C++ AV_WL32函数代码示例

void av_md5_final(AVMD5 *ctx, uint8_t *dst)
{
    int i;
    uint64_t finalcount = av_le2ne64(ctx->len << 3);

    av_md5_update(ctx, "\200", 1);
    while ((ctx->len & 63) != 56)
        av_md5_update(ctx, "", 1);

    av_md5_update(ctx, (uint8_t *)&finalcount, 8);

    for (i = 0; i < 4; i++)
        AV_WL32(dst + 4*i, ctx->ABCD[3 - i]);
}

void av_cold av_lfg_init(AVLFG *c, unsigned int seed){
    uint8_t tmp[16]={0};
    int i;

    for(i=8; i<64; i+=4){
        AV_WL32(tmp, seed); tmp[4]=i;
        av_md5_sum(tmp, tmp,  16);
        c->state[i  ]= AV_RL32(tmp);
        c->state[i+1]= AV_RL32(tmp+4);
        c->state[i+2]= AV_RL32(tmp+8);
        c->state[i+3]= AV_RL32(tmp+12);
    }
    c->index=0;
}

static int read_packet(AVFormatContext *s, AVPacket *pkt)
{
    JVDemuxContext *jv = s->priv_data;
    AVIOContext *pb = s->pb;
    AVStream *ast = s->streams[0];

    while (!s->pb->eof_reached && jv->pts < ast->nb_index_entries) {
        const AVIndexEntry *e   = ast->index_entries + jv->pts;
        const JVFrame      *jvf = jv->frames + jv->pts;

        switch(jv->state) {
        case JV_AUDIO:
            jv->state++;
            if (jvf->audio_size ) {
                if (av_get_packet(s->pb, pkt, jvf->audio_size) < 0)
                    return AVERROR(ENOMEM);
                pkt->stream_index = 0;
                pkt->pts          = e->timestamp;
                pkt->flags       |= PKT_FLAG_KEY;
                return 0;
            }
        case JV_VIDEO:
            jv->state++;
            if (jvf->video_size || jvf->palette_size) {
                int size = jvf->video_size + jvf->palette_size;
                if (av_new_packet(pkt, size + JV_PREAMBLE_SIZE))
                    return AVERROR(ENOMEM);

                AV_WL32(pkt->data, jvf->video_size);
                pkt->data[4]      = jvf->video_type;
                if (avio_read(pb, pkt->data + JV_PREAMBLE_SIZE, size) < 0)
                    return AVERROR(EIO);

                pkt->size         = size + JV_PREAMBLE_SIZE;
                pkt->stream_index = 1;
                pkt->pts          = jv->pts;
                if (jvf->video_type != 1)
                    pkt->flags |= PKT_FLAG_KEY;
                return 0;
            }
        case JV_PADDING:
            avio_skip(pb, FFMAX(e->size - jvf->audio_size - jvf->video_size
                                        - jvf->palette_size, 0));
            jv->state = JV_AUDIO;
            jv->pts++;
        }
    }

    return AVERROR(EIO);
}

/** Send a prepared MMST command packet. */
static int send_command_packet(MMSContext *mms)
{
    int len= mms->write_out_ptr - mms->out_buffer;
    int exact_length = (len + 7) & ~7;
    int first_length= exact_length - 16;
    int len8= first_length/8;
    int write_result;

    // update packet length fields.
    AV_WL32(mms->out_buffer + 8, first_length);
    AV_WL32(mms->out_buffer + 16, len8);
    AV_WL32(mms->out_buffer + 32, len8-2);
    memset(mms->write_out_ptr, 0, exact_length - len);

