--- /dev/null
+/*
+ (c) Copyright 1998-2000 - Tord Jansson
+ ======================================
+
+ This file is part of the BladeEnc MP3 Encoder, based on
+ ISO's reference code for MPEG Layer 3 compression, and might
+ contain smaller or larger sections that are directly taken
+ from ISO's reference code.
+
+ All changes to the ISO reference code herein are either
+ copyrighted by Tord Jansson (tord.jansson@swipnet.se)
+ or sublicensed to Tord Jansson by a third party.
+
+ BladeEnc is free software; you can redistribute this file
+ 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.
+
+
+
+ ------------ Changes ------------
+
+ 2000-12-11 Andre Piotrowski
+
+ - reformatted
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <assert.h>
+
+#include "common.h"
+#include "l3side.h"
+#include "loop.h"
+#include "huffman.h"
+#include "l3bitstream.h"
+#include "reservoir.h"
+
+
+
+
+
+/*
+ Layer3 bit reservoir:
+ Described in C.1.5.4.2.2 of the IS
+*/
+
+static int ResvSize = 0; /* in bits */
+static int ResvMax = 0; /* in bits */
+
+
+
+
+
+void fixStatic_reservoir (void)
+{
+ ResvSize = 0;
+ ResvMax = 0;
+}
+
+
+
+
+
+/*
+ ResvFrameBegin:
+ Called at the beginning of a frame. Updates the maximum
+ size of the reservoir, and checks to make sure main_data_begin
+ was set properly by the formatter
+*/
+void ResvFrameBegin
+(
+ frame_params *fr_ps,
+ III_side_info_t *l3_side,
+ int mean_bits,
+ int frameLength
+)
+{
+ layer *info;
+ int fullFrameBits, mode_gr;
+ int expectedResvSize, resvLimit;
+
+
+ info = fr_ps->header;
+ mode_gr = 2;
+ resvLimit = 4088; /* main_data_begin has 9 bits in MPEG 1 */
+
+
+ /*
+ main_data_begin was set by the formatter to the
+ expected value for the next call -- this should
+ agree with our reservoir size
+ */
+ expectedResvSize = l3_side->main_data_begin * 8;
+/* assert (expectedResvSize == ResvSize); */
+
+ fullFrameBits = mean_bits * mode_gr;
+
+ /*
+ determine maximum size of reservoir:
+ ResvMax + frameLength <= 7680;
+
+ limit max size to resvLimit bits because
+ main_data_begin cannot indicate a
+ larger value
+ */
+ ResvMax = MIN(MAX (0, 7680-frameLength), resvLimit);
+}
+
+
+
+
+
+/*
+ ResvMaxBits:
+ Called at the beginning of each granule to get the max bit
+ allowance for the current granule based on reservoir size
+ and perceptual entropy.
+*/
+int ResvMaxBits
+(
+ frame_params *fr_ps,
+ III_side_info_t *l3_side,
+ double *pe,
+ int mean_bits
+)
+{
+ int more_bits, max_bits, add_bits, over_bits;
+
+
+ mean_bits /= fr_ps->stereo;
+
+ max_bits = mean_bits;
+
+ if (ResvMax != 0)
+ {
+ more_bits = (int) (*pe * 3.1 - mean_bits);
+
+ if (more_bits > 100)
+ {
+ int frac = (ResvSize * 6) / 10;
+
+ add_bits = MIN(frac, more_bits);
+ }
+ else
+ add_bits = 0;
+
+ over_bits = ResvSize - ((ResvMax * 8) / 10) - add_bits;
+ if (over_bits > 0)
+ add_bits += over_bits;
+
+ max_bits += add_bits;
+ }
+
+ if (max_bits > 4095)
+ max_bits = 4095;
+
+ return max_bits;
+}
+
+
+
+
+
+/*
+ ResvAdjust:
+ Called after a granule's bit allocation. Readjusts the size of
+ the reservoir to reflect the granule's usage.
+*/
+void ResvAdjust
+(
+ frame_params *fr_ps,
+ gr_info *cod_info,
+ III_side_info_t *l3_side,
+ int mean_bits
+)
+{
+ ResvSize += (mean_bits / fr_ps->stereo) - cod_info->part2_3_length;
+}
+
+
+
+
+
+/*
+ ResvFrameEnd:
+ Called after all granules in a frame have been allocated. Makes sure
+ that the reservoir size is within limits, possibly by adding stuffing
+ bits. Note that stuffing bits are added by increasing a granule's
+ part2_3_length. The bitstream formatter will detect this and write the
+ appropriate stuffing bits to the bitstream.
+*/
+void ResvFrameEnd
+(
+ frame_params *fr_ps,
+ III_side_info_t *l3_side,
+ int mean_bits
+)
+{
+ layer *info;
+ gr_info *cod_info;
+ int mode_gr, gr, ch, stereo, ancillary_pad, stuffingBits;
+ int over_bits;
+
+ info = fr_ps->header;
+ stereo = fr_ps->stereo;
+ mode_gr = 2;
+
+ ancillary_pad = 0;
+
+ /* just in case mean_bits is odd, this is necessary... */
+ if ((stereo == 2) && (mean_bits & 1))
+ ResvSize ++;
+
+ stuffingBits = ancillary_pad;
+
+ if ((over_bits = ResvSize - ResvMax) > 0)
+ {
+ stuffingBits += over_bits;
+ ResvSize -= over_bits;
+ }
+
+ /* we must be byte aligned */
+ if ((over_bits = ResvSize % 8) != 0)
+ {
+ stuffingBits += over_bits;
+ ResvSize -= over_bits;
+ }
+
+ if (stuffingBits)
+ {
+ /*
+ plan a: put all into the first granule
+ This was preferred by someone designing a
+ real-time decoder...
+ */
+ cod_info = &l3_side->gr[0].ch[0].tt;
+
+ if (cod_info->part2_3_length + stuffingBits < 4095)
+ cod_info->part2_3_length += stuffingBits;
+ else
+ {
+ /* plan b: distribute throughout the granules */
+ for (gr = 0; gr < mode_gr; gr++)
+ {
+ for (ch = 0; ch < stereo; ch++)
+ {
+ int extraBits, bitsThisGr;
+ gr_info *cod_info = &l3_side->gr[gr].ch[ch].tt;
+
+ if (stuffingBits == 0)
+ break;
+ extraBits = 4095 - cod_info->part2_3_length;
+ bitsThisGr = (extraBits < stuffingBits) ? extraBits : stuffingBits;
+ cod_info->part2_3_length += bitsThisGr;
+ stuffingBits -= bitsThisGr;
+ }
+ }
+ /*
+ If any stuffing bits remain, we elect to spill them
+ into ancillary data. The bitstream formatter will do this if
+ l3side->resvDrain is set
+ */
+ l3_side->resvDrain = stuffingBits;
+ }
+ }
+}
git.asbjorn.biz / swftools.git / blobdiff