pnm.c

ffmpeg源码分析

        n = avctx->width;
        h1 = (h * 3) / 2;
        break;
    default:
        return -1;
    }
    snprintf(s->bytestream, s->bytestream_end - s->bytestream,
             "P%c\n%d %d\n",
             c, avctx->width, h1);
    s->bytestream += strlen(s->bytestream);
    if (avctx->pix_fmt != PIX_FMT_MONOWHITE) {
        snprintf(s->bytestream, s->bytestream_end - s->bytestream,
                 "%d\n", 255);
        s->bytestream += strlen(s->bytestream);
    }

    ptr = p->data[0];
    linesize = p->linesize[0];
    for(i=0;i<h;i++) {
        memcpy(s->bytestream, ptr, n);
        s->bytestream += n;
        ptr += linesize;
    }

    if (avctx->pix_fmt == PIX_FMT_YUV420P) {
        h >>= 1;
        n >>= 1;
        ptr1 = p->data[1];
        ptr2 = p->data[2];
        for(i=0;i<h;i++) {
            memcpy(s->bytestream, ptr1, n);
            s->bytestream += n;
            memcpy(s->bytestream, ptr2, n);
            s->bytestream += n;
                ptr1 += p->linesize[1];
                ptr2 += p->linesize[2];
        }
    }
    return s->bytestream - s->bytestream_start;
}

static int pam_encode_frame(AVCodecContext *avctx, unsigned char *outbuf, int buf_size, void *data){
    PNMContext *s = avctx->priv_data;
    AVFrame *pict = data;
    AVFrame * const p= (AVFrame*)&s->picture;
    int i, h, w, n, linesize, depth, maxval;
    const char *tuple_type;
    uint8_t *ptr;

    if(buf_size < avpicture_get_size(avctx->pix_fmt, avctx->width, avctx->height) + 200){
        av_log(avctx, AV_LOG_ERROR, "encoded frame too large\n");
        return -1;
    }

    *p = *pict;
    p->pict_type= FF_I_TYPE;
    p->key_frame= 1;

    s->bytestream_start=
    s->bytestream= outbuf;
    s->bytestream_end= outbuf+buf_size;

    h = avctx->height;
    w = avctx->width;
    switch(avctx->pix_fmt) {
    case PIX_FMT_MONOWHITE:
        n = (w + 7) >> 3;
        depth = 1;
        maxval = 1;
        tuple_type = "BLACKANDWHITE";
        break;
    case PIX_FMT_GRAY8:
        n = w;
        depth = 1;
        maxval = 255;
        tuple_type = "GRAYSCALE";
        break;
    case PIX_FMT_RGB24:
        n = w * 3;
        depth = 3;
        maxval = 255;
        tuple_type = "RGB";
        break;
    case PIX_FMT_RGBA32:
        n = w * 4;
        depth = 4;
        maxval = 255;
        tuple_type = "RGB_ALPHA";
        break;
    default:
        return -1;
    }
    snprintf(s->bytestream, s->bytestream_end - s->bytestream,
             "P7\nWIDTH %d\nHEIGHT %d\nDEPTH %d\nMAXVAL %d\nTUPLETYPE %s\nENDHDR\n",
             w, h, depth, maxval, tuple_type);
    s->bytestream += strlen(s->bytestream);

    ptr = p->data[0];
    linesize = p->linesize[0];

    if (avctx->pix_fmt == PIX_FMT_RGBA32) {
        int j;
        unsigned int v;

        for(i=0;i<h;i++) {
            for(j=0;j<w;j++) {
                v = ((uint32_t *)ptr)[j];
                *s->bytestream++ = v >> 16;
                *s->bytestream++ = v >> 8;
                *s->bytestream++ = v;
                *s->bytestream++ = v >> 24;
            }
            ptr += linesize;
        }
    } else {
        for(i=0;i<h;i++) {
            memcpy(s->bytestream, ptr, n);
            s->bytestream += n;
            ptr += linesize;
        }
    }
    return s->bytestream - s->bytestream_start;
}

#if 0
static int pnm_probe(AVProbeData *pd)
{
    const char *p = pd->buf;
    if (pd->buf_size >= 8 &&
        p[0] == 'P' &&
        p[1] >= '4' && p[1] <= '6' &&
        pnm_space(p[2]) )
        return AVPROBE_SCORE_MAX - 1; /* to permit pgmyuv probe */
    else
        return 0;
}

static int pgmyuv_probe(AVProbeData *pd)
{
    if (match_ext(pd->filename, "pgmyuv"))
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

static int pam_probe(AVProbeData *pd)
{
    const char *p = pd->buf;
    if (pd->buf_size >= 8 &&
        p[0] == 'P' &&
        p[1] == '7' &&
        p[2] == '\n')
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}
#endif

