C++ bytestream_get_be16函数代码示例

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;
    }
}

/**
 * Parse the presentation segment packet.
 *
 * The presentation segment contains details on the video
 * width, video height, x & y subtitle position.
 *
 * @param avctx contains the current codec context
 * @param buf pointer to the packet to process
 * @param buf_size size of packet to process
 * @todo TODO: Implement cropping
 * @todo TODO: Implement forcing of subtitles
 * @todo TODO: Blanking of subtitle
 */
static void parse_presentation_segment(AVCodecContext *avctx,
                                       const uint8_t *buf, int buf_size)
{
    PGSSubContext *ctx = avctx->priv_data;

    int x, y;
    uint8_t block;

    int w = bytestream_get_be16(&buf);
    int h = bytestream_get_be16(&buf);

    dprintf(avctx, "Video Dimensions %dx%d\n",
            w, h);
    if (av_image_check_size(w, h, 0, avctx) >= 0)
        avcodec_set_dimensions(avctx, w, h);

    /* Skip 1 bytes of unknown, frame rate? */
    buf++;

    ctx->presentation.id_number = bytestream_get_be16(&buf);

    /* Next byte is the state. */
    block = bytestream_get_byte(&buf);;
    if (block == 0x80) {
        /*
         * Skip 7 bytes of unknown:
         *     palette_update_flag (0x80),
         *     palette_id_to_use,
         *     Object Number (if > 0 determines if more data to process),
         *     object_id_ref (2 bytes),
         *     window_id_ref,
         *     composition_flag (0x80 - object cropped, 0x40 - object forced)
         */
        buf += 7;

        x = bytestream_get_be16(&buf);
        y = bytestream_get_be16(&buf);

        /* TODO If cropping, cropping_x, cropping_y, cropping_width, cropping_height (all 2 bytes).*/

        dprintf(avctx, "Subtitle Placement x=%d, y=%d\n", x, y);

        if (x > avctx->width || y > avctx->height) {
            av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",
                   x, y, avctx->width, avctx->height);
            x = 0; y = 0;
        }

        /* Fill in dimensions */
        ctx->presentation.x = x;
        ctx->presentation.y = y;
    } else if (block == 0x00) {
        /* TODO: Blank context as subtitle should not be displayed.
         *       If the subtitle is blanked now the subtitle is not
         *       on screen long enough to read, due to a delay in
         *       initial display timing.
         */
    }
}

/**
 * Parse the presentation segment packet.
 *
 * The presentation segment contains details on the video
 * width, video height, x & y subtitle position.
 *
 * @param avctx contains the current codec context
 * @param buf pointer to the packet to process
 * @param buf_size size of packet to process
 * @todo TODO: Implement cropping
 * @todo TODO: Implement forcing of subtitles
 */
static void parse_presentation_segment(AVCodecContext *avctx,
                                       const uint8_t *buf, int buf_size)
{
    PGSSubContext *ctx = avctx->priv_data;

    int x, y;

    int w = bytestream_get_be16(&buf);
    int h = bytestream_get_be16(&buf);

    av_dlog(avctx, "Video Dimensions %dx%d\n",
            w, h);
    if (av_image_check_size(w, h, 0, avctx) >= 0)
        avcodec_set_dimensions(avctx, w, h);

    /* Skip 1 bytes of unknown, frame rate? */
    buf++;

    ctx->presentation.id_number = bytestream_get_be16(&buf);

    /*
     * Skip 3 bytes of unknown:
     *     state
     *     palette_update_flag (0x80),
     *     palette_id_to_use,
     */
    buf += 3;

    ctx->presentation.object_number = bytestream_get_byte(&buf);
    if (!ctx->presentation.object_number)
        return;

    /*
     * Skip 4 bytes of unknown:
     *     object_id_ref (2 bytes),
     *     window_id_ref,
     *     composition_flag (0x80 - object cropped, 0x40 - object forced)
     */
    buf += 4;

    x = bytestream_get_be16(&buf);
    y = bytestream_get_be16(&buf);

