dv.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

    DECLARE_ALIGNED_16(DCTELEM, block[64]);
    EncBlockInfo  enc_blks[5*6];
    PutBitContext pbs[5*6];
    PutBitContext* pb;
    EncBlockInfo* enc_blk;
    int       vs_bit_size = 0;
    int       qnos[5];

    assert((((int)block) & 15) == 0);

    enc_blk = &enc_blks[0];
    pb = &pbs[0];
    for(mb_index = 0; mb_index < 5; mb_index++) {
        v = *mb_pos_ptr++;
        mb_x = v & 0xff;
        mb_y = v >> 8;
        if (s->sys->pix_fmt == PIX_FMT_YUV422P) {
            y_ptr = s->picture.data[0] + (mb_y * s->picture.linesize[0] * 8) + (mb_x * 4);
        } else { /* 4:1:1 */
            y_ptr = s->picture.data[0] + (mb_y * s->picture.linesize[0] * 8) + (mb_x * 8);
        }
        if (s->sys->pix_fmt == PIX_FMT_YUV420P) {
            c_offset = (((mb_y >> 1) * s->picture.linesize[1] * 8) + ((mb_x >> 1) * 8));
        } else { /* 4:2:2 or 4:1:1 */
            c_offset = ((mb_y * s->picture.linesize[1] * 8) + ((mb_x >> 2) * 8));
        }
        do_edge_wrap = 0;
        qnos[mb_index] = 15; /* No quantization */
        ptr = dif + mb_index*80 + 4;
        for(j = 0;j < 6; j++) {
            int dummy = 0;
            if (s->sys->pix_fmt == PIX_FMT_YUV422P) { /* 4:2:2 */
                if (j == 0 || j == 2) {
                    /* Y0 Y1 */
                    data = y_ptr + ((j>>1) * 8);
                    linesize = s->picture.linesize[0];
                } else if (j > 3) {
                    /* Cr Cb */
                    data = s->picture.data[6 - j] + c_offset;
                    linesize = s->picture.linesize[6 - j];
                } else {
                    /* j=1 and j=3 are "dummy" blocks, used for AC data only */
                    data = 0;
                    linesize = 0;
                    dummy = 1;
                }
            } else { /* 4:1:1 or 4:2:0 */
                if (j < 4) {  /* Four Y blocks */
                    /* NOTE: at end of line, the macroblock is handled as 420 */
                    if (s->sys->pix_fmt == PIX_FMT_YUV411P && mb_x < (704 / 8)) {
                        data = y_ptr + (j * 8);
                    } else {
                        data = y_ptr + ((j & 1) * 8) + ((j >> 1) * 8 * s->picture.linesize[0]);
                    }
                    linesize = s->picture.linesize[0];
                } else {      /* Cr and Cb blocks */
                    /* don't ask Fabrice why they inverted Cb and Cr ! */
                    data = s->picture.data[6 - j] + c_offset;
                    linesize = s->picture.linesize[6 - j];
                    if (s->sys->pix_fmt == PIX_FMT_YUV411P && mb_x >= (704 / 8))
                        do_edge_wrap = 1;
                }
            }

            /* Everything is set up -- now just copy data -> DCT block */
            if (do_edge_wrap) {  /* Edge wrap copy: 4x16 -> 8x8 */
                uint8_t* d;
                DCTELEM *b = block;
                for (i=0;i<8;i++) {
                   d = data + 8 * linesize;
                   b[0] = data[0]; b[1] = data[1]; b[2] = data[2]; b[3] = data[3];
                   b[4] =    d[0]; b[5] =    d[1]; b[6] =    d[2]; b[7] =    d[3];
                   data += linesize;
                   b += 8;
                }
            } else {             /* Simple copy: 8x8 -> 8x8 */
                if (!dummy)
                    s->get_pixels(block, data, linesize);
            }

            if(s->avctx->flags & CODEC_FLAG_INTERLACED_DCT)
                enc_blk->dct_mode = dv_guess_dct_mode(block);
            else
                enc_blk->dct_mode = 0;
            enc_blk->area_q[0] = enc_blk->area_q[1] = enc_blk->area_q[2] = enc_blk->area_q[3] = 0;
            enc_blk->partial_bit_count = 0;
            enc_blk->partial_bit_buffer = 0;
            enc_blk->cur_ac = 0;

            if (dummy) {
                /* We rely on the fact that encoding all zeros leads to an immediate EOB,
                   which is precisely what the spec calls for in the "dummy" blocks. */
                memset(block, 0, sizeof(block));
            } else {
                s->fdct[enc_blk->dct_mode](block);
            }

