libavcodec/xfaceenc.c
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 /*
  * Copyright (c) 1990 James Ashton - Sydney University
  * Copyright (c) 2012 Stefano Sabatini
  *
  * 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
  * X-Face encoder, based on libcompface, by James Ashton.
  */
 
 #include "xface.h"
 #include "avcodec.h"
 #include "internal.h"
 
 typedef struct XFaceContext {
     AVClass *class;
     uint8_t bitmap[XFACE_PIXELS]; ///< image used internally for decoding
     int max_line_len;             ///< max line length for compressed data
     int set_header;               ///< set X-Face header in the output
 } XFaceContext;
 
 static int all_same(char *bitmap, int w, int h)
 {
     char val, *row;
     int x;
 
     val = *bitmap;
     while (h--) {
         row = bitmap;
         x = w;
         while (x--)
             if (*(row++) != val)
                 return 0;
         bitmap += XFACE_WIDTH;
     }
     return 1;
 }
 
 static int all_black(char *bitmap, int w, int h)
 {
     if (w > 3) {
         w /= 2;
         h /= 2;
         return (all_black(bitmap, w, h) && all_black(bitmap + w, w, h) &&
                 all_black(bitmap + XFACE_WIDTH * h, w, h) &&
                 all_black(bitmap + XFACE_WIDTH * h + w, w, h));
     } else {
         /* at least one pixel in the 2x2 grid is non-zero */
         return *bitmap || *(bitmap + 1) ||
                *(bitmap + XFACE_WIDTH) || *(bitmap + XFACE_WIDTH + 1);
     }
 }
 
 static int all_white(char *bitmap, int w, int h)
 {
     return *bitmap == 0 && all_same(bitmap, w, h);
 }
 
 typedef struct {
     const ProbRange *prob_ranges[XFACE_PIXELS*2];
     int prob_ranges_idx;
 } ProbRangesQueue;
 
 static inline int pq_push(ProbRangesQueue *pq, const ProbRange *p)
 {
     if (pq->prob_ranges_idx >= XFACE_PIXELS * 2 - 1)
         return -1;
     pq->prob_ranges[pq->prob_ranges_idx++] = p;
     return 0;
 }
 
 static void push_greys(ProbRangesQueue *pq, char *bitmap, int w, int h)
 {
     if (w > 3) {
         w /= 2;
         h /= 2;
         push_greys(pq, bitmap,                       w, h);
         push_greys(pq, bitmap + w,                   w, h);
         push_greys(pq, bitmap + XFACE_WIDTH * h,     w, h);
         push_greys(pq, bitmap + XFACE_WIDTH * h + w, w, h);
     } else {
         const ProbRange *p = ff_xface_probranges_2x2 +
                  *bitmap +
             2 * *(bitmap + 1) +
             4 * *(bitmap + XFACE_WIDTH) +
             8 * *(bitmap + XFACE_WIDTH + 1);
         pq_push(pq, p);
     }
 }
 
 static void encode_block(char *bitmap, int w, int h, int level, ProbRangesQueue *pq)
 {
     if (all_white(bitmap, w, h)) {
         pq_push(pq, &ff_xface_probranges_per_level[level][XFACE_COLOR_WHITE]);
     } else if (all_black(bitmap, w, h)) {
         pq_push(pq, &ff_xface_probranges_per_level[level][XFACE_COLOR_BLACK]);
         push_greys(pq, bitmap, w, h);
     } else {
         pq_push(pq, &ff_xface_probranges_per_level[level][XFACE_COLOR_GREY]);
         w /= 2;
         h /= 2;
         level++;
         encode_block(bitmap,                       w, h, level, pq);
         encode_block(bitmap + w,                   w, h, level, pq);
         encode_block(bitmap + h * XFACE_WIDTH,     w, h, level, pq);
         encode_block(bitmap + w + h * XFACE_WIDTH, w, h, level, pq);
     }
 }
 
 static av_cold int xface_encode_init(AVCodecContext *avctx)
 {
     avctx->coded_frame = avcodec_alloc_frame();
     if (!avctx->coded_frame)
         return AVERROR(ENOMEM);
     avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
 
     return 0;
 }
 
 static void push_integer(BigInt *b, const ProbRange *prange)
 {
     uint8_t r;
 
