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/* $Id$ */
/* Copyright (c) 1995 Oregon Graduate Institute of Science and Technology
* P.O.Box 91000-1000, Portland, OR 97291, USA;
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of O.G.I. not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. O.G.I. makes no representations about the
* suitability of this software for any purpose. It is provided "as is"
* without express or implied warranty.
*
* O.G.I. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
* ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
* O.G.I. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
* DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Author: Shanwei Cen
* Department of Computer Science and Engineering
* email: scen@cse.ogi.edu
*/
#include <string.h>
#include "sendpt.h"
ACE_RCSID(mpeg_shared, sendpt, "$Id$")
/* parameters:
pat -- pattern
buf -- buffer for holding sendpattern computed;
len -- length of pattern and send pattern (number of frames);
f -- number of frames to send (represented by result send pattern);
*/
void ComputeSendPattern(char * pat, char * buf, int len, int f)
{
memset(buf, 0, len);
if (f >= len)
{
memset(buf, 1, len);
}
else if (f <= 1)
{
buf[0] = 1;
}
else
{
int i, is = 0, ps = 0, bs = 0;
memset(buf, 1, len);
for (i = 0; i < len; i++)
{
if (pat[i] == 'I')
is ++;
else if (pat[i] == 'P')
ps ++;
else /* B frame */
bs ++;
}
f = len - f; /* number of frames to drop */
if (f < bs) /* drops only B frames */
{
double scale = (double)bs / (double)f;
int ptr = 0, ptr1 = 0;
for (i = 0; i < len; i ++)
{
if (pat[i] == 'B')
{
if ( ptr == (int) ((double)ptr1 * scale + 0.5))
{
buf[i] = 0;
ptr1 ++;
}
ptr ++;
}
}
goto endOfCompute;
}
/* drop all B frames */
for (i = 0; i < len; i ++)
if (pat[i] == 'B')
buf[i] = 0;
if (f == bs)
goto endOfCompute;
if (f > bs && f < bs + ps) /* drop also some P frames */
{
int ptr = len - 1;
for (i = 0; i < is; i ++)
{
int j;
for (j = 0; j < (f - bs) / is; j ++)
{
while (pat[ptr] != 'P') ptr --;
buf[ptr] = 0;
ptr --;
}
while (pat[ptr] != 'I') ptr --;
}
ptr = len - 1;
for (i = 0; i < (f - bs) % is; i ++)
{
while (pat[ptr] != 'P' || buf[ptr] == 0) ptr --;
buf[ptr] = 0;
while (pat[ptr] != 'I') ptr --;
}
goto endOfCompute;
}
/* drop all P frames */
for (i = 0; i < len; i ++)
if (pat[i] == 'P')
buf[i] = 0;
if (f > bs + ps) /* needs to drop some I frames */
{
double scale = (double)is / (double)(f - bs - ps);
int ptr = 0, ptr1 = 0;
for (i = 0; i < len; i ++)
{
if (pat[i] == 'I')
{
if ( ptr == (int) ((double)ptr1 * scale + 0.5))
{
buf[i] = 0;
ptr1 ++;
}
ptr ++;
}
}
goto endOfCompute;
}
}
endOfCompute:;
}
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