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420 lines
12 KiB
420 lines
12 KiB
/* Copyright (C) 2005 Ole André Vadla Ravnås <oleavr@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include "mimic-private.h"
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#define LUMINANCE_THRESHOLD 32.0f
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#define CHROMINANCE_THRESHOLD 36.0f
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static void encode_main(MimCtx *ctx, guchar *out_buf, gboolean is_pframe);
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/**
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* Encode a MIMIC-encoded frame from RGB data.
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*
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* @param ctx the mimic context
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* @param input_buffer buffer containing pixeldata in RGB 24-bpp packed pixel top-down format
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* @param output_buffer buffer that will receive the MIMIC-encoded frame
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* (use #mimic_get_property to determine the required buffer size)
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* @param output_length pointer to an integer that receives the length of the encoded data
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* written to output_buffer
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* @param make_keyframe whether the encoder should make this frame a keyframe
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* @returns #TRUE on success
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*/
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gboolean mimic_encode_frame(MimCtx *ctx,
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const guchar *input_buffer,
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guchar *output_buffer,
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gint *output_length,
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gboolean make_keyframe)
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{
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guchar *output_y, *output_cb, *output_cr;
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/*
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* Some sanity checks.
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*/
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if (ctx == NULL || input_buffer == NULL ||
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output_buffer == NULL || output_length == NULL)
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{
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return FALSE;
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}
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if (!ctx->encoder_initialized)
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return FALSE;
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/*
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* Initialize state.
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*/
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ctx->chunk_ptr = (guint32 *) (output_buffer + 20);
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ctx->cur_chunk = 0;
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ctx->cur_chunk_len = 0;
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if (ctx->frame_num == 0)
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make_keyframe = TRUE;
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/*
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* Write header.
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*/
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memset(output_buffer, 0, 20);
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*((guint16 *) (output_buffer + 0)) = GUINT16_TO_LE(256);
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*((guint16 *) (output_buffer + 2)) = GUINT16_TO_LE(ctx->quality);
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*((guint16 *) (output_buffer + 4)) = GUINT16_TO_LE(ctx->frame_width);
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*((guint16 *) (output_buffer + 6)) = GUINT16_TO_LE(ctx->frame_height);
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*((guint32 *) (output_buffer + 12)) = GUINT32_TO_LE((make_keyframe == 0));
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*(output_buffer + 16) = ctx->num_coeffs;
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*(output_buffer + 17) = 0;
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/*
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* Perform RGB to YUV 420 conversion.
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*/
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output_y = ctx->cur_frame_buf;
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output_cr = ctx->cur_frame_buf + ctx->y_size;
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output_cb = ctx->cur_frame_buf + ctx->y_size + ctx->crcb_size;
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_rgb_to_yuv(input_buffer,
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output_y,
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output_cb,
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output_cr,
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ctx->frame_width,
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ctx->frame_height);
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/*
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* Encode frame.
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*/
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encode_main(ctx, output_buffer, (make_keyframe == FALSE));
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/*
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* Write out any pending bits to stream by zero-padding with 32 bits.
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*/
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_write_bits(ctx, 0, 32);
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/*
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* Calculate bytes written.
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*/
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*output_length = (guchar *) ctx->chunk_ptr - output_buffer;
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/*
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* Increment frame counter.
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*/
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ctx->frame_num++;
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return TRUE;
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}
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static gdouble compare_blocks(const guchar *p1,
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const guchar *p2,
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gint stride,
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gint row_count,
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gboolean is_chrom);
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/*
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* encode_main
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*
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* Main encoding loop.
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*/
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static void encode_main(MimCtx *ctx, guchar *out_buf, gboolean is_pframe)
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{
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gint x, y, i, offset, chrom_ch;
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gint dct_block[64];
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guchar *src, *dst, *p1, *p2;
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gdouble match;
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gboolean encoded;
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/*
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* Round down small differences in luminance channel.
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*/
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if (is_pframe) {
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p1 = ctx->cur_frame_buf;
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p2 = ctx->prev_frame_buf;
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for (i = 0; i < ctx->y_size; i++) {
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if (abs(p2[0] - p1[0]) < 7)
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p1[0] = p2[0];
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p1++;
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p2++;
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}
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}
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/*
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* Encode Y plane.
