C++ AV_RB64函数代码示例

static int qdraw_probe(AVProbeData *p)
{
    const uint8_t *b = p->buf;

    if (   p->buf_size >= 528
        && (AV_RB64(b + 520) & 0xFFFFFFFFFFFF) == 0x001102ff0c00
        && AV_RB16(b + 520)
        && AV_RB16(b + 518))
        return AVPROBE_SCORE_MAX * 3 / 4;
    if (   (AV_RB64(b + 8) & 0xFFFFFFFFFFFF) == 0x001102ff0c00
        && AV_RB16(b + 8)
        && AV_RB16(b + 6))
        return AVPROBE_SCORE_EXTENSION / 4;
    return 0;
}

static void ff_amf_tag_contents(void *ctx, const uint8_t *data, const uint8_t *data_end)
{
    unsigned int size;
    char buf[1024];

    if (data >= data_end)
        return;
    switch (*data++) {
    case AMF_DATA_TYPE_NUMBER:
        av_log(ctx, AV_LOG_DEBUG, " number %g\n", av_int2dbl(AV_RB64(data)));
        return;
    case AMF_DATA_TYPE_BOOL:
        av_log(ctx, AV_LOG_DEBUG, " bool %d\n", *data);
        return;
    case AMF_DATA_TYPE_STRING:
    case AMF_DATA_TYPE_LONG_STRING:
        if (data[-1] == AMF_DATA_TYPE_STRING) {
            size = bytestream_get_be16(&data);
        } else {
            size = bytestream_get_be32(&data);
        }
        size = FFMIN(size, sizeof(buf) - 1);
        memcpy(buf, data, size);
        buf[size] = 0;
        av_log(ctx, AV_LOG_DEBUG, " string '%s'\n", buf);
        return;
    case AMF_DATA_TYPE_NULL:
        av_log(ctx, AV_LOG_DEBUG, " NULL\n");
        return;
    case AMF_DATA_TYPE_ARRAY:
        data += 4;
    case AMF_DATA_TYPE_OBJECT:
        av_log(ctx, AV_LOG_DEBUG, " {\n");
        for (;;) {
            int t;
            size = bytestream_get_be16(&data);
            av_strlcpy(buf, data, FFMIN(sizeof(buf), size + 1));
            if (!size) {
                av_log(ctx, AV_LOG_DEBUG, " }\n");
                data++;
                break;
            }
            if (size >= data_end - data)
                return;
            data += size;
            av_log(ctx, AV_LOG_DEBUG, "  %s: ", buf);
            ff_amf_tag_contents(ctx, data, data_end);
            t = ff_amf_tag_size(data, data_end);
            if (t < 0 || t >= data_end - data)
                return;
            data += t;
        }
        return;
    case AMF_DATA_TYPE_OBJECT_END:
        av_log(ctx, AV_LOG_DEBUG, " }\n");
        return;
    default:
        return;
    }
}

static int rtcp_parse_packet(RTPDemuxContext *s, const unsigned char *buf, int len)
{
    int payload_len;
    while (len >= 2) {
        switch (buf[1]) {
        case RTCP_SR:
            if (len < 16) {
                av_log(NULL, AV_LOG_ERROR, "Invalid length for RTCP SR packet\n");
                return AVERROR_INVALIDDATA;
            }
            payload_len = (AV_RB16(buf + 2) + 1) * 4;

            s->last_rtcp_ntp_time = AV_RB64(buf + 8);
            s->last_rtcp_timestamp = AV_RB32(buf + 16);
            if (s->first_rtcp_ntp_time == AV_NOPTS_VALUE) {
                s->first_rtcp_ntp_time = s->last_rtcp_ntp_time;
                if (!s->base_timestamp)
                    s->base_timestamp = s->last_rtcp_timestamp;
                s->rtcp_ts_offset = s->last_rtcp_timestamp - s->base_timestamp;
            }

            buf += payload_len;
            len -= payload_len;
            break;
        case RTCP_BYE:
            return -RTCP_BYE;
        default:
            return -1;
        }
    }
    return -1;
}

