C++ AV_WB16函数代码示例

static int rmff_dump_cont(rmff_cont_t *cont, char *buffer, int bufsize) {

  int p;

  if (!cont) return 0;

  if (bufsize < RMFF_CONTHEADER_SIZE + cont->title_len + cont->author_len +
      cont->copyright_len + cont->comment_len)
    return -1;

  AV_WB32(buffer, cont->object_id);
  AV_WB32(buffer+4, cont->size);
  AV_WB16(buffer+8, cont->object_version);

  AV_WB16(buffer+10, cont->title_len);
  memcpy(&buffer[12], cont->title, cont->title_len);
  p=12+cont->title_len;

  AV_WB16(buffer+p, cont->author_len);
  memcpy(&buffer[p+2], cont->author, cont->author_len);
  p+=2+cont->author_len;

  AV_WB16(buffer+p, cont->copyright_len);
  memcpy(&buffer[p+2], cont->copyright, cont->copyright_len);
  p+=2+cont->copyright_len;

  AV_WB16(buffer+p, cont->comment_len);
  memcpy(&buffer[p+2], cont->comment, cont->comment_len);

  return RMFF_CONTHEADER_SIZE + cont->title_len + cont->author_len +
         cont->copyright_len + cont->comment_len;
}

static int dnxhd_write_header(AVCodecContext *avctx, uint8_t *buf)
{
    DNXHDEncContext *ctx = avctx->priv_data;
    const uint8_t header_prefix[5] = { 0x00,0x00,0x02,0x80,0x01 };

    memcpy(buf, header_prefix, 5);
    buf[5] = ctx->interlaced ? ctx->cur_field+2 : 0x01;
    buf[6] = 0x80; // crc flag off
    buf[7] = 0xa0; // reserved
    AV_WB16(buf + 0x18, avctx->height); // ALPF
    AV_WB16(buf + 0x1a, avctx->width);  // SPL
    AV_WB16(buf + 0x1d, avctx->height); // NAL

    buf[0x21] = 0x38; // FIXME 8 bit per comp
    buf[0x22] = 0x88 + (ctx->frame.interlaced_frame<<2);
    AV_WB32(buf + 0x28, ctx->cid); // CID
    buf[0x2c] = ctx->interlaced ? 0 : 0x80;

    buf[0x5f] = 0x01; // UDL

    buf[0x167] = 0x02; // reserved
    AV_WB16(buf + 0x16a, ctx->m.mb_height * 4 + 4); // MSIPS
    buf[0x16d] = ctx->m.mb_height; // Ns
    buf[0x16f] = 0x10; // reserved

    ctx->msip = buf + 0x170;
    return 0;
}

void ff_rtp_send_aac(AVFormatContext *s1, const uint8_t *buff, int size)
{
    RTPMuxContext *s = s1->priv_data;
    AVStream *st = s1->streams[0];
    const int max_au_headers_size = 2 + 2 * s->max_frames_per_packet;
    int len, max_packet_size = s->max_payload_size - max_au_headers_size;
    uint8_t *p;

    /* skip ADTS header, if present */
    if ((s1->streams[0]->codecpar->extradata_size) == 0) {
        size -= 7;
        buff += 7;
    }

    /* test if the packet must be sent */
    len = (s->buf_ptr - s->buf);
    if (s->num_frames &&
        (s->num_frames == s->max_frames_per_packet ||
         (len + size) > s->max_payload_size ||
         av_compare_ts(s->cur_timestamp - s->timestamp, st->time_base,
                       s1->max_delay, AV_TIME_BASE_Q) >= 0)) {
        int au_size = s->num_frames * 2;

        p = s->buf + max_au_headers_size - au_size - 2;
        if (p != s->buf) {
            memmove(p + 2, s->buf + 2, au_size);
        }
        /* Write the AU header size */
        AV_WB16(p, au_size * 8);

        ff_rtp_send_data(s1, p, s->buf_ptr - p, 1);