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*/
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for (y = 0; y < ctx->num_vblocks_y; y++) {
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for (x = 0; x < ctx->num_hblocks_y; x++) {
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/* Calculate final offset into buffer. */
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offset = (ctx->y_stride * 8 * y) + (x * 8);
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src = NULL;
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encoded = FALSE;
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if (is_pframe) {
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/* Is the current block similar enough to what it was in the previous frame? */
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match = compare_blocks(ctx->cur_frame_buf + offset,
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ctx->prev_frame_buf + offset,
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ctx->y_stride, 8,
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FALSE);
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if (match > LUMINANCE_THRESHOLD) {
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/* Yes: write out '1' to indicate a no-change condition. */
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_write_bits(ctx, 1, 1);
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src = ctx->prev_frame_buf + offset;
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encoded = TRUE;
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} else {
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/* No: Is the current block similar enough to what it was in one
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* of the (up to) 15 last frames preceding the previous? */
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gint best_index = 0;
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gdouble best_match = 0.0;
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gint num_backrefs = ctx->frame_num - 1;
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if (num_backrefs > 15)
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num_backrefs = 15;
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for (i = 1; i <= num_backrefs; i++) {
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match = compare_blocks(ctx->buf_ptrs[(ctx->ptr_index + i) % 16] + offset,
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ctx->cur_frame_buf + offset,
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ctx->y_stride, 8,
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FALSE);
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if (match > LUMINANCE_THRESHOLD && match > best_match) {
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best_index = i;
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best_match = match;
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}
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}
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if (best_index != 0) {
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/* Yes: write out '01' to indicate a "change but like previous"-condition,
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* followed by 4 bits containing the back-reference. */
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_write_bits(ctx, 0, 1);
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_write_bits(ctx, 1, 1);
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_write_bits(ctx, best_index, 4);
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src = ctx->buf_ptrs[(ctx->ptr_index + best_index) % 16] + offset;
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encoded = TRUE;
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}
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}
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}
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if (!encoded) {
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/* Keyframe or in any case no? ;-) Well, encode it then. */
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if (is_pframe) {
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_write_bits(ctx, 0, 1);
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_write_bits(ctx, 0, 1);
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}
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_fdct_quant_block(ctx,
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dct_block,
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ctx->cur_frame_buf + offset,
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ctx->y_stride,
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FALSE,
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ctx->num_coeffs);
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_vlc_encode_block(ctx,
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dct_block,
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ctx->num_coeffs);
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}
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/* And if there was some kind of no-change condition,
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* we want to copy the previous block. */
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if (src != NULL) {
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dst = ctx->cur_frame_buf + offset;
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for (i = 0; i < 8; i++) {
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memcpy(dst, src, 8);
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src += ctx->y_stride;
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dst += ctx->y_stride;
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}
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}
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}
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}
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/*
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* Encode Cr and Cb planes.
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*/
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for (chrom_ch = 0; chrom_ch < 2; chrom_ch++) {
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/* Calculate base offset into buffer. */
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gint base_offset = ctx->y_size + (ctx->crcb_size * chrom_ch);
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for (y = 0; y < ctx->num_vblocks_cbcr; y++) {
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guchar tmp_block[64];
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guint num_rows = 8;
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/* The last row of blocks in chrominance for 160x120 resolution
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* is half the normal height and must be accounted for. */
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if (y + 1 == ctx->num_vblocks_cbcr && ctx->frame_height % 16 != 0)
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num_rows = 4;
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for (x = 0; x < ctx->num_hblocks_cbcr; x++) {
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/* Calculate final offset into buffer. */
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offset = base_offset + (ctx->crcb_stride * 8 * y) + (x * 8);
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src = NULL;
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encoded = FALSE;
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if (is_pframe) {
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/* Is the current block similar enough to what it was in the previous frame? */
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match = compare_blocks(ctx->prev_frame_buf + offset,
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ctx->cur_frame_buf + offset,
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ctx->crcb_stride, num_rows,
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TRUE);
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if (match > CHROMINANCE_THRESHOLD) {
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/* Yes: write out '0' to indicate a no-change condition. */
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_write_bits(ctx, 0, 1);
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encoded = TRUE;
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src = ctx->prev_frame_buf + offset;
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dst = ctx->cur_frame_buf + offset;
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for (i = 0; i < num_rows; i++) {
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memcpy(dst, src, 8);
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src += ctx->crcb_stride;
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dst += ctx->crcb_stride;
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}
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}
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}
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if (!encoded) {
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/* Keyframe or just not similar enough? ;-) Well, encode it then. */
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if (is_pframe)
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_write_bits(ctx, 1, 1);
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/* Use a temporary array to handle cases where the
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* current block is not of normal height (see above). */
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src = ctx->cur_frame_buf + offset;
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dst = tmp_block;
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for (i = 0; i < 8; i++) {
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memcpy(dst, src, 8);
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if (i < (num_rows - 1))
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src += ctx->crcb_stride;
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dst += 8;
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}
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_fdct_quant_block(ctx,
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dct_block,
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tmp_block,
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8,
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TRUE,
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ctx->num_coeffs);
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_vlc_encode_block(ctx,
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dct_block,
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ctx->num_coeffs);
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}
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}
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}
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}
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/*
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* Make a copy of the current frame and store in
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* the circular pointer list of 16 entries.
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*/
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ctx->prev_frame_buf = ctx->buf_ptrs[ctx->ptr_index];
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memcpy(ctx->prev_frame_buf, ctx->cur_frame_buf,
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ctx->y_size + (ctx->crcb_size * 2));
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if (--ctx->ptr_index < 0)
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ctx->ptr_index = 15;
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}
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/*
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* compare_blocks
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*
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* Helper-function used to compare two blocks and
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* determine how similar they are.
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*/
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static gdouble compare_blocks(const guchar *p1,
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const guchar *p2,
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gint stride,
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gint row_count,
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gboolean is_chrom)
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{
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gint i, j, sum;
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gdouble d;
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sum = 0;
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for (i = 0; i < row_count; i++) {
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for (j = 0; j < 8; j++) {
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gint d = p2[j] - p1[j];
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sum += d * d;
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}
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p1 += stride;
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p2 += stride;
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}
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if (is_chrom) {
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if (row_count == 8)
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d = sum * 0.015625;
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else
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d = sum * 0.03125;
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} else {
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d = sum / 64;
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}
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if (d == 0.0f)
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return 100.0f;
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else
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return (10.0f * log(65025.0f / d)) / G_LN10;
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}
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