static int read_tfra(MOVContext *mov, AVIOContext *f)
{
    MOVFragmentIndex* index = NULL;
    int version, fieldlength, i, j, err;
    int64_t pos = avio_tell(f);
    uint32_t size = avio_rb32(f);
    if (avio_rb32(f) != MKBETAG('t', 'f', 'r', 'a')) {
        return -1;
    }
    av_log(mov->fc, AV_LOG_VERBOSE, "found tfra\n");
    index = av_mallocz(sizeof(MOVFragmentIndex));
    if (!index) {
        return AVERROR(ENOMEM);
    }
    mov->fragment_index_count++;
    if ((err = av_reallocp(&mov->fragment_index_data,
                           mov->fragment_index_count *
                           sizeof(MOVFragmentIndex*))) < 0) {
        av_freep(&index);
        return err;
    }
    mov->fragment_index_data[mov->fragment_index_count - 1] =
        index;

    version = avio_r8(f);
    avio_rb24(f);
    index->track_id = avio_rb32(f);
    fieldlength = avio_rb32(f);
    index->item_count = avio_rb32(f);
    index->items = av_mallocz(
            index->item_count * sizeof(MOVFragmentIndexItem));
    if (!index->items) {
        return AVERROR(ENOMEM);
    }
    for (i = 0; i < index->item_count; i++) {
        int64_t time, offset;
        if (version == 1) {
            time   = avio_rb64(f);
            offset = avio_rb64(f);
        } else {
            time   = avio_rb32(f);
            offset = avio_rb32(f);
        }
        index->items[i].time = time;
        index->items[i].moof_offset = offset;
        for (j = 0; j < ((fieldlength >> 4) & 3) + 1; j++)
            avio_r8(f);
        for (j = 0; j < ((fieldlength >> 2) & 3) + 1; j++)
            avio_r8(f);
        for (j = 0; j < ((fieldlength >> 0) & 3) + 1; j++)
            avio_r8(f);
    }

    avio_seek(f, pos + size, SEEK_SET);
    return 0;
}