rmdec.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * "Real" compatible demuxer.
 * Copyright (c) 2000, 2001 Fabrice Bellard.
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include "avformat.h"
#include "rm.h"
#include "avstring.h"

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

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

static void get_str16(ByteIOContext *pb, char *buf, int buf_size)
{
    get_strl(pb, buf, buf_size, get_be16(pb));
}

static void get_str8(ByteIOContext *pb, char *buf, int buf_size)
{
    get_strl(pb, buf, buf_size, get_byte(pb));
}

static int 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;
            st->need_parsing = AVSTREAM_PARSE_FULL;
        } 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;

            if(rm->audio_framesize >= UINT_MAX / sub_packet_h){
                av_log(s, AV_LOG_ERROR, "rm->audio_framesize * sub_packet_h too large\n");
                return -1;
            }

            rm->audiobuf = av_malloc(rm->audio_framesize * sub_packet_h);
        } else if ((!strcmp(buf, "cook")) || (!strcmp(buf, "atrc"))) {
            int codecdata_length, i;
            get_be16(pb); get_byte(pb);
            if (((version >> 16) & 0xff) == 5)
                get_byte(pb);
            codecdata_length = get_be32(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;
            }

            if (!strcmp(buf, "cook")) st->codec->codec_id = CODEC_ID_COOK;
            else st->codec->codec_id = CODEC_ID_ATRAC3;
            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;

            if(rm->audio_framesize >= UINT_MAX / sub_packet_h){
                av_log(s, AV_LOG_ERROR, "rm->audio_framesize * sub_packet_h too large\n");
                return -1;
            }

            rm->audiobuf = av_malloc(rm->audio_framesize * sub_packet_h);
        } else if (!strcmp(buf, "raac") || !strcmp(buf, "racp")) {
            int codecdata_length, i;
            get_be16(pb); get_byte(pb);
            if (((version >> 16) & 0xff) == 5)
                get_byte(pb);
            st->codec->codec_id = CODEC_ID_AAC;
            codecdata_length = get_be32(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;
            }
            if (codecdata_length >= 1) {
                st->codec->extradata_size = codecdata_length - 1;
                st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
                get_byte(pb);
                for(i = 0; i < st->codec->extradata_size; i++)
                    ((uint8_t*)st->codec->extradata)[i] = get_byte(pb);
            }
        } else {
            st->codec->codec_id = CODEC_ID_NONE;
            av_strlcpy(st->codec->codec_name, buf, sizeof(st->codec->codec_name));
        }
        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));
        }
    }
    return 0;
}

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)
        return -1;
    return rm_read_audio_stream_info(s, st, 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 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(EIO);
    }

    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_str16(pb, s->title, sizeof(s->title));
            get_str16(pb, s->author, sizeof(s->author));
            get_str16(pb, s->copyright, sizeof(s->copyright));
            get_str16(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 */
                if (rm_read_audio_stream_info(s, st, 0))
                    return -1;
            } 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);

                if(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE <= (unsigned)st->codec->extradata_size){
                    //check is redundant as get_buffer() will catch this
                    av_log(s, AV_LOG_ERROR, "st->codec->extradata_size too large\n");
                    return -1;
                }
                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;
                switch(((uint8_t*)st->codec->extradata)[4]>>4){
                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;
                }
            }
skip:
            /* skip codec info */
            size = url_ftell(pb) - codec_pos;
            url_fskip(pb, codec_data_size - size);
            break;
        case MKTAG('D', 'A', 'T', 'A'):
            goto header_end;
        default:
            /* unknown tag: skip it */
            url_fskip(pb, tag_size - 10);
            break;
        }
    }