www.pudn.com > mediator15src.zip > unpacketizer.cpp
/*
* unpacketizer.cpp
* Copyright (C) 2001-2002 Arno Hornberger
*
* This file is part of MPEG Mediator, a free MPEG stream converter.
*
* MPEG Mediator is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* MPEG Mediator is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "unpacketizer.h"
void Unpacketizer::SetStream(AsyncStream *stream)
{
bs = stream;
mpeg2 = false;
Seek(bs->Tell());
}
__int64 Unpacketizer::Tell()
{
if (!sync_pack)
return payload_pos;
else
return seek_pos;
}
void Unpacketizer::Seek(__int64 pos)
{
seek_pos = pos;
program_mux_base = 0;
program_mux_rate = 1;
scr_pack = 0;
scr_base = 0;
scr_offset = 0;
sync_pack = true;
}
void Unpacketizer::Resync()
{
if (!sync_pack)
bs->Seek(payload_pos);
else
bs->Seek(seek_pos);
}
void Unpacketizer::GetPayloadBytes(unsigned char *dest, int numbytes)
{
if (numbytes > payload_bytes - (int)(payload_pos - payload_start))
return; // read only within this packet!
bs->GetBytes(dest, numbytes);
payload_pos += numbytes;
}
void Unpacketizer::FlushPayloadBytes(int numbytes)
{
if (numbytes > payload_bytes - (int)(payload_pos - payload_start))
return;
bs->FlushBytes(numbytes);
payload_pos += numbytes;
}
unsigned char Unpacketizer::GetPayloadByte()
{
unsigned char val;
if (payload_pos >= payload_start + payload_bytes)
return 0; // read out of bounds
val = bs->GetByte();
payload_pos++;
return val;
}
void Unpacketizer::NextPacket()
{
__int64 scr_pack_old, scr_old;
unsigned long code;
int header_data_length, packet_length;
int i;
if (!sync_pack) // Go to next startcode
bs->Seek(payload_start + payload_bytes);
else
bs->Seek(seek_pos);
search_packet:
code = bs->GetBits(32);
if (sync_pack)
{
try
{
while (code != ((START_CODE_PREFIX << 8) | PACK_START_CODE))
code = (code << 8) | bs->GetByte();
}
catch (DemuxExcept &e)
{
if (e.WhatCode() == DemuxExcept::END_OF_STREAM)
throw DemuxExcept(DemuxExcept::NO_PROGRAM_STREAM);
else
throw;
}
mpeg2 = (bs->LookAhead(2) == 1);
}
else {
while (code >> 8 != START_CODE_PREFIX)
code = (code << 8) | bs->GetByte();
}
stream_id = (int)(code & 0x000000ff);
switch (stream_id)
{
case PACK_START_CODE:
if (sync_pack)
scr_old = 0;
else
scr_old = GetSCR(bs->Tell() - 5);
bs->GetBits(2);
if (!mpeg2)
bs->GetBits(2);
scr_pack_old = scr_pack;
scr_pack = bs->GetBits(3); // SCR[32..30]
bs->FlushBit(); // marker_bit
scr_pack <<= 15;
scr_pack |= bs->GetBits(15); // SCR[29..15]
bs->FlushBit(); // marker_bit
scr_pack <<= 15;
scr_pack |= bs->GetBits(15); // SCR[14..0]
// there are encoders out there which
// start at negative scr's
if ((scr_pack & 0x00000001fff00000) == 0x00000001fff00000)
scr_pack |= 0xfffffffe00000000;
program_mux_base = bs->Tell(); // should be ok in MPEG-1 and MPEG-2
bs->FlushBit(); // marker_bit
scr_pack *= 300;
if (mpeg2) {
if (scr_pack >= 0)
scr_pack += bs->GetBits(9);
else
scr_pack -= bs->GetBits(9);
}
if (scr_pack < scr_pack_old) // ensure linear time
{
scr_base = scr_pack;
scr_offset = scr_old;
}
bs->FlushBit(); // marker_bit
program_mux_rate = bs->GetBits(22);
if (program_mux_rate == 0)
throw DemuxExcept(DemuxExcept::MUXRATE_ZERO_ERROR);
bs->FlushBit(); // marker_bit
if (mpeg2)
{
bs->FlushBit(); // marker_bit
bs->GetBits(5); // reserved
i = (int)(bs->GetBits(3)); // pack_stuffing_length
bs->FlushBytes(i);
}
sync_pack = false;
goto search_packet;
case SYSTEM_HEADER_START_CODE:
i = (int)(bs->GetBits(16)); // header_length
bs->FlushBytes(i);
goto search_packet;
case PROGRAM_END_CODE:
throw DemuxExcept(DemuxExcept::END_OF_STREAM);
default:
packet_length = (int)(bs->GetBits(16));
switch (stream_id)
{
case PROGRAM_STREAM_MAP:
case PRIVATE_STREAM_2:
case ECM_STREAM:
case EMM_STREAM:
case PROGRAM_STREAM_DIRECTORY:
case DSMCC_STREAM:
case ITUTRECH222TYPEE_STREAM:
case PADDING_STREAM:
bs->FlushBytes(packet_length);
goto search_packet;
default:
if (mpeg2)
{
bs->GetByte();
pts_dts_flags = (int)(bs->GetBits(2));
bs->GetBits(6);
header_data_length = (int)(bs->GetBits(8));
payload_bytes = packet_length - header_data_length - 3;
