rm.c

现在关于h.264的源码很多

{
    RMContext *rm = s->priv_data;
    ByteIOContext *pb = &s->pb;
    StreamInfo *stream = rm->video_stream;
    int key_frame = !!(flags & PKT_FLAG_KEY);

    /* XXX: this is incorrect: should be a parameter */

    /* Well, I spent some time finding the meaning of these bits. I am
       not sure I understood everything, but it works !! */
#if 1
    write_packet_header(s, stream, size + 7, key_frame);
    /* bit 7: '1' if final packet of a frame converted in several packets */
    put_byte(pb, 0x81);
    /* bit 7: '1' if I frame. bits 6..0 : sequence number in current
       frame starting from 1 */
    if (key_frame) {
        put_byte(pb, 0x81);
    } else {
        put_byte(pb, 0x01);
    }
    put_be16(pb, 0x4000 + (size)); /* total frame size */
    put_be16(pb, 0x4000 + (size));              /* offset from the start or the end */
#else
    /* full frame */
    write_packet_header(s, size + 6);
    put_byte(pb, 0xc0);
    put_be16(pb, 0x4000 + size); /* total frame size */
    put_be16(pb, 0x4000 + packet_number * 126); /* position in stream */
#endif
    put_byte(pb, stream->nb_frames & 0xff);

    put_buffer(pb, buf, size);
    put_flush_packet(pb);

    stream->nb_frames++;
    return 0;
}

static int rm_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    if (s->streams[pkt->stream_index]->codec->codec_type ==
        CODEC_TYPE_AUDIO)
        return rm_write_audio(s, pkt->data, pkt->size, pkt->flags);
    else
        return rm_write_video(s, pkt->data, pkt->size, pkt->flags);
}

static int rm_write_trailer(AVFormatContext *s)
{
    RMContext *rm = s->priv_data;
    int data_size, index_pos, i;
    ByteIOContext *pb = &s->pb;

    if (!url_is_streamed(&s->pb)) {
        /* end of file: finish to write header */
        index_pos = url_fseek(pb, 0, SEEK_CUR);
        data_size = index_pos - rm->data_pos;

        /* index */
        put_tag(pb, "INDX");
        put_be32(pb, 10 + 10 * s->nb_streams);
        put_be16(pb, 0);

        for(i=0;i<s->nb_streams;i++) {
            put_be32(pb, 0); /* zero indices */
            put_be16(pb, i); /* stream number */
            put_be32(pb, 0); /* next index */
        }
        /* undocumented end header */
        put_be32(pb, 0);
        put_be32(pb, 0);

        url_fseek(pb, 0, SEEK_SET);
        for(i=0;i<s->nb_streams;i++)
            rm->streams[i].total_frames = rm->streams[i].nb_frames;
        rv10_write_header(s, data_size, index_pos);
    } else {
        /* undocumented end header */
        put_be32(pb, 0);
        put_be32(pb, 0);
    }
    put_flush_packet(pb);
    return 0;
}
#endif //CONFIG_MUXERS

/***************************************************/

static void get_str(ByteIOContext *pb, char *buf, int buf_size)
{
    int len, i;
    char *q;

    len = get_be16(pb);
    q = buf;
    for(i=0;i<len;i++) {
        if (i < buf_size - 1)
            *q++ = get_byte(pb);
    }
    *q = '\0';
}

static void get_str8(ByteIOContext *pb, char *buf, int buf_size)
{
    int len, i;
    char *q;

    len = get_byte(pb);
    q = buf;
    for(i=0;i<len;i++) {
        if (i < buf_size - 1)
            *q++ = get_byte(pb);
    }
    *q = '\0';
}

static void rm_read_audio_stream_info(AVFormatContext *s, AVStream *st,
                                      int read_all)
{
    RMContext *rm = s->priv_data;
    ByteIOContext *pb = &s->pb;
    char buf[256];
    uint32_t version;
    int i;

    /* ra type header */
    version = get_be32(pb); /* version */
    if (((version >> 16) & 0xff) == 3) {
        int64_t startpos = url_ftell(pb);
        /* very old version */
        for(i = 0; i < 14; i++)
            get_byte(pb);
        get_str8(pb, s->title, sizeof(s->title));
        get_str8(pb, s->author, sizeof(s->author));
        get_str8(pb, s->copyright, sizeof(s->copyright));
        get_str8(pb, s->comment, sizeof(s->comment));
        if ((startpos + (version & 0xffff)) >= url_ftell(pb) + 2) {
        // fourcc (should always be "lpcJ")
        get_byte(pb);
        get_str8(pb, buf, sizeof(buf));
        }
        // Skip extra header crap (this should never happen)
        if ((startpos + (version & 0xffff)) > url_ftell(pb))
            url_fskip(pb, (version & 0xffff) + startpos - url_ftell(pb));
        st->codec->sample_rate = 8000;
        st->codec->channels = 1;
        st->codec->codec_type = CODEC_TYPE_AUDIO;
        st->codec->codec_id = CODEC_ID_RA_144;
    } else {
        int flavor, sub_packet_h, coded_framesize, sub_packet_size;
        /* old version (4) */
        get_be32(pb); /* .ra4 */
        get_be32(pb); /* data size */
        get_be16(pb); /* version2 */
        get_be32(pb); /* header size */
        flavor= get_be16(pb); /* add codec info / flavor */
        rm->coded_framesize = coded_framesize = get_be32(pb); /* coded frame size */
        get_be32(pb); /* ??? */
        get_be32(pb); /* ??? */
        get_be32(pb); /* ??? */
        rm->sub_packet_h = sub_packet_h = get_be16(pb); /* 1 */
        st->codec->block_align= get_be16(pb); /* frame size */
        rm->sub_packet_size = sub_packet_size = get_be16(pb); /* sub packet size */
        get_be16(pb); /* ??? */
        if (((version >> 16) & 0xff) == 5) {
            get_be16(pb); get_be16(pb); get_be16(pb); }
        st->codec->sample_rate = get_be16(pb);
        get_be32(pb);
        st->codec->channels = get_be16(pb);
        if (((version >> 16) & 0xff) == 5) {
            get_be32(pb);
            buf[0] = get_byte(pb);
            buf[1] = get_byte(pb);
            buf[2] = get_byte(pb);
            buf[3] = get_byte(pb);
            buf[4] = 0;
        } else {
        get_str8(pb, buf, sizeof(buf)); /* desc */
        get_str8(pb, buf, sizeof(buf)); /* desc */
        }
        st->codec->codec_type = CODEC_TYPE_AUDIO;
        if (!strcmp(buf, "dnet")) {
            st->codec->codec_id = CODEC_ID_AC3;
        } else if (!strcmp(buf, "28_8")) {
            st->codec->codec_id = CODEC_ID_RA_288;
            st->codec->extradata_size= 0;
            rm->audio_framesize = st->codec->block_align;
            st->codec->block_align = coded_framesize;
            rm->audiobuf = av_malloc(rm->audio_framesize * sub_packet_h);
        } else if (!strcmp(buf, "cook")) {
            int codecdata_length, i;
            get_be16(pb); get_byte(pb);
            if (((version >> 16) & 0xff) == 5)
                get_byte(pb);
            codecdata_length = get_be32(pb);
            st->codec->codec_id = CODEC_ID_COOK;
            st->codec->extradata_size= codecdata_length;
            st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
            for(i = 0; i < codecdata_length; i++)
                ((uint8_t*)st->codec->extradata)[i] = get_byte(pb);
            rm->audio_framesize = st->codec->block_align;
            st->codec->block_align = rm->sub_packet_size;
            rm->audiobuf = av_malloc(rm->audio_framesize * sub_packet_h);
        } else {
            st->codec->codec_id = CODEC_ID_NONE;
            pstrcpy(st->codec->codec_name, sizeof(st->codec->codec_name),
                    buf);
        }
        if (read_all) {
            get_byte(pb);
            get_byte(pb);
            get_byte(pb);

            get_str8(pb, s->title, sizeof(s->title));
            get_str8(pb, s->author, sizeof(s->author));
            get_str8(pb, s->copyright, sizeof(s->copyright));
            get_str8(pb, s->comment, sizeof(s->comment));
        }
    }
}

static int rm_read_header_old(AVFormatContext *s, AVFormatParameters *ap)
{
    RMContext *rm = s->priv_data;
    AVStream *st;

    rm->old_format = 1;
    st = av_new_stream(s, 0);
    if (!st)
        goto fail;
    rm_read_audio_stream_info(s, st, 1);
    return 0;
 fail:
    return -1;
}

static int rm_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
    RMContext *rm = s->priv_data;
    AVStream *st;
    ByteIOContext *pb = &s->pb;
    unsigned int tag, v;
    int tag_size, size, codec_data_size, i;
    int64_t codec_pos;
    unsigned int h263_hack_version, start_time, duration;
    char buf[128];
    int flags = 0;

    tag = get_le32(pb);
    if (tag == MKTAG('.', 'r', 'a', 0xfd)) {
        /* very old .ra format */
        return rm_read_header_old(s, ap);
    } else if (tag != MKTAG('.', 'R', 'M', 'F')) {
        return AVERROR_IO;
    }

    get_be32(pb); /* header size */
    get_be16(pb);
    get_be32(pb);
    get_be32(pb); /* number of headers */