static int pnm_parse(AVCodecParserContext *s,
                           AVCodecContext *avctx,
                           uint8_t **poutbuf, int *poutbuf_size,
                           const uint8_t *buf, int buf_size)
{
    ParseContext *pc = s->priv_data;
    PNMContext pnmctx;
    int next;

    for(; pc->overread>0; pc->overread--){
        pc->buffer[pc->index++]= pc->buffer[pc->overread_index++];
    }
retry:
    if(pc->index){
        pnmctx.bytestream_start=
        pnmctx.bytestream= pc->buffer;
        pnmctx.bytestream_end= pc->buffer + pc->index;
    }else{
        pnmctx.bytestream_start=
        pnmctx.bytestream= (uint8_t *) buf; /* casts avoid warnings */
        pnmctx.bytestream_end= (uint8_t *) buf + buf_size;
    }
    if(pnm_decode_header(avctx, &pnmctx) < 0){
        if(pnmctx.bytestream < pnmctx.bytestream_end){
            if(pc->index){
                pc->index=0;
            }else{
                buf++;
                buf_size--;
            }
            goto retry;
        }
#if 0
        if(pc->index && pc->index*2 + FF_INPUT_BUFFER_PADDING_SIZE < pc->buffer_size && buf_size > pc->index){
            memcpy(pc->buffer + pc->index, buf, pc->index);
            pc->index += pc->index;
            buf += pc->index;
            buf_size -= pc->index;
            goto retry;
        }
#endif
        next= END_NOT_FOUND;
    }else{
        next= pnmctx.bytestream - pnmctx.bytestream_start
            + avpicture_get_size(avctx->pix_fmt, avctx->width, avctx->height);
        if(pnmctx.bytestream_start!=buf)
            next-= pc->index;
        if(next > buf_size)
            next= END_NOT_FOUND;
    }

    if(ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size)<0){
        *poutbuf = NULL;
        *poutbuf_size = 0;
        return buf_size;
    }
    *poutbuf = (uint8_t *)buf;
    *poutbuf_size = buf_size;
    return next;
}

AVCodecParser pnm_parser = {
    { CODEC_ID_PGM, CODEC_ID_PGMYUV, CODEC_ID_PPM, CODEC_ID_PBM, CODEC_ID_PAM},
    sizeof(ParseContext),
    NULL,
    pnm_parse,
    ff_parse_close,
};

#ifdef CONFIG_PGM_ENCODER
AVCodec pgm_encoder = {
    "pgm",
    CODEC_TYPE_VIDEO,
    CODEC_ID_PGM,
    sizeof(PNMContext),
    common_init,
    pnm_encode_frame,
    NULL, //encode_end,
    pnm_decode_frame,
    .pix_fmts= (enum PixelFormat[]){PIX_FMT_GRAY8, -1},
};
#endif // CONFIG_PGM_ENCODER

#ifdef CONFIG_PGMYUV_ENCODER
AVCodec pgmyuv_encoder = {
    "pgmyuv",
    CODEC_TYPE_VIDEO,
    CODEC_ID_PGMYUV,
    sizeof(PNMContext),
    common_init,
    pnm_encode_frame,
    NULL, //encode_end,
    pnm_decode_frame,
    .pix_fmts= (enum PixelFormat[]){PIX_FMT_YUV420P, -1},
};
#endif // CONFIG_PGMYUV_ENCODER

#ifdef CONFIG_PPM_ENCODER
AVCodec ppm_encoder = {
    "ppm",
    CODEC_TYPE_VIDEO,
    CODEC_ID_PPM,
    sizeof(PNMContext),
    common_init,
    pnm_encode_frame,
    NULL, //encode_end,
    pnm_decode_frame,
    .pix_fmts= (enum PixelFormat[]){PIX_FMT_RGB24, -1},
};
#endif // CONFIG_PPM_ENCODER

#ifdef CONFIG_PBM_ENCODER
AVCodec pbm_encoder = {
    "pbm",
    CODEC_TYPE_VIDEO,
    CODEC_ID_PBM,
    sizeof(PNMContext),
    common_init,
    pnm_encode_frame,
    NULL, //encode_end,
    pnm_decode_frame,
    .pix_fmts= (enum PixelFormat[]){PIX_FMT_MONOWHITE, -1},
};
#endif // CONFIG_PBM_ENCODER

#ifdef CONFIG_PAM_ENCODER
AVCodec pam_encoder = {
    "pam",
    CODEC_TYPE_VIDEO,
    CODEC_ID_PAM,
    sizeof(PNMContext),
    common_init,
    pam_encode_frame,
    NULL, //encode_end,
    pnm_decode_frame,
    .pix_fmts= (enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_RGBA32, PIX_FMT_GRAY8, PIX_FMT_MONOWHITE, -1},
};
#endif // CONFIG_PAM_ENCODER