    /* TODO If cropping, cropping_x, cropping_y, cropping_width, cropping_height (all 2 bytes).*/

    av_dlog(avctx, "Subtitle Placement x=%d, y=%d\n", x, y);

    if (x > avctx->width || y > avctx->height)
    {
        av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",
               x, y, avctx->width, avctx->height);
        x = 0;
        y = 0;
    }

    /* Fill in dimensions */
    ctx->presentation.x = x;
    ctx->presentation.y = y;
}

/**
 * Parses the picture segment packet.
 *
 * The picture segment contains details on the sequence id,
 * width, height and Run Length Encoded (RLE) bitmap data.
 *
 * @param avctx contains the current codec context
 * @param buf pointer to the packet to process
 * @param buf_size size of packet to process
 * @todo TODO: Enable support for RLE data over multiple packets
 */
static int parse_picture_segment(AVCodecContext *avctx,
                                  const uint8_t *buf, int buf_size)
{
    PGSSubContext *ctx = avctx->priv_data;

    uint8_t sequence_desc;
    unsigned int rle_bitmap_len, width, height;

    /* skip 3 unknown bytes: Object ID (2 bytes), Version Number */
    buf += 3;

    /* Read the Sequence Description to determine if start of RLE data or appended to previous RLE */
    sequence_desc = bytestream_get_byte(&buf);

    if (!(sequence_desc & 0x80)) {
        av_log(avctx, AV_LOG_ERROR, "Decoder does not support object data over multiple packets.\n");
        return -1;
    }

    /* Decode rle bitmap length */
    rle_bitmap_len = bytestream_get_be24(&buf);

    /* Check to ensure we have enough data for rle_bitmap_length if just a single packet */
    if (rle_bitmap_len > buf_size - 7) {
        av_log(avctx, AV_LOG_ERROR, "Not enough RLE data for specified length of %d.\n", rle_bitmap_len);
        return -1;
    }

    ctx->picture.rle_data_len = rle_bitmap_len;

    /* Get bitmap dimensions from data */
    width  = bytestream_get_be16(&buf);
    height = bytestream_get_be16(&buf);

    /* Make sure the bitmap is not too large */
    if (ctx->presentation.video_w < width || ctx->presentation.video_h < height) {
        av_log(avctx, AV_LOG_ERROR, "Bitmap dimensions larger then video.\n");
        return -1;
    }

    ctx->picture.w = width;
    ctx->picture.h = height;

    av_fast_malloc(&ctx->picture.rle, &ctx->picture.rle_buffer_size, rle_bitmap_len);

    if (!ctx->picture.rle)
        return -1;

    memcpy(ctx->picture.rle, buf, rle_bitmap_len);

    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 ff_amf_tag_size(const uint8_t *data, const uint8_t *data_end)
{
    const uint8_t *base = data;

    if (data >= data_end)
        return -1;
    switch (*data++) {
    case AMF_DATA_TYPE_NUMBER:      return 9;
    case AMF_DATA_TYPE_BOOL:        return 2;
    case AMF_DATA_TYPE_STRING:      return 3 + AV_RB16(data);
    case AMF_DATA_TYPE_LONG_STRING: return 5 + AV_RB32(data);
    case AMF_DATA_TYPE_NULL:        return 1;
    case AMF_DATA_TYPE_ARRAY:
        data += 4;
    case AMF_DATA_TYPE_OBJECT:
        for (;;) {
            int size = bytestream_get_be16(&data);
            int t;
            if (!size) {
                data++;
                break;
            }
            if (size < 0 || size >= data_end - data)
                return -1;
            data += size;
            t = ff_amf_tag_size(data, data_end);
            if (t < 0 || t >= data_end - data)
                return -1;
            data += t;
        }
        return data - base;
    case AMF_DATA_TYPE_OBJECT_END:  return 1;
    default:                        return -1;
    }
}

static int alac_set_info(ALACContext *alac)
{
    const unsigned char *ptr = alac->avctx->extradata;

    ptr += 4; /* size */
    ptr += 4; /* alac */
    ptr += 4; /* 0 ? */

    if(AV_RB32(ptr) >= UINT_MAX/4){
        av_log(alac->avctx, AV_LOG_ERROR, "setinfo_max_samples_per_frame too large\n");
        return -1;
    }

