예제 #1
0
/* write the header (used two times if non streamed) */
static int asf_write_header1(AVFormatContext *s, int64_t file_size, int64_t data_chunk_size)
{
    ASFContext *asf = s->priv_data;
    ByteIOContext *pb = s->pb;
    AVMetadataTag *title, *author, *copyright, *comment;
    int header_size, n, extra_size, extra_size2, wav_extra_size, file_time;
    int has_title;
    int metadata_count;
    AVCodecContext *enc;
    int64_t header_offset, cur_pos, hpos;
    int bit_rate;
    int64_t duration;

    title     = av_metadata_get(s->metadata, "title"    , NULL, 0);
    author    = av_metadata_get(s->metadata, "author"   , NULL, 0);
    copyright = av_metadata_get(s->metadata, "copyright", NULL, 0);
    comment   = av_metadata_get(s->metadata, "comment"  , NULL, 0);

    duration = asf->duration + PREROLL_TIME * 10000;
    has_title = title || author || copyright || comment;
    metadata_count = s->metadata ? s->metadata->count : 0;

    bit_rate = 0;
    for(n=0;n<s->nb_streams;n++) {
        enc = s->streams[n]->codec;

        av_set_pts_info(s->streams[n], 32, 1, 1000); /* 32 bit pts in ms */

        bit_rate += enc->bit_rate;
    }

    if (asf->is_streamed) {
        put_chunk(s, 0x4824, 0, 0xc00); /* start of stream (length will be patched later) */
    }

    put_guid(pb, &ff_asf_header);
    put_le64(pb, -1); /* header length, will be patched after */
    put_le32(pb, 3 + has_title + !!metadata_count + s->nb_streams); /* number of chunks in header */
    put_byte(pb, 1); /* ??? */
    put_byte(pb, 2); /* ??? */

    /* file header */
    header_offset = url_ftell(pb);
    hpos = put_header(pb, &ff_asf_file_header);
    put_guid(pb, &ff_asf_my_guid);
    put_le64(pb, file_size);
    file_time = 0;
    put_le64(pb, unix_to_file_time(file_time));
    put_le64(pb, asf->nb_packets); /* number of packets */
    put_le64(pb, duration); /* end time stamp (in 100ns units) */
    put_le64(pb, asf->duration); /* duration (in 100ns units) */
    put_le64(pb, PREROLL_TIME); /* start time stamp */
    put_le32(pb, (asf->is_streamed || url_is_streamed(pb)) ? 3 : 2); /* ??? */
    put_le32(pb, asf->packet_size); /* packet size */
    put_le32(pb, asf->packet_size); /* packet size */
    put_le32(pb, bit_rate); /* Nominal data rate in bps */
    end_header(pb, hpos);

    /* unknown headers */
    hpos = put_header(pb, &ff_asf_head1_guid);
    put_guid(pb, &ff_asf_head2_guid);
    put_le32(pb, 6);
    put_le16(pb, 0);
    end_header(pb, hpos);

    /* title and other infos */
    if (has_title) {
        hpos = put_header(pb, &ff_asf_comment_header);
        put_le16(pb, title     ? 2 * (strlen(title->value    ) + 1) : 0);
        put_le16(pb, author    ? 2 * (strlen(author->value   ) + 1) : 0);
        put_le16(pb, copyright ? 2 * (strlen(copyright->value) + 1) : 0);
        put_le16(pb, comment   ? 2 * (strlen(comment->value  ) + 1) : 0);
        put_le16(pb, 0);
        if (title    ) put_str16_nolen(pb, title->value    );
        if (author   ) put_str16_nolen(pb, author->value   );
        if (copyright) put_str16_nolen(pb, copyright->value);
        if (comment  ) put_str16_nolen(pb, comment->value  );
        end_header(pb, hpos);
    }
    if (metadata_count) {
        AVMetadataTag *tag = NULL;
        hpos = put_header(pb, &ff_asf_extended_content_header);
        put_le16(pb, metadata_count);
        while ((tag = av_metadata_get(s->metadata, "", tag, AV_METADATA_IGNORE_SUFFIX))) {
            put_le16(pb, 2*(strlen(tag->key) + 3) + 1);
            put_le16(pb, 'W');
            put_le16(pb, 'M');
            put_le16(pb, '/');
            put_str16_nolen(pb, tag->key);
            put_le16(pb, 0);
            put_le16(pb, 2*strlen(tag->value) + 1);
            put_str16_nolen(pb, tag->value);
        }
        end_header(pb, hpos);
    }

