } while (av_isdigit(c));

            switch (c) {
            case '%':
                goto addchar;
            case 'd':
                if (!(flags & AV_FRAME_FILENAME_FLAGS_MULTIPLE) && percentd_found)
                    goto fail;
                percentd_found = 1;
                if (number < 0)
                    nd += 1;
                snprintf(buf1, sizeof(buf1), "%0*d", nd, number);
                len = strlen(buf1);
                if ((q - buf + len) > buf_size - 1)
                    goto fail;
                memcpy(q, buf1, len);
                q += len;
                break;
            default:
                goto fail;
            }
        } else {
addchar:
            if ((q - buf) < buf_size - 1)
                *q++ = c;
        }
    }
    if (!percentd_found)
        goto fail;
    *q = '\0';
    return 0;
fail:
    *q = '\0';
    return -1;
}

int av_get_frame_filename(char *buf, int buf_size, const char *path, int number)
{
    return av_get_frame_filename2(buf, buf_size, path, number, 0);
}

void av_url_split(char *proto, int proto_size,
                  char *authorization, int authorization_size,
                  char *hostname, int hostname_size,
                  int *port_ptr, char *path, int path_size, const char *url)
{
    const char *p, *ls, *at, *at2, *col, *brk;

    if (port_ptr)
        *port_ptr = -1;
    if (proto_size > 0)
        proto[0] = 0;
    if (authorization_size > 0)
        authorization[0] = 0;
    if (hostname_size > 0)
        hostname[0] = 0;
    if (path_size > 0)
        path[0] = 0;

    /* parse protocol */
    if ((p = strchr(url, ':'))) {
        av_strlcpy(proto, url, FFMIN(proto_size, p + 1 - url));
        p++; /* skip ':' */
        if (*p == '/')
            p++;
        if (*p == '/')
            p++;
    } else {
        /* no protocol means plain filename */
        av_strlcpy(path, url, path_size);
        return;
    }

    /* separate path from hostname */
    ls = p + strcspn(p, "/?#");
    av_strlcpy(path, ls, path_size);

    /* the rest is hostname, use that to parse auth/port */
    if (ls != p) {
        /* authorization (user[:pass]@hostname) */
        at2 = p;
        while ((at = strchr(p, '@')) && at < ls) {
            av_strlcpy(authorization, at2,
                       FFMIN(authorization_size, at + 1 - at2));
            p = at + 1; /* skip '@' */
        }

        if (*p == '[' && (brk = strchr(p, ']')) && brk < ls) {
            /* [host]:port */
            av_strlcpy(hostname, p + 1,
                       FFMIN(hostname_size, brk - p));
            if (brk[1] == ':' && port_ptr)
                *port_ptr = atoi(brk + 2);
        } else if ((col = strchr(p, ':')) && col < ls) {
            av_strlcpy(hostname, p,
                       FFMIN(col + 1 - p, hostname_size));
            if (port_ptr)
                *port_ptr = atoi(col + 1);
        } else
            av_strlcpy(hostname, p,
                       FFMIN(ls + 1 - p, hostname_size));
    }
}

int ff_mkdir_p(const char *path)
{
    int ret = 0;
    char *temp = av_strdup(path);
    char *pos = temp;
    char tmp_ch = '\0';

    if (!path || !temp) {
        return -1;
    }

    if (!av_strncasecmp(temp, "/", 1) || !av_strncasecmp(temp, "\\", 1)) {
        pos++;
    } else if (!av_strncasecmp(temp, "./", 2) || !av_strncasecmp(temp, ".\\", 2)) {
        pos += 2;
    }

    for ( ; *pos != '\0'; ++pos) {
        if (*pos == '/' || *pos == '\\') {
            tmp_ch = *pos;
            *pos = '\0';
            ret = mkdir(temp, 0755);
            *pos = tmp_ch;
        }
    }

    if ((*(pos - 1) != '/') && (*(pos - 1) != '\\')) {
        ret = mkdir(temp, 0755);
    }

    av_free(temp);
    return ret;
}

char *ff_data_to_hex(char *buff, const uint8_t *src, int s, int lowercase)
{
    static const char hex_table_uc[16] = { '0', '1', '2', '3',
                                           '4', '5', '6', '7',
                                           '8', '9', 'A', 'B',
                                           'C', 'D', 'E', 'F' };
    static const char hex_table_lc[16] = { '0', '1', '2', '3',
                                           '4', '5', '6', '7',
                                           '8', '9', 'a', 'b',
                                           'c', 'd', 'e', 'f' };
    const char *hex_table = lowercase ? hex_table_lc : hex_table_uc;

    for (int i = 0; i < s; i++) {
        buff[i * 2]     = hex_table[src[i] >> 4];
        buff[i * 2 + 1] = hex_table[src[i] & 0xF];
    }
    buff[2 * s] = '\0';

    return buff;
}

int ff_hex_to_data(uint8_t *data, const char *p)
{
    int c, len, v;