        s->num_frames = 0;
    }
    if (s->num_frames == 0) {
        s->buf_ptr = s->buf + max_au_headers_size;
        s->timestamp = s->cur_timestamp;
    }

    if (size <= max_packet_size) {
        p = s->buf + s->num_frames++ * 2 + 2;
        AV_WB16(p, size * 8);
        memcpy(s->buf_ptr, buff, size);
        s->buf_ptr += size;
    } else {
        int au_size = size;

        max_packet_size = s->max_payload_size - 4;
        p = s->buf;
        AV_WB16(p, 2 * 8);
        while (size > 0) {
            len = FFMIN(size, max_packet_size);
            AV_WB16(&p[2], au_size * 8);
            memcpy(p + 4, buff, len);
            ff_rtp_send_data(s1, p, len + 4, len == size);
            size -= len;
            buff += len;
        }
    }
}

static void mp3_update_xing(AVFormatContext *s)
{
    MP3Context  *mp3 = s->priv_data;
    AVReplayGain *rg;
    uint16_t tag_crc;
    uint8_t *toc;
    int i, rg_size;

    /* replace "Xing" identification string with "Info" for CBR files. */
    if (!mp3->has_variable_bitrate)
        AV_WL32(mp3->xing_frame + mp3->xing_offset, MKTAG('I', 'n', 'f', 'o'));

    AV_WB32(mp3->xing_frame + mp3->xing_offset + 8,  mp3->frames);
    AV_WB32(mp3->xing_frame + mp3->xing_offset + 12, mp3->size);

    toc    = mp3->xing_frame + mp3->xing_offset + 16;
    toc[0] = 0;  // first toc entry has to be zero.
    for (i = 1; i < XING_TOC_SIZE; ++i) {
        int j = i * mp3->pos / XING_TOC_SIZE;
        int seek_point = 256LL * mp3->bag[j] / mp3->size;
        toc[i] = FFMIN(seek_point, 255);
    }

    /* write replaygain */
    rg = (AVReplayGain*)av_stream_get_side_data(s->streams[0], AV_PKT_DATA_REPLAYGAIN,
                                                &rg_size);
    if (rg && rg_size >= sizeof(*rg)) {
        uint16_t val;

        AV_WB32(mp3->xing_frame + mp3->xing_offset + 131,
                av_rescale(rg->track_peak, 1 << 23, 100000));

        if (rg->track_gain != INT32_MIN) {
            val  = FFABS(rg->track_gain / 10000) & ((1 << 9) - 1);
            val |= (rg->track_gain < 0) << 9;
            val |= 1 << 13;
            AV_WB16(mp3->xing_frame + mp3->xing_offset + 135, val);
        }

        if (rg->album_gain != INT32_MIN) {
            val  = FFABS(rg->album_gain / 10000) & ((1 << 9) - 1);
            val |= (rg->album_gain < 0) << 9;
            val |= 1 << 14;
            AV_WB16(mp3->xing_frame + mp3->xing_offset + 137, val);
        }
    }

    AV_WB32(mp3->xing_frame + mp3->xing_offset + XING_SIZE - 8, mp3->audio_size);
    AV_WB16(mp3->xing_frame + mp3->xing_offset + XING_SIZE - 4, mp3->audio_crc);

    tag_crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI_LE), 0, mp3->xing_frame, 190);
    AV_WB16(mp3->xing_frame + mp3->xing_offset + XING_SIZE - 2, tag_crc);

    avio_seek(s->pb,  mp3->xing_frame_offset, SEEK_SET);
    avio_write(s->pb, mp3->xing_frame, mp3->xing_frame_size);
    avio_seek(s->pb, 0, SEEK_END);
}

/**
 * Adds a superblock header around a set of subpackets.
 *
 * @return <0 on error, else 0.
 */
static int qdm2_restore_block(PayloadContext *qdm, AVStream *st, AVPacket *pkt)
{
    int to_copy, n, res, include_csum;
    uint8_t *p, *csum_pos = NULL;