    /* stream headers */
    for(n=0;n<s->nb_streams;n++) {
        int64_t es_pos;
        //        ASFStream *stream = &asf->streams[n];

        enc = s->streams[n]->codec;
        asf->streams[n].num = n + 1;
        asf->streams[n].seq = 0;


        switch(enc->codec_type) {
        case CODEC_TYPE_AUDIO:
            wav_extra_size = 0;
            extra_size = 18 + wav_extra_size;
            extra_size2 = 8;
            break;
        default:
        case CODEC_TYPE_VIDEO:
            wav_extra_size = enc->extradata_size;
            extra_size = 0x33 + wav_extra_size;
            extra_size2 = 0;
            break;
        }

        hpos = put_header(pb, &ff_asf_stream_header);
        if (enc->codec_type == CODEC_TYPE_AUDIO) {
            put_guid(pb, &ff_asf_audio_stream);
            put_guid(pb, &ff_asf_audio_conceal_spread);
        } else {
            put_guid(pb, &ff_asf_video_stream);
            put_guid(pb, &ff_asf_video_conceal_none);
        }
        put_le64(pb, 0); /* ??? */
        es_pos = url_ftell(pb);
        put_le32(pb, extra_size); /* wav header len */
        put_le32(pb, extra_size2); /* additional data len */
        put_le16(pb, n + 1); /* stream number */
        put_le32(pb, 0); /* ??? */

        if (enc->codec_type == CODEC_TYPE_AUDIO) {
            /* WAVEFORMATEX header */
            int wavsize = put_wav_header(pb, enc);
            if ((enc->codec_id != CODEC_ID_MP3) && (enc->codec_id != CODEC_ID_MP2) && (enc->codec_id != CODEC_ID_ADPCM_IMA_WAV) && (enc->extradata_size==0)) {
                wavsize += 2;
                put_le16(pb, 0);
            }

            if (wavsize < 0)
                return -1;
            if (wavsize != extra_size) {
                cur_pos = url_ftell(pb);
                url_fseek(pb, es_pos, SEEK_SET);
                put_le32(pb, wavsize); /* wav header len */
                url_fseek(pb, cur_pos, SEEK_SET);
            }
            /* ERROR Correction */
            put_byte(pb, 0x01);
            if(enc->codec_id == CODEC_ID_ADPCM_G726 || !enc->block_align){
                put_le16(pb, 0x0190);
                put_le16(pb, 0x0190);
            }else{
                put_le16(pb, enc->block_align);
                put_le16(pb, enc->block_align);
            }
            put_le16(pb, 0x01);
            put_byte(pb, 0x00);
        } else {
            put_le32(pb, enc->width);
            put_le32(pb, enc->height);
            put_byte(pb, 2); /* ??? */
            put_le16(pb, 40 + enc->extradata_size); /* size */

            /* BITMAPINFOHEADER header */
            put_bmp_header(pb, enc, codec_bmp_tags, 1);
        }
        end_header(pb, hpos);
    }

    /* media comments */

    hpos = put_header(pb, &ff_asf_codec_comment_header);
    put_guid(pb, &ff_asf_codec_comment1_header);
    put_le32(pb, s->nb_streams);
    for(n=0;n<s->nb_streams;n++) {
        AVCodec *p;

        enc = s->streams[n]->codec;
        p = avcodec_find_encoder(enc->codec_id);

        if(enc->codec_type == CODEC_TYPE_AUDIO)
            put_le16(pb, 2);
        else if(enc->codec_type == CODEC_TYPE_VIDEO)
            put_le16(pb, 1);
        else
            put_le16(pb, -1);

        if(enc->codec_id == CODEC_ID_WMAV2)
            put_str16(pb, "Windows Media Audio V8");
        else
            put_str16(pb, p ? p->name : enc->codec_name);
        put_le16(pb, 0); /* no parameters */


        /* id */
        if (enc->codec_type == CODEC_TYPE_AUDIO) {
            put_le16(pb, 2);
            put_le16(pb, enc->codec_tag);
        } else {
            put_le16(pb, 4);
            put_le32(pb, enc->codec_tag);
        }
        if(!enc->codec_tag)
            return -1;
    }
    end_header(pb, hpos);

