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IPU: Implement start code validation for BDEC/IDEC 

According to MPEG specs when 8 "0" bits are found, we should check for 000001xxh. Recommended way is to check 24 bits (000001h), and if they won't match discard 8 bits and try again until valid code is found, or stream ends.
This commit is contained in:
Goatman13 2022-05-29 18:48:39 +02:00 committed by refractionpcsx2
parent 8d3c82de19
commit 2dd9d8338b
1 changed files with 32 additions and 2 deletions
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34
pcsx2/IPU/mpeg2lib/Mpeg.cpp
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@ -920,6 +920,7 @@ finish_idec:
case 3:
{
u8 bit8;
u32 start_check;
if (!getBits8((u8*)&bit8, 0))
{
ipu_cmd.pos[0] = 3;
@ -929,7 +930,21 @@ finish_idec:
if (bit8 == 0)
{
g_BP.Align();
ipuRegs.ctrl.SCD = 1;
do
{
if (!g_BP.FillBuffer(24))
{
ipu_cmd.pos[0] = 3;
return false;
}
start_check = UBITS(24);
if (start_check == 1)
{
ipuRegs.ctrl.SCD = 1;
break;
}
DUMPBITS(8);
} while (start_check != 1);
}
}
[[fallthrough]];
@ -1196,6 +1211,7 @@ __fi bool mpeg2_slice()
case 4:
{
u8 bit8;
u32 start_check;
if (!getBits8((u8*)&bit8, 0))
{
ipu_cmd.pos[0] = 4;
@ -1205,7 +1221,21 @@ __fi bool mpeg2_slice()
if (bit8 == 0)
{
g_BP.Align();
ipuRegs.ctrl.SCD = 1;
do
{
if (!g_BP.FillBuffer(24))
{
ipu_cmd.pos[0] = 4;
return false;
}
start_check = UBITS(24);
if (start_check == 1)
{
ipuRegs.ctrl.SCD = 1;
break;
}
DUMPBITS(8);
} while (start_check != 1);
}
}
[[fallthrough]];