static int xpm_probe(AVProbeData *p)
{
    const uint8_t *b = p->buf;

    if (AV_RB64(b) == 0x2f2a2058504d202a && *(b+8) == '/')
        return AVPROBE_SCORE_MAX - 1;
    return 0;
}

static int png_probe(AVProbeData *p)
{
    const uint8_t *b = p->buf;

    if (AV_RB64(b) == 0x89504e470d0a1a0a)
        return AVPROBE_SCORE_MAX - 1;
    return 0;
}

static int rtcp_parse_packet(RTPDemuxContext *s, const unsigned char *buf, int len)
{
    if (buf[1] != 200)
        return -1;
    s->last_rtcp_ntp_time = AV_RB64(buf + 8);
    s->last_rtcp_timestamp = AV_RB32(buf + 16);
    return 0;
}

/* return < 0 if eof */
static int ffm_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    int size;
    FFMContext *ffm = s->priv_data;
    int duration, ret;

    switch(ffm->read_state) {
    case READ_HEADER:
        if ((ret = ffm_is_avail_data(s, FRAME_HEADER_SIZE+4)) < 0)
            return ret;

        av_dlog(s, "pos=%08"PRIx64" spos=%"PRIx64", write_index=%"PRIx64" size=%"PRIx64"\n",
               avio_tell(s->pb), s->pb->pos, ffm->write_index, ffm->file_size);
        if (ffm_read_data(s, ffm->header, FRAME_HEADER_SIZE, 1) !=
            FRAME_HEADER_SIZE)
            return -1;
        if (ffm->header[1] & FLAG_DTS)
            if (ffm_read_data(s, ffm->header+16, 4, 1) != 4)
                return -1;
        ffm->read_state = READ_DATA;
        /* fall through */
    case READ_DATA:
        size = AV_RB24(ffm->header + 2);
        if ((ret = ffm_is_avail_data(s, size)) < 0)
            return ret;

        duration = AV_RB24(ffm->header + 5);

        if (av_new_packet(pkt, size) < 0) {
            return AVERROR(ENOMEM);
        }
        pkt->stream_index = ffm->header[0];
        if ((unsigned)pkt->stream_index >= s->nb_streams) {
            av_log(s, AV_LOG_ERROR, "invalid stream index %d\n", pkt->stream_index);
            av_free_packet(pkt);
            ffm->read_state = READ_HEADER;
            return -1;
        }
        pkt->pos = avio_tell(s->pb);
        if (ffm->header[1] & FLAG_KEY_FRAME)
            pkt->flags |= AV_PKT_FLAG_KEY;

        ffm->read_state = READ_HEADER;
        if (ffm_read_data(s, pkt->data, size, 0) != size) {
            /* bad case: desynchronized packet. we cancel all the packet loading */
            av_free_packet(pkt);
            return -1;
        }
        pkt->pts = AV_RB64(ffm->header+8);
        if (ffm->header[1] & FLAG_DTS)
            pkt->dts = pkt->pts - AV_RB32(ffm->header+16);
        else
            pkt->dts = pkt->pts;
        pkt->duration = duration;
        break;
    }
    return 0;
}

static int j2k_probe(AVProbeData *p)
{
    const uint8_t *b = p->buf;

    if (AV_RB64(b) == 0x0000000c6a502020 ||
        AV_RB32(b) == 0xff4fff51)
        return AVPROBE_SCORE_EXTENSION + 1;
    return 0;
}

static int dds_probe(AVProbeData *p)
{
    const uint8_t *b = p->buf;

    if (   AV_RB64(b) == 0x444453207c000000
        && AV_RL32(b +  8)
        && AV_RL32(b + 12))
        return AVPROBE_SCORE_MAX - 1;
    return 0;
}

static int redspark_probe(AVProbeData *p)
{
    uint32_t key, data;
    uint8_t header[8];

