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  1. /*
  2.  * Flash Screen Video encoder
  3.  * Copyright (C) 2004 Alex Beregszaszi
  4.  * Copyright (C) 2006 Benjamin Larsson
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. /* Encoding development sponsored by http://fh-campuswien.ac.at */
  24.  
  25. /**
  26.  * @file
  27.  * Flash Screen Video encoder
  28.  * @author Alex Beregszaszi
  29.  * @author Benjamin Larsson
  30.  *
  31.  * A description of the bitstream format for Flash Screen Video version 1/2
  32.  * is part of the SWF File Format Specification (version 10), which can be
  33.  * downloaded from http://www.adobe.com/devnet/swf.html.
  34.  */
  35.  
  36. /*
  37.  * Encoding ideas: A basic encoder would just use a fixed block size.
  38.  * Block sizes can be multiples of 16, from 16 to 256. The blocks don't
  39.  * have to be quadratic. A brute force search with a set of different
  40.  * block sizes should give a better result than to just use a fixed size.
  41.  *
  42.  * TODO:
  43.  * Don't reencode the frame in brute force mode if the frame is a dupe.
  44.  * Speed up. Make the difference check faster.
  45.  */
  46.  
  47. #include <stdio.h>
  48. #include <stdlib.h>
  49. #include <zlib.h>
  50.  
  51. #include "avcodec.h"
  52. #include "internal.h"
  53. #include "put_bits.h"
  54. #include "bytestream.h"
  55.  
  56.  
  57. typedef struct FlashSVContext {
  58.     AVCodecContext *avctx;
  59.     uint8_t        *previous_frame;
  60.     AVFrame         frame;
  61.     int             image_width, image_height;
  62.     int             block_width, block_height;
  63.     uint8_t        *tmpblock;
  64.     uint8_t        *encbuffer;
  65.     int             block_size;
  66.     z_stream        zstream;
  67.     int             last_key_frame;
  68. } FlashSVContext;
  69.  
  70. static int copy_region_enc(uint8_t *sptr, uint8_t *dptr, int dx, int dy,
  71.                            int h, int w, int stride, uint8_t *pfptr)
  72. {
  73.     int i, j;
  74.     uint8_t *nsptr;
  75.     uint8_t *npfptr;
  76.     int diff = 0;
  77.  
  78.     for (i = dx + h; i > dx; i--) {
  79.         nsptr  = sptr  + i * stride + dy * 3;
  80.         npfptr = pfptr + i * stride + dy * 3;
  81.         for (j = 0; j < w * 3; j++) {
  82.             diff    |= npfptr[j] ^ nsptr[j];
  83.             dptr[j]  = nsptr[j];
  84.         }
  85.         dptr += w * 3;
  86.     }
  87.     if (diff)
  88.         return 1;
  89.     return 0;
  90. }
  91.  
  92. static av_cold int flashsv_encode_init(AVCodecContext *avctx)
  93. {
  94.     FlashSVContext *s = avctx->priv_data;
  95.  
  96.     s->avctx = avctx;
  97.  
  98.     if (avctx->width > 4095 || avctx->height > 4095) {
  99.         av_log(avctx, AV_LOG_ERROR,
  100.                "Input dimensions too large, input must be max 4096x4096 !\n");
  101.         return AVERROR_INVALIDDATA;
  102.     }
  103.  
  104.     // Needed if zlib unused or init aborted before deflateInit
  105.     memset(&s->zstream, 0, sizeof(z_stream));
  106.  
  107.     s->last_key_frame = 0;
  108.  
  109.     s->image_width  = avctx->width;
  110.     s->image_height = avctx->height;
  111.  
  112.     s->tmpblock  = av_mallocz(3 * 256 * 256);
  113.     s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);
  114.  
  115.     if (!s->tmpblock || !s->encbuffer) {
  116.         av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
  117.         return AVERROR(ENOMEM);
  118.     }
  119.  
  120.     return 0;
  121. }
  122.  
  123.  
  124. static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf,
  125.                             int buf_size, int block_width, int block_height,
  126.                             uint8_t *previous_frame, int *I_frame)
  127. {
  128.  
  129.     PutBitContext pb;
  130.     int h_blocks, v_blocks, h_part, v_part, i, j;
  131.     int buf_pos, res;
  132.     int pred_blocks = 0;
  133.  
  134.     init_put_bits(&pb, buf, buf_size * 8);
  135.  
  136.     put_bits(&pb,  4, block_width / 16 - 1);
  137.     put_bits(&pb, 12, s->image_width);
  138.     put_bits(&pb,  4, block_height / 16 - 1);
  139.     put_bits(&pb, 12, s->image_height);
  140.     flush_put_bits(&pb);
  141.     buf_pos = 4;
  142.  
  143.     h_blocks = s->image_width  / block_width;
  144.     h_part   = s->image_width  % block_width;
  145.     v_blocks = s->image_height / block_height;
  146.     v_part   = s->image_height % block_height;
  147.  
  148.     /* loop over all block columns */
  149.     for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
  150.  
  151.         int y_pos = j * block_height; // vertical position in frame
  152.         int cur_blk_height = (j < v_blocks) ? block_height : v_part;
  153.  