    // write it out.
    write_result= url_write(mms->mms_hd, mms->out_buffer, exact_length);
    if(write_result != exact_length) {
        dprintf(NULL, "url_write returned: %d != %d\n",
                write_result, exact_length);
        return AVERROR_IO;
    }

    return 0;
}

static int encode_init(AVCodecContext * avctx){
    WMACodecContext *s = avctx->priv_data;
    int i, flags1, flags2;
    uint8_t *extradata;

    s->avctx = avctx;

    if(avctx->channels > MAX_CHANNELS)
        return -1;

    if(avctx->bit_rate < 24*1000)
        return -1;

    /* extract flag infos */
    flags1 = 0;
    flags2 = 1;
    if (avctx->codec->id == CODEC_ID_WMAV1) {
        extradata= av_malloc(4);
        avctx->extradata_size= 4;
        AV_WL16(extradata, flags1);
        AV_WL16(extradata+2, flags2);
    } else if (avctx->codec->id == CODEC_ID_WMAV2) {
        extradata= av_mallocz(10);
        avctx->extradata_size= 10;
        AV_WL32(extradata, flags1);
        AV_WL16(extradata+4, flags2);
    }else
        assert(0);
    avctx->extradata= extradata;
    s->use_exp_vlc = flags2 & 0x0001;
    s->use_bit_reservoir = flags2 & 0x0002;
    s->use_variable_block_len = flags2 & 0x0004;

    ff_wma_init(avctx, flags2);

    /* init MDCT */
    for(i = 0; i < s->nb_block_sizes; i++)
        ff_mdct_init(&s->mdct_ctx[i], s->frame_len_bits - i + 1, 0, 1.0);

    avctx->block_align=
    s->block_align= avctx->bit_rate*(int64_t)s->frame_len / (avctx->sample_rate*8);
//av_log(NULL, AV_LOG_ERROR, "%d %d %d %d\n", s->block_align, avctx->bit_rate, s->frame_len, avctx->sample_rate);
    avctx->frame_size= s->frame_len;

    return 0;
}

static void rgbpack_fields(void *ctx_,
                           uint8_t *src[AVS_MAX_COMPONENTS],
                           int sstrides[AVS_MAX_COMPONENTS],
                           uint8_t *dst[AVS_MAX_COMPONENTS],
                           int dstrides[AVS_MAX_COMPONENTS],
                           int w, int h)
{
    RGBPackContext *ctx = ctx_;
    uint8_t *rgb[3], *dest;
    unsigned val;
    int i, j, c;

    rgb[0] = src[0];
    rgb[1] = src[1];
    rgb[2] = src[2];
    dest   = dst[0];

    for (j = 0; j < h; j++) {
        for (i = 0; i < w; i++) {
            val = 0;
            if (ctx->inbpp <= 8) {
                for (c = 0; c < 3; c++)
                    val |= rgb[c][i] << ctx->shift[c];
            } else {
                for (c = 0; c < 3; c++)
                    val |= AV_RN16(rgb[c] + i * 2) << ctx->shift[c];
            }
            switch (ctx->step) {
            case 1:
                dest[i] = val;
                break;
            case 2:
                if (ctx->be) AV_WB16(dest + i * 2, val);
                else         AV_WL16(dest + i * 2, val);
                break;
            case 4:
                if (ctx->be) AV_WB32(dest + i * 4, val);
                else         AV_WL32(dest + i * 4, val);
                break;
            }
        }
        for (c = 0; c < 3; c++)
            rgb[c] += sstrides[0];
        dest += dstrides[0];
    }
}

int ff_read_riff_info(AVFormatContext *s, int64_t size)
{
    int64_t start, end, cur;
    AVIOContext *pb = s->pb;

    start = avio_tell(pb);
    end = start + size;

    while ((cur = avio_tell(pb)) >= 0 && cur <= end - 8 /* = tag + size */) {
        uint32_t chunk_code;
        int64_t chunk_size;
        char key[5] = {0};
        char *value;

        chunk_code = avio_rl32(pb);
        chunk_size = avio_rl32(pb);
        if (chunk_size > end || end - chunk_size < cur || chunk_size == UINT_MAX) {
            av_log(s, AV_LOG_ERROR, "too big INFO subchunk\n");
            return AVERROR_INVALIDDATA;
        }

        chunk_size += (chunk_size & 1);

        value = av_malloc(chunk_size + 1);
        if (!value) {
            av_log(s, AV_LOG_ERROR, "out of memory, unable to read INFO tag\n");
            return AVERROR(ENOMEM);
        }

