asf.c

ffmpeg源码分析

                sizeX= get_le32(pb); /* size */
                st->codec->width = get_le32(pb);
                st->codec->height = get_le32(pb);
                /* not available for asf */
                get_le16(pb); /* panes */
                st->codec->bits_per_sample = get_le16(pb); /* depth */
                tag1 = get_le32(pb);
                url_fskip(pb, 20);
//                av_log(NULL, AV_LOG_DEBUG, "size:%d tsize:%d sizeX:%d\n", size, total_size, sizeX);
                size= sizeX;
                if (size > 40) {
                    st->codec->extradata_size = size - 40;
                    st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
                    get_buffer(pb, st->codec->extradata, st->codec->extradata_size);
                }

        /* Extract palette from extradata if bpp <= 8 */
        /* This code assumes that extradata contains only palette */
        /* This is true for all paletted codecs implemented in ffmpeg */
        if (st->codec->extradata_size && (st->codec->bits_per_sample <= 8)) {
            st->codec->palctrl = av_mallocz(sizeof(AVPaletteControl));
#ifdef WORDS_BIGENDIAN
            for (i = 0; i < FFMIN(st->codec->extradata_size, AVPALETTE_SIZE)/4; i++)
                st->codec->palctrl->palette[i] = bswap_32(((uint32_t*)st->codec->extradata)[i]);
#else
            memcpy(st->codec->palctrl->palette, st->codec->extradata,
                   FFMIN(st->codec->extradata_size, AVPALETTE_SIZE));
#endif
            st->codec->palctrl->palette_changed = 1;
        }

                st->codec->codec_tag = tag1;
                st->codec->codec_id = codec_get_id(codec_bmp_tags, tag1);
                if(tag1 == MKTAG('D', 'V', 'R', ' '))
                    st->need_parsing = 1;
            }
            pos2 = url_ftell(pb);
            url_fskip(pb, gsize - (pos2 - pos1 + 24));
        } else if (!memcmp(&g, &data_header, sizeof(GUID))) {
            break;
        } else if (!memcmp(&g, &comment_header, sizeof(GUID))) {
            int len1, len2, len3, len4, len5;

            len1 = get_le16(pb);
            len2 = get_le16(pb);
            len3 = get_le16(pb);
            len4 = get_le16(pb);
            len5 = get_le16(pb);
            get_str16_nolen(pb, len1, s->title, sizeof(s->title));
            get_str16_nolen(pb, len2, s->author, sizeof(s->author));
            get_str16_nolen(pb, len3, s->copyright, sizeof(s->copyright));
            get_str16_nolen(pb, len4, s->comment, sizeof(s->comment));
            url_fskip(pb, len5);
       } else if (!memcmp(&g, &extended_content_header, sizeof(GUID))) {
                int desc_count, i;

                desc_count = get_le16(pb);
                for(i=0;i<desc_count;i++)
                {
                        int name_len,value_type,value_len,value_num = 0;
                        char *name, *value;

                        name_len = get_le16(pb);
                        name = (char *)av_mallocz(name_len);
                        get_str16_nolen(pb, name_len, name, name_len);
                        value_type = get_le16(pb);
                        value_len = get_le16(pb);
                        if ((value_type == 0) || (value_type == 1)) // unicode or byte
                        {
                                value = (char *)av_mallocz(value_len);
                                get_str16_nolen(pb, value_len, value, value_len);
                                if (strcmp(name,"WM/AlbumTitle")==0) { pstrcpy(s->album, sizeof(s->album), value); }
                                av_free(value);
                        }
                        if ((value_type >= 2) && (value_type <= 5)) // boolean or DWORD or QWORD or WORD
                        {
                                if (value_type==2) value_num = get_le32(pb);
                                if (value_type==3) value_num = get_le32(pb);
                                if (value_type==4) value_num = get_le64(pb);
                                if (value_type==5) value_num = get_le16(pb);
                                if (strcmp(name,"WM/Track")==0) s->track = value_num + 1;
                                if (strcmp(name,"WM/TrackNumber")==0) s->track = value_num;
                        }
                        av_free(name);
                }
        } else if (!memcmp(&g, &ext_stream_header, sizeof(GUID))) {
            int ext_len, payload_ext_ct, stream_ct;
            uint32_t ext_d;
            int64_t pos_ex_st;
            pos_ex_st = url_ftell(pb);

