* Flash Screen Video encoder
* @author Alex Beregszaszi
* @author Benjamin Larsson
+ *
+ * A description of the bitstream format for Flash Screen Video version 1/2
+ * is part of the SWF File Format Specification (version 10), which can be
+ * downloaded from http://www.adobe.com/devnet/swf.html.
*/
-/* Bitstream description
- * The picture is divided into blocks that are zlib-compressed.
- *
- * The decoder is fed complete frames, the frameheader contains:
- * 4 bits of block width
- * 12 bits of frame width
- * 4 bits of block height
- * 12 bits of frame height
- *
- * Directly after the header are the compressed blocks. The blocks
- * have their compressed size represented with 16 bits in the beginning.
- * 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 multiples of 16, from 16 to 256. The blocks don't
* have to be quadratic. A brute force search with a set of different
/* loop over all block columns */
for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
- int hp = j * block_height; // horizontal position in frame
- int hs = (j < v_blocks) ? block_height : v_part; // size of block
+ int y_pos = j * block_height; // vertical position in frame
+ int cur_blk_height = (j < v_blocks) ? block_height : v_part;
/* loop over all block rows */
for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
- int wp = i * block_width; // vertical position in frame
- int ws = (i < h_blocks) ? block_width : h_part; // size of block
+ int x_pos = i * block_width; // horizontal position in frame
+ int cur_blk_width = (i < h_blocks) ? block_width : h_part;
int ret = Z_OK;
uint8_t *ptr = buf + buf_pos;
/* copy the block to the temp buffer before compression
* (if it differs from the previous frame's block) */
res = copy_region_enc(p->data[0], s->tmpblock,
- s->image_height - (hp + hs + 1),
- wp, hs, ws, p->linesize[0], previous_frame);
+ s->image_height - (y_pos + cur_blk_height + 1),
+ x_pos, cur_blk_height, cur_blk_width,
+ p->linesize[0], previous_frame);
if (res || *I_frame) {
unsigned long zsize = 3 * block_width * block_height;
- ret = compress2(ptr + 2, &zsize, s->tmpblock, 3 * ws * hs, 9);
+ ret = compress2(ptr + 2, &zsize, s->tmpblock,
+ 3 * cur_blk_width * cur_blk_height, 9);
//ret = deflateReset(&s->zstream);
if (ret != Z_OK)
av_log(s->avctx, AV_LOG_ERROR,
"error while compressing block %dx%d\n", i, j);
- bytestream_put_be16(&ptr, (unsigned int) zsize);
+ bytestream_put_be16(&ptr, zsize);
buf_pos += zsize + 2;
- av_dlog(avctx, "buf_pos = %d\n", buf_pos);
+ av_dlog(s->avctx, "buf_pos = %d\n", buf_pos);
} else {
pred_blocks++;
bytestream_put_be16(&ptr, 0);
.pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
.long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
};
-