        AV_WL32(key, chunk_code);

        if (avio_read(pb, value, chunk_size) != chunk_size) {
            av_freep(key);
            av_freep(value);
            av_log(s, AV_LOG_ERROR, "premature end of file while reading INFO tag\n");
            return AVERROR_INVALIDDATA;
        }

        value[chunk_size] = 0;

        av_dict_set(&s->metadata, key, value, AV_DICT_DONT_STRDUP_VAL);
    }

    return 0;
}

static int dxv_decompress_dxt1(AVCodecContext *avctx)
{
    DXVContext *ctx = avctx->priv_data;
    GetByteContext *gbc = &ctx->gbc;
    uint32_t value, prev, op;
    int idx = 0, state = 0;
    int pos = 2;

    /* Copy the first two elements */
    AV_WL32(ctx->tex_data, bytestream2_get_le32(gbc));
    AV_WL32(ctx->tex_data + 4, bytestream2_get_le32(gbc));

    /* Process input until the whole texture has been filled */
    while (pos < ctx->tex_size / 4) {
        CHECKPOINT(2);

        /* Copy two elements from a previous offset or from the input buffer */
        if (op) {
            prev = AV_RL32(ctx->tex_data + 4 * (pos - idx));
            AV_WL32(ctx->tex_data + 4 * pos, prev);
            pos++;

            prev = AV_RL32(ctx->tex_data + 4 * (pos - idx));
            AV_WL32(ctx->tex_data + 4 * pos, prev);
            pos++;
        } else {
            CHECKPOINT(2);

            if (op)
                prev = AV_RL32(ctx->tex_data + 4 * (pos - idx));
            else
                prev = bytestream2_get_le32(gbc);
            AV_WL32(ctx->tex_data + 4 * pos, prev);
            pos++;

            CHECKPOINT(2);

            if (op)
                prev = AV_RL32(ctx->tex_data + 4 * (pos - idx));
            else
                prev = bytestream2_get_le32(gbc);
            AV_WL32(ctx->tex_data + 4 * pos, prev);
            pos++;
        }
    }

    return 0;
}

static int v410_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                             const AVFrame *pic, int *got_packet)
{
    uint8_t *dst;
    uint16_t *y, *u, *v;
    uint32_t val;
    int i, j, ret;

    if ((ret = ff_alloc_packet(pkt, avctx->width * avctx->height * 4)) < 0) {
        av_log(avctx, AV_LOG_ERROR, "Error getting output packet.\n");
        return ret;
    }
    dst = pkt->data;

    avctx->coded_frame->reference = 0;
    avctx->coded_frame->key_frame = 1;
    avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;

    y = (uint16_t *)pic->data[0];
    u = (uint16_t *)pic->data[1];
    v = (uint16_t *)pic->data[2];

    for (i = 0; i < avctx->height; i++) {
        for (j = 0; j < avctx->width; j++) {
            val  = u[j] << 2;
            val |= y[j] << 12;
            val |= (uint32_t) v[j] << 22;
            AV_WL32(dst, val);
            dst += 4;
        }
        y += pic->linesize[0] >> 1;
        u += pic->linesize[1] >> 1;
        v += pic->linesize[2] >> 1;
    }

    pkt->flags |= AV_PKT_FLAG_KEY;
    *got_packet = 1;
    return 0;
}

static void drawtext(AVFrame *pic, int x, int y, const char *txt, uint32_t color)
{
    const uint8_t *font;
    int font_height;
    int i;

    font = avpriv_cga_font, font_height = 8;