    /* patch the header size fields */

    cur_pos = url_ftell(pb);
    header_size = cur_pos - header_offset;
    if (asf->is_streamed) {
        header_size += 8 + 30 + 50;

        url_fseek(pb, header_offset - 10 - 30, SEEK_SET);
        put_le16(pb, header_size);
        url_fseek(pb, header_offset - 2 - 30, SEEK_SET);
        put_le16(pb, header_size);

        header_size -= 8 + 30 + 50;
    }
    header_size += 24 + 6;
    url_fseek(pb, header_offset - 14, SEEK_SET);
    put_le64(pb, header_size);
    url_fseek(pb, cur_pos, SEEK_SET);

    /* movie chunk, followed by packets of packet_size */
    asf->data_offset = cur_pos;
    put_guid(pb, &ff_asf_data_header);
    put_le64(pb, data_chunk_size);
    put_guid(pb, &ff_asf_my_guid);
    put_le64(pb, asf->nb_packets); /* nb packets */
    put_byte(pb, 1); /* ??? */
    put_byte(pb, 1); /* ??? */
    return 0;
}
예제 #2
0
static int avi_write_header(AVFormatContext *s)
{
    AVIContext *avi = s->priv_data;
    ByteIOContext *pb = &s->pb;
    int bitrate, n, i, nb_frames, au_byterate, au_ssize, au_scale;
    AVCodecContext *stream, *video_enc;
    offset_t list1, list2, strh, strf;

    /* header list */
    avi->riff_id = 0;
    list1 = avi_start_new_riff(avi, pb, "AVI ", "hdrl");

    /* avi header */
    put_tag(pb, "avih");
    put_le32(pb, 14 * 4);
    bitrate = 0;

    video_enc = NULL;
    for(n=0;n<s->nb_streams;n++) {
        stream = s->streams[n]->codec;
        bitrate += stream->bit_rate;
        if (stream->codec_type == CODEC_TYPE_VIDEO)
            video_enc = stream;
    }

    nb_frames = 0;

    if(video_enc){
        put_le32(pb, (uint32_t)(INT64_C(1000000) * video_enc->time_base.num / video_enc->time_base.den));
    } else {
        put_le32(pb, 0);
    }
    put_le32(pb, bitrate / 8); /* XXX: not quite exact */
    put_le32(pb, 0); /* padding */
    if (url_is_streamed(pb))
        put_le32(pb, AVIF_TRUSTCKTYPE | AVIF_ISINTERLEAVED); /* flags */
    else
        put_le32(pb, AVIF_TRUSTCKTYPE | AVIF_HASINDEX | AVIF_ISINTERLEAVED); /* flags */
    avi->frames_hdr_all = url_ftell(pb); /* remember this offset to fill later */
    put_le32(pb, nb_frames); /* nb frames, filled later */
    put_le32(pb, 0); /* initial frame */
    put_le32(pb, s->nb_streams); /* nb streams */
    put_le32(pb, 1024 * 1024); /* suggested buffer size */
    if(video_enc){
        put_le32(pb, video_enc->width);
        put_le32(pb, video_enc->height);
    } else {
        put_le32(pb, 0);
        put_le32(pb, 0);
    }
    put_le32(pb, 0); /* reserved */
    put_le32(pb, 0); /* reserved */
    put_le32(pb, 0); /* reserved */
    put_le32(pb, 0); /* reserved */

    /* stream list */
    for(i=0;i<n;i++) {
        list2 = start_tag(pb, "LIST");
        put_tag(pb, "strl");

        stream = s->streams[i]->codec;

        /* FourCC should really be set by the codec itself */
        if (! stream->codec_tag) {
            stream->codec_tag = codec_get_bmp_tag(stream->codec_id);
        }

        /* stream generic header */
        strh = start_tag(pb, "strh");
        switch(stream->codec_type) {
        case CODEC_TYPE_VIDEO: put_tag(pb, "vids"); break;
        case CODEC_TYPE_AUDIO: put_tag(pb, "auds"); break;
//        case CODEC_TYPE_TEXT : put_tag(pb, "txts"); break;
        case CODEC_TYPE_DATA : put_tag(pb, "dats"); break;
        }
        if(stream->codec_type == CODEC_TYPE_VIDEO)
            put_le32(pb, stream->codec_tag);
        else
            put_le32(pb, 1);
        put_le32(pb, 0); /* flags */
        put_le16(pb, 0); /* priority */
        put_le16(pb, 0); /* language */
        put_le32(pb, 0); /* initial frame */

        ff_parse_specific_params(stream, &au_byterate, &au_ssize, &au_scale);

        put_le32(pb, au_scale); /* scale */
        put_le32(pb, au_byterate); /* rate */
        av_set_pts_info(s->streams[i], 64, au_scale, au_byterate);

        put_le32(pb, 0); /* start */
        avi->frames_hdr_strm[i] = url_ftell(pb); /* remember this offset to fill later */
        if (url_is_streamed(pb))
            put_le32(pb, AVI_MAX_RIFF_SIZE); /* FIXME: this may be broken, but who cares */
        else
            put_le32(pb, 0); /* length, XXX: filled later */