            get_le64(pb);
            get_le64(pb);
            get_le32(pb);
            get_le32(pb);
            get_le32(pb);
            get_le32(pb);
            get_le32(pb);
            get_le32(pb);
            get_le32(pb);
            get_le32(pb);
            get_le16(pb);
            get_le16(pb);
            get_le64(pb);
            stream_ct = get_le16(pb);
            payload_ext_ct = get_le16(pb);

            for (i=0; i<stream_ct; i++){
                get_le16(pb);
                ext_len = get_le16(pb);
                url_fseek(pb, ext_len, SEEK_CUR);
            }

            for (i=0; i<payload_ext_ct; i++){
                get_guid(pb, &g);
                ext_d=get_le16(pb);
                ext_len=get_le32(pb);
                url_fseek(pb, ext_len, SEEK_CUR);
            }

            // there could be a optional stream properties object to follow
            // if so the next iteration will pick it up
        } else if (!memcmp(&g, &head1_guid, sizeof(GUID))) {
            int v1, v2;
            get_guid(pb, &g);
            v1 = get_le32(pb);
            v2 = get_le16(pb);
#if 0
        } else if (!memcmp(&g, &codec_comment_header, sizeof(GUID))) {
            int len, v1, n, num;
            char str[256], *q;
            char tag[16];

            get_guid(pb, &g);
            print_guid(&g);

            n = get_le32(pb);
            for(i=0;i<n;i++) {
                num = get_le16(pb); /* stream number */
                get_str16(pb, str, sizeof(str));
                get_str16(pb, str, sizeof(str));
                len = get_le16(pb);
                q = tag;
                while (len > 0) {
                    v1 = get_byte(pb);
                    if ((q - tag) < sizeof(tag) - 1)
                        *q++ = v1;
                    len--;
                }
                *q = '\0';
            }
#endif
        } else if (url_feof(pb)) {
            goto fail;
        } else {
            url_fseek(pb, gsize - 24, SEEK_CUR);
        }
    }
    get_guid(pb, &g);
    get_le64(pb);
    get_byte(pb);
    get_byte(pb);
    if (url_feof(pb))
        goto fail;
    asf->data_offset = url_ftell(pb);
    asf->packet_size_left = 0;

    return 0;

 fail:
     for(i=0;i<s->nb_streams;i++) {
        AVStream *st = s->streams[i];
        if (st) {
            av_free(st->priv_data);
            av_free(st->codec->extradata);
        }
        av_free(st);
    }
    return -1;
}

#define DO_2BITS(bits, var, defval) \
    switch (bits & 3) \
    { \
    case 3: var = get_le32(pb); rsize += 4; break; \
    case 2: var = get_le16(pb); rsize += 2; break; \
    case 1: var = get_byte(pb); rsize++; break; \
    default: var = defval; break; \
    }

static int asf_get_packet(AVFormatContext *s)
{
    ASFContext *asf = s->priv_data;
    ByteIOContext *pb = &s->pb;
    uint32_t packet_length, padsize;
    int rsize = 9;
    int c;

    assert((url_ftell(&s->pb) - s->data_offset) % asf->packet_size == 0);

    c = get_byte(pb);
    if (c != 0x82) {
        if (!url_feof(pb))
            av_log(s, AV_LOG_ERROR, "ff asf bad header %x  at:%"PRId64"\n", c, url_ftell(pb));
    }
    if ((c & 0x0f) == 2) { // always true for now
        if (get_le16(pb) != 0) {
            if (!url_feof(pb))
                av_log(s, AV_LOG_ERROR, "ff asf bad non zero\n");
            return AVERROR_IO;
        }
        rsize+=2;
/*    }else{
        if (!url_feof(pb))
            printf("ff asf bad header %x  at:%lld\n", c, url_ftell(pb));
        return AVERROR_IO;*/
    }

    asf->packet_flags = get_byte(pb);
    asf->packet_property = get_byte(pb);