     ff_big_div(b, prange->range, &r);
     ff_big_mul(b, 0);
     ff_big_add(b, r + prange->offset);
 }
 
 static int xface_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                               const AVFrame *frame, int *got_packet)
 {
     XFaceContext *xface = avctx->priv_data;
     ProbRangesQueue pq = {{ 0 }, 0};
     uint8_t bitmap_copy[XFACE_PIXELS];
     BigInt b = {0};
     int i, j, k, ret = 0;
     const uint8_t *buf;
     uint8_t *p;
     char intbuf[XFACE_MAX_DIGITS];
 
     if (avctx->width || avctx->height) {
         if (avctx->width != XFACE_WIDTH || avctx->height != XFACE_HEIGHT) {
             av_log(avctx, AV_LOG_ERROR,
                    "Size value %dx%d not supported, only accepts a size of %dx%d\n",
                    avctx->width, avctx->height, XFACE_WIDTH, XFACE_HEIGHT);
             return AVERROR(EINVAL);
         }
     }
     avctx->width  = XFACE_WIDTH;
     avctx->height = XFACE_HEIGHT;
 
     /* convert image from MONOWHITE to 1=black 0=white bitmap */
     buf = frame->data[0];
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     i = j = 0;
     do {
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         for (k = 0; k < 8; k++)
             xface->bitmap[i++] = (buf[j]>>(7-k))&1;
         if (++j == XFACE_WIDTH/8) {
             buf += frame->linesize[0];
             j = 0;
         }
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     } while (i < XFACE_PIXELS);
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     /* create a copy of bitmap */
     memcpy(bitmap_copy, xface->bitmap, XFACE_PIXELS);
     ff_xface_generate_face(xface->bitmap, bitmap_copy);
 
     encode_block(xface->bitmap,                         16, 16, 0, &pq);
     encode_block(xface->bitmap + 16,                    16, 16, 0, &pq);
     encode_block(xface->bitmap + 32,                    16, 16, 0, &pq);
     encode_block(xface->bitmap + XFACE_WIDTH * 16,      16, 16, 0, &pq);
     encode_block(xface->bitmap + XFACE_WIDTH * 16 + 16, 16, 16, 0, &pq);
     encode_block(xface->bitmap + XFACE_WIDTH * 16 + 32, 16, 16, 0, &pq);
     encode_block(xface->bitmap + XFACE_WIDTH * 32,      16, 16, 0, &pq);
     encode_block(xface->bitmap + XFACE_WIDTH * 32 + 16, 16, 16, 0, &pq);
     encode_block(xface->bitmap + XFACE_WIDTH * 32 + 32, 16, 16, 0, &pq);
 
     while (pq.prob_ranges_idx > 0)
         push_integer(&b, pq.prob_ranges[--pq.prob_ranges_idx]);
 
     /* write the inverted big integer in b to intbuf */
     i = 0;
     while (b.nb_words) {
         uint8_t r;
         ff_big_div(&b, XFACE_PRINTS, &r);
         intbuf[i++] = r + XFACE_FIRST_PRINT;
     }
 
     if ((ret = ff_alloc_packet2(avctx, pkt, i+2)) < 0)
         return ret;
 
     /* revert the number, and close the buffer */
     p = pkt->data;
     while (--i >= 0)
         *(p++) = intbuf[i];
     *(p++) = '\n';
     *(p++) = 0;
 
     pkt->flags |= AV_PKT_FLAG_KEY;
     *got_packet = 1;
 
     return 0;
 }
 
 static av_cold int xface_encode_close(AVCodecContext *avctx)
 {
     av_freep(&avctx->coded_frame);
 
     return 0;
 }
 
 AVCodec ff_xface_encoder = {
     .name           = "xface",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_XFACE,
     .priv_data_size = sizeof(XFaceContext),
     .init           = xface_encode_init,
     .close          = xface_encode_close,
     .encode2        = xface_encode_frame,
     .pix_fmts       = (const enum PixelFormat[]) { AV_PIX_FMT_MONOWHITE, AV_PIX_FMT_NONE },
     .long_name      = NULL_IF_CONFIG_SMALL("X-face image"),
 };