int compare_files(state *s, char *fn1, char *fn2)
{
FILE *h1, *h2;
int status;
if ((h1 = fopen(fn1,"rb")) == NULL)
{
perror(fn1);
return TRUE;
}
if ((h2 = fopen(fn2,"rb")) == NULL)
{
perror(fn2);
fclose(h1);
return TRUE;
}
if (find_file_size(fn1,h1,&s->size1))
return TRUE;
if (find_file_size(fn2,h2,&s->size2))
return TRUE;
if (s->size1 != s->size2)
print_error ("%s: files are not the same size", __progname);
status = compare_blocks(s,h1,h2);
fclose(h1);
fclose(h2);
return status;
}
/*
* encode_main
*
* Main encoding loop.
*/
static void encode_main(MimCtx *ctx, guchar *out_buf, gboolean is_pframe)
{
gint x, y, i, offset, chrom_ch;
gint dct_block[64];
guchar *src, *dst, *p1, *p2;
gdouble match;
gboolean encoded;
/*
* Round down small differences in luminance channel.
*/
if (is_pframe) {
p1 = ctx->cur_frame_buf;
p2 = ctx->prev_frame_buf;
for (i = 0; i < ctx->y_size; i++) {
if (abs(p2[0] - p1[0]) < 7)
p1[0] = p2[0];
p1++;
p2++;
}
}
/*
* Encode Y plane.
*/
for (y = 0; y < ctx->num_vblocks_y; y++) {
for (x = 0; x < ctx->num_hblocks_y; x++) {
/* Calculate final offset into buffer. */
offset = (ctx->y_stride * 8 * y) + (x * 8);
src = NULL;
encoded = FALSE;
if (is_pframe) {
/* Is the current block similar enough to what it was in the previous frame? */
match = compare_blocks(ctx->cur_frame_buf + offset,
ctx->prev_frame_buf + offset,
ctx->y_stride, 8,
FALSE);
if (match > LUMINANCE_THRESHOLD) {
/* Yes: write out '1' to indicate a no-change condition. */
_write_bits(ctx, 1, 1);
src = ctx->prev_frame_buf + offset;
encoded = TRUE;
} else {
/* No: Is the current block similar enough to what it was in one
* of the (up to) 15 last frames preceding the previous? */
gint best_index = 0;
gdouble best_match = 0.0;
gint num_backrefs = ctx->frame_num - 1;
if (num_backrefs > 15)
num_backrefs = 15;
for (i = 1; i <= num_backrefs; i++) {
match = compare_blocks(ctx->buf_ptrs[(ctx->ptr_index + i) % 16] + offset,
ctx->cur_frame_buf + offset,
ctx->y_stride, 8,
FALSE);
if (match > LUMINANCE_THRESHOLD && match > best_match) {
best_index = i;
best_match = match;
}
}
if (best_index != 0) {
/* Yes: write out '01' to indicate a "change but like previous"-condition,
* followed by 4 bits containing the back-reference. */
_write_bits(ctx, 0, 1);
_write_bits(ctx, 1, 1);
_write_bits(ctx, best_index, 4);
src = ctx->buf_ptrs[(ctx->ptr_index + best_index) % 16] + offset;
encoded = TRUE;
}
}
}
if (!encoded) {
/* Keyframe or in any case no? ;-) Well, encode it then. */
if (is_pframe) {
_write_bits(ctx, 0, 1);
_write_bits(ctx, 0, 1);
}
_fdct_quant_block(ctx,
dct_block,
ctx->cur_frame_buf + offset,
ctx->y_stride,
FALSE,
ctx->num_coeffs);
_vlc_encode_block(ctx,
dct_block,
ctx->num_coeffs);
}
/* And if there was some kind of no-change condition,
* we want to copy the previous block. */
if (src != NULL) {
dst = ctx->cur_frame_buf + offset;
for (i = 0; i < 8; i++) {
memcpy(dst, src, 8);
src += ctx->y_stride;
dst += ctx->y_stride;
}
}
}
}
/*
* Encode Cr and Cb planes.
*/
for (chrom_ch = 0; chrom_ch < 2; chrom_ch++) {
/* Calculate base offset into buffer. */
gint base_offset = ctx->y_size + (ctx->crcb_size * chrom_ch);
for (y = 0; y < ctx->num_vblocks_cbcr; y++) {
guchar tmp_block[64];
guint num_rows = 8;
/* The last row of blocks in chrominance for 160x120 resolution
* is half the normal height and must be accounted for. */
if (y + 1 == ctx->num_vblocks_cbcr && ctx->frame_height % 16 != 0)
num_rows = 4;
for (x = 0; x < ctx->num_hblocks_cbcr; x++) {
/* Calculate final offset into buffer. */
offset = base_offset + (ctx->crcb_stride * 8 * y) + (x * 8);
src = NULL;
encoded = FALSE;
if (is_pframe) {
/* Is the current block similar enough to what it was in the previous frame? */
match = compare_blocks(ctx->prev_frame_buf + offset,
ctx->cur_frame_buf + offset,
ctx->crcb_stride, num_rows,
TRUE);
if (match > CHROMINANCE_THRESHOLD) {
/* Yes: write out '0' to indicate a no-change condition. */
_write_bits(ctx, 0, 1);
encoded = TRUE;
src = ctx->prev_frame_buf + offset;
dst = ctx->cur_frame_buf + offset;
for (i = 0; i < num_rows; i++) {
memcpy(dst, src, 8);
src += ctx->crcb_stride;
dst += ctx->crcb_stride;
}
}
}
if (!encoded) {
/* Keyframe or just not similar enough? ;-) Well, encode it then. */
if (is_pframe)
_write_bits(ctx, 1, 1);
/* Use a temporary array to handle cases where the
* current block is not of normal height (see above). */
src = ctx->cur_frame_buf + offset;
dst = tmp_block;
for (i = 0; i < 8; i++) {
memcpy(dst, src, 8);
if (i < (num_rows - 1))
src += ctx->crcb_stride;
dst += 8;
}
_fdct_quant_block(ctx,
dct_block,
tmp_block,
8,
TRUE,
ctx->num_coeffs);
_vlc_encode_block(ctx,
dct_block,
ctx->num_coeffs);
}
}
}
}
/*
* Make a copy of the current frame and store in
* the circular pointer list of 16 entries.
*/
ctx->prev_frame_buf = ctx->buf_ptrs[ctx->ptr_index];
memcpy(ctx->prev_frame_buf, ctx->cur_frame_buf,
ctx->y_size + (ctx->crcb_size * 2));
if (--ctx->ptr_index < 0)
ctx->ptr_index = 15;
}
