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ffmpeg/libav/mpeg.c

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/*
* Output a MPEG1 multiplexed video/audio stream
* Copyright (c) 2000 Gerard Lantau.
*
* This program 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.
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/time.h>
#include "avformat.h"
#define MAX_PAYLOAD_SIZE 4096
#define NB_STREAMS 2
typedef struct {
UINT8 buffer[MAX_PAYLOAD_SIZE];
int buffer_ptr;
UINT8 id;
int max_buffer_size; /* in bytes */
int packet_number;
float pts;
INT64 start_pts;
} StreamInfo;
typedef struct {
int packet_size; /* required packet size */
int packet_data_max_size; /* maximum data size inside a packet */
int packet_number;
int pack_header_freq; /* frequency (in packets^-1) at which we send pack headers */
int system_header_freq;
int mux_rate; /* bitrate in units of 50 bytes/s */
/* stream info */
int audio_bound;
int video_bound;
} MpegMuxContext;
#define PACK_START_CODE ((unsigned int)0x000001ba)
#define SYSTEM_HEADER_START_CODE ((unsigned int)0x000001bb)
#define PACKET_START_CODE_MASK ((unsigned int)0xffffff00)
#define PACKET_START_CODE_PREFIX ((unsigned int)0x00000100)
#define ISO_11172_END_CODE ((unsigned int)0x000001b9)
/* mpeg2 */
#define PROGRAM_STREAM_MAP 0x1bc
#define PRIVATE_STREAM_1 0x1bd
#define PADDING_STREAM 0x1be
#define PRIVATE_STREAM_2 0x1bf
#define AUDIO_ID 0xc0
#define VIDEO_ID 0xe0
static int put_pack_header(AVFormatContext *ctx,
UINT8 *buf, long long timestamp)
{
MpegMuxContext *s = ctx->priv_data;
PutBitContext pb;
init_put_bits(&pb, buf, 128, NULL, NULL);
put_bits(&pb, 32, PACK_START_CODE);
put_bits(&pb, 4, 0x2);
put_bits(&pb, 3, (timestamp >> 30) & 0x07);
put_bits(&pb, 1, 1);
put_bits(&pb, 15, (timestamp >> 15) & 0x7fff);
put_bits(&pb, 1, 1);
put_bits(&pb, 15, (timestamp) & 0x7fff);
put_bits(&pb, 1, 1);
put_bits(&pb, 1, 1);
put_bits(&pb, 22, s->mux_rate);
put_bits(&pb, 1, 1);
flush_put_bits(&pb);
return pb.buf_ptr - pb.buf;
}
static int put_system_header(AVFormatContext *ctx, UINT8 *buf)
{
MpegMuxContext *s = ctx->priv_data;
int size, rate_bound, i, private_stream_coded, id;
PutBitContext pb;
init_put_bits(&pb, buf, 128, NULL, NULL);
put_bits(&pb, 32, SYSTEM_HEADER_START_CODE);
put_bits(&pb, 16, 0);
put_bits(&pb, 1, 1);
rate_bound = s->mux_rate; /* maximum bit rate of the multiplexed stream */
put_bits(&pb, 22, rate_bound);
put_bits(&pb, 1, 1); /* marker */
put_bits(&pb, 6, s->audio_bound);
put_bits(&pb, 1, 1); /* variable bitrate */
put_bits(&pb, 1, 1); /* non constrainted bit stream */
put_bits(&pb, 1, 0); /* audio locked */
put_bits(&pb, 1, 0); /* video locked */
put_bits(&pb, 1, 1); /* marker */
put_bits(&pb, 5, s->video_bound);
put_bits(&pb, 8, 0xff); /* reserved byte */
/* audio stream info */
private_stream_coded = 0;
for(i=0;i<ctx->nb_streams;i++) {
StreamInfo *stream = ctx->streams[i]->priv_data;
id = stream->id;
if (id < 0xc0) {
/* special case for private streams (AC3 use that) */
if (private_stream_coded)
continue;
private_stream_coded = 1;
id = 0xbd;
}
put_bits(&pb, 8, id); /* stream ID */
put_bits(&pb, 2, 3);
if (id < 0xe0) {
/* audio */
put_bits(&pb, 1, 0);
put_bits(&pb, 13, stream->max_buffer_size / 128);
} else {
/* video */
put_bits(&pb, 1, 1);
put_bits(&pb, 13, stream->max_buffer_size / 1024);
}
}
flush_put_bits(&pb);
size = pb.buf_ptr - pb.buf;
/* patch packet size */