    for (i = 0; txt[i]; i++) {
        int char_y, mask;

        uint8_t *p = pic->data[0] + y * pic->linesize[0] + (x + i * 8) * 4;
        for (char_y = 0; char_y < font_height; char_y++) {
            for (mask = 0x80; mask; mask >>= 1) {
                if (font[txt[i] * font_height + char_y] & mask)
                    AV_WL32(p, color);
                p += 4;
            }
            p += pic->linesize[0] - 8 * 4;
        }
    }
}

int ff_side_data_set_encoder_stats(AVPacket *pkt, int quality, int64_t *error, int error_count, int pict_type)
{
    uint8_t *side_data;
    int side_data_size;
    int i;

    side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_QUALITY_STATS, &side_data_size);
    if (!side_data) {
        side_data_size = 4+4+8*error_count;
        side_data = av_packet_new_side_data(pkt, AV_PKT_DATA_QUALITY_STATS,
                                            side_data_size);
    }

    if (!side_data || side_data_size < 4+4+8*error_count)
        return AVERROR(ENOMEM);

    AV_WL32(side_data   , quality  );
    side_data[4] = pict_type;
    side_data[5] = error_count;
    for (i = 0; i<error_count; i++)
        AV_WL64(side_data+8 + 8*i , error[i]);

    return 0;
}

static int rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
                                     AVStream *st, RMStream *ast, int read_all)
{
    char buf[256];
    uint32_t version;
    int ret;

    /* ra type header */
    version = avio_rb16(pb); /* version */
    if (version == 3) {
        unsigned bytes_per_minute;
        int header_size = avio_rb16(pb);
        int64_t startpos = avio_tell(pb);
        avio_skip(pb, 8);
        bytes_per_minute = avio_rb16(pb);
        avio_skip(pb, 4);
        rm_read_metadata(s, pb, 0);
        if ((startpos + header_size) >= avio_tell(pb) + 2) {
            // fourcc (should always be "lpcJ")
            avio_r8(pb);
            get_str8(pb, buf, sizeof(buf));
        }
        // Skip extra header crap (this should never happen)
        if ((startpos + header_size) > avio_tell(pb))
            avio_skip(pb, header_size + startpos - avio_tell(pb));
        if (bytes_per_minute)
            st->codec->bit_rate = 8LL * bytes_per_minute / 60;
        st->codec->sample_rate = 8000;
        st->codec->channels = 1;
        st->codec->channel_layout = AV_CH_LAYOUT_MONO;
        st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
        st->codec->codec_id = AV_CODEC_ID_RA_144;
        ast->deint_id = DEINT_ID_INT0;
    } else {
        int flavor, sub_packet_h, coded_framesize, sub_packet_size;
        int codecdata_length;
        unsigned bytes_per_minute;
        /* old version (4) */
        avio_skip(pb, 2); /* unused */
        avio_rb32(pb); /* .ra4 */
        avio_rb32(pb); /* data size */
        avio_rb16(pb); /* version2 */
        avio_rb32(pb); /* header size */
        flavor= avio_rb16(pb); /* add codec info / flavor */
        ast->coded_framesize = coded_framesize = avio_rb32(pb); /* coded frame size */
        avio_rb32(pb); /* ??? */
        bytes_per_minute = avio_rb32(pb);
        if (version == 4) {
            if (bytes_per_minute)
                st->codec->bit_rate = 8LL * bytes_per_minute / 60;
        }
        avio_rb32(pb); /* ??? */
        ast->sub_packet_h = sub_packet_h = avio_rb16(pb); /* 1 */
        st->codec->block_align= avio_rb16(pb); /* frame size */
        ast->sub_packet_size = sub_packet_size = avio_rb16(pb); /* sub packet size */
        avio_rb16(pb); /* ??? */
        if (version == 5) {
            avio_rb16(pb); avio_rb16(pb); avio_rb16(pb);
        }
        st->codec->sample_rate = avio_rb16(pb);
        avio_rb32(pb);
        st->codec->channels = avio_rb16(pb);
        if (version == 5) {
            ast->deint_id = avio_rl32(pb);
            avio_read(pb, buf, 4);
            buf[4] = 0;
        } else {
            AV_WL32(buf, 0);
            get_str8(pb, buf, sizeof(buf)); /* desc */
            ast->deint_id = AV_RL32(buf);
            get_str8(pb, buf, sizeof(buf)); /* desc */
        }
        st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
        st->codec->codec_tag  = AV_RL32(buf);
        st->codec->codec_id   = ff_codec_get_id(ff_rm_codec_tags,
                                                st->codec->codec_tag);