    /* buffer size / 2 ? */
    alac->setinfo_max_samples_per_frame = bytestream_get_be32(&ptr);
    alac->setinfo_7a                    = *ptr++;
    alac->setinfo_sample_size           = *ptr++;
    alac->setinfo_rice_historymult      = *ptr++;
    alac->setinfo_rice_initialhistory   = *ptr++;
    alac->setinfo_rice_kmodifier        = *ptr++;
    /* channels? */
    alac->setinfo_7f                    = *ptr++;
    alac->setinfo_80                    = bytestream_get_be16(&ptr);
    /* max coded frame size */
    alac->setinfo_82                    = bytestream_get_be32(&ptr);
    /* bitrate ? */
    alac->setinfo_86                    = bytestream_get_be32(&ptr);
    /* samplerate */
    alac->setinfo_8a_rate               = bytestream_get_be32(&ptr);

    allocate_buffers(alac);

    return 0;
}

int ff_amf_match_string(const uint8_t *data, int size, const char *str)
{
    int len = strlen(str);
    int amf_len, type;

    if (size < 1)
        return 0;

    type = *data++;

    if (type != AMF_DATA_TYPE_LONG_STRING &&
        type != AMF_DATA_TYPE_STRING)
        return 0;

    if (type == AMF_DATA_TYPE_LONG_STRING) {
        if ((size -= 4 + 1) < 0)
            return 0;
        amf_len = bytestream_get_be32(&data);
    } else {
        if ((size -= 2 + 1) < 0)
            return 0;
        amf_len = bytestream_get_be16(&data);
    }

    if (amf_len > size)
        return 0;

    if (amf_len != len)
        return 0;

    return !memcmp(data, str, len);
}

av_cold void ff_init_range_decoder(RangeCoder *c, const uint8_t *buf,
                                   int buf_size)
{
    /* cast to avoid compiler warning */
    ff_init_range_encoder(c, (uint8_t *)buf, buf_size);

    c->low = bytestream_get_be16((const uint8_t **)&c->bytestream);
}

static int dts_probe(AVProbeData *p)
{
    const uint8_t *buf, *bufp;
    uint32_t state = -1;
    int markers[3] = {0};
    int sum, max;
    int64_t diff = 0;

    buf = p->buf;

    for(; buf < (p->buf+p->buf_size)-2; buf+=2) {
        bufp = buf;
        state = (state << 16) | bytestream_get_be16(&bufp);

        /* regular bitstream */
        if (state == DCA_MARKER_RAW_BE || state == DCA_MARKER_RAW_LE)
            markers[0]++;

        /* 14 bits big-endian bitstream */
        if (state == DCA_MARKER_14B_BE)
            if ((bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
                markers[1]++;

        /* 14 bits little-endian bitstream */
        if (state == DCA_MARKER_14B_LE)
            if ((bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
                markers[2]++;

        if (buf - p->buf >= 4)
            diff += FFABS(AV_RL16(buf) - AV_RL16(buf-4));
    }
    sum = markers[0] + markers[1] + markers[2];
    max = markers[1] > markers[0];
    max = markers[2] > markers[max] ? 2 : max;
    if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
        markers[max] * 4 > sum * 3 &&
        diff / p->buf_size > 200)
        return AVPROBE_SCORE_EXTENSION + 1;

    return 0;
}

int ff_amf_tag_size(const uint8_t *data, const uint8_t *data_end)
{
    const uint8_t *base = data;
    AMFDataType type;
    unsigned nb   = -1;
    int parse_key = 1;

