/* * H261 encoder * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> * Copyright (c) 2004 Maarten Daniels * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * H.261 encoder. */ #include "libavutil/attributes.h" #include "libavutil/avassert.h" #include "avcodec.h" #include "mpegvideo.h" #include "h263.h" #include "h261.h" int ff_h261_get_picture_format(int width, int height) { // QCIF if (width == 176 && height == 144) return 0; // CIF else if (width == 352 && height == 288) return 1; // ERROR else return -1; } void ff_h261_encode_picture_header(MpegEncContext *s, int picture_number) { H261Context *h = (H261Context *)s; int format, temp_ref; avpriv_align_put_bits(&s->pb); /* Update the pointer to last GOB */ s->ptr_lastgob = put_bits_ptr(&s->pb); put_bits(&s->pb, 20, 0x10); /* PSC */ temp_ref = s->picture_number * (int64_t)30000 * s->avctx->time_base.num / (1001 * (int64_t)s->avctx->time_base.den); // FIXME maybe this should use a timestamp put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */ put_bits(&s->pb, 1, 0); /* split screen off */ put_bits(&s->pb, 1, 0); /* camera off */ put_bits(&s->pb, 1, 0); /* freeze picture release off */ format = ff_h261_get_picture_format(s->width, s->height); put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */ put_bits(&s->pb, 1, 0); /* still image mode */ put_bits(&s->pb, 1, 0); /* reserved */ put_bits(&s->pb, 1, 0); /* no PEI */ if (format == 0) h->gob_number = -1; else h->gob_number = 0; h->current_mba = 0; } /** * Encode a group of blocks header. */ static void h261_encode_gob_header(MpegEncContext *s, int mb_line) { H261Context *h = (H261Context *)s; if (ff_h261_get_picture_format(s->width, s->height) == 0) { h->gob_number += 2; // QCIF } else { h->gob_number++; // CIF } put_bits(&s->pb, 16, 1); /* GBSC */ put_bits(&s->pb, 4, h->gob_number); /* GN */ put_bits(&s->pb, 5, s->qscale); /* GQUANT */ put_bits(&s->pb, 1, 0); /* no GEI */ h->current_mba = 0; h->previous_mba = 0; h->current_mv_x = 0; h->current_mv_y = 0; } void ff_h261_reorder_mb_index(MpegEncContext *s) { int index = s->mb_x + s->mb_y * s->mb_width; if (index % 33 == 0) h261_encode_gob_header(s, 0); /* for CIF the GOB's are fragmented in the middle of a scanline * that's why we need to adjust the x and y index of the macroblocks */ if (ff_h261_get_picture_format(s->width, s->height) == 1) { // CIF s->mb_x = index % 11; index /= 11; s->mb_y = index % 3; index /= 3; s->mb_x += 11 * (index % 2); index /= 2; s->mb_y += 3 * index; ff_init_block_index(s); ff_update_block_index(s); } } static void h261_encode_motion(H261Context *h, int val) { MpegEncContext *const s = &h->s; int sign, code; if (val == 0) { code = 0; put_bits(&s->pb, ff_h261_mv_tab[code][1], ff_h261_mv_tab[code][0]); } else { if (val > 15) val -= 32; if (val < -16) val += 32; sign = val < 0; code = sign ? -val : val; put_bits(&s->pb, ff_h261_mv_tab[code][1], ff_h261_mv_tab[code][0]); put_bits(&s->pb, 1, sign); } } static inline int get_cbp(MpegEncContext *s, int16_t block[6][64]) { int i, cbp; cbp = 0; for (i = 0; i < 6; i++) if (s->block_last_index[i] >= 0) cbp |= 1 << (5 - i); return cbp; } /** * Encode an 8x8 block. * @param block the 8x8 block * @param n block index (0-3 are luma, 4-5 are chroma) */ static void h261_encode_block(H261Context *h, int16_t *block, int n) { MpegEncContext *const s = &h->s; int level, run, i, j, last_index, last_non_zero, sign, slevel, code; RLTable *rl; rl = &ff_h261_rl_tcoeff; if (s->mb_intra) { /* DC coef */ level = block[0]; /* 255 cannot be represented, so we clamp */ if (level > 254) { level = 254; block[0] = 254; } /* 0 cannot be represented also */ else if (level < 1) { level = 1; block[0] = 1; } if (level == 128) put_bits(&s->pb, 8, 0xff); else put_bits(&s->pb, 8, level); i = 1; } else if ((block[0] == 1 || block[0] == -1) && (s->block_last_index[n] > -1)) { // special case put_bits(&s->pb, 2, block[0] > 0 ? 