            dv_set_class_number(block, enc_blk,
                                enc_blk->dct_mode ? ff_zigzag248_direct : ff_zigzag_direct,
                                enc_blk->dct_mode ? dv_weight_248 : dv_weight_88,
                                j/4);

            init_put_bits(pb, ptr, block_sizes[j]/8);
            put_bits(pb, 9, (uint16_t)(((enc_blk->mb[0] >> 3) - 1024 + 2) >> 2));
            put_bits(pb, 1, enc_blk->dct_mode);
            put_bits(pb, 2, enc_blk->cno);

            vs_bit_size += enc_blk->bit_size[0] + enc_blk->bit_size[1] +
                           enc_blk->bit_size[2] + enc_blk->bit_size[3];
            ++enc_blk;
            ++pb;
            ptr += block_sizes[j]/8;
        }
    }

    if (vs_total_ac_bits < vs_bit_size)
        dv_guess_qnos(&enc_blks[0], &qnos[0]);

    for (i=0; i<5; i++) {
       dif[i*80 + 3] = qnos[i];
    }

    /* First pass over individual cells only */
    for (j=0; j<5*6; j++)
       dv_encode_ac(&enc_blks[j], &pbs[j], &pbs[j+1]);

    /* Second pass over each MB space */
    for (j=0; j<5*6; j+=6) {
        pb= &pbs[j];
        for (i=0; i<6; i++) {
            if (enc_blks[i+j].partial_bit_count)
                pb=dv_encode_ac(&enc_blks[i+j], pb, &pbs[j+6]);
        }
    }

    /* Third and final pass over the whole vides segment space */
    pb= &pbs[0];
    for (j=0; j<5*6; j++) {
       if (enc_blks[j].partial_bit_count)
           pb=dv_encode_ac(&enc_blks[j], pb, &pbs[6*5]);
       if (enc_blks[j].partial_bit_count)
            av_log(NULL, AV_LOG_ERROR, "ac bitstream overflow\n");
    }

    for (j=0; j<5*6; j++)
       flush_put_bits(&pbs[j]);
}

static int dv_decode_mt(AVCodecContext *avctx, void* sl)
{
    DVVideoContext *s = avctx->priv_data;
    int slice = (size_t)sl;

    /* which DIF channel is this? */
    int chan = slice / (s->sys->difseg_size * 27);

    /* slice within the DIF channel */
    int chan_slice = slice % (s->sys->difseg_size * 27);

    /* byte offset of this channel's data */
    int chan_offset = chan * s->sys->difseg_size * 150 * 80;

    dv_decode_video_segment(s, &s->buf[((chan_slice/27)*6+(chan_slice/3)+chan_slice*5+7)*80 + chan_offset],
                            &s->sys->video_place[slice*5]);
    return 0;
}

#ifdef CONFIG_ENCODERS
static int dv_encode_mt(AVCodecContext *avctx, void* sl)
{
    DVVideoContext *s = avctx->priv_data;
    int slice = (size_t)sl;

    /* which DIF channel is this? */
    int chan = slice / (s->sys->difseg_size * 27);

    /* slice within the DIF channel */
    int chan_slice = slice % (s->sys->difseg_size * 27);

    /* byte offset of this channel's data */
    int chan_offset = chan * s->sys->difseg_size * 150 * 80;

    dv_encode_video_segment(s, &s->buf[((chan_slice/27)*6+(chan_slice/3)+chan_slice*5+7)*80 + chan_offset],
                            &s->sys->video_place[slice*5]);
    return 0;
}
#endif

#ifdef CONFIG_DECODERS
/* NOTE: exactly one frame must be given (120000 bytes for NTSC,
   144000 bytes for PAL - or twice those for 50Mbps) */
static int dvvideo_decode_frame(AVCodecContext *avctx,
                                 void *data, int *data_size,
                                 uint8_t *buf, int buf_size)
{
    DVVideoContext *s = avctx->priv_data;

    s->sys = dv_frame_profile(buf);
    if (!s->sys || buf_size < s->sys->frame_size)
        return -1; /* NOTE: we only accept several full frames */

    if(s->picture.data[0])
        avctx->release_buffer(avctx, &s->picture);

    s->picture.reference = 0;
    s->picture.key_frame = 1;
    s->picture.pict_type = FF_I_TYPE;
    avctx->pix_fmt = s->sys->pix_fmt;
    avcodec_set_dimensions(avctx, s->sys->width, s->sys->height);
    if(avctx->get_buffer(avctx, &s->picture) < 0) {
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return -1;
    }
    s->picture.interlaced_frame = 1;
    s->picture.top_field_first = 0;

    s->buf = buf;
    avctx->execute(avctx, dv_decode_mt, (void**)&dv_anchor[0], NULL,
                   s->sys->n_difchan * s->sys->difseg_size * 27);

    emms_c();