if (pts_dts_flags == 0)
bs->FlushBytes(header_data_length);
else
{
if (pts_dts_flags == 2)
{
bs->GetBits(4);
pts = bs->GetBits(3); // PTS
bs->FlushBit();
pts <<= 15;
pts |= bs->GetBits(15);
bs->FlushBit();
pts <<= 15;
pts |= bs->GetBits(15);
bs->FlushBit();
pts *= 300;
if (pts < (scr_pack - 27000000 * 5))
throw DemuxExcept(DemuxExcept::TIMESTAMP_UNDERFLOW);
pts -= scr_base;
pts += scr_offset;
bs->FlushBytes(header_data_length - 5);
}
else if (pts_dts_flags == 3)
{
bs->GetBits(4);
pts = bs->GetBits(3); // PTS
bs->FlushBit();
pts <<= 15;
pts |= bs->GetBits(15);
bs->FlushBit();
pts <<= 15;
pts |= bs->GetBits(15);
bs->FlushBit();
pts *= 300;
if (pts < (scr_pack - 27000000 * 5))
throw DemuxExcept(DemuxExcept::TIMESTAMP_UNDERFLOW);
pts -= scr_base;
pts += scr_offset;
bs->GetBits(4);
dts = bs->GetBits(3); // DTS
bs->FlushBit();
dts <<= 15;
dts |= bs->GetBits(15);
bs->FlushBit();
dts <<= 15;
dts |= bs->GetBits(15);
bs->FlushBit();
dts *= 300;
// if (dts < scr_pack)
// throw DemuxExcept(DemuxExcept::TIMESTAMP_UNDERFLOW);
dts -= scr_base;
dts += scr_offset;
bs->FlushBytes(header_data_length - 10);
}
else
throw DemuxExcept(DemuxExcept::PROGRAM_STREAM_SYNTAX_ERROR);
}
}
else // MPEG-1
{
payload_bytes = packet_length;
while (bs->LookAhead(1) == 1)
{
bs->GetByte(); // remove stuffing bytes
payload_bytes--;
}
if (bs->LookAhead(2) == 1)
{
bs->GetByte(); // P-STD_buffer_size
bs->GetByte(); // and P-STD_buffer_scale
payload_bytes -= 2;
}
if (bs->LookAhead(4) == 2)
{
bs->GetBits(4);
pts = bs->GetBits(3); // PTS
bs->FlushBit();
pts <<= 15;
pts |= bs->GetBits(15);
bs->FlushBit();
pts <<= 15;
pts |= bs->GetBits(15);
bs->FlushBit();
pts *= 300;
if (pts < (scr_pack - 27000000 * 5))
throw DemuxExcept(DemuxExcept::TIMESTAMP_UNDERFLOW);
pts -= scr_base;
pts += scr_offset;
pts_dts_flags = 2;
payload_bytes -= 5;
}
else if (bs->LookAhead(4) == 3)
{
bs->GetBits(4);
pts = bs->GetBits(3); // PTS
bs->FlushBit();
pts <<= 15;
pts |= bs->GetBits(15);
bs->FlushBit();
pts <<= 15;
pts |= bs->GetBits(15);
bs->FlushBit();
pts *= 300;
if (pts < (scr_pack - 27000000 * 5))
throw DemuxExcept(DemuxExcept::TIMESTAMP_UNDERFLOW);
pts -= scr_base;
pts += scr_offset;
bs->GetBits(4);
dts = bs->GetBits(3); // DTS
bs->FlushBit();
dts <<= 15;
dts |= bs->GetBits(15);
bs->FlushBit();
dts <<= 15;
dts |= bs->GetBits(15);
bs->FlushBit();
dts *= 300;
// if (dts < scr_pack)
// throw DemuxExcept(DemuxExcept::TIMESTAMP_UNDERFLOW);
dts -= scr_base;
dts += scr_offset;
pts_dts_flags = 3;
payload_bytes -= 10;
}
else
{
if (bs->GetByte() != 0x0f)
throw DemuxExcept(DemuxExcept::PROGRAM_STREAM_SYNTAX_ERROR);
pts_dts_flags = 0;
payload_bytes--;
}
}
if (stream_id == PRIVATE_STREAM_1) {
substream_id = (int)(bs->GetByte());
payload_bytes--;
if ((substream_id >= SUBSTREAM_AC3_0) &&
(substream_id <= SUBSTREAM_AC3_7)) {
audio_framecount = (int)(bs->GetByte());
audio_frameoffset = (int)(bs->GetBits(16));
payload_bytes -= 3;
}
else if ((substream_id >= SUBSTREAM_LPCM_0) &&
(substream_id <= SUBSTREAM_LPCM_7)) {
audio_framecount = (int)(bs->GetByte());
audio_frameoffset = (int)(bs->GetBits(16));
// byte 0: LPCM-frames starting in this packet
// byte 1,2: start of first LPCM-frame (+ 4 bytes offset?!)
// byte 3: unknown (kindof a counter ?)
// byte 4,5: format identifier
//
// format identifier is 0x0180 for 16bit, 48kHz, stereo
// framesize in this mode is 80 samples (320 bytes)
//
// format identifier is 0x4180 for 20bit, 48kHz, stereo
// framesize in this mode is 80 samples (400 bytes)
//
// format identifier is 0x9180 for 24bit, 96kHz, stereo
// framesize in this mode is 160 samples (960 bytes)
bs->GetByte();
lpcm_type = bs->GetBits(16);
payload_bytes -= 6;
}
else if ((substream_id >= SUBSTREAM_DTS_0) &&
(substream_id <= SUBSTREAM_DTS_7)) {
bs->FlushBytes(3); // meaning of this header unknown
payload_bytes -= 3;
}
}
payload_start = bs->Tell();
payload_pos = payload_start;
// Prefetch payload,
// keep ringbuffer "linear"
// (performance issue)
bs->FlushBytes(payload_bytes);
bs->Seek(payload_start);
break;
}
break;
}
}