/* 将数据从hdr结构翻译为fr_ps */
void hdr_to_frps(frame_params *fr_ps)
{
layer *hdr = fr_ps->header; /* (or pass in as arg?) */
fr_ps->actual_mode = hdr->mode;
fr_ps->stereo = (hdr->mode == MPG_MD_MONO) ? 1 : 2;
fr_ps->sblimit = SBLIMIT;
if(hdr->mode == MPG_MD_JOINT_STEREO)
fr_ps->jsbound = js_bound(hdr->lay, hdr->mode_ext);
else
fr_ps->jsbound = fr_ps->sblimit;
}
void II_main_bit_allocation
(
DOUBLE perm_smr[2][SBLIMIT],
UINT scfsi[2][SBLIMIT],
UINT bit_alloc[2][SBLIMIT],
INT* adb,
FRAME* pFrame,
PSETTINGS pSettings
)
{
int noisy_sbs;
int rq_db, av_db = *adb;
// If mode equals to joint stereo, find the optimum jsbound setting
if( pFrame->actual_mode == MPG_MD_JOINT_STEREO)
{
// Start with standard stereo setup
pFrame->pHeader->mode = MPG_MD_STEREO;
pFrame->pHeader->mode_ext = 0;
pFrame->jsbound = pFrame->sblimit;
// Calculate the required bits
if((rq_db=II_bits_for_nonoise(perm_smr, scfsi, pFrame,0)) > *adb)
{
int mode_ext=4;
// Were a few bits short, switch to joint stereo
pFrame->pHeader->mode = MPG_MD_JOINT_STEREO;
// Start with mode extention 3 (is decremented first in while loop)
do
{
// Decrease mode extention
mode_ext--;
// Get new joint stereo subband boundary
pFrame->jsbound = js_bound(pFrame->pHeader->lay, mode_ext);
// Calculate the number of required bits with the new settings
rq_db = II_bits_for_nonoise(perm_smr, scfsi, pFrame,0);
// Check if we have enough bits, and if we still can lower the
// joint stereo subband boundary
} while( (rq_db > *adb) && (mode_ext > 0));
pFrame->pHeader->mode_ext = mode_ext;
} /* well we either eliminated noisy sbs or mode_ext == 0 */
}
if (pSettings->bUseVbr == FALSE)
{
noisy_sbs = II_a_bit_allocation(perm_smr, scfsi, bit_alloc, adb, pFrame);
}
else
{
int nCurrentAllocTab=0;
int nReqBits=0;
int nChanIdx = pSettings->pFrame->nChannels-1;
int i;
// Start with minimum bitrate
for (i=0;i<15;i++)
{
if ( pSettings->nMinBitRateIndex<=AllowedBrIdx[nChanIdx][i])
break;
}
pFrame->pHeader->bitrate_index=AllowedBrIdx[nChanIdx][i++];
// Recalculate the sbLimit and select proper ALLOC table
hdr_to_frps(pFrame);
// Determine the available bits for this frame, with current bitrate settings
*adb = available_bits(pSettings);
// Work out how many bits are needed for there to be no noise (ie all MNR > 0.0 + VBRLEVEL)
// Keep bumping up the bitrate until we have more than this number of bits
nCurrentAllocTab=pFrame->tab_num;
if (pSettings->nFrame==192)
{
printf("break\n");
}
nReqBits=II_bits_for_nonoise(perm_smr, scfsi, pFrame,pSettings->nVbrQuality+(nCurrentAllocTab==2)?20:0);
// nReqBits=II_bits_for_nonoise(perm_smr, scfsi, pFrame,pSettings->nVbrQuality);
if ( pSettings->nDebugLevel > 3 )
{
DebugPrintf("VBR: req_bits=%i for bitrate setting %d adb=%d table=%d\n",
nReqBits,
bitrate[pFrame->pHeader->version][pFrame->pHeader->lay-1][pFrame->pHeader->bitrate_index],
*adb,
nCurrentAllocTab
);
}
while ( (nReqBits > *adb) && (AllowedBrIdx[nChanIdx][i]!=-1) )
{
// We are not there yet, increase bit rate if possible
pFrame->pHeader->bitrate_index=AllowedBrIdx[nChanIdx][i++];
// Limit to maximum bitrate index
//if (pFrame->pHeader->bitrate_index > 14)
// pFrame->pHeader->bitrate_index = 14;
// Get new frame header parameters for this bitrate setting
hdr_to_frps(pFrame);
// Did we switch from alloc table? If so, calculate new required bits
if (nCurrentAllocTab!=pFrame->tab_num)
{
nReqBits=II_bits_for_nonoise(perm_smr, scfsi, pFrame,pSettings->nVbrQuality);
nCurrentAllocTab=pFrame->tab_num;
}
// Get the number of available bits for the new frame settings
*adb = available_bits(pSettings);
if ( pSettings->nDebugLevel > 2 )
{
DebugPrintf("VBR: req_bits=%i for bitrate setting %d adb=%d table=%d\n",
nReqBits,
bitrate[pFrame->pHeader->version][pFrame->pHeader->lay-1][pFrame->pHeader->bitrate_index],
*adb,
nCurrentAllocTab
);
}
}
noisy_sbs = VBR_bit_allocation(perm_smr, scfsi, bit_alloc, adb, pFrame,pSettings);
}
if ( pSettings->nDebugLevel > 2 )
{
DebugPrintf("VBR frame=%d bitrate=%4d, noisy_sbs=%4d , adb is %3d sblimit=%2d sbound=%2d\n",
pSettings->nFrame,
bitrate[pFrame->pHeader->version][pFrame->pHeader->lay-1][pFrame->pHeader->bitrate_index],
noisy_sbs,
*adb,
pFrame->sblimit,
pFrame->jsbound
);
}
}