    for(;;) {
        if (url_feof(pb))
            goto fail;
        tag = get_le32(pb);
        tag_size = get_be32(pb);
        get_be16(pb);
#if 0
        printf("tag=%c%c%c%c (%08x) size=%d\n",
               (tag) & 0xff,
               (tag >> 8) & 0xff,
               (tag >> 16) & 0xff,
               (tag >> 24) & 0xff,
               tag,
               tag_size);
#endif
        if (tag_size < 10 && tag != MKTAG('D', 'A', 'T', 'A'))
            goto fail;
        switch(tag) {
        case MKTAG('P', 'R', 'O', 'P'):
            /* file header */
            get_be32(pb); /* max bit rate */
            get_be32(pb); /* avg bit rate */
            get_be32(pb); /* max packet size */
            get_be32(pb); /* avg packet size */
            get_be32(pb); /* nb packets */
            get_be32(pb); /* duration */
            get_be32(pb); /* preroll */
            get_be32(pb); /* index offset */
            get_be32(pb); /* data offset */
            get_be16(pb); /* nb streams */
            flags = get_be16(pb); /* flags */
            break;
        case MKTAG('C', 'O', 'N', 'T'):
            get_str(pb, s->title, sizeof(s->title));
            get_str(pb, s->author, sizeof(s->author));
            get_str(pb, s->copyright, sizeof(s->copyright));
            get_str(pb, s->comment, sizeof(s->comment));
            break;
        case MKTAG('M', 'D', 'P', 'R'):
            st = av_new_stream(s, 0);
            if (!st)
                goto fail;
            st->id = get_be16(pb);
            get_be32(pb); /* max bit rate */
            st->codec->bit_rate = get_be32(pb); /* bit rate */
            get_be32(pb); /* max packet size */
            get_be32(pb); /* avg packet size */
            start_time = get_be32(pb); /* start time */
            get_be32(pb); /* preroll */
            duration = get_be32(pb); /* duration */
            st->start_time = start_time;
            st->duration = duration;
            get_str8(pb, buf, sizeof(buf)); /* desc */
            get_str8(pb, buf, sizeof(buf)); /* mimetype */
            codec_data_size = get_be32(pb);
            codec_pos = url_ftell(pb);
            st->codec->codec_type = CODEC_TYPE_DATA;
            av_set_pts_info(st, 64, 1, 1000);

            v = get_be32(pb);
            if (v == MKTAG(0xfd, 'a', 'r', '.')) {
                /* ra type header */
                rm_read_audio_stream_info(s, st, 0);
            } else {
                int fps, fps2;
                if (get_le32(pb) != MKTAG('V', 'I', 'D', 'O')) {
                fail1:
                    av_log(st->codec, AV_LOG_ERROR, "Unsupported video codec\n");
                    goto skip;
                }
                st->codec->codec_tag = get_le32(pb);
//                av_log(NULL, AV_LOG_DEBUG, "%X %X\n", st->codec->codec_tag, MKTAG('R', 'V', '2', '0'));
                if (   st->codec->codec_tag != MKTAG('R', 'V', '1', '0')
                    && st->codec->codec_tag != MKTAG('R', 'V', '2', '0')
                    && st->codec->codec_tag != MKTAG('R', 'V', '3', '0')
                    && st->codec->codec_tag != MKTAG('R', 'V', '4', '0'))
                    goto fail1;
                st->codec->width = get_be16(pb);
                st->codec->height = get_be16(pb);
                st->codec->time_base.num= 1;
                fps= get_be16(pb);
                st->codec->codec_type = CODEC_TYPE_VIDEO;
                get_be32(pb);
                fps2= get_be16(pb);
                get_be16(pb);

                st->codec->extradata_size= codec_data_size - (url_ftell(pb) - codec_pos);
                st->codec->extradata= av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
                get_buffer(pb, st->codec->extradata, st->codec->extradata_size);

//                av_log(NULL, AV_LOG_DEBUG, "fps= %d fps2= %d\n", fps, fps2);
                st->codec->time_base.den = fps * st->codec->time_base.num;
                /* modification of h263 codec version (!) */
#ifdef WORDS_BIGENDIAN
                h263_hack_version = ((uint32_t*)st->codec->extradata)[1];
#else
                h263_hack_version = bswap_32(((uint32_t*)st->codec->extradata)[1]);
#endif
                st->codec->sub_id = h263_hack_version;
                switch((h263_hack_version>>28)){
                case 1: st->codec->codec_id = CODEC_ID_RV10; break;
                case 2: st->codec->codec_id = CODEC_ID_RV20; break;
                case 3: st->codec->codec_id = CODEC_ID_RV30; break;
                case 4: st->codec->codec_id = CODEC_ID_RV40; break;
                default: goto fail1;
                }