    /* return image */
    *data_size = sizeof(AVFrame);
    *(AVFrame*)data= s->picture;

    return s->sys->frame_size;
}
#endif


static inline int dv_write_pack(enum dv_pack_type pack_id, DVVideoContext *c, uint8_t* buf)
{
    /*
     * Here's what SMPTE314M says about these two:
     *    (page 6) APTn, AP1n, AP2n, AP3n: These data shall be identical
     *             as track application IDs (APTn = 001, AP1n =
     *             001, AP2n = 001, AP3n = 001), if the source signal
     *             comes from a digital VCR. If the signal source is
     *             unknown, all bits for these data shall be set to 1.
     *    (page 12) STYPE: STYPE defines a signal type of video signal
     *                     00000b = 4:1:1 compression
     *                     00100b = 4:2:2 compression
     *                     XXXXXX = Reserved
     * Now, I've got two problems with these statements:
     *   1. it looks like APT == 111b should be a safe bet, but it isn't.
     *      It seems that for PAL as defined in IEC 61834 we have to set
     *      APT to 000 and for SMPTE314M to 001.
     *   2. It is not at all clear what STYPE is used for 4:2:0 PAL
     *      compression scheme (if any).
     */
    int apt = (c->sys->pix_fmt == PIX_FMT_YUV420P ? 0 : 1);
    int stype = (c->sys->pix_fmt == PIX_FMT_YUV422P ? 4 : 0);

    uint8_t aspect = 0;
    if((int)(av_q2d(c->avctx->sample_aspect_ratio) * c->avctx->width / c->avctx->height * 10) == 17) /* 16:9 */
        aspect = 0x02;

    buf[0] = (uint8_t)pack_id;
    switch (pack_id) {
    case dv_header525: /* I can't imagine why these two weren't defined as real */
    case dv_header625: /* packs in SMPTE314M -- they definitely look like ones */
          buf[1] = 0xf8 |               /* reserved -- always 1 */
                   (apt & 0x07);        /* APT: Track application ID */
          buf[2] = (0 << 7)    | /* TF1: audio data is 0 - valid; 1 - invalid */
                   (0x0f << 3) | /* reserved -- always 1 */
                   (apt & 0x07); /* AP1: Audio application ID */
          buf[3] = (0 << 7)    | /* TF2: video data is 0 - valid; 1 - invalid */
                   (0x0f << 3) | /* reserved -- always 1 */
                   (apt & 0x07); /* AP2: Video application ID */
          buf[4] = (0 << 7)    | /* TF3: subcode(SSYB) is 0 - valid; 1 - invalid */
                   (0x0f << 3) | /* reserved -- always 1 */
                   (apt & 0x07); /* AP3: Subcode application ID */
          break;
    case dv_video_source:
          buf[1] = 0xff; /* reserved -- always 1 */
          buf[2] = (1 << 7) | /* B/W: 0 - b/w, 1 - color */
                   (1 << 6) | /* following CLF is valid - 0, invalid - 1 */
                   (3 << 4) | /* CLF: color frames id (see ITU-R BT.470-4) */
                   0xf; /* reserved -- always 1 */
          buf[3] = (3 << 6) | /* reserved -- always 1 */
                   (c->sys->dsf << 5) | /*  system: 60fields/50fields */
                   stype; /* signal type video compression */
          buf[4] = 0xff; /* VISC: 0xff -- no information */
          break;
    case dv_video_control:
          buf[1] = (0 << 6) | /* Copy generation management (CGMS) 0 -- free */
                   0x3f; /* reserved -- always 1 */
          buf[2] = 0xc8 | /* reserved -- always b11001xxx */
                   aspect;
          buf[3] = (1 << 7) | /* Frame/field flag 1 -- frame, 0 -- field */
                   (1 << 6) | /* First/second field flag 0 -- field 2, 1 -- field 1 */
                   (1 << 5) | /* Frame change flag 0 -- same picture as before, 1 -- different */
                   (1 << 4) | /* 1 - interlaced, 0 - noninterlaced */
                   0xc; /* reserved -- always b1100 */
          buf[4] = 0xff; /* reserved -- always 1 */
          break;
    default:
          buf[1] = buf[2] = buf[3] = buf[4] = 0xff;
    }
    return 5;
}

static void dv_format_frame(DVVideoContext* c, uint8_t* buf)
{
    int chan, i, j, k;

    for (chan = 0; chan < c->sys->n_difchan; chan++) {
        for (i = 0; i < c->sys->difseg_size; i++) {
            memset(buf, 0xff, 80 * 6); /* First 6 DIF blocks are for control data */