    /* create packet to hold subpkts into a superblock */
    assert(qdm->cache > 0);
    for (n = 0; n < 0x80; n++)
        if (qdm->len[n] > 0)
            break;
    assert(n < 0x80);

    if ((res = av_new_packet(pkt, qdm->block_size)) < 0)
        return res;
    memset(pkt->data, 0, pkt->size);
    pkt->stream_index  = st->index;
    p                  = pkt->data;

    /* superblock header */
    if (qdm->len[n] > 0xff) {
        *p++ = qdm->block_type | 0x80;
        AV_WB16(p, qdm->len[n]);
        p   += 2;
    } else {
        *p++ = qdm->block_type;
        *p++ = qdm->len[n];
    }
    if ((include_csum = (qdm->block_type == 2 || qdm->block_type == 4))) {
        csum_pos = p;
        p       += 2;
    }

    /* subpacket data */
    to_copy = FFMIN(qdm->len[n], pkt->size - (p - pkt->data));
    memcpy(p, qdm->buf[n], to_copy);
    qdm->len[n] = 0;

    /* checksum header */
    if (include_csum) {
        unsigned int total = 0;
        uint8_t *q;

        for (q = pkt->data; q < &pkt->data[qdm->block_size]; q++)
            total += *q;
        AV_WB16(csum_pos, (uint16_t) total);
    }

    return 0;
}

static void get_theora_extradata(AVCodecContext *ctx,
		GstStructure *in_struc)
{
	const GValue *array;
	const GValue *value;
	GstBuffer *buf;
	size_t size = 0;
	uint8_t *p;

	array = gst_structure_get_value(in_struc, "streamheader");
	if (!array)
		return;

	/* get size */
	for (unsigned i = 0; i < gst_value_array_get_size(array); i++) {
		value = gst_value_array_get_value(array, i);
		buf = gst_value_get_buffer(value);
		size += buf->size + 2;
	}

	/* fill it up */
	ctx->extradata = p = av_mallocz(size + FF_INPUT_BUFFER_PADDING_SIZE);
	for (unsigned i = 0; i < gst_value_array_get_size(array); i++) {
		value = gst_value_array_get_value(array, i);
		buf = gst_value_get_buffer(value);
		AV_WB16(p, buf->size);
		p += 2;
		memcpy(p, buf->data, buf->size);
		p += buf->size;
	}
	ctx->extradata_size = p - ctx->extradata;
}

static int tcp_write_packet(AVFormatContext *s, RTSPStream *rtsp_st)
{
    RTSPState *rt = s->priv_data;
    AVFormatContext *rtpctx = rtsp_st->transport_priv;
    uint8_t *buf, *ptr;
    int size;
    uint8_t interleave_header[4];

    size = url_close_dyn_buf(rtpctx->pb, &buf);
    ptr = buf;
    while (size > 4) {
        uint32_t packet_len = AV_RB32(ptr);
        int id;
        ptr += 4;
        size -= 4;
        if (packet_len > size || packet_len < 2)
            break;
        if (ptr[1] >= 200 && ptr[1] <= 204)
            id = rtsp_st->interleaved_max; /* RTCP */
        else
            id = rtsp_st->interleaved_min; /* RTP */
        interleave_header[0] = '$';
        interleave_header[1] = id;
        AV_WB16(interleave_header + 2, packet_len);
        url_write(rt->rtsp_hd, interleave_header, 4);
        url_write(rt->rtsp_hd, ptr, packet_len);
        ptr += packet_len;
        size -= packet_len;
    }
    av_free(buf);
    url_open_dyn_packet_buf(&rtpctx->pb, RTSP_TCP_MAX_PACKET_SIZE);
    return 0;
}

