libavformat/oggparsetheora.c

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

        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);
        }
        st->codec->time_base.den = get_bits_long(&gb, 32);
        st->codec->time_base.num = get_bits_long(&gb, 32);
        if (!(st->codec->time_base.num > 0 && st->codec->time_base.den > 0)) {
            av_log(s, AV_LOG_WARNING, "Invalid time base in theora stream, assuming 25 FPS\n");
            st->codec->time_base.num = 1;
            st->codec->time_base.den = 25;
        }
        av_set_pts_info(st, 64, st->codec->time_base.num, st->codec->time_base.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 = gp >> thp->gpshift;
    uint64_t 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;
}

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

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