        /* suggested buffer size */ //FIXME set at the end to largest chunk
        if(stream->codec_type == CODEC_TYPE_VIDEO)
            put_le32(pb, 1024 * 1024);
        else if(stream->codec_type == CODEC_TYPE_AUDIO)
            put_le32(pb, 12 * 1024);
        else
            put_le32(pb, 0);
        put_le32(pb, -1); /* quality */
        put_le32(pb, au_ssize); /* sample size */
        put_le32(pb, 0);
        put_le16(pb, stream->width);
        put_le16(pb, stream->height);
        end_tag(pb, strh);

      if(stream->codec_type != CODEC_TYPE_DATA){
        strf = start_tag(pb, "strf");
        switch(stream->codec_type) {
        case CODEC_TYPE_VIDEO:
            put_bmp_header(pb, stream, codec_bmp_tags, 0);
            break;
        case CODEC_TYPE_AUDIO:
            if (put_wav_header(pb, stream) < 0) {
                av_free(avi);
                return -1;
            }
            break;
        default:
            return -1;
        }
        end_tag(pb, strf);
      }

        if (!url_is_streamed(pb)) {
            unsigned char tag[5];
            int j;

            /* Starting to lay out AVI OpenDML master index.
             * We want to make it JUNK entry for now, since we'd
             * like to get away without making AVI an OpenDML one
             * for compatibility reasons.
             */
            avi->indexes[i].entry = avi->indexes[i].ents_allocated = 0;
            avi->indexes[i].indx_start = start_tag(pb, "JUNK");
            put_le16(pb, 4);        /* wLongsPerEntry */
            put_byte(pb, 0);        /* bIndexSubType (0 == frame index) */
            put_byte(pb, 0);        /* bIndexType (0 == AVI_INDEX_OF_INDEXES) */
            put_le32(pb, 0);        /* nEntriesInUse (will fill out later on) */
            put_tag(pb, avi_stream2fourcc(&tag[0], i, stream->codec_type));
                                    /* dwChunkId */
            put_le64(pb, 0);        /* dwReserved[3]
            put_le32(pb, 0);           Must be 0.    */
            for (j=0; j < AVI_MASTER_INDEX_SIZE * 2; j++)
                 put_le64(pb, 0);
            end_tag(pb, avi->indexes[i].indx_start);
        }

        end_tag(pb, list2);
    }

    if (!url_is_streamed(pb)) {
        /* AVI could become an OpenDML one, if it grows beyond 2Gb range */
        avi->odml_list = start_tag(pb, "JUNK");
        put_tag(pb, "odml");
        put_tag(pb, "dmlh");
        put_le32(pb, 248);
        for (i = 0; i < 248; i+= 4)
             put_le32(pb, 0);
        end_tag(pb, avi->odml_list);
    }

    end_tag(pb, list1);

    list2 = start_tag(pb, "LIST");
    put_tag(pb, "INFO");
    avi_write_info_tag(pb, "INAM", s->title);
    avi_write_info_tag(pb, "IART", s->author);
    avi_write_info_tag(pb, "ICOP", s->copyright);
    avi_write_info_tag(pb, "ICMT", s->comment);
    avi_write_info_tag(pb, "IPRD", s->album);
    avi_write_info_tag(pb, "IGNR", s->genre);
    if (s->track) {
        char str_track[4];
        snprintf(str_track, 4, "%d", s->track);
        avi_write_info_tag(pb, "IPRT", str_track);
    }
    if(!(s->streams[0]->codec->flags & CODEC_FLAG_BITEXACT))
        avi_write_info_tag(pb, "ISFT", LIBAVFORMAT_IDENT);
    end_tag(pb, list2);