/** Concatenate an ogg_packet into the extradata. */
static int concatenate_packet(unsigned int* offset,
                              AVCodecContext* avc_context,
                              const ogg_packet* packet)
{
    const char* message = NULL;
    int newsize = avc_context->extradata_size + 2 + packet->bytes;
    int err = AVERROR_INVALIDDATA;

    if (packet->bytes < 0) {
        message = "ogg_packet has negative size";
    } else if (packet->bytes > 0xffff) {
        message = "ogg_packet is larger than 65535 bytes";
    } else if (newsize < avc_context->extradata_size) {
        message = "extradata_size would overflow";
    } else {
        if ((err = av_reallocp(&avc_context->extradata, newsize)) < 0) {
            avc_context->extradata_size = 0;
            message = "av_realloc failed";
        }
    }
    if (message) {
        av_log(avc_context, AV_LOG_ERROR, "concatenate_packet failed: %s\n", message);
        return err;
    }

    avc_context->extradata_size = newsize;
    AV_WB16(avc_context->extradata + (*offset), packet->bytes);
    *offset += 2;
    memcpy(avc_context->extradata + (*offset), packet->packet, packet->bytes);
    (*offset) += packet->bytes;
    return 0;
}

static void adx_encode(ADXContext *c, uint8_t *adx, const int16_t *wav,
                       ADXChannelState *prev, int channels)
{
    PutBitContext pb;
    int scale;
    int i, j;
    int s0, s1, s2, d;
    int max = 0;
    int min = 0;

    s1 = prev->s1;
    s2 = prev->s2;
    for (i = 0, j = 0; j < 32; i += channels, j++) {
        s0 = wav[i];
        d = ((s0 << COEFF_BITS) - c->coeff[0] * s1 - c->coeff[1] * s2) >> COEFF_BITS;
        if (max < d)
            max = d;
        if (min > d)
            min = d;
        s2 = s1;
        s1 = s0;
    }

    if (max == 0 && min == 0) {
        prev->s1 = s1;
        prev->s2 = s2;
        memset(adx, 0, BLOCK_SIZE);
        return;
    }

    if (max / 7 > -min / 8)
        scale = max / 7;
    else
        scale = -min / 8;

    if (scale == 0)
        scale = 1;

    AV_WB16(adx, scale);

    init_put_bits(&pb, adx + 2, 16);

    s1 = prev->s1;
    s2 = prev->s2;
    for (i = 0, j = 0; j < 32; i += channels, j++) {
        d = ((wav[i] << COEFF_BITS) - c->coeff[0] * s1 - c->coeff[1] * s2) >> COEFF_BITS;

        d = av_clip(ROUNDED_DIV(d, scale), -8, 7);

        put_sbits(&pb, 4, d);

        s0 = ((d << COEFF_BITS) * scale + c->coeff[0] * s1 + c->coeff[1] * s2) >> COEFF_BITS;
        s2 = s1;
        s1 = s0;
    }
    prev->s1 = s1;
    prev->s2 = s2;

    flush_put_bits(&pb);
}

int avpriv_dca_convert_bitstream(const uint8_t *src, int src_size, uint8_t *dst,
                             int max_size)
{
    uint32_t mrk;
    int i, tmp;
    PutBitContext pb;

    if ((unsigned) src_size > (unsigned) max_size)
        src_size = max_size;

    mrk = AV_RB32(src);
    switch (mrk) {
    case DCA_SYNCWORD_CORE_BE:
        memcpy(dst, src, src_size);
        return src_size;
    case DCA_SYNCWORD_CORE_LE:
        for (i = 0; i < (src_size + 1) >> 1; i++) {
            AV_WB16(dst, AV_RL16(src));
            src += 2;
            dst += 2;
        }
        return src_size;
    case DCA_SYNCWORD_CORE_14B_BE:
    case DCA_SYNCWORD_CORE_14B_LE:
        init_put_bits(&pb, dst, max_size);
        for (i = 0; i < (src_size + 1) >> 1; i++, src += 2) {
            tmp = ((mrk == DCA_SYNCWORD_CORE_14B_BE) ? AV_RB16(src) : AV_RL16(src)) & 0x3FFF;
            put_bits(&pb, 14, tmp);
        }
        flush_put_bits(&pb);
        return (put_bits_count(&pb) + 7) >> 3;
    default:
        return AVERROR_INVALIDDATA;
    }
}