    len = 0;
    v   = 1;
    for (;;) {
        p += strspn(p, SPACE_CHARS);
        if (*p == '\0')
            break;
        c = av_toupper((unsigned char) *p++);
        if (c >= '0' && c <= '9')
            c = c - '0';
        else if (c >= 'A' && c <= 'F')
            c = c - 'A' + 10;
        else
            break;
        v = (v << 4) | c;
        if (v & 0x100) {
            if (data)
                data[len] = v;
            len++;
            v = 1;
        }
    }
    return len;
}

void avpriv_set_pts_info(AVStream *st, int pts_wrap_bits,
                         unsigned int pts_num, unsigned int pts_den)
{
    FFStream *const sti = ffstream(st);
    AVRational new_tb;
    if (av_reduce(&new_tb.num, &new_tb.den, pts_num, pts_den, INT_MAX)) {
        if (new_tb.num != pts_num)
            av_log(NULL, AV_LOG_DEBUG,
                   "st:%d removing common factor %d from timebase\n",
                   st->index, pts_num / new_tb.num);
    } else
        av_log(NULL, AV_LOG_WARNING,
               "st:%d has too large timebase, reducing\n", st->index);

    if (new_tb.num <= 0 || new_tb.den <= 0) {
        av_log(NULL, AV_LOG_ERROR,
               "Ignoring attempt to set invalid timebase %d/%d for st:%d\n",
               new_tb.num, new_tb.den,
               st->index);
        return;
    }
    st->time_base     = new_tb;
    sti->avctx->pkt_timebase = new_tb;
    st->pts_wrap_bits = pts_wrap_bits;
}

void ff_parse_key_value(const char *str, ff_parse_key_val_cb callback_get_buf,
                        void *context)
{
    const char *ptr = str;

    /* Parse key=value pairs. */
    for (;;) {
        const char *key;
        char *dest = NULL, *dest_end;
        int key_len, dest_len = 0;

        /* Skip whitespace and potential commas. */
        while (*ptr && (av_isspace(*ptr) || *ptr == ','))
            ptr++;
        if (!*ptr)
            break;

        key = ptr;

        if (!(ptr = strchr(key, '=')))
            break;
        ptr++;
        key_len = ptr - key;

        callback_get_buf(context, key, key_len, &dest, &dest_len);
        dest_end = dest ? dest + dest_len - 1 : NULL;

        if (*ptr == '\"') {
            ptr++;
            while (*ptr && *ptr != '\"') {
                if (*ptr == '\\') {
                    if (!ptr[1])
                        break;
                    if (dest && dest < dest_end)
                        *dest++ = ptr[1];
                    ptr += 2;
                } else {
                    if (dest && dest < dest_end)
                        *dest++ = *ptr;
                    ptr++;
                }
            }
            if (*ptr == '\"')
                ptr++;
        } else {
            for (; *ptr && !(av_isspace(*ptr) || *ptr == ','); ptr++)
                if (dest && dest < dest_end)
                    *dest++ = *ptr;
        }
        if (dest)
            *dest = 0;
    }
}

int ff_find_stream_index(const AVFormatContext *s, int id)
{
    for (unsigned i = 0; i < s->nb_streams; i++)
        if (s->streams[i]->id == id)
            return i;
    return -1;
}

int avformat_network_init(void)
{
#if CONFIG_NETWORK
    int ret;
    if ((ret = ff_network_init()) < 0)
        return ret;
    if ((ret = ff_tls_init()) < 0)
        return ret;
#endif
    return 0;
}

int avformat_network_deinit(void)
{
#if CONFIG_NETWORK
    ff_network_close();
    ff_tls_deinit();
#endif
    return 0;
}

void ff_format_io_close_default(AVFormatContext *s, AVIOContext *pb)
{
    avio_close(pb);
}

int ff_format_io_close(AVFormatContext *s, AVIOContext **pb)
{
    int ret = 0;
    if (*pb) {
        if (s->io_close == ff_format_io_close_default || s->io_close == NULL)
            ret = s->io_close2(s, *pb);
        else
            s->io_close(s, *pb);
    }
    *pb = NULL;
    return ret;
}

int ff_is_http_proto(const char *filename) {
    const char *proto = avio_find_protocol_name(filename);
    return proto ? (!av_strcasecmp(proto, "http") || !av_strcasecmp(proto, "https")) : 0;
}

int ff_bprint_to_codecpar_extradata(AVCodecParameters *par, struct AVBPrint *buf)
{
    int ret;
    char *str;

    ret = av_bprint_finalize(buf, &str);
    if (ret < 0)
        return ret;
    if (!av_bprint_is_complete(buf)) {
        av_free(str);
        return AVERROR(ENOMEM);
    }

    par->extradata = str;
    /* Note: the string is NUL terminated (so extradata can be read as a
     * string), but the ending character is not accounted in the size (in
     * binary formats you are likely not supposed to mux that character). When
     * extradata is copied, it is also padded with AV_INPUT_BUFFER_PADDING_SIZE
     * zeros. */
    par->extradata_size = buf->len;
    return 0;
}

void ff_format_set_url(AVFormatContext *s, char *url)
{
    av_assert0(url);
    av_freep(&s->url);
    s->url = url;
}