libavcodec/flashsv.c - third_party/ffmpeg - Git at Google

 /*
  * Flash Screen Video decoder
  * Copyright (C) 2004 Alex Beregszaszi
  * Copyright (C) 2006 Benjamin Larsson
  *
  * 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
  * Flash Screen Video decoder
  * @author Alex Beregszaszi
  * @author Benjamin Larsson
  */

 /* Bitstream description
  * The picture is divided into blocks that are zlib compressed.
  *
  * The decoder is fed complete frames, the frameheader contains:
  * 4bits of block width
  * 12bits of frame width
  * 4bits of block height
  * 12bits of frame height
  *
  * Directly after the header are the compressed blocks. The blocks
  * have their compressed size represented with 16bits in the beginnig.
  * If the size = 0 then the block is unchanged from the previous frame.
  * All blocks are decompressed until the buffer is consumed.
  *
  * Encoding ideas, a basic encoder would just use a fixed block size.
  * Block sizes can be multipels of 16, from 16 to 256. The blocks don't
  * have to be quadratic. A brute force search with a set of diffrent
  * block sizes should give a better result then to just use a fixed size.
  */

 #include <stdio.h>
 #include <stdlib.h>
 #include <zlib.h>

 #include "avcodec.h"
 #include "get_bits.h"

 typedef struct FlashSVContext {
     AVCodecContext *avctx;
     AVFrame         frame;
     int             image_width, image_height;
     int             block_width, block_height;
     uint8_t        *tmpblock;
     int             block_size;
     z_stream        zstream;
 } FlashSVContext;


 static void copy_region(uint8_t *sptr, uint8_t *dptr,
                         int dx, int dy, int h, int w, int stride)
 {
     int i;

     for (i = dx + h; i > dx; i--) {
         memcpy(dptr + (i * stride) + dy * 3, sptr, w * 3);
         sptr += w * 3;
     }
 }


 static av_cold int flashsv_decode_init(AVCodecContext *avctx)
 {
     FlashSVContext *s = avctx->priv_data;
     int zret; // Zlib return code

     s->avctx          = avctx;
     s->zstream.zalloc = Z_NULL;
     s->zstream.zfree  = Z_NULL;
     s->zstream.opaque = Z_NULL;
     zret = inflateInit(&(s->zstream));
     if (zret != Z_OK) {
         av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
         return 1;
     }
     avctx->pix_fmt = PIX_FMT_BGR24;
     avcodec_get_frame_defaults(&s->frame);
     s->frame.data[0] = NULL;

     return 0;
 }


 static int flashsv_decode_frame(AVCodecContext *avctx, void *data,
                                 int *data_size, AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
     FlashSVContext *s  = avctx->priv_data;
     int h_blocks, v_blocks, h_part, v_part, i, j;
     GetBitContext gb;

     /* no supplementary picture */
     if (buf_size == 0)
         return 0;
     if (buf_size < 4)
         return -1;

     init_get_bits(&gb, buf, buf_size * 8);

     /* start to parse the bitstream */
     s->block_width  = 16 * (get_bits(&gb,  4) + 1);
     s->image_width  =       get_bits(&gb, 12);
     s->block_height = 16 * (get_bits(&gb,  4) + 1);
     s->image_height =       get_bits(&gb, 12);

     /* calculate amount of blocks and the size of the border blocks */
     h_blocks = s->image_width  / s->block_width;
     h_part   = s->image_width  % s->block_width;
     v_blocks = s->image_height / s->block_height;
     v_part   = s->image_height % s->block_height;

     /* the block size could change between frames, make sure the buffer
      * is large enough, if not, get a larger one */
     if (s->block_size < s->block_width * s->block_height) {
         av_free(s->tmpblock);
         if ((s->tmpblock = av_malloc(3 * s->block_width * s->block_height)) == NULL) {
             av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
             return AVERROR(ENOMEM);
         }
     }
     s->block_size = s->block_width * s->block_height;

     /* init the image size once */
     if ((avctx->width == 0) && (avctx->height == 0)) {
         avctx->width  = s->image_width;
         avctx->height = s->image_height;
     }

     /* check for changes of image width and image height */
     if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
         av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
         av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d  vs  ch = %d, cv = %d\n", avctx->height,
         avctx->width, s->image_height, s->image_width);
         return -1;
     }

     av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
            s->image_width, s->image_height, s->block_width, s->block_height,
            h_blocks, v_blocks, h_part, v_part);

     s->frame.reference    = 1;
     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
     if (avctx->reget_buffer(avctx, &s->frame) < 0) {
         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
         return -1;
     }

     /* loop over all block columns */
     for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {

         int hp = j * s->block_height; // horiz position in frame
         int hs = (j < v_blocks) ? s->block_height : v_part; // size of block


         /* loop over all block rows */
         for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
             int wp = i * s->block_width; // vert position in frame
             int ws = (i < h_blocks) ? s->block_width : h_part; // size of block