static int sctp_wait_fd(int fd, int write)
{
    int ev          = write ? POLLOUT : POLLIN;
    struct pollfd p = { .fd = fd, .events = ev, .revents = 0 };
    int ret;

    ret = poll(&p, 1, 100);
    return ret < 0 ? ff_neterrno() : p.revents & ev ? 0 : AVERROR(EAGAIN);
}

static int sctp_read(URLContext *h, uint8_t *buf, int size)
{
    SCTPContext *s = h->priv_data;
    int ret;

    if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
        ret = sctp_wait_fd(s->fd, 0);
        if (ret < 0)
            return ret;
    }

    if (s->max_streams) {
        /*StreamId is introduced as a 2byte code into the stream*/
        struct sctp_sndrcvinfo info = { 0 };
        ret = ff_sctp_recvmsg(s->fd, buf + 2, size - 2, NULL, 0, &info, 0);
        AV_WB16(buf, info.sinfo_stream);
        ret = ret < 0 ? ret : ret + 2;
    } else
        ret = recv(s->fd, buf, size, 0);

    return ret < 0 ? ff_neterrno() : ret;
}

static void jpeg_table_header(AVCodecContext *avctx, PutBitContext *p,
                              ScanTable *intra_scantable,
                              uint16_t luma_intra_matrix[64],
                              uint16_t chroma_intra_matrix[64],
                              int hsample[3])
{
    int i, j, size;
    uint8_t *ptr;
    MpegEncContext *s = avctx->priv_data;

    if (avctx->codec_id != AV_CODEC_ID_LJPEG) {
        int matrix_count = 1 + !!memcmp(luma_intra_matrix,
                                        chroma_intra_matrix,
                                        sizeof(luma_intra_matrix[0]) * 64);
    if (s->force_duplicated_matrix)
        matrix_count = 2;
    /* quant matrixes */
    put_marker(p, DQT);
    put_bits(p, 16, 2 + matrix_count * (1 + 64));
    put_bits(p, 4, 0); /* 8 bit precision */
    put_bits(p, 4, 0); /* table 0 */
    for(i=0;i<64;i++) {
        j = intra_scantable->permutated[i];
        put_bits(p, 8, luma_intra_matrix[j]);
    }

        if (matrix_count > 1) {
            put_bits(p, 4, 0); /* 8 bit precision */
            put_bits(p, 4, 1); /* table 1 */
            for(i=0;i<64;i++) {
                j = intra_scantable->permutated[i];
                put_bits(p, 8, chroma_intra_matrix[j]);
            }
        }
    }

    if(avctx->active_thread_type & FF_THREAD_SLICE){
        put_marker(p, DRI);
        put_bits(p, 16, 4);
        put_bits(p, 16, (avctx->width-1)/(8*hsample[0]) + 1);
    }

    /* huffman table */
    put_marker(p, DHT);
    flush_put_bits(p);
    ptr = put_bits_ptr(p);
    put_bits(p, 16, 0); /* patched later */
    size = 2;
    size += put_huffman_table(p, 0, 0, avpriv_mjpeg_bits_dc_luminance,
                              avpriv_mjpeg_val_dc);
    size += put_huffman_table(p, 0, 1, avpriv_mjpeg_bits_dc_chrominance,
                              avpriv_mjpeg_val_dc);

    size += put_huffman_table(p, 1, 0, avpriv_mjpeg_bits_ac_luminance,
                              avpriv_mjpeg_val_ac_luminance);
    size += put_huffman_table(p, 1, 1, avpriv_mjpeg_bits_ac_chrominance,
                              avpriv_mjpeg_val_ac_chrominance);
    AV_WB16(ptr, size);
}

static void jpeg_put_comments(AVCodecContext *avctx, PutBitContext *p)
{
    int size;
    uint8_t *ptr;

    if (avctx->sample_aspect_ratio.num > 0 && avctx->sample_aspect_ratio.den > 0) {
        /* JFIF header */
        put_marker(p, APP0);
        put_bits(p, 16, 16);
        avpriv_put_string(p, "JFIF", 1); /* this puts the trailing zero-byte too */
        /* The most significant byte is used for major revisions, the least
         * significant byte for minor revisions. Version 1.02 is the current
         * released revision. */
        put_bits(p, 16, 0x0102);
        put_bits(p,  8, 0);              /* units type: 0 - aspect ratio */
        put_bits(p, 16, avctx->sample_aspect_ratio.num);
        put_bits(p, 16, avctx->sample_aspect_ratio.den);
        put_bits(p, 8, 0); /* thumbnail width */
        put_bits(p, 8, 0); /* thumbnail height */
    }