  154.         /* loop over all block rows */
  155.         for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
  156.             int x_pos = i * block_width; // horizontal position in frame
  157.             int cur_blk_width = (i < h_blocks) ? block_width : h_part;
  158.             int ret = Z_OK;
  159.             uint8_t *ptr = buf + buf_pos;
  160.  
  161.             /* copy the block to the temp buffer before compression
  162.              * (if it differs from the previous frame's block) */
  163.             res = copy_region_enc(p->data[0], s->tmpblock,
  164.                                   s->image_height - (y_pos + cur_blk_height + 1),
  165.                                   x_pos, cur_blk_height, cur_blk_width,
  166.                                   p->linesize[0], previous_frame);
  167.  
  168.             if (res || *I_frame) {
  169.                 unsigned long zsize = 3 * block_width * block_height;
  170.                 ret = compress2(ptr + 2, &zsize, s->tmpblock,
  171.                                 3 * cur_blk_width * cur_blk_height, 9);
  172.  
  173.                 //ret = deflateReset(&s->zstream);
  174.                 if (ret != Z_OK)
  175.                     av_log(s->avctx, AV_LOG_ERROR,
  176.                            "error while compressing block %dx%d\n", i, j);
  177.  
  178.                 bytestream_put_be16(&ptr, zsize);
  179.                 buf_pos += zsize + 2;
  180.                 av_dlog(s->avctx, "buf_pos = %d\n", buf_pos);
  181.             } else {
  182.                 pred_blocks++;
  183.                 bytestream_put_be16(&ptr, 0);
  184.                 buf_pos += 2;
  185.             }
  186.         }
  187.     }
  188.  
  189.     if (pred_blocks)
  190.         *I_frame = 0;
  191.     else
  192.         *I_frame = 1;
  193.  
  194.     return buf_pos;
  195. }
  196.  
  197.  
  198. static int flashsv_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
  199.                                 const AVFrame *pict, int *got_packet)
  200. {
  201.     FlashSVContext * const s = avctx->priv_data;
  202.     AVFrame * const p = &s->frame;
  203.     uint8_t *pfptr;
  204.     int res;
  205.     int I_frame = 0;
  206.     int opt_w = 4, opt_h = 4;
  207.  
  208.     *p = *pict;
  209.  
  210.     /* First frame needs to be a keyframe */
  211.     if (avctx->frame_number == 0) {
  212.         s->previous_frame = av_mallocz(FFABS(p->linesize[0]) * s->image_height);
  213.         if (!s->previous_frame) {
  214.             av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
  215.             return AVERROR(ENOMEM);
  216.         }
  217.         I_frame = 1;
  218.     }
  219.  
  220.     if (p->linesize[0] < 0)
  221.         pfptr = s->previous_frame - (s->image_height - 1) * p->linesize[0];
  222.     else
  223.         pfptr = s->previous_frame;
  224.  
  225.     /* Check the placement of keyframes */
  226.     if (avctx->gop_size > 0 &&
  227.         avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
  228.         I_frame = 1;
  229.     }
  230.  
  231.     if ((res = ff_alloc_packet2(avctx, pkt, s->image_width * s->image_height * 3)) < 0)
  232.         return res;
  233.  
  234.     pkt->size = encode_bitstream(s, p, pkt->data, pkt->size, opt_w * 16, opt_h * 16,
  235.                                  pfptr, &I_frame);
  236.  
  237.     //save the current frame
  238.     if (p->linesize[0] > 0)
  239.         memcpy(s->previous_frame, p->data[0], s->image_height * p->linesize[0]);
  240.     else
  241.         memcpy(s->previous_frame,
  242.                p->data[0] + p->linesize[0] * (s->image_height - 1),
  243.                s->image_height * FFABS(p->linesize[0]));
  244.  
  245.     //mark the frame type so the muxer can mux it correctly
  246.     if (I_frame) {
  247.         p->pict_type      = AV_PICTURE_TYPE_I;
  248.         p->key_frame      = 1;
  249.         s->last_key_frame = avctx->frame_number;
  250.         av_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);
  251.     } else {
  252.         p->pict_type = AV_PICTURE_TYPE_P;
  253.         p->key_frame = 0;
  254.     }
  255.  
  256.     avctx->coded_frame = p;
  257.  
  258.     if (p->key_frame)
  259.         pkt->flags |= AV_PKT_FLAG_KEY;
  260.     *got_packet = 1;
  261.  
  262.     return 0;
  263. }
  264.  
  265. static av_cold int flashsv_encode_end(AVCodecContext *avctx)
  266. {
  267.     FlashSVContext *s = avctx->priv_data;
  268.  
  269.     deflateEnd(&s->zstream);
  270.  
  271.     av_free(s->encbuffer);
  272.     av_free(s->previous_frame);
  273.     av_free(s->tmpblock);
  274.  
  275.     return 0;
  276. }
  277.  
  278. AVCodec ff_flashsv_encoder = {
  279.     .name           = "flashsv",
  280.     .long_name      = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
  281.     .type           = AVMEDIA_TYPE_VIDEO,
  282.     .id             = AV_CODEC_ID_FLASHSV,
  283.     .priv_data_size = sizeof(FlashSVContext),
  284.     .init           = flashsv_encode_init,
  285.     .encode2        = flashsv_encode_frame,
  286.     .close          = flashsv_encode_end,
  287.     .pix_fmts       = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },
  288. };
  289.