buf[4] = (size - 6) >> 8;
buf[5] = (size - 6) & 0xff;
return size;
}
static int mpeg_mux_init(AVFormatContext *ctx)
{
MpegMuxContext *s;
int bitrate, i, mpa_id, mpv_id, ac3_id;
AVStream *st;
StreamInfo *stream;
s = malloc(sizeof(MpegMuxContext));
if (!s)
return -1;
memset(s, 0, sizeof(MpegMuxContext));
ctx->priv_data = s;
s->packet_number = 0;
/* XXX: hardcoded */
s->packet_size = 2048;
/* startcode(4) + length(2) + flags(1) */
s->packet_data_max_size = s->packet_size - 7;
s->audio_bound = 0;
s->video_bound = 0;
mpa_id = AUDIO_ID;
ac3_id = 0x80;
mpv_id = VIDEO_ID;
for(i=0;i<ctx->nb_streams;i++) {
st = ctx->streams[i];
stream = av_mallocz(sizeof(StreamInfo));
if (!stream)
goto fail;
st->priv_data = stream;
switch(st->codec.codec_type) {
case CODEC_TYPE_AUDIO:
if (st->codec.codec_id == CODEC_ID_AC3)
stream->id = ac3_id++;
else
stream->id = mpa_id++;
stream->max_buffer_size = 4 * 1024;
s->audio_bound++;
break;
case CODEC_TYPE_VIDEO:
stream->id = mpv_id++;
stream->max_buffer_size = 46 * 1024;
s->video_bound++;
break;
}
}
/* we increase slightly the bitrate to take into account the
headers. XXX: compute it exactly */
bitrate = 2000;
for(i=0;i<ctx->nb_streams;i++) {
st = ctx->streams[i];
bitrate += st->codec.bit_rate;
}
s->mux_rate = (bitrate + (8 * 50) - 1) / (8 * 50);
/* every 2 seconds */
s->pack_header_freq = 2 * bitrate / s->packet_size / 8;
/* every 10 seconds */
s->system_header_freq = s->pack_header_freq * 5;
for(i=0;i<ctx->nb_streams;i++) {
stream = ctx->streams[i]->priv_data;
stream->buffer_ptr = 0;
stream->packet_number = 0;
stream->pts = 0;
stream->start_pts = -1;
}
return 0;
fail:
for(i=0;i<ctx->nb_streams;i++) {
free(ctx->streams[i]->priv_data);
}
free(s);
return -ENOMEM;
}
/* flush the packet on stream stream_index */
static void flush_packet(AVFormatContext *ctx, int stream_index)
{
MpegMuxContext *s = ctx->priv_data;
StreamInfo *stream = ctx->streams[stream_index]->priv_data;
UINT8 *buf_ptr;
int size, payload_size, startcode, id, len, stuffing_size, i;
INT64 timestamp;
UINT8 buffer[128];
id = stream->id;
timestamp = stream->start_pts;
#if 0
printf("packet ID=%2x PTS=%0.3f\n",
id, timestamp / 90000.0);
#endif
buf_ptr = buffer;
if ((s->packet_number % s->pack_header_freq) == 0) {
/* output pack and systems header if needed */
size = put_pack_header(ctx, buf_ptr, timestamp);
buf_ptr += size;
if ((s->packet_number % s->system_header_freq) == 0) {
size = put_system_header(ctx, buf_ptr);
buf_ptr += size;
}
}
size = buf_ptr - buffer;
put_buffer(&ctx->pb, buffer, size);
/* packet header */
payload_size = s->packet_size - (size + 6 + 5);
if (id < 0xc0) {
startcode = PRIVATE_STREAM_1;
payload_size -= 4;
} else {
startcode = 0x100 + id;
}
stuffing_size = payload_size - stream->buffer_ptr;
if (stuffing_size < 0)
stuffing_size = 0;
put_be32(&ctx->pb, startcode);
put_be16(&ctx->pb, payload_size + 5);
/* stuffing */
for(i=0;i<stuffing_size;i++)
put_byte(&ctx->pb, 0xff);
/* presentation time stamp */
put_byte(&ctx->pb,
(0x02 << 4) |
(((timestamp >> 30) & 0x07) << 1) |
1);
put_be16(&ctx->pb, (((timestamp >> 15) & 0x7fff) << 1) | 1);
put_be16(&ctx->pb, (((timestamp) & 0x7fff) << 1) | 1);
if (startcode == PRIVATE_STREAM_1) {
put_byte(&ctx->pb, id);
if (id >= 0x80 && id <= 0xbf) {
/* XXX: need to check AC3 spec */
put_byte(&ctx->pb, 1);
put_byte(&ctx->pb, 0);
put_byte(&ctx->pb, 2);
}
}
/* output data */