    /* comment */
    if (!(avctx->flags & AV_CODEC_FLAG_BITEXACT)) {
        put_marker(p, COM);
        flush_put_bits(p);
        ptr = put_bits_ptr(p);
        put_bits(p, 16, 0); /* patched later */
        avpriv_put_string(p, LIBAVCODEC_IDENT, 1);
        size = strlen(LIBAVCODEC_IDENT)+3;
        AV_WB16(ptr, size);
    }

    if (((avctx->pix_fmt == AV_PIX_FMT_YUV420P ||
          avctx->pix_fmt == AV_PIX_FMT_YUV422P ||
          avctx->pix_fmt == AV_PIX_FMT_YUV444P) && avctx->color_range != AVCOL_RANGE_JPEG)
        || avctx->color_range == AVCOL_RANGE_MPEG) {
        put_marker(p, COM);
        flush_put_bits(p);
        ptr = put_bits_ptr(p);
        put_bits(p, 16, 0); /* patched later */
        avpriv_put_string(p, "CS=ITU601", 1);
        size = strlen("CS=ITU601")+3;
        AV_WB16(ptr, size);
    }
}

static int text2movsub(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
                     uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size, int keyframe){
    if (buf_size > 0xffff) return 0;
    *poutbuf_size = buf_size + 2;
    *poutbuf = av_malloc(*poutbuf_size + FF_INPUT_BUFFER_PADDING_SIZE);
    AV_WB16(*poutbuf, buf_size);
    memcpy(*poutbuf + 2, buf, buf_size);
    return 1;
}

static void jpeg_put_comments(AVCodecContext *avctx, PutBitContext *p)
{
    int size;
    uint8_t *ptr;

    if (avctx->sample_aspect_ratio.num > 0 && avctx->sample_aspect_ratio.den > 0) {
        /* JFIF header */
        put_marker(p, APP0);
        put_bits(p, 16, 16);
        avpriv_put_string(p, "JFIF", 1); /* this puts the trailing zero-byte too */
        put_bits(p, 16, 0x0102);         /* v 1.02 */
        put_bits(p,  8, 0);              /* units type: 0 - aspect ratio */
        put_bits(p, 16, avctx->sample_aspect_ratio.num);
        put_bits(p, 16, avctx->sample_aspect_ratio.den);
        put_bits(p, 8, 0); /* thumbnail width */
        put_bits(p, 8, 0); /* thumbnail height */
    }

    /* comment */
    if (!(avctx->flags & CODEC_FLAG_BITEXACT)) {
        put_marker(p, COM);
        flush_put_bits(p);
        ptr = put_bits_ptr(p);
        put_bits(p, 16, 0); /* patched later */
        avpriv_put_string(p, LIBAVCODEC_IDENT, 1);
        size = strlen(LIBAVCODEC_IDENT)+3;
        AV_WB16(ptr, size);
    }

    if (avctx->pix_fmt == AV_PIX_FMT_YUV420P ||
        avctx->pix_fmt == AV_PIX_FMT_YUV422P ||
        avctx->pix_fmt == AV_PIX_FMT_YUV444P) {
        put_marker(p, COM);
        flush_put_bits(p);
        ptr = put_bits_ptr(p);
        put_bits(p, 16, 0); /* patched later */
        avpriv_put_string(p, "CS=ITU601", 1);
        size = strlen("CS=ITU601")+3;
        AV_WB16(ptr, size);
    }
}