        switch (st->codec->codec_id) {
        case AV_CODEC_ID_AC3:
            st->need_parsing = AVSTREAM_PARSE_FULL;
            break;
        case AV_CODEC_ID_RA_288:
            st->codec->extradata_size= 0;
            ast->audio_framesize = st->codec->block_align;
            st->codec->block_align = coded_framesize;
            break;
        case AV_CODEC_ID_COOK:
            st->need_parsing = AVSTREAM_PARSE_HEADERS;
        case AV_CODEC_ID_ATRAC3:
        case AV_CODEC_ID_SIPR:
            if (read_all) {
                codecdata_length = 0;
            } else {
                avio_rb16(pb); avio_r8(pb);
                if (version == 5)
                    avio_r8(pb);
                codecdata_length = avio_rb32(pb);
                if(codecdata_length + FF_INPUT_BUFFER_PADDING_SIZE <= (unsigned)codecdata_length){
                    av_log(s, AV_LOG_ERROR, "codecdata_length too large\n");
                    return -1;
//.........这里部分代码省略.........

static int rm_assemble_video_frame(AVFormatContext *s, AVIOContext *pb,
                                   RMDemuxContext *rm, RMStream *vst,
                                   AVPacket *pkt, int len, int *pseq,
                                   int64_t *timestamp)
{
    int hdr;
    int seq = 0, pic_num = 0, len2 = 0, pos = 0; //init to silcense compiler warning
    int type;
    int ret;

    hdr = avio_r8(pb); len--;
    type = hdr >> 6;

    if(type != 3){  // not frame as a part of packet
        seq = avio_r8(pb); len--;
    }
    if(type != 1){  // not whole frame
        len2 = get_num(pb, &len);
        pos  = get_num(pb, &len);
        pic_num = avio_r8(pb); len--;
    }
    if(len<0) {
        av_log(s, AV_LOG_ERROR, "Insufficient data\n");
        return -1;
    }
    rm->remaining_len = len;
    if(type&1){     // frame, not slice
        if(type == 3){  // frame as a part of packet
            len= len2;
            *timestamp = pos;
        }
        if(rm->remaining_len < len) {
            av_log(s, AV_LOG_ERROR, "Insufficient remaining len\n");
            return -1;
        }
        rm->remaining_len -= len;
        if(av_new_packet(pkt, len + 9) < 0)
            return AVERROR(EIO);
        pkt->data[0] = 0;
        AV_WL32(pkt->data + 1, 1);
        AV_WL32(pkt->data + 5, 0);
        if ((ret = avio_read(pb, pkt->data + 9, len)) != len) {
            av_free_packet(pkt);
            av_log(s, AV_LOG_ERROR, "Failed to read %d bytes\n", len);
            return ret < 0 ? ret : AVERROR(EIO);
        }
        return 0;
    }
    //now we have to deal with single slice