    DO_2BITS(asf->packet_flags >> 5, packet_length, asf->packet_size);
    DO_2BITS(asf->packet_flags >> 1, padsize, 0); // sequence ignored
    DO_2BITS(asf->packet_flags >> 3, padsize, 0); // padding length

    asf->packet_timestamp = get_le32(pb);
    get_le16(pb); /* duration */
    // rsize has at least 11 bytes which have to be present

    if (asf->packet_flags & 0x01) {
        asf->packet_segsizetype = get_byte(pb); rsize++;
        asf->packet_segments = asf->packet_segsizetype & 0x3f;
    } else {
        asf->packet_segments = 1;
        asf->packet_segsizetype = 0x80;
    }
    asf->packet_size_left = packet_length - padsize - rsize;
    if (packet_length < asf->hdr.min_pktsize)
        padsize += asf->hdr.min_pktsize - packet_length;
    asf->packet_padsize = padsize;
#ifdef DEBUG
    printf("packet: size=%d padsize=%d  left=%d\n", asf->packet_size, asf->packet_padsize, asf->packet_size_left);
#endif
    return 0;
}

static int asf_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    ASFContext *asf = s->priv_data;
    ASFStream *asf_st = 0;
    ByteIOContext *pb = &s->pb;
    //static int pc = 0;
    for (;;) {
        int rsize = 0;
        if (asf->packet_size_left < FRAME_HEADER_SIZE
            || asf->packet_segments < 1) {
            //asf->packet_size_left <= asf->packet_padsize) {
            int ret = asf->packet_size_left + asf->packet_padsize;
            //printf("PacketLeftSize:%d  Pad:%d Pos:%Ld\n", asf->packet_size_left, asf->packet_padsize, url_ftell(pb));
            if((url_ftell(&s->pb) + ret - s->data_offset) % asf->packet_size)
                ret += asf->packet_size - ((url_ftell(&s->pb) + ret - s->data_offset) % asf->packet_size);
            /* fail safe */
            url_fskip(pb, ret);
            asf->packet_pos= url_ftell(&s->pb);
            ret = asf_get_packet(s);
            //printf("READ ASF PACKET  %d   r:%d   c:%d\n", ret, asf->packet_size_left, pc++);
            if (ret < 0 || url_feof(pb))
                return AVERROR_IO;
            asf->packet_time_start = 0;
            continue;
        }
        if (asf->packet_time_start == 0) {
            /* read frame header */
            int num = get_byte(pb);
            asf->packet_segments--;
            rsize++;
            asf->packet_key_frame = (num & 0x80) >> 7;
            asf->stream_index = asf->asfid2avid[num & 0x7f];
            // sequence should be ignored!
            DO_2BITS(asf->packet_property >> 4, asf->packet_seq, 0);
            DO_2BITS(asf->packet_property >> 2, asf->packet_frag_offset, 0);
            DO_2BITS(asf->packet_property, asf->packet_replic_size, 0);
//printf("key:%d stream:%d seq:%d offset:%d replic_size:%d\n", asf->packet_key_frame, asf->stream_index, asf->packet_seq, //asf->packet_frag_offset, asf->packet_replic_size);
            if (asf->packet_replic_size > 1) {
                assert(asf->packet_replic_size >= 8);
                // it should be always at least 8 bytes - FIXME validate
                asf->packet_obj_size = get_le32(pb);
                asf->packet_frag_timestamp = get_le32(pb); // timestamp
                if (asf->packet_replic_size > 8)
                    url_fskip(pb, asf->packet_replic_size - 8);