    if (data >= data_end)
        return -1;
    switch ((type = *data++)) {
    case AMF_DATA_TYPE_NUMBER:      return 9;
    case AMF_DATA_TYPE_BOOL:        return 2;
    case AMF_DATA_TYPE_STRING:      return 3 + AV_RB16(data);
    case AMF_DATA_TYPE_LONG_STRING: return 5 + AV_RB32(data);
    case AMF_DATA_TYPE_NULL:        return 1;
    case AMF_DATA_TYPE_ARRAY:
        parse_key = 0;
    case AMF_DATA_TYPE_MIXEDARRAY:
        nb = bytestream_get_be32(&data);
    case AMF_DATA_TYPE_OBJECT:
        while (nb-- > 0 || type != AMF_DATA_TYPE_ARRAY) {
            int t;
            if (parse_key) {
                int size = bytestream_get_be16(&data);
                if (!size) {
                    data++;
                    break;
                }
                if (size < 0 || size >= data_end - data)
                    return -1;
                data += size;
            }
            t = ff_amf_tag_size(data, data_end);
            if (t < 0 || t >= data_end - data)
                return -1;
            data += t;
        }
        return data - base;
    case AMF_DATA_TYPE_OBJECT_END:  return 1;
    default:                        return -1;
    }
}

static int oggvorbis_decode_init(AVCodecContext *avccontext) {
    OggVorbisDecContext *context = avccontext->priv_data ;
    uint8_t *p= avccontext->extradata;
    int i, hsizes[3];
    unsigned char *headers[3], *extradata = avccontext->extradata;

    vorbis_info_init(&context->vi) ;
    vorbis_comment_init(&context->vc) ;

    if(! avccontext->extradata_size || ! p) {
        av_log(avccontext, AV_LOG_ERROR, "vorbis extradata absent\n");
        return -1;
    }

    if(p[0] == 0 && p[1] == 30) {
        for(i = 0; i < 3; i++){
            hsizes[i] = bytestream_get_be16((const uint8_t **)&p);
            headers[i] = p;
            p += hsizes[i];
        }
    } else if(*p == 2) {
        unsigned int offset = 1;
        p++;
        for(i=0; i<2; i++) {
            hsizes[i] = 0;
            while((*p == 0xFF) && (offset < avccontext->extradata_size)) {
                hsizes[i] += 0xFF;
                offset++;
                p++;
            }
            if(offset >= avccontext->extradata_size - 1) {
                av_log(avccontext, AV_LOG_ERROR,
                       "vorbis header sizes damaged\n");
                return -1;
            }
            hsizes[i] += *p;
            offset++;
            p++;
        }
        hsizes[2] = avccontext->extradata_size - hsizes[0]-hsizes[1]-offset;
#if 0
        av_log(avccontext, AV_LOG_DEBUG,
               "vorbis header sizes: %d, %d, %d, / extradata_len is %d \n",
               hsizes[0], hsizes[1], hsizes[2], avccontext->extradata_size);
#endif
        headers[0] = extradata + offset;
        headers[1] = extradata + offset + hsizes[0];
        headers[2] = extradata + offset + hsizes[0] + hsizes[1];
    } else {
        av_log(avccontext, AV_LOG_ERROR,
               "vorbis initial header len is wrong: %d\n", *p);
        return -1;
    }

    for(i=0; i<3; i++){
        context->op.b_o_s= i==0;
        context->op.bytes = hsizes[i];
        context->op.packet = headers[i];
        if(vorbis_synthesis_headerin(&context->vi, &context->vc, &context->op)<0){
            av_log(avccontext, AV_LOG_ERROR, "%d. vorbis header damaged\n", i+1);
            return -1;
        }
    }

    avccontext->channels = context->vi.channels;
    avccontext->sample_rate = context->vi.rate;
    avccontext->sample_fmt = AV_SAMPLE_FMT_S16;
    avccontext->time_base= (AVRational){1, avccontext->sample_rate};

    vorbis_synthesis_init(&context->vd, &context->vi);
    vorbis_block_init(&context->vd, &context->vb);

    return 0 ;
}

/**
 * Parse the presentation segment packet.
 *
 * The presentation segment contains details on the video
 * width, video height, x & y subtitle position.
 *
 * @param avctx contains the current codec context
 * @param buf pointer to the packet to process
 * @param buf_size size of packet to process
 * @todo TODO: Implement cropping
 */
static void parse_presentation_segment(AVCodecContext *avctx,
                                       const uint8_t *buf, int buf_size)
{
    PGSSubContext *ctx = avctx->priv_data;

    int w = bytestream_get_be16(&buf);
    int h = bytestream_get_be16(&buf);

    uint16_t object_index;

    av_dlog(avctx, "Video Dimensions %dx%d\n",
            w, h);
    if (av_image_check_size(w, h, 0, avctx) >= 0)
        avcodec_set_dimensions(avctx, w, h);