    /* Decrypt first 8 bytes of the header */
    data = AV_RB32(p->buf);
    key  = data ^ 0x52656453;
    data ^= key;
    AV_WB32(header, data);
    key = rol(key, 11);

    key += rol(key, 3);
    data = AV_RB32(p->buf + 4) ^ key;
    AV_WB32(header + 4, data);

    if (AV_RB64(header) == AV_RB64("RedSpark"))
        return AVPROBE_SCORE_MAX;

    return 0;
}

int ff_amf_get_field_value(const uint8_t *data, const uint8_t *data_end,
                           const uint8_t *name, uint8_t *dst, int dst_size)
{
	int namelen = strlen((char *)name);
	int len;

	while (*data != AMF_DATA_TYPE_OBJECT && data < data_end)
	{
		len = ff_amf_tag_size(data, data_end);
		if (len < 0)
			len = data_end - data;
		data += len;
	}
	if (data_end - data < 3)
		return -1;
	data++;
	for (;;)
	{
		int size = bytestream_get_be16(&data);
		if (!size)
			break;
		if (data + size >= data_end || data + size < data)
			return -1;
		data += size;
		if (size == namelen && !memcmp(data-size, name, namelen))
		{
			switch (*data++)
			{
			case AMF_DATA_TYPE_NUMBER:
				snprintf((char *)dst, dst_size, "%g", av_int2dbl(AV_RB64(data)));
				break;
			case AMF_DATA_TYPE_BOOL:
				snprintf((char *)dst, dst_size, "%s", *data ? "true" : "false");
				break;
			case AMF_DATA_TYPE_STRING:
				len = bytestream_get_be16(&data);
				av_strlcpy((char *)dst, (const char*)data, FFMIN(len+1, dst_size));
				break;
			default:
				return -1;
			}
			return 0;
		}
		len = ff_amf_tag_size(data, data_end);
		if (len < 0 || data + len >= data_end || data + len < data)
			return -1;
		data += len;
	}
	return -1;
}

int av_packet_split_side_data(AVPacket *pkt){
    if (!pkt->side_data_elems && pkt->size >12 && AV_RB64(pkt->data + pkt->size - 8) == FF_MERGE_MARKER){
        int i;
        unsigned int size, orig_pktsize = pkt->size;
        uint8_t *p;

        p = pkt->data + pkt->size - 8 - 5;
        for (i=1; ; i++){
            size = AV_RB32(p);
            if (size>INT_MAX || p - pkt->data < size)
                return 0;
            if (p[4]&128)
                break;
            p-= size+5;
        }

        pkt->side_data = av_malloc(i * sizeof(*pkt->side_data));
        if (!pkt->side_data)
            return AVERROR(ENOMEM);

        p= pkt->data + pkt->size - 8 - 5;
        for (i=0; ; i++){
            size= AV_RB32(p);
            av_assert0(size<=INT_MAX && p - pkt->data >= size);
            pkt->side_data[i].data = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
            pkt->side_data[i].size = size;
            pkt->side_data[i].type = p[4]&127;
            if (!pkt->side_data[i].data)
                return AVERROR(ENOMEM);
            memcpy(pkt->side_data[i].data, p-size, size);
            pkt->size -= size + 5;
            if(p[4]&128)
                break;
            p-= size+5;
        }
        pkt->size -= 8;
        /* FFMIN() prevents overflow in case the packet wasn't allocated with
         * proper padding.
         * If the side data is smaller than the buffer padding size, the
         * remaining bytes should have already been filled with zeros by the
         * original packet allocation anyway. */
        memset(pkt->data + pkt->size, 0,
               FFMIN(orig_pktsize - pkt->size, FF_INPUT_BUFFER_PADDING_SIZE));
        pkt->side_data_elems = i+1;
        return 1;
    }
    return 0;
}

int av_packet_split_side_data(AVPacket *pkt){
    if (!pkt->side_data_elems && pkt->size >12 && AV_RB64(pkt->data + pkt->size - 8) == FF_MERGE_MARKER){
        int i;
        unsigned int size;
        uint8_t *p;

