gstreamer/gst-libs/ext/mplex/ac3strm_in.cc

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/*
* ac3strm_in.c: AC3 Audio strem class members handling scanning and
* buffering raw input stream.
*
* Copyright (C) 2001 Andrew Stevens <andrew.stevens@philips.com>
* Copyright (C) 2000,2001 Brent Byeler for original header-structure
* parsing code.
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public License
* as published by the Free Software Foundation.
*
* This program 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 <config.h>
#include <math.h>
#include <stdlib.h>
#include "audiostrm.hh"
#include "outputstream.hh"
#include <cassert>
#define AC3_SYNCWORD 0x0b77
#define AC3_PACKET_SAMPLES 1536
/// table for the available AC3 bitrates
static const unsigned int ac3_bitrate_index[32] =
{
32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192,
224, 256, 320, 384, 448, 512, 576, 640,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
static const unsigned int ac3_frame_size[3][32] =
{
{64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384,
448, 512, 640, 768, 896, 1024, 1152, 1280,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{69, 87, 104, 121, 139, 174, 208, 243, 278, 348, 417,
487, 557, 696, 835, 975, 1114, 1253, 1393,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{96, 120, 144, 168, 192, 240, 288, 336, 384, 480, 576,
672, 768, 960, 1152, 1344, 1536, 1728, 1920,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
};
/// table for the available AC3 frequencies
static const unsigned int ac3_frequency[4] = { 48000, 44100, 32000, 0 };
AC3Stream::AC3Stream (IBitStream & ibs, OutputStream & into):
AudioStream (ibs, into)
{
}
bool
AC3Stream::Probe (IBitStream & bs)
{
return bs.getbits (16) == AC3_SYNCWORD;
}
/*************************************************************************
*
* Reads initial stream parameters and displays feedback banner to users
* @param stream_num AC3 substream ID
*************************************************************************/
void
AC3Stream::Init (const int stream_num)
{
unsigned int framesize_code;
this->stream_num = stream_num;
MuxStream::Init (PRIVATE_STR_1, 1, // Buffer scale
default_buffer_size,
muxinto.vcd_zero_stuffing,
muxinto.buffers_in_audio, muxinto.always_buffers_in_audio);
mjpeg_info ("Scanning for header info: AC3 Audio stream %02x", stream_num);
InitAUbuffer ();
AU_start = bs.bitcount ();
if (bs.getbits (16) == AC3_SYNCWORD) {
num_syncword++;
bs.getbits (16); // CRC field
frequency = bs.getbits (2); // Sample rate code
framesize_code = bs.getbits (6); // Frame size code
framesize = ac3_frame_size[frequency][framesize_code >> 1];
framesize = (framesize_code & 1) && frequency == 1 ? (framesize + 1) << 1 : (framesize << 1);
size_frames[0] = framesize;
size_frames[1] = framesize;
num_frames[0]++;
access_unit.start = AU_start;
access_unit.length = framesize;
bit_rate = ac3_bitrate_index[framesize_code >> 1];
samples_per_second = ac3_frequency[frequency];
/* Presentation time-stamping */
access_unit.PTS = static_cast < clockticks > (decoding_order) *
static_cast < clockticks > (AC3_PACKET_SAMPLES) *
static_cast < clockticks > (CLOCKS) / samples_per_second;
access_unit.DTS = access_unit.PTS;
access_unit.dorder = decoding_order;
++decoding_order;
aunits.append (access_unit);
} else {
mjpeg_error ("Invalid AC3 Audio stream header.");
exit (1);
}
OutputHdrInfo ();
}
/// @returns the current bitrate
unsigned int
AC3Stream::NominalBitRate ()
{
return bit_rate;
}
/// Prefills the internal buffer for output multiplexing.
/// @param frames_to_buffer the number of audio frames to read ahead
void
AC3Stream::FillAUbuffer (unsigned int frames_to_buffer)
{
unsigned int framesize_code;
last_buffered_AU += frames_to_buffer;
mjpeg_debug ("Scanning %d MPEG audio frames to frame %d", frames_to_buffer, last_buffered_AU);
static int header_skip = 5; // Initially skipped past 5 bytes of header
int skip;
bool bad_last_frame = false;
while (!bs.eos () &&
decoding_order < last_buffered_AU) {
skip = access_unit.length - header_skip;
if (skip & 0x1)
bs.getbits (8);
if (skip & 0x2)
bs.getbits (16);
skip = skip >> 2;
for (int i = 0; i < skip; i++) {
bs.getbits (32);
}
prev_offset = AU_start;
AU_start = bs.bitcount ();
if (AU_start - prev_offset != access_unit.length * 8) {
bad_last_frame = true;
break;
}
/* Check we have reached the end of have another catenated
stream to process before finishing ... */
if ((syncword = bs.getbits (16)) != AC3_SYNCWORD) {
if (!bs.eos ()) {
mjpeg_error_exit1 ("Can't find next AC3 frame - broken bit-stream?");
}
break;
}
bs.getbits (16); // CRC field
bs.getbits (2); // Sample rate code TOOD: check for change!