    *pseq = seq;
    if((seq & 0x7F) == 1 || vst->curpic_num != pic_num){
        if (len2 > ffio_limit(pb, len2)) {
            av_log(s, AV_LOG_ERROR, "Impossibly sized packet\n");
            return AVERROR_INVALIDDATA;
        }
        vst->slices = ((hdr & 0x3F) << 1) + 1;
        vst->videobufsize = len2 + 8*vst->slices + 1;
        av_free_packet(&vst->pkt); //FIXME this should be output.
        if(av_new_packet(&vst->pkt, vst->videobufsize) < 0)
            return AVERROR(ENOMEM);
        memset(vst->pkt.data, 0, vst->pkt.size);
        vst->videobufpos = 8*vst->slices + 1;
        vst->cur_slice = 0;
        vst->curpic_num = pic_num;
        vst->pktpos = avio_tell(pb);
    }
    if(type == 2)
        len = FFMIN(len, pos);

    if(++vst->cur_slice > vst->slices) {
        av_log(s, AV_LOG_ERROR, "cur slice %d, too large\n", vst->cur_slice);
        return 1;
    }
    if(!vst->pkt.data)
        return AVERROR(ENOMEM);
    AV_WL32(vst->pkt.data - 7 + 8*vst->cur_slice, 1);
    AV_WL32(vst->pkt.data - 3 + 8*vst->cur_slice, vst->videobufpos - 8*vst->slices - 1);
    if(vst->videobufpos + len > vst->videobufsize) {
        av_log(s, AV_LOG_ERROR, "outside videobufsize\n");
        return 1;
    }
    if (avio_read(pb, vst->pkt.data + vst->videobufpos, len) != len)
        return AVERROR(EIO);
    vst->videobufpos += len;
    rm->remaining_len-= len;

    if (type == 2 || vst->videobufpos == vst->videobufsize) {
        vst->pkt.data[0] = vst->cur_slice-1;
        *pkt= vst->pkt;
        vst->pkt.data= NULL;
        vst->pkt.size= 0;
        vst->pkt.buf = NULL;
#if FF_API_DESTRUCT_PACKET
FF_DISABLE_DEPRECATION_WARNINGS
        vst->pkt.destruct = NULL;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
        if(vst->slices != vst->cur_slice) //FIXME find out how to set slices correct from the begin
            memmove(pkt->data + 1 + 8*vst->cur_slice, pkt->data + 1 + 8*vst->slices,
//.........这里部分代码省略.........

int ff_read_riff_info(AVFormatContext *s, int64_t size)
{
    int64_t start, end, cur;
    AVIOContext *pb = s->pb;

    start = avio_tell(pb);
    end   = start + size;

    while ((cur = avio_tell(pb)) >= 0 &&
           cur <= end - 8 /* = tag + size */) {
        uint32_t chunk_code;
        int64_t chunk_size;
        char key[5] = { 0 };
        char *value;

        chunk_code = avio_rl32(pb);
        chunk_size = avio_rl32(pb);
        if (url_feof(pb)) {
            if (chunk_code || chunk_size) {
                av_log(s, AV_LOG_WARNING, "INFO subchunk truncated\n");
                return AVERROR_INVALIDDATA;
            }
            return AVERROR_EOF;
        }
        if (chunk_size > end ||
            end - chunk_size < cur ||
            chunk_size == UINT_MAX) {
            avio_seek(pb, -9, SEEK_CUR);
            chunk_code = avio_rl32(pb);
            chunk_size = avio_rl32(pb);
            if (chunk_size > end || end - chunk_size < cur || chunk_size == UINT_MAX) {
                av_log(s, AV_LOG_WARNING, "too big INFO subchunk\n");
                return AVERROR_INVALIDDATA;
            }
        }

        chunk_size += (chunk_size & 1);

        if (!chunk_code) {
            if (chunk_size)
                avio_skip(pb, chunk_size);
            else if (pb->eof_reached) {
                av_log(s, AV_LOG_WARNING, "truncated file\n");
                return AVERROR_EOF;
            }
            continue;
        }

        value = av_mallocz(chunk_size + 1);
        if (!value) {
            av_log(s, AV_LOG_ERROR,
                   "out of memory, unable to read INFO tag\n");
            return AVERROR(ENOMEM);
        }