2 : 3); i = 1; } else { i = 0; } /* AC coefs */ last_index = s->block_last_index[n]; last_non_zero = i - 1; for (; i <= last_index; i++) { j = s->intra_scantable.permutated[i]; level = block[j]; if (level) { run = i - last_non_zero - 1; sign = 0; slevel = level; if (level < 0) { sign = 1; level = -level; } code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level); if (run == 0 && level < 16) code += 1; put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]); if (code == rl->n) { put_bits(&s->pb, 6, run); av_assert1(slevel != 0); av_assert1(level <= 127); put_sbits(&s->pb, 8, slevel); } else { put_bits(&s->pb, 1, sign); } last_non_zero = i; } } if (last_index > -1) put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]); // EOB } void ff_h261_encode_mb(MpegEncContext *s, int16_t block[6][64], int motion_x, int motion_y) { H261Context *h = (H261Context *)s; int mvd, mv_diff_x, mv_diff_y, i, cbp; cbp = 63; // avoid warning mvd = 0; h->current_mba++; h->mtype = 0; if (!s->mb_intra) { /* compute cbp */ cbp = get_cbp(s, block); /* mvd indicates if this block is motion compensated */ mvd = motion_x | motion_y; if ((cbp | mvd | s->dquant) == 0) { /* skip macroblock */ s->skip_count++; h->current_mv_x = 0; h->current_mv_y = 0; return; } } /* MB is not skipped, encode MBA */ put_bits(&s->pb, ff_h261_mba_bits[(h->current_mba - h->previous_mba) - 1], ff_h261_mba_code[(h->current_mba - h->previous_mba) - 1]); /* calculate MTYPE */ if (!s->mb_intra) { h->mtype++; if (mvd || s->loop_filter) h->mtype += 3; if (s->loop_filter) h->mtype += 3; if (cbp || s->dquant) h->mtype++; av_assert1(h->mtype > 1); } if (s->dquant) h->mtype++; put_bits(&s->pb, ff_h261_mtype_bits[h->mtype], ff_h261_mtype_code[h->mtype]); h->mtype = ff_h261_mtype_map[h->mtype]; if (IS_QUANT(h->mtype)) { ff_set_qscale(s, s->qscale + s->dquant); put_bits(&s->pb, 5, s->qscale); } if (IS_16X16(h->mtype)) { mv_diff_x = (motion_x >> 1) - h->current_mv_x; mv_diff_y = (motion_y >> 1) - h->current_mv_y; h->current_mv_x = (motion_x >> 1); h->current_mv_y = (motion_y >> 1); h261_encode_motion(h, mv_diff_x); h261_encode_motion(h, mv_diff_y); } h->previous_mba = h->current_mba; if (HAS_CBP(h->mtype)) { av_assert1(cbp > 0); put_bits(&s->pb, ff_h261_cbp_tab[cbp - 1][1], ff_h261_cbp_tab[cbp - 1][0]); } for (i = 0; i < 6; i++) /* encode each block */ h261_encode_block(h, block[i], i); if ((h->current_mba == 11) || (h->current_mba == 22) || (h->current_mba == 33) || (!IS_16X16(h->mtype))) { h->current_mv_x = 0; h->current_mv_y = 0; } } av_cold void ff_h261_encode_init(MpegEncContext *s) { ff_h261_common_init(); s->min_qcoeff = -127; s->max_qcoeff = 127; s->y_dc_scale_table = s->c_dc_scale_table = ff_mpeg1_dc_scale_table; } FF_MPV_GENERIC_CLASS(h261) AVCodec ff_h261_encoder = { .name = "h261", .type = AVMEDIA_TYPE_VIDEO, .id = AV_CODEC_ID_H261, .priv_data_size = sizeof(H261Context), .init = ff_MPV_encode_init, .encode2 = ff_MPV_encode_picture, .close = ff_MPV_encode_end, .pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV420P, AV_PIX_FMT_NONE }, .long_name = NULL_IF_CONFIG_SMALL("H.261"), .priv_class = &h261_class, };