framesize_code = bs.getbits (6);
framesize = ac3_frame_size[frequency][framesize_code >> 1];
framesize = (framesize_code & 1) && frequency == 1 ? (framesize + 1) << 1 : (framesize << 1);
access_unit.start = AU_start;
access_unit.length = framesize;
access_unit.PTS = static_cast < clockticks > (decoding_order) *
static_cast < clockticks > (AC3_PACKET_SAMPLES) *
static_cast < clockticks > (CLOCKS) / samples_per_second;;
access_unit.DTS = access_unit.PTS;
access_unit.dorder = decoding_order;
decoding_order++;
aunits.append (access_unit);
num_frames[0]++;
num_syncword++;
#ifdef DEBUG_AC3_HEADERS
/* Some stuff to generate frame-header information */
printf ("bsid = %d\n", bs.getbits (5));
printf ("bsmode = 0x%1x\n", bs.getbits (3));
int acmode = bs.getbits (3);
printf ("acmode = 0x%1x\n", acmode);
if ((acmode & 0x1) && (acmode != 1))
printf ("cmixlev = %d\n", bs.getbits (2));
if ((acmode & 0x4))
printf ("smixlev = %d\n", bs.getbits (2));
if (acmode == 2)
printf ("dsurr = %d\n", bs.getbits (2));
printf ("lfeon = %d\n", bs.getbits (1));
printf ("dialnorm = %02d\n", bs.getbits (5));
int compre = bs.getbits (1);
printf ("compre = %d\n", compre);
if (compre)
printf ("compr = %02d\n", bs.getbits (8));
int langcode = bs.getbits (1);
printf ("langcode = %d\n", langcode);
if (langcode)
printf ("langcod = 0x%02x\n", bs.getbits (8));
while (bs.bitcount () % 8 != 0)
bs.getbits (1);
header_skip = (bs.bitcount () - AU_start) / 8;
#endif
if (num_syncword >= old_frames + 10) {
mjpeg_debug ("Got %d frame headers.", num_syncword);
old_frames = num_syncword;
}
}
if (bad_last_frame) {
mjpeg_error_exit1 ("Last AC3 frame ended prematurely!\n");
}
last_buffered_AU = decoding_order;
eoscan = bs.eos ();
}
/// Closes the AC3 stream and prints some statistics.
void
AC3Stream::Close ()
{
stream_length = AU_start >> 3;
mjpeg_info ("AUDIO_STATISTICS: %02x", stream_id);
mjpeg_info ("Audio stream length %lld bytes.", stream_length);
mjpeg_info ("Syncwords : %8u", num_syncword);
mjpeg_info ("Frames : %8u padded", num_frames[0]);
mjpeg_info ("Frames : %8u unpadded", num_frames[1]);
bs.close ();
}
/*************************************************************************
OutputAudioInfo
gibt gesammelte Informationen zu den Audio Access Units aus.
Prints information on audio access units
*************************************************************************/
void
AC3Stream::OutputHdrInfo ()
{
mjpeg_info ("AC3 AUDIO STREAM:");
mjpeg_info ("Bit rate : %8u bytes/sec (%3u kbit/sec)", bit_rate * 128, bit_rate);
if (frequency == 3)
mjpeg_info ("Frequency : reserved");
else
mjpeg_info ("Frequency : %d Hz", ac3_frequency[frequency]);
}
/**
Reads the bytes neccessary to complete the current packet payload.
@param to_read number of bytes to read
@param dst byte buffer pointer to read to
@returns the number of bytes read
*/
unsigned int
AC3Stream::ReadPacketPayload (uint8_t * dst, unsigned int to_read)
{
static unsigned int aus = 0;
static unsigned int rd = 0;
unsigned int bytes_read = bs.read_buffered_bytes (dst + 4, to_read - 4);
rd += bytes_read;
clockticks decode_time;
unsigned int first_header = (new_au_next_sec || au_unsent > bytes_read)
? 0 : au_unsent;
// BUG BUG BUG: how do we set the 1st header pointer if we have
// the *middle* part of a large frame?
assert (first_header <= to_read - 2);
unsigned int syncwords = 0;
unsigned int bytes_muxed = bytes_read;
if (bytes_muxed == 0 || MuxCompleted ()) {
goto completion;
}
/* Work through what's left of the current AU and the following AU's
updating the info until we reach a point where an AU had to be
split between packets.
NOTE: It *is* possible for this loop to iterate.
The DTS/PTS field for the packet in this case would have been
given the that for the first AU to start in the packet.
*/
decode_time = RequiredDTS ();
while (au_unsent < bytes_muxed) {
// BUG BUG BUG: if we ever had odd payload / packet size we might
// split an AC3 frame in the middle of the syncword!
assert (bytes_muxed > 1);
bufmodel.Queued (au_unsent, decode_time);
bytes_muxed -= au_unsent;
if (new_au_next_sec)
++syncwords;
aus += au->length;
if (!NextAU ()) {
goto completion;
}
new_au_next_sec = true;
decode_time = RequiredDTS ();
};
// We've now reached a point where the current AU overran or
// fitted exactly. We need to distinguish the latter case
// so we can record whether the next packet starts with an
// existing AU or not - info we need to decide what PTS/DTS
// info to write at the start of the next packet.
if (au_unsent > bytes_muxed) {
if (new_au_next_sec)
++syncwords;
bufmodel.Queued (bytes_muxed, decode_time);
au_unsent -= bytes_muxed;
new_au_next_sec = false;
} else // if (au_unsent == bytes_muxed)
{
bufmodel.Queued (bytes_muxed, decode_time);
if (new_au_next_sec)
++syncwords;
aus += au->length;
new_au_next_sec = NextAU ();
}
completion:
// Generate the AC3 header...
// Note the index counts from the low byte of the offset so
// the smallest value is 1!
dst[0] = AC3_SUB_STR_0 + stream_num;
dst[1] = syncwords;
dst[2] = (first_header + 1) >> 8;
dst[3] = (first_header + 1) & 0xff;
return bytes_read + 4;
}
/*
* Local variables:
* c-file-style: "stroustrup"
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/