            /* DV header: 1DIF */
            buf += dv_write_dif_id(dv_sect_header, chan, i, 0, buf);
            buf += dv_write_pack((c->sys->dsf ? dv_header625 : dv_header525), c, buf);
            buf += 72; /* unused bytes */

            /* DV subcode: 2DIFs */
            for (j = 0; j < 2; j++) {
                buf += dv_write_dif_id(dv_sect_subcode, chan, i, j, buf);
                for (k = 0; k < 6; k++)
                     buf += dv_write_ssyb_id(k, (i < c->sys->difseg_size/2), buf) + 5;
                buf += 29; /* unused bytes */
            }

            /* DV VAUX: 3DIFS */
            for (j = 0; j < 3; j++) {
                buf += dv_write_dif_id(dv_sect_vaux, chan, i, j, buf);
                buf += dv_write_pack(dv_video_source,  c, buf);
                buf += dv_write_pack(dv_video_control, c, buf);
                buf += 7*5;
                buf += dv_write_pack(dv_video_source,  c, buf);
                buf += dv_write_pack(dv_video_control, c, buf);
                buf += 4*5 + 2; /* unused bytes */
            }

            /* DV Audio/Video: 135 Video DIFs + 9 Audio DIFs */
            for (j = 0; j < 135; j++) {
                if (j%15 == 0) {
                    memset(buf, 0xff, 80);
                    buf += dv_write_dif_id(dv_sect_audio, chan, i, j/15, buf);
                    buf += 77; /* audio control & shuffled PCM audio */
                }
                buf += dv_write_dif_id(dv_sect_video, chan, i, j, buf);
                buf += 77; /* 1 video macro block: 1 bytes control
                              4 * 14 bytes Y 8x8 data
                              10 bytes Cr 8x8 data
                              10 bytes Cb 8x8 data */
            }
        }
    }
}


#ifdef CONFIG_ENCODERS
static int dvvideo_encode_frame(AVCodecContext *c, uint8_t *buf, int buf_size,
                                void *data)
{
    DVVideoContext *s = c->priv_data;

    s->sys = dv_codec_profile(c);
    if (!s->sys)
        return -1;
    if(buf_size < s->sys->frame_size)
        return -1;

    c->pix_fmt = s->sys->pix_fmt;
    s->picture = *((AVFrame *)data);
    s->picture.key_frame = 1;
    s->picture.pict_type = FF_I_TYPE;

    s->buf = buf;
    c->execute(c, dv_encode_mt, (void**)&dv_anchor[0], NULL,
               s->sys->n_difchan * s->sys->difseg_size * 27);

    emms_c();

    dv_format_frame(s, buf);

    return s->sys->frame_size;
}
#endif

static int dvvideo_close(AVCodecContext *c)
{
    DVVideoContext *s = c->priv_data;

    if(s->picture.data[0])
        c->release_buffer(c, &s->picture);

    return 0;
}


#ifdef CONFIG_DVVIDEO_ENCODER
AVCodec dvvideo_encoder = {
    "dvvideo",
    CODEC_TYPE_VIDEO,
    CODEC_ID_DVVIDEO,
    sizeof(DVVideoContext),
    dvvideo_init,
    dvvideo_encode_frame,
    .pix_fmts = (enum PixelFormat[]) {PIX_FMT_YUV411P, PIX_FMT_YUV422P, PIX_FMT_YUV420P, -1},
};
#endif // CONFIG_DVVIDEO_ENCODER

#ifdef CONFIG_DVVIDEO_DECODER
AVCodec dvvideo_decoder = {
    "dvvideo",
    CODEC_TYPE_VIDEO,
    CODEC_ID_DVVIDEO,
    sizeof(DVVideoContext),
    dvvideo_init,
    NULL,
    dvvideo_close,
    dvvideo_decode_frame,
    CODEC_CAP_DR1,
    NULL
};
#endif