             /* get the size of the compressed zlib chunk */
             int size = get_bits(&gb, 16);
             if (8 * size > get_bits_left(&gb)) {
                 avctx->release_buffer(avctx, &s->frame);
                 s->frame.data[0] = NULL;
                 return -1;
             }

             if (size == 0) {
                 /* no change, don't do anything */
             } else {
                 /* decompress block */
                 int ret = inflateReset(&(s->zstream));
                 if (ret != Z_OK) {
                     av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
                     /* return -1; */
                 }
                 s->zstream.next_in   = buf + (get_bits_count(&gb) / 8);
                 s->zstream.avail_in  = size;
                 s->zstream.next_out  = s->tmpblock;
                 s->zstream.avail_out = s->block_size * 3;
                 ret = inflate(&(s->zstream), Z_FINISH);
                 if (ret == Z_DATA_ERROR) {
                     av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
                     inflateSync(&(s->zstream));
                     ret = inflate(&(s->zstream), Z_FINISH);
                 }

                 if ((ret != Z_OK) && (ret != Z_STREAM_END)) {
                     av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
                     /* return -1; */
                 }
                 copy_region(s->tmpblock, s->frame.data[0], s->image_height - (hp + hs + 1),
                             wp, hs, ws, s->frame.linesize[0]);
                 skip_bits_long(&gb, 8 * size);   /* skip the consumed bits */
             }
         }
     }

     *data_size = sizeof(AVFrame);
     *(AVFrame*)data = s->frame;

     if ((get_bits_count(&gb) / 8) != buf_size)
         av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
                buf_size, (get_bits_count(&gb) / 8));

     /* report that the buffer was completely consumed */
     return buf_size;
 }


 static av_cold int flashsv_decode_end(AVCodecContext *avctx)
 {
     FlashSVContext *s = avctx->priv_data;
     inflateEnd(&(s->zstream));
     /* release the frame if needed */
     if (s->frame.data[0])
         avctx->release_buffer(avctx, &s->frame);

     /* free the tmpblock */
     av_free(s->tmpblock);

     return 0;
 }


 AVCodec ff_flashsv_decoder = {
     .name           = "flashsv",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = CODEC_ID_FLASHSV,
     .priv_data_size = sizeof(FlashSVContext),
     .init           = flashsv_decode_init,
     .close          = flashsv_decode_end,
     .decode         = flashsv_decode_frame,
     .capabilities   = CODEC_CAP_DR1,
     .pix_fmts       = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
     .long_name      = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),
 };
	/*
	* Flash Screen Video decoder
	* Copyright (C) 2004 Alex Beregszaszi
	* Copyright (C) 2006 Benjamin Larsson
	*
	* 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
	* Flash Screen Video decoder
	* @author Alex Beregszaszi
	* @author Benjamin Larsson
	*/

	/* Bitstream description
	* The picture is divided into blocks that are zlib compressed.
	*
	* The decoder is fed complete frames, the frameheader contains:
	* 4bits of block width
	* 12bits of frame width
	* 4bits of block height
	* 12bits of frame height
	*
	* Directly after the header are the compressed blocks. The blocks
	* have their compressed size represented with 16bits in the beginnig.
	* If the size = 0 then the block is unchanged from the previous frame.
	* All blocks are decompressed until the buffer is consumed.
	*
	* Encoding ideas, a basic encoder would just use a fixed block size.
	* Block sizes can be multipels of 16, from 16 to 256. The blocks don't
	* have to be quadratic. A brute force search with a set of diffrent
	* block sizes should give a better result then to just use a fixed size.
	*/

	#include <stdio.h>
	#include <stdlib.h>
	#include <zlib.h>

	#include "avcodec.h"
	#include "get_bits.h"

	typedef struct FlashSVContext {
	AVCodecContext *avctx;
	AVFrame frame;
	int image_width, image_height;
	int block_width, block_height;
	uint8_t *tmpblock;
	int block_size;
	z_stream zstream;
	} FlashSVContext;


	static void copy_region(uint8_t sptr, uint8_t dptr,
	int dx, int dy, int h, int w, int stride)
	{
	int i;

	for (i = dx + h; i > dx; i--) {
	memcpy(dptr + (i * stride) + dy * 3, sptr, w * 3);
	sptr += w * 3;
	}
	}


	static av_cold int flashsv_decode_init(AVCodecContext *avctx)
	{
	FlashSVContext *s = avctx->priv_data;
	int zret; // Zlib return code

	s->avctx = avctx;
	s->zstream.zalloc = Z_NULL;
	s->zstream.zfree = Z_NULL;
	s->zstream.opaque = Z_NULL;
	zret = inflateInit(&(s->zstream));
	if (zret != Z_OK) {
	av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
	return 1;
	}
	avctx->pix_fmt = PIX_FMT_BGR24;
	avcodec_get_frame_defaults(&s->frame);
	s->frame.data[0] = NULL;

	return 0;
	}


	static int flashsv_decode_frame(AVCodecContext avctx, void data,
	int data_size, AVPacket avpkt)
	{
	const uint8_t *buf = avpkt->data;
	int buf_size = avpkt->size;
	FlashSVContext *s = avctx->priv_data;
	int h_blocks, v_blocks, h_part, v_part, i, j;
	GetBitContext gb;