        AV_WL32(key, chunk_code);

        if (avio_read(pb, value, chunk_size) != chunk_size) {
            av_log(s, AV_LOG_WARNING,
                   "premature end of file while reading INFO tag\n");
        }

        av_dict_set(&s->metadata, key, value, AV_DICT_DONT_STRDUP_VAL);
    }

    return 0;
}

static int wv_read_packet(AVFormatContext *s,
                          AVPacket *pkt)
{
    WVContext *wc = s->priv_data;
    int ret;
    int size, ver, off;
    int64_t pos;
    uint32_t block_samples;

    if (s->pb->eof_reached)
        return AVERROR_EOF;
    if(wc->block_parsed) {
        if ((ret = wv_read_block_header(s, s->pb, 0)) < 0)
            return ret;
    }

    pos = wc->pos;
    off = wc->multichannel ? 4 : 0;
    if(av_new_packet(pkt, wc->blksize + WV_EXTRA_SIZE + off) < 0)
        return AVERROR(ENOMEM);
    if(wc->multichannel)
        AV_WL32(pkt->data, wc->blksize + WV_EXTRA_SIZE + 12);
    memcpy(pkt->data + off, wc->extra, WV_EXTRA_SIZE);
    ret = avio_read(s->pb, pkt->data + WV_EXTRA_SIZE + off, wc->blksize);
    if(ret != wc->blksize) {
        av_free_packet(pkt);
        return AVERROR(EIO);
    }
    while(!(wc->flags & WV_END_BLOCK)) {
        if(avio_rl32(s->pb) != MKTAG('w', 'v', 'p', 'k')) {
            av_free_packet(pkt);
            return AVERROR_INVALIDDATA;
        }
        if((ret = av_append_packet(s->pb, pkt, 4)) < 0) {
            av_free_packet(pkt);
            return ret;
        }
        size = AV_RL32(pkt->data + pkt->size - 4);
        if(size < 24 || size > WV_BLOCK_LIMIT) {
            av_free_packet(pkt);
            av_log(s, AV_LOG_ERROR, "Incorrect block size %d\n", size);
            return AVERROR_INVALIDDATA;
        }
        wc->blksize = size;
        ver = avio_rl16(s->pb);
        if(ver < 0x402 || ver > 0x410) {
            av_free_packet(pkt);
            av_log(s, AV_LOG_ERROR, "Unsupported version %03X\n", ver);
            return AVERROR_PATCHWELCOME;
        }
        avio_r8(s->pb); // track no
        avio_r8(s->pb); // track sub index
        wc->samples = avio_rl32(s->pb); // total samples in file
        wc->soff = avio_rl32(s->pb); // offset in samples of current block
        if((ret = av_append_packet(s->pb, pkt, WV_EXTRA_SIZE)) < 0) {
            av_free_packet(pkt);
            return ret;
        }
        memcpy(wc->extra, pkt->data + pkt->size - WV_EXTRA_SIZE, WV_EXTRA_SIZE);

        if ((ret = wv_read_block_header(s, s->pb, 1)) < 0) {
            av_free_packet(pkt);
            return ret;
        }
        ret = av_append_packet(s->pb, pkt, wc->blksize);
        if(ret < 0) {
            av_free_packet(pkt);
            return ret;
        }
    }
    pkt->stream_index = 0;
    wc->block_parsed = 1;
    pkt->pts = wc->soff;
    block_samples = AV_RN32(wc->extra);
    if (block_samples > INT32_MAX)
        av_log(s, AV_LOG_WARNING, "Too many samples in block: %"PRIu32"\n", block_samples);
    else
        pkt->duration = block_samples;

    av_add_index_entry(s->streams[0], pos, pkt->pts, 0, 0, AVINDEX_KEYFRAME);
    return 0;
}