mkvtoolnix/p_ac3.cpp
2003-06-15 14:03:28 +00:00

188 lines
4.9 KiB
C++

/*
mkvmerge -- utility for splicing together matroska files
from component media subtypes
p_ac3.h
Written by Moritz Bunkus <moritz@bunkus.org>
Distributed under the GPL
see the file COPYING for details
or visit http://www.gnu.org/copyleft/gpl.html
*/
/*!
\file
\version $Id$
\brief AC3 output module
\author Moritz Bunkus <moritz@bunkus.org>
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include "pr_generic.h"
#include "ac3_common.h"
#include "p_ac3.h"
#include "matroska.h"
using namespace LIBMATROSKA_NAMESPACE;
ac3_packetizer_c::ac3_packetizer_c(generic_reader_c *nreader,
unsigned long nsamples_per_sec,
int nchannels, track_info_t *nti)
throw (error_c): generic_packetizer_c(nreader, nti) {
packetno = 0;
bytes_output = 0;
packet_buffer = NULL;
buffer_size = 0;
samples_per_sec = nsamples_per_sec;
channels = nchannels;
set_track_type(track_audio);
duplicate_data_on_add(false);
}
ac3_packetizer_c::~ac3_packetizer_c() {
if (packet_buffer != NULL)
safefree(packet_buffer);
}
void ac3_packetizer_c::add_to_buffer(unsigned char *buf, int size) {
unsigned char *new_buffer;
new_buffer = (unsigned char *)saferealloc(packet_buffer, buffer_size + size);
memcpy(new_buffer + buffer_size, buf, size);
packet_buffer = new_buffer;
buffer_size += size;
}
int ac3_packetizer_c::ac3_packet_available() {
int pos;
ac3_header_t ac3header;
if (packet_buffer == NULL)
return 0;
pos = find_ac3_header(packet_buffer, buffer_size, &ac3header);
if (pos < 0)
return 0;
return 1;
}
void ac3_packetizer_c::remove_ac3_packet(int pos, int framesize) {
int new_size;
unsigned char *temp_buf;
new_size = buffer_size - (pos + framesize);
if (new_size != 0)
temp_buf = (unsigned char *)safememdup(&packet_buffer[pos + framesize],
new_size);
else
temp_buf = NULL;
safefree(packet_buffer);
packet_buffer = temp_buf;
buffer_size = new_size;
}
unsigned char *ac3_packetizer_c::get_ac3_packet(unsigned long *header,
ac3_header_t *ac3header) {
int pos;
unsigned char *buf;
double pims;
if (packet_buffer == NULL)
return 0;
pos = find_ac3_header(packet_buffer, buffer_size, ac3header);
if (pos < 0)
return 0;
if ((pos + ac3header->bytes) > buffer_size)
return 0;
pims = ((double)ac3header->bytes) * 1000.0 /
((double)ac3header->bit_rate / 8.0);
if (ti->async.displacement < 0) {
/*
* AC3 audio synchronization. displacement < 0 means skipping an
* appropriate number of packets at the beginning.
*/
ti->async.displacement += (int)pims;
if (ti->async.displacement > -(pims / 2))
ti->async.displacement = 0;
remove_ac3_packet(pos, ac3header->bytes);
return 0;
}
if (verbose && (pos > 1))
fprintf(stdout, "ac3_packetizer: skipping %d bytes (no valid AC3 header "
"found). This might make audio/video go out of sync, but this "
"stream is damaged.\n", pos);
buf = (unsigned char *)safememdup(packet_buffer + pos, ac3header->bytes);
if (ti->async.displacement > 0) {
/*
* AC3 audio synchronization. displacement > 0 is solved by duplicating
* the very first AC3 packet as often as necessary. I cannot create
* a packet with total silence because I don't know how, and simply
* settings the packet's values to 0 does not work as the AC3 header
* contains a CRC of its data.
*/
ti->async.displacement -= (int)pims;
if (ti->async.displacement < (pims / 2))
ti->async.displacement = 0;
return buf;
}
remove_ac3_packet(pos, ac3header->bytes);
return buf;
}
void ac3_packetizer_c::set_headers() {
set_codec_id(MKV_A_AC3);
set_audio_sampling_freq((float)samples_per_sec);
set_audio_channels(channels);
generic_packetizer_c::set_headers();
}
int ac3_packetizer_c::process(unsigned char *buf, int size,
int64_t timecode, int64_t, int64_t, int64_t) {
unsigned char *packet;
unsigned long header;
ac3_header_t ac3header;
int64_t my_timecode;
debug_enter("ac3_packetizer_c::process");
if (timecode != -1)
my_timecode = timecode;
add_to_buffer(buf, size);
while ((packet = get_ac3_packet(&header, &ac3header)) != NULL) {
if (timecode == -1)
my_timecode = (int64_t)(1000.0 * packetno * 1536 * ti->async.linear /
samples_per_sec);
add_packet(packet, ac3header.bytes, my_timecode,
(int64_t)(1000.0 * 1536 * ti->async.linear / samples_per_sec));
packetno++;
}
debug_leave("ac3_packetizer_c::process");
return EMOREDATA;
}
void ac3_packetizer_c::dump_debug_info() {
fprintf(stderr, "DBG> ac3_packetizer_c: queue: %d; buffer size: %d\n",
packet_queue.size(), buffer_size);
}