	/* no supplementary picture */
	if (buf_size == 0)
	return 0;
	if (buf_size < 4)
	return -1;

	init_get_bits(&gb, buf, buf_size * 8);

	/* start to parse the bitstream */
	s->block_width = 16 * (get_bits(&gb, 4) + 1);
	s->image_width = get_bits(&gb, 12);
	s->block_height = 16 * (get_bits(&gb, 4) + 1);
	s->image_height = get_bits(&gb, 12);

	/* calculate amount of blocks and the size of the border blocks */
	h_blocks = s->image_width / s->block_width;
	h_part = s->image_width % s->block_width;
	v_blocks = s->image_height / s->block_height;
	v_part = s->image_height % s->block_height;

	/* the block size could change between frames, make sure the buffer
	* is large enough, if not, get a larger one */
	if (s->block_size < s->block_width * s->block_height) {
	av_free(s->tmpblock);
	if ((s->tmpblock = av_malloc(3 * s->block_width * s->block_height)) == NULL) {
	av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
	return AVERROR(ENOMEM);
	}
	}
	s->block_size = s->block_width * s->block_height;

	/* init the image size once */
	if ((avctx->width == 0) && (avctx->height == 0)) {
	avctx->width = s->image_width;
	avctx->height = s->image_height;
	}

	/* check for changes of image width and image height */
	if ((avctx->width != s->image_width) \|\| (avctx->height != s->image_height)) {
	av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
	av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d vs ch = %d, cv = %d\n", avctx->height,
	avctx->width, s->image_height, s->image_width);
	return -1;
	}

	av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
	s->image_width, s->image_height, s->block_width, s->block_height,
	h_blocks, v_blocks, h_part, v_part);

	s->frame.reference = 1;
	s->frame.buffer_hints = FF_BUFFER_HINTS_VALID \| FF_BUFFER_HINTS_PRESERVE \| FF_BUFFER_HINTS_REUSABLE;
	if (avctx->reget_buffer(avctx, &s->frame) < 0) {
	av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
	return -1;
	}

	/* loop over all block columns */
	for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {

	int hp = j * s->block_height; // horiz position in frame
	int hs = (j < v_blocks) ? s->block_height : v_part; // size of block


	/* loop over all block rows */
	for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
	int wp = i * s->block_width; // vert position in frame
	int ws = (i < h_blocks) ? s->block_width : h_part; // size of block

	/* get the size of the compressed zlib chunk */
	int size = get_bits(&gb, 16);
	if (8 * size > get_bits_left(&gb)) {
	avctx->release_buffer(avctx, &s->frame);
	s->frame.data[0] = NULL;
	return -1;
	}

	if (size == 0) {
	/* no change, don't do anything */
	} else {
	/* decompress block */
	int ret = inflateReset(&(s->zstream));
	if (ret != Z_OK) {
	av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
	/* return -1; */
	}
	s->zstream.next_in = buf + (get_bits_count(&gb) / 8);
	s->zstream.avail_in = size;
	s->zstream.next_out = s->tmpblock;
	s->zstream.avail_out = s->block_size * 3;
	ret = inflate(&(s->zstream), Z_FINISH);
	if (ret == Z_DATA_ERROR) {
	av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
	inflateSync(&(s->zstream));
	ret = inflate(&(s->zstream), Z_FINISH);
	}

	if ((ret != Z_OK) && (ret != Z_STREAM_END)) {
	av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
	/* return -1; */
	}
	copy_region(s->tmpblock, s->frame.data[0], s->image_height - (hp + hs + 1),
	wp, hs, ws, s->frame.linesize[0]);
	skip_bits_long(&gb, 8 * size); /* skip the consumed bits */
	}
	}
	}

	*data_size = sizeof(AVFrame);
	(AVFrame)data = s->frame;

	if ((get_bits_count(&gb) / 8) != buf_size)
	av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
	buf_size, (get_bits_count(&gb) / 8));

	/* report that the buffer was completely consumed */
	return buf_size;
	}


	static av_cold int flashsv_decode_end(AVCodecContext *avctx)
	{
	FlashSVContext *s = avctx->priv_data;
	inflateEnd(&(s->zstream));
	/* release the frame if needed */
	if (s->frame.data[0])
	avctx->release_buffer(avctx, &s->frame);

	/* free the tmpblock */
	av_free(s->tmpblock);

	return 0;
	}


	AVCodec ff_flashsv_decoder = {
	.name = "flashsv",
	.type = AVMEDIA_TYPE_VIDEO,
	.id = CODEC_ID_FLASHSV,
	.priv_data_size = sizeof(FlashSVContext),
	.init = flashsv_decode_init,
	.close = flashsv_decode_end,
	.decode = flashsv_decode_frame,
	.capabilities = CODEC_CAP_DR1,
	.pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
	.long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),
	};