    /* Skip 1 bytes of unknown, frame rate? */
    buf++;

    ctx->presentation.id_number = bytestream_get_be16(&buf);

    /*
     * Skip 3 bytes of unknown:
     *     state
     *     palette_update_flag (0x80),
     *     palette_id_to_use,
     */
    buf += 3;

    ctx->presentation.object_count = bytestream_get_byte(&buf);
    if (!ctx->presentation.object_count)
        return;

    /* Verify that enough bytes are remaining for all of the objects. */
    buf_size -= 11;
    if (buf_size < ctx->presentation.object_count * 8) {
        ctx->presentation.object_count = 0;
        return;
    }

    av_freep(&ctx->presentation.objects);
    ctx->presentation.objects = av_malloc(sizeof(PGSSubPictureReference) * ctx->presentation.object_count);
    if (!ctx->presentation.objects) {
        ctx->presentation.object_count = 0;
        return;
    }

    for (object_index = 0; object_index < ctx->presentation.object_count; ++object_index) {
        PGSSubPictureReference *reference = &ctx->presentation.objects[object_index];
        reference->picture_id             = bytestream_get_be16(&buf);

         /*
         * Skip 2 bytes of unknown:
         *     window_id_ref,
         *     composition_flag (0x80 - object cropped, 0x40 - object forced)
         */
        buf++;
		reference->composition = bytestream_get_byte(&buf);
        reference->x = bytestream_get_be16(&buf);
        reference->y = bytestream_get_be16(&buf);

        /* TODO If cropping, cropping_x, cropping_y, cropping_width, cropping_height (all 2 bytes).*/
        av_dlog(avctx, "Subtitle Placement ID=%d, x=%d, y=%d\n", reference->picture_id, reference->x, reference->y);

        if (reference->x > avctx->width || reference->y > avctx->height) {
            av_log(avctx, AV_LOG_ERROR, "Subtitle out of video bounds. x = %d, y = %d, video width = %d, video height = %d.\n",
                   reference->x, reference->y, avctx->width, avctx->height);
            reference->x = 0;
            reference->y = 0;
        }
    }
}

static int decode(AVCodecContext *avctx, void *data, int *data_size,
                  AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size       = avpkt->size;

    const uint8_t *buf_end;
    uint8_t       segment_type;
    int           segment_length;

#ifdef DEBUG_PACKET_CONTENTS
    int i;

    av_log(avctx, AV_LOG_INFO, "PGS sub packet:\n");

    for (i = 0; i < buf_size; i++) {
        av_log(avctx, AV_LOG_INFO, "%02x ", buf[i]);
        if (i % 16 == 15)
            av_log(avctx, AV_LOG_INFO, "\n");
    }

    if (i & 15)
        av_log(avctx, AV_LOG_INFO, "\n");
#endif

    *data_size = 0;

    /* Ensure that we have received at a least a segment code and segment length */
    if (buf_size < 3)
        return -1;

    buf_end = buf + buf_size;

    /* Step through buffer to identify segments */
    while (buf < buf_end) {
        segment_type   = bytestream_get_byte(&buf);
        segment_length = bytestream_get_be16(&buf);

        av_dlog(avctx, "Segment Length %d, Segment Type %x\n", segment_length, segment_type);

        if (segment_type != DISPLAY_SEGMENT && segment_length > buf_end - buf)
            break;

        switch (segment_type) {
        case PALETTE_SEGMENT:
            parse_palette_segment(avctx, buf, segment_length);
            break;
        case PICTURE_SEGMENT:
            parse_picture_segment(avctx, buf, segment_length);
            break;
        case PRESENTATION_SEGMENT:
            parse_presentation_segment(avctx, buf, segment_length);
            break;
        case WINDOW_SEGMENT:
            /*
             * Window Segment Structure (No new information provided):
             *     2 bytes: Unkown,
             *     2 bytes: X position of subtitle,
             *     2 bytes: Y position of subtitle,
             *     2 bytes: Width of subtitle,
             *     2 bytes: Height of subtitle.
             */
            break;
        case DISPLAY_SEGMENT:
            *data_size = display_end_segment(avctx, data, buf, segment_length);
            break;
        default:
            av_log(avctx, AV_LOG_ERROR, "Unknown subtitle segment type 0x%x, length %d\n",
                   segment_type, segment_length);
            break;
        }

        buf += segment_length;
    }

    return buf_size;
}

static int cook_decode_init(AVCodecContext *avctx)
{
    COOKContext *q = avctx->priv_data;
    const uint8_t *edata_ptr = avctx->extradata;