put_buffer(&ctx->pb, stream->buffer, payload_size - stuffing_size);
put_flush_packet(&ctx->pb);
/* preserve remaining data */
len = stream->buffer_ptr - payload_size;
if (len < 0)
len = 0;
memmove(stream->buffer, stream->buffer + stream->buffer_ptr - len, len);
stream->buffer_ptr = len;
s->packet_number++;
stream->packet_number++;
stream->start_pts = -1;
}
static int mpeg_mux_write_packet(AVFormatContext *ctx,
int stream_index, UINT8 *buf, int size)
{
MpegMuxContext *s = ctx->priv_data;
AVStream *st = ctx->streams[stream_index];
StreamInfo *stream = st->priv_data;
int len;
while (size > 0) {
/* set pts */
if (stream->start_pts == -1)
stream->start_pts = stream->pts * 90000.0;
len = s->packet_data_max_size - stream->buffer_ptr;
if (len > size)
len = size;
memcpy(stream->buffer + stream->buffer_ptr, buf, len);
stream->buffer_ptr += len;
buf += len;
size -= len;
while (stream->buffer_ptr >= s->packet_data_max_size) {
/* output the packet */
if (stream->start_pts == -1)
stream->start_pts = stream->pts * 90000.0;
flush_packet(ctx, stream_index);
}
}
if (st->codec.codec_type == CODEC_TYPE_AUDIO) {
stream->pts += (float)st->codec.frame_size / st->codec.sample_rate;
} else {
stream->pts += FRAME_RATE_BASE / (float)st->codec.frame_rate;
}
return 0;
}
static int mpeg_mux_end(AVFormatContext *ctx)
{
StreamInfo *stream;
int i;
/* flush each packet */
for(i=0;i<ctx->nb_streams;i++) {
stream = ctx->streams[i]->priv_data;
if (stream->buffer_ptr > 0)
flush_packet(ctx, i);
}
/* write the end header */
put_be32(&ctx->pb, ISO_11172_END_CODE);
put_flush_packet(&ctx->pb);
return 0;
}
/*********************************************/
/* demux code */
#define MAX_SYNC_SIZE 100000
typedef struct MpegDemuxContext {
int header_state;
int mux_rate; /* 50 byte/s unit */
} MpegDemuxContext;
static int find_start_code(ByteIOContext *pb, int *size_ptr,
UINT32 *header_state)
{
unsigned int state, v;
int val, n;
state = *header_state;
n = *size_ptr;
while (n > 0) {
if (url_feof(pb))
break;
v = get_byte(pb);
n--;
if (state == 0x000001) {
state = ((state << 8) | v) & 0xffffff;
val = state;
goto found;
}
state = ((state << 8) | v) & 0xffffff;
}
val = -1;
found:
*header_state = state;
*size_ptr = n;
return val;
}
static int mpeg_mux_read_header(AVFormatContext *s,
AVFormatParameters *ap)
{
MpegDemuxContext *m;
int size, startcode, c, rate_bound, audio_bound, video_bound, mux_rate, val;
int codec_id, n, i, type;
AVStream *st;
m = av_mallocz(sizeof(MpegDemuxContext));
if (!m)
return -ENOMEM;
s->priv_data = m;
/* search first pack header */
m->header_state = 0xff;
size = MAX_SYNC_SIZE;
for(;;) {
while (size > 0) {
startcode = find_start_code(&s->pb, &size, &m->header_state);
if (startcode == PACK_START_CODE)
goto found;
}
return -ENODATA;
found:
/* search system header just after pack header */
/* parse pack header */
get_byte(&s->pb); /* ts1 */
get_be16(&s->pb); /* ts2 */
get_be16(&s->pb); /* ts3 */
mux_rate = get_byte(&s->pb) << 16;
mux_rate |= get_byte(&s->pb) << 8;
mux_rate |= get_byte(&s->pb);
mux_rate &= (1 << 22) - 1;
m->mux_rate = mux_rate;
startcode = find_start_code(&s->pb, &size, &m->header_state);
if (startcode == SYSTEM_HEADER_START_CODE)
break;
}
size = get_be16(&s->pb);
rate_bound = get_byte(&s->pb) << 16;
rate_bound |= get_byte(&s->pb) << 8;
rate_bound |= get_byte(&s->pb);
rate_bound = (rate_bound >> 1) & ((1 << 22) - 1);
audio_bound = get_byