libavformat/oggparsetheora.c

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#include <stdlib.h>
#include "libavutil/bswap.h"
#include "libavcodec/get_bits.h"
#include "avformat.h"
#include "internal.h"
#include "oggdec.h"

struct theora_params {
    int gpshift;
    int gpmask;
    unsigned version;
};

static int
theora_header (AVFormatContext * s, int idx)
{
    struct ogg *ogg = s->priv_data;
    struct ogg_stream *os = ogg->streams + idx;
    AVStream *st = s->streams[idx];
    struct theora_params *thp = os->private;
    int cds = st->codec->extradata_size + os->psize + 2;
    uint8_t *cdp;

    if(!(os->buf[os->pstart] & 0x80))
        return 0;

    if(!thp){
        thp = av_mallocz(sizeof(*thp));
        os->private = thp;
    }

    if (os->buf[os->pstart] == 0x80) {
        GetBitContext gb;
        int width, height;
        AVRational timebase;

        init_get_bits(&gb, os->buf + os->pstart, os->psize*8);

        skip_bits_long(&gb, 7*8); /* 0x80"theora" */

        thp->version = get_bits_long(&gb, 24);
        if (thp->version < 0x030100)
        {
            av_log(s, AV_LOG_ERROR,
                "Too old or unsupported Theora (%x)\n", thp->version);
            return -1;
        }

        width  = get_bits(&gb, 16) << 4;
        height = get_bits(&gb, 16) << 4;
        avcodec_set_dimensions(st->codec, width, height);

        if (thp->version >= 0x030400)
            skip_bits(&gb, 100);

        if (thp->version >= 0x030200) {
            width  = get_bits_long(&gb, 24);
            height = get_bits_long(&gb, 24);
            if (   width  <= st->codec->width  && width  > st->codec->width-16
                && height <= st->codec->height && height > st->codec->height-16)
                avcodec_set_dimensions(st->codec, width, height);

            skip_bits(&gb, 16);
        }
        timebase.den = get_bits_long(&gb, 32);
        timebase.num = get_bits_long(&gb, 32);
        if (!(timebase.num > 0 && timebase.den > 0)) {
            av_log(s, AV_LOG_WARNING, "Invalid time base in theora stream, assuming 25 FPS\n");
            timebase.num = 1;
            timebase.den = 25;
        }
        avpriv_set_pts_info(st, 64, timebase.num, timebase.den);

        st->sample_aspect_ratio.num = get_bits_long(&gb, 24);
        st->sample_aspect_ratio.den = get_bits_long(&gb, 24);

        if (thp->version >= 0x030200)
            skip_bits_long(&gb, 38);
        if (thp->version >= 0x304000)
            skip_bits(&gb, 2);

        thp->gpshift = get_bits(&gb, 5);
        thp->gpmask = (1 << thp->gpshift) - 1;

        st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
        st->codec->codec_id = CODEC_ID_THEORA;
        st->need_parsing = AVSTREAM_PARSE_HEADERS;

    } else if (os->buf[os->pstart] == 0x83) {
        ff_vorbis_comment (s, &st->metadata, os->buf + os->pstart + 7, os->psize - 8);
    }

    st->codec->extradata = av_realloc (st->codec->extradata,
                                       cds + FF_INPUT_BUFFER_PADDING_SIZE);
    cdp = st->codec->extradata + st->codec->extradata_size;
    *cdp++ = os->psize >> 8;
    *cdp++ = os->psize & 0xff;
    memcpy (cdp, os->buf + os->pstart, os->psize);
    st->codec->extradata_size = cds;

    return 1;
}

static uint64_t
theora_gptopts(AVFormatContext *ctx, int idx, uint64_t gp, int64_t *dts)
{
    struct ogg *ogg = ctx->priv_data;
    struct ogg_stream *os = ogg->streams + idx;
    struct theora_params *thp = os->private;
    uint64_t iframe, pframe;

    if (!thp)
        return AV_NOPTS_VALUE;

    iframe = gp >> thp->gpshift;
    pframe = gp & thp->gpmask;

    if (thp->version < 0x030201)
        iframe++;

    if(!pframe)
        os->pflags |= AV_PKT_FLAG_KEY;

    if (dts)
        *dts = iframe + pframe;

    return iframe + pframe;
}

static int theora_packet(AVFormatContext *s, int idx)
{
    struct ogg *ogg = s->priv_data;
    struct ogg_stream *os = ogg->streams + idx;
    int duration;

    /* first packet handling
       here we parse the duration of each packet in the first page and compare
       the total duration to the page granule to find the encoder delay and
       set the first timestamp */

    if ((!os->lastpts || os->lastpts == AV_NOPTS_VALUE) && !(os->flags & OGG_FLAG_EOS)) {
        int seg;

        duration = 1;
        for (seg = os->segp; seg < os->nsegs; seg++) {
            if (os->segments[seg] < 255)
                duration ++;
        }

        os->lastpts = os->lastdts   = theora_gptopts(s, idx, os->granule, NULL) - duration;
        if(s->streams[idx]->start_time == AV_NOPTS_VALUE) {
            s->streams[idx]->start_time = os->lastpts;
            if (s->streams[idx]->duration)
                s->streams[idx]->duration -= s->streams[idx]->start_time;
        }
    }

    /* parse packet duration */
    if (os->psize > 0) {
        os->pduration = 1;
    }

    return 0;
}

const struct ogg_codec ff_theora_codec = {
    .magic = "\200theora",
    .magicsize = 7,
    .header = theora_header,
    .packet = theora_packet,
    .gptopts = theora_gptopts
};

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