    /* Take care of the codec specific extradata. */
    if (avctx->extradata_size <= 0) {
        av_log(avctx,AV_LOG_ERROR,"Necessary extradata missing!\n");
        return -1;
    } else {
        /* 8 for mono, 16 for stereo, ? for multichannel
           Swap to right endianness so we don't need to care later on. */
        av_log(avctx,AV_LOG_DEBUG,"codecdata_length=%d\n",avctx->extradata_size);
        if (avctx->extradata_size >= 8){
            q->cookversion = bytestream_get_be32(&edata_ptr);
            q->samples_per_frame =  bytestream_get_be16(&edata_ptr);
            q->subbands = bytestream_get_be16(&edata_ptr);
        }
        if (avctx->extradata_size >= 16){
            bytestream_get_be32(&edata_ptr);    //Unknown unused
            q->js_subband_start = bytestream_get_be16(&edata_ptr);
            q->js_vlc_bits = bytestream_get_be16(&edata_ptr);
        }
    }

    /* Take data from the AVCodecContext (RM container). */
    q->sample_rate = avctx->sample_rate;
    q->nb_channels = avctx->channels;
    q->bit_rate = avctx->bit_rate;

    /* Initialize RNG. */
    av_init_random(1, &q->random_state);

    /* Initialize extradata related variables. */
    q->samples_per_channel = q->samples_per_frame / q->nb_channels;
    q->bits_per_subpacket = avctx->block_align * 8;

    /* Initialize default data states. */
    q->log2_numvector_size = 5;
    q->total_subbands = q->subbands;

    /* Initialize version-dependent variables */
    av_log(NULL,AV_LOG_DEBUG,"q->cookversion=%x\n",q->cookversion);
    q->joint_stereo = 0;
    switch (q->cookversion) {
        case MONO:
            if (q->nb_channels != 1) {
                av_log(avctx,AV_LOG_ERROR,"Container channels != 1, report sample!\n");
                return -1;
            }
            av_log(avctx,AV_LOG_DEBUG,"MONO\n");
            break;
        case STEREO:
            if (q->nb_channels != 1) {
                q->bits_per_subpacket = q->bits_per_subpacket/2;
            }
            av_log(avctx,AV_LOG_DEBUG,"STEREO\n");
            break;
        case JOINT_STEREO:
            if (q->nb_channels != 2) {
                av_log(avctx,AV_LOG_ERROR,"Container channels != 2, report sample!\n");
                return -1;
            }
            av_log(avctx,AV_LOG_DEBUG,"JOINT_STEREO\n");
            if (avctx->extradata_size >= 16){
                q->total_subbands = q->subbands + q->js_subband_start;
                q->joint_stereo = 1;
            }
            if (q->samples_per_channel > 256) {
                q->log2_numvector_size  = 6;
            }
            if (q->samples_per_channel > 512) {
                q->log2_numvector_size  = 7;
            }
            break;
        case MC_COOK:
            av_log(avctx,AV_LOG_ERROR,"MC_COOK not supported!\n");
            return -1;
            break;
        default:
            av_log(avctx,AV_LOG_ERROR,"Unknown Cook version, report sample!\n");
            return -1;
            break;
    }

    /* Initialize variable relations */
    q->numvector_size = (1 << q->log2_numvector_size);

    /* Generate tables */
    init_pow2table();
    init_gain_table(q);
    init_cplscales_table(q);

    if (init_cook_vlc_tables(q) != 0)
        return -1;


    if(avctx->block_align >= UINT_MAX/2)
        return -1;

//.........这里部分代码省略.........