        p = pkt->data + pkt->size - 8 - 5;
        for (i=1; ; i++){
            size = AV_RB32(p);
            if (size>INT_MAX - 5 || p - pkt->data < size)
                return 0;
            if (p[4]&128)
                break;
            if (p - pkt->data < size + 5)
                return 0;
            p-= size+5;
        }

        if (i > AV_PKT_DATA_NB)
            return AVERROR(ERANGE);

        pkt->side_data = av_malloc_array(i, sizeof(*pkt->side_data));
        if (!pkt->side_data)
            return AVERROR(ENOMEM);

        p= pkt->data + pkt->size - 8 - 5;
        for (i=0; ; i++){
            size= AV_RB32(p);
            av_assert0(size<=INT_MAX - 5 && p - pkt->data >= size);
            pkt->side_data[i].data = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
            pkt->side_data[i].size = size;
            pkt->side_data[i].type = p[4]&127;
            if (!pkt->side_data[i].data)
                return AVERROR(ENOMEM);
            memcpy(pkt->side_data[i].data, p-size, size);
            pkt->size -= size + 5;
            if(p[4]&128)
                break;
            p-= size+5;
        }
        pkt->size -= 8;
        pkt->side_data_elems = i+1;
        return 1;
    }
    return 0;
}

static int mov_text_decode_frame(AVCodecContext *avctx,
                            void *data, int *got_sub_ptr, AVPacket *avpkt)
{
    AVSubtitle *sub = data;
    MovTextContext *m = avctx->priv_data;
    int ret, ts_start, ts_end;
    AVBPrint buf;
    char *ptr = avpkt->data;
    char *end;
    int text_length, tsmb_type, ret_tsmb;
    uint64_t tsmb_size;
    const uint8_t *tsmb;

    if (!ptr || avpkt->size < 2)
        return AVERROR_INVALIDDATA;

    /*
     * A packet of size two with value zero is an empty subtitle
     * used to mark the end of the previous non-empty subtitle.
     * We can just drop them here as we have duration information
     * already. If the value is non-zero, then it's technically a
     * bad packet.
     */
    if (avpkt->size == 2)
        return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;

    /*
     * The first two bytes of the packet are the length of the text string
     * In complex cases, there are style descriptors appended to the string
     * so we can't just assume the packet size is the string size.
     */
    text_length = AV_RB16(ptr);
    end = ptr + FFMIN(2 + text_length, avpkt->size);
    ptr += 2;

    ts_start = av_rescale_q(avpkt->pts,
                            avctx->time_base,
                            (AVRational){1,100});
    ts_end   = av_rescale_q(avpkt->pts + avpkt->duration,
                            avctx->time_base,
                            (AVRational){1,100});

    tsmb_size = 0;
    m->tracksize = 2 + text_length;
    m->style_entries = 0;
    m->box_flags = 0;
    m->count_s = 0;
    // Note that the spec recommends lines be no longer than 2048 characters.
    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
    if (text_length + 2 != avpkt->size) {
        while (m->tracksize + 8 <= avpkt->size) {
            // A box is a minimum of 8 bytes.
            tsmb = ptr + m->tracksize - 2;
            tsmb_size = AV_RB32(tsmb);
            tsmb += 4;
            tsmb_type = AV_RB32(tsmb);
            tsmb += 4;

            if (tsmb_size == 1) {
                if (m->tracksize + 16 > avpkt->size)
                    break;
                tsmb_size = AV_RB64(tsmb);
                tsmb += 8;
                m->size_var = 16;
            } else
                m->size_var = 8;
            //size_var is equal to 8 or 16 depending on the size of box

            if (m->tracksize + tsmb_size > avpkt->size)
                break;

            for (size_t i = 0; i < box_count; i++) {
                if (tsmb_type == box_types[i].type) {
                    if (m->tracksize + m->size_var + box_types[i].base_size > avpkt->size)
                        break;
                    ret_tsmb = box_types[i].decode(tsmb, m, avpkt);
                    if (ret_tsmb == -1)
                        break;
                }
            }
            m->tracksize = m->tracksize + tsmb_size;
        }
        text_to_ass(&buf, ptr, end, m);
        mov_text_cleanup(m);
    } else
        text_to_ass(&buf, ptr, end, m);

    ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_end - ts_start);
    av_bprint_finalize(&buf, NULL);
    if (ret < 0)
        return ret;
    *got_sub_ptr = sub->num_rects > 0;
    return avpkt->size;
}

static int mov_text_decode_frame(AVCodecContext *avctx,
                            void *data, int *got_sub_ptr, AVPacket *avpkt)
{
    AVSubtitle *sub = data;
    int ret, ts_start, ts_end;
    AVBPrint buf;
    char *ptr = avpkt->data;
    char *end;
    //char *ptr_temp;
    int text_length, tsmb_type, style_entries;
    uint64_t tsmb_size, tracksize;
    StyleBox **s = {0, };
    StyleBox *s_temp;
    const uint8_t *tsmb;
    int count, i, size_var;

    if (!ptr || avpkt->size < 2)
        return AVERROR_INVALIDDATA;

    /*
     * A packet of size two with value zero is an empty subtitle
     * used to mark the end of the previous non-empty subtitle.
     * We can just drop them here as we have duration information
     * already. If the value is non-zero, then it's technically a
     * bad packet.
     */
    if (avpkt->size == 2)
        return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;

    /*
     * The first two bytes of the packet are the length of the text string
     * In complex cases, there are style descriptors appended to the string
     * so we can't just assume the packet size is the string size.
     */
    text_length = AV_RB16(ptr);
    end = ptr + FFMIN(2 + text_length, avpkt->size);
    ptr += 2;

    ts_start = av_rescale_q(avpkt->pts,
                            avctx->time_base,
                            (AVRational){1,100});
    ts_end   = av_rescale_q(avpkt->pts + avpkt->duration,
                            avctx->time_base,
                            (AVRational){1,100});

    tsmb_size = 0;
    tracksize = 2 + text_length;
    // Note that the spec recommends lines be no longer than 2048 characters.
    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
    if (text_length + 2 != avpkt->size) {
        while (tracksize + 8 <= avpkt->size) {
            // A box is a minimum of 8 bytes.
            tsmb = ptr + tracksize - 2;
            tsmb_size = AV_RB32(tsmb);
            tsmb += 4;
            tsmb_type = AV_RB32(tsmb);
            tsmb += 4;

            if (tsmb_size == 1) {
                if (tracksize + 16 > avpkt->size)
                    break;
                tsmb_size = AV_RB64(tsmb);
                tsmb += 8;
                size_var = 18;
            } else
                size_var = 10;
            //size_var is equal to 10 or 18 depending on the size of box

            if (tracksize + tsmb_size > avpkt->size)
                break;

            if (tsmb_type == MKBETAG('s','t','y','l')) {
                if (tracksize + size_var > avpkt->size)
                    break;
                style_entries = AV_RB16(tsmb);
                tsmb += 2;

                // A single style record is of length 12 bytes.
                if (tracksize + size_var + style_entries * 12 > avpkt->size)
                    break;
                count = 0;

                for(i = 0; i < style_entries; i++) {
                    s_temp = av_malloc(sizeof(*s_temp));
                    if (!s_temp)
                        goto error;

                    s_temp->style_start = AV_RB16(tsmb);
                    tsmb += 2;
                    s_temp->style_end = AV_RB16(tsmb);
                    tsmb += 2;
                    // fontID = AV_RB16(tsmb);
                    tsmb += 2;
                    s_temp->style_flag = AV_RB8(tsmb);
                    av_dynarray_add(&s, &count, s_temp);
                    if(!s)
                        goto error;
                    //fontsize=AV_RB8(tsmb);
                    tsmb += 2;
                    // text-color-rgba
//.........这里部分代码省略.........