    /* some padding for easier tag editing */
    list2 = start_tag(pb, "JUNK");
    for (i = 0; i < 1016; i += 4)
        put_le32(pb, 0);
    end_tag(pb, list2);

    avi->movi_list = start_tag(pb, "LIST");
    put_tag(pb, "movi");

    put_flush_packet(pb);

    return 0;
}
예제 #3
0
/* write the header (used two times if non streamed) */
static int asf_write_header1(AVFormatContext *s, int64_t file_size, int64_t data_chunk_size)
{
    ASFContext *asf = s->priv_data;
    ByteIOContext *pb = &s->pb;
    int header_size, n, extra_size, extra_size2, wav_extra_size, file_time;
    int has_title;
    AVCodecContext *enc;
    int64_t header_offset, cur_pos, hpos;
    int bit_rate;
    int64_t duration;

    duration = asf->duration + preroll_time * 10000;
    has_title = (s->title[0] || s->author[0] || s->copyright[0] || s->comment[0]);

    bit_rate = 0;
    for(n=0;n<s->nb_streams;n++) {
        enc = s->streams[n]->codec;

        av_set_pts_info(s->streams[n], 32, 1, 1000); /* 32 bit pts in ms */

        bit_rate += enc->bit_rate;
    }

    if (asf->is_streamed) {
        put_chunk(s, 0x4824, 0, 0xc00); /* start of stream (length will be patched later) */
    }

    put_guid(pb, &asf_header);
    put_le64(pb, -1); /* header length, will be patched after */
    put_le32(pb, 3 + has_title + s->nb_streams); /* number of chunks in header */
    put_byte(pb, 1); /* ??? */
    put_byte(pb, 2); /* ??? */

    /* file header */
    header_offset = url_ftell(pb);
    hpos = put_header(pb, &file_header);
    put_guid(pb, &my_guid);
    put_le64(pb, file_size);
    file_time = 0;
    put_le64(pb, unix_to_file_time(file_time));
    put_le64(pb, asf->nb_packets); /* number of packets */
    put_le64(pb, duration); /* end time stamp (in 100ns units) */
    put_le64(pb, duration); /* duration (in 100ns units) */
    put_le32(pb, preroll_time); /* start time stamp */
    put_le32(pb, 0); /* ??? */
    put_le32(pb, asf->is_streamed ? 1 : 0); /* ??? */
    put_le32(pb, asf->packet_size); /* packet size */
    put_le32(pb, asf->packet_size); /* packet size */
    put_le32(pb, bit_rate); /* Nominal data rate in bps */
    end_header(pb, hpos);

    /* unknown headers */
    hpos = put_header(pb, &head1_guid);
    put_guid(pb, &head2_guid);
    put_le32(pb, 6);
    put_le16(pb, 0);
    end_header(pb, hpos);

    /* title and other infos */
    if (has_title) {
        hpos = put_header(pb, &comment_header);
        if ( s->title[0]     ) { put_le16(pb, 2 * (strlen(s->title    ) + 1)); } else { put_le16(pb, 0); }
        if ( s->author[0]    ) { put_le16(pb, 2 * (strlen(s->author   ) + 1)); } else { put_le16(pb, 0); }
        if ( s->copyright[0] ) { put_le16(pb, 2 * (strlen(s->copyright) + 1)); } else { put_le16(pb, 0); }
        if ( s->comment[0]   ) { put_le16(pb, 2 * (strlen(s->comment  ) + 1)); } else { put_le16(pb, 0); }
        put_le16(pb, 0);
        if ( s->title[0]     ) put_str16_nolen(pb, s->title);
        if ( s->author[0]    ) put_str16_nolen(pb, s->author);
        if ( s->copyright[0] ) put_str16_nolen(pb, s->copyright);
        if ( s->comment[0]   ) put_str16_nolen(pb, s->comment);
        end_header(pb, hpos);
    }

    /* stream headers */
    for(n=0;n<s->nb_streams;n++) {
        int64_t es_pos;
        const uint8_t *er_spr = NULL;
        int er_spr_len = 0;
        //        ASFStream *stream = &asf->streams[n];

        enc = s->streams[n]->codec;
        asf->streams[n].num = n + 1;
        asf->streams[n].seq = 0;


        if (enc->codec_type == CODEC_TYPE_AUDIO) {
            if (enc->codec_id == CODEC_ID_ADPCM_G726) {
                er_spr     = error_spread_ADPCM_G726;
                er_spr_len = sizeof(error_spread_ADPCM_G726);
            }
        }

        switch(enc->codec_type) {
        case CODEC_TYPE_AUDIO:
            wav_extra_size = 0;
            extra_size = 18 + wav_extra_size;
            extra_size2 = er_spr_len;
            break;
        default:
        case CODEC_TYPE_VIDEO:
            wav_extra_size = enc->extradata_size;
            extra_size = 0x33 + wav_extra_size;
            extra_size2 = 0;
            break;
        }

        hpos = put_header(pb, &stream_header);
        if (enc->codec_type == CODEC_TYPE_AUDIO) {
            put_guid(pb, &audio_stream);
            if ((er_spr != NULL) && (er_spr_len != 0)) {
                put_guid(pb, &audio_conceal_spread);
            } else {
                put_guid(pb, &video_conceal_none);
            }
        } else {
            put_guid(pb, &video_stream);
            put_guid(pb, &video_conceal_none);
        }
        put_le64(pb, 0); /* ??? */
        es_pos = url_ftell(pb);
        put_le32(pb, extra_size); /* wav header len */
        put_le32(pb, extra_size2); /* additional data len */
        put_le16(pb, n + 1); /* stream number */
        put_le32(pb, 0); /* ??? */

        if (enc->codec_type == CODEC_TYPE_AUDIO) {
            /* WAVEFORMATEX header */
            int wavsize = put_wav_header(pb, enc);
            if ((enc->codec_id != CODEC_ID_MP3) && (enc->codec_id != CODEC_ID_MP2) && (enc->codec_id != CODEC_ID_ADPCM_IMA_WAV) && (enc->extradata_size==0)) {
                wavsize += 2;
                put_le16(pb, 0);
            }

            if (wavsize < 0)
                return -1;
            if (wavsize != extra_size) {
                cur_pos = url_ftell(pb);
                url_fseek(pb, es_pos, SEEK_SET);
                put_le32(pb, wavsize); /* wav header len */
                url_fseek(pb, cur_pos, SEEK_SET);
            }
            /* ERROR Correction */
            if ((er_spr != NULL) && (er_spr_len != 0))
                put_buffer(pb, er_spr, er_spr_len);
        } else {
            put_le32(pb, enc->width);
            put_le32(pb, enc->height);
            put_byte(pb, 2); /* ??? */
            put_le16(pb, 40 + enc->extradata_size); /* size */

            /* BITMAPINFOHEADER header */
            put_bmp_header(pb, enc, codec_bmp_tags, 1);
        }
        end_header(pb, hpos);
    }

    /* media comments */

    hpos = put_header(pb, &codec_comment_header);
    put_guid(pb, &codec_comment1_header);
    put_le32(pb, s->nb_streams);
    for(n=0;n<s->nb_streams;n++) {
        AVCodec *p;

        enc = s->streams[n]->codec;
        p = avcodec_find_encoder(enc->codec_id);

        put_le16(pb, asf->streams[n].num);
        put_str16(pb, p ? p->name : enc->codec_name);
        put_le16(pb, 0); /* no parameters */


        /* id */
        if (enc->codec_type == CODEC_TYPE_AUDIO) {
            put_le16(pb, 2);
            if(!enc->codec_tag)
                enc->codec_tag = codec_get_tag(codec_wav_tags, enc->codec_id);
            if(!enc->codec_tag)
                return -1;
            put_le16(pb, enc->codec_tag);
        } else {
            put_le16(pb, 4);
            if(!enc->codec_tag)
                enc->codec_tag = codec_get_tag(codec_bmp_tags, enc->codec_id);
            if(!enc->codec_tag)
                return -1;
            put_le32(pb, enc->codec_tag);
        }
    }
    end_header(pb, hpos);

    /* patch the header size fields */

    cur_pos = url_ftell(pb);
    header_size = cur_pos - header_offset;
    if (asf->is_streamed) {
        header_size += 8 + 30 + 50;

        url_fseek(pb, header_offset - 10 - 30, SEEK_SET);
        put_le16(pb, header_size);
        url_fseek(pb, header_offset - 2 - 30, SEEK_SET);
        put_le16(pb, header_size);

        header_size -= 8 + 30 + 50;
    }
    header_size += 24 + 6;
    url_fseek(pb, header_offset - 14, SEEK_SET);
    put_le64(pb, header_size);
    url_fseek(pb, cur_pos, SEEK_SET);

    /* movie chunk, followed by packets of packet_size */
    asf->data_offset = cur_pos;
    put_guid(pb, &data_header);
    put_le64(pb, data_chunk_size);
    put_guid(pb, &my_guid);
    put_le64(pb, asf->nb_packets); /* nb packets */
    put_byte(pb, 1); /* ??? */
    put_byte(pb, 1); /* ??? */
    return 0;
}