ogg2.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

/*
 * Ogg bitstream support
 * Luca Barbato <[e-mail]>
 * Based on tcvp implementation
 *
 */

/**
    Copyright (C) 2005  Michael Ahlberg, Måns Rullgård

    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
    files (the "Software"), to deal in the Software without
    restriction, including without limitation the rights to use, copy,
    modify, merge, publish, distribute, sublicense, and/or sell copies
    of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
    WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
**/


#include <stdio.h>
#include "ogg2.h"
#include "avformat.h"

#define MAX_PAGE_SIZE 65307
#define DECODER_BUFFER_SIZE MAX_PAGE_SIZE

static ogg_codec_t *ogg_codecs[] = {
    &vorbis_codec,
    &theora_codec,
    &flac_codec,
    &old_flac_codec,
    &ogm_video_codec,
    &ogm_audio_codec,
    &ogm_old_codec,
    NULL
};

#if 0                           // CONFIG_MUXERS
static int
ogg_write_header (AVFormatContext * avfcontext)
{
}

static int
ogg_write_packet (AVFormatContext * avfcontext, AVPacket * pkt)
{
}


static int
ogg_write_trailer (AVFormatContext * avfcontext)
{
}


AVOutputFormat ogg_muxer = {
    "ogg",
    "Ogg format",
    "application/ogg",
    "ogg",
    sizeof (OggContext),
    CODEC_ID_VORBIS,
    0,
    ogg_write_header,
    ogg_write_packet,
    ogg_write_trailer,
};
#endif //CONFIG_MUXERS

//FIXME We could avoid some structure duplication
static int
ogg_save (AVFormatContext * s)
{
    ogg_t *ogg = s->priv_data;
    ogg_state_t *ost =
        av_malloc(sizeof (*ost) + (ogg->nstreams-1) * sizeof (*ogg->streams));
    int i;
    ost->pos = url_ftell (&s->pb);;
    ost->curidx = ogg->curidx;
    ost->next = ogg->state;
    ost->nstreams = ogg->nstreams;
    memcpy(ost->streams, ogg->streams, ogg->nstreams * sizeof(*ogg->streams));

    for (i = 0; i < ogg->nstreams; i++){
        ogg_stream_t *os = ogg->streams + i;
        os->buf = av_malloc (os->bufsize);
        memset (os->buf, 0, os->bufsize);
        memcpy (os->buf, ost->streams[i].buf, os->bufpos);
    }

    ogg->state = ost;

    return 0;
}

static int
ogg_restore (AVFormatContext * s, int discard)
{
    ogg_t *ogg = s->priv_data;
    ByteIOContext *bc = &s->pb;
    ogg_state_t *ost = ogg->state;
    int i;

    if (!ost)
        return 0;

    ogg->state = ost->next;

    if (!discard){
        for (i = 0; i < ogg->nstreams; i++)
            av_free (ogg->streams[i].buf);

        url_fseek (bc, ost->pos, SEEK_SET);
        ogg->curidx = ost->curidx;
        ogg->nstreams = ost->nstreams;
        memcpy(ogg->streams, ost->streams,
               ost->nstreams * sizeof(*ogg->streams));
    }

    av_free (ost);

    return 0;
}

static int
ogg_reset (ogg_t * ogg)
{
    int i;

    for (i = 0; i < ogg->nstreams; i++){
        ogg_stream_t *os = ogg->streams + i;
        os->bufpos = 0;
        os->pstart = 0;
        os->psize = 0;
        os->granule = -1;
        os->lastgp = -1;
        os->nsegs = 0;
        os->segp = 0;
    }

    ogg->curidx = -1;

    return 0;
}

static ogg_codec_t *
ogg_find_codec (uint8_t * buf, int size)
{
    int i;

    for (i = 0; ogg_codecs[i]; i++)
        if (size >= ogg_codecs[i]->magicsize &&
            !memcmp (buf, ogg_codecs[i]->magic, ogg_codecs[i]->magicsize))
            return ogg_codecs[i];

    return NULL;
}

static int
ogg_find_stream (ogg_t * ogg, int serial)
{
    int i;

    for (i = 0; i < ogg->nstreams; i++)
        if (ogg->streams[i].serial == serial)
            return i;

    return -1;
}

static int
ogg_new_stream (AVFormatContext * s, uint32_t serial)
{

    ogg_t *ogg = s->priv_data;
    int idx = ogg->nstreams++;
    AVStream *st;
    ogg_stream_t *os;

    ogg->streams = av_realloc (ogg->streams,
                               ogg->nstreams * sizeof (*ogg->streams));
    memset (ogg->streams + idx, 0, sizeof (*ogg->streams));
    os = ogg->streams + idx;
    os->serial = serial;
    os->bufsize = DECODER_BUFFER_SIZE;
    os->buf = av_malloc(os->bufsize);
    os->header = -1;

    st = av_new_stream (s, idx);
    if (!st)
        return AVERROR(ENOMEM);

    av_set_pts_info(st, 64, 1, 1000000);

    return idx;
}

static int
ogg_new_buf(ogg_t *ogg, int idx)
{
    ogg_stream_t *os = ogg->streams + idx;
    uint8_t *nb = av_malloc(os->bufsize);
    int size = os->bufpos - os->pstart;
    if(os->buf){
        memcpy(nb, os->buf + os->pstart, size);
        av_free(os->buf);
    }
    os->buf = nb;
    os->bufpos = size;
    os->pstart = 0;

    return 0;
}

static int
ogg_read_page (AVFormatContext * s, int *str)
{
    ByteIOContext *bc = &s->pb;
    ogg_t *ogg = s->priv_data;
    ogg_stream_t *os;
    int i = 0;
    int flags, nsegs;
    uint64_t gp;
    uint32_t serial;
    uint32_t seq;
    uint32_t crc;
    int size, idx;
    uint8_t sync[4];
    int sp = 0;

    if (get_buffer (bc, sync, 4) < 4)
        return -1;

    do{
        int c;

        if (sync[sp & 3] == 'O' &&
            sync[(sp + 1) & 3] == 'g' &&
            sync[(sp + 2) & 3] == 'g' && sync[(sp + 3) & 3] == 'S')
            break;

        c = url_fgetc (bc);
        if (c < 0)
            return -1;
        sync[sp++ & 3] = c;
    }while (i++ < MAX_PAGE_SIZE);

    if (i >= MAX_PAGE_SIZE){
        av_log (s, AV_LOG_INFO, "ogg, can't find sync word\n");
        return -1;
    }

    if (url_fgetc (bc) != 0)      /* version */
        return -1;

    flags = url_fgetc (bc);
    gp = get_le64 (bc);
    serial = get_le32 (bc);
    seq = get_le32 (bc);
    crc = get_le32 (bc);
    nsegs = url_fgetc (bc);

    idx = ogg_find_stream (ogg, serial);
    if (idx < 0){
        idx = ogg_new_stream (s, serial);
        if (idx < 0)
            return -1;
    }

    os = ogg->streams + idx;

    if(os->psize > 0)
        ogg_new_buf(ogg, idx);

    if (get_buffer (bc, os->segments, nsegs) < nsegs)
        return -1;

    os->nsegs = nsegs;
    os->segp = 0;

    size = 0;
    for (i = 0; i < nsegs; i++)
        size += os->segments[i];

    if (flags & OGG_FLAG_CONT){
        if (!os->psize){
            while (os->segp < os->nsegs){
                int seg = os->segments[os->segp++];
                os->pstart += seg;
                if (seg < 255)
                  break;
            }
        }
    }else{
      os->psize = 0;
    }

    if (os->bufsize - os->bufpos < size){
        uint8_t *nb = av_malloc (os->bufsize *= 2);
        memcpy (nb, os->buf, os->bufpos);
        av_free (os->buf);
        os->buf = nb;
    }

    if (get_buffer (bc, os->buf + os->bufpos, size) < size)
        return -1;

    os->lastgp = os->granule;
    os->bufpos += size;
    os->granule = gp;
    os->flags = flags;

    if (str)
        *str = idx;

    return 0;
}

static int
ogg_packet (AVFormatContext * s, int *str, int *dstart, int *dsize)
{
    ogg_t *ogg = s->priv_data;
    int idx;
    ogg_stream_t *os;
    int complete = 0;
    int segp = 0, psize = 0;

#if 0
    av_log (s, AV_LOG_DEBUG, "ogg_packet: curidx=%i\n", ogg->curidx);
#endif

    do{
        idx = ogg->curidx;

        while (idx < 0){
            if (ogg_read_page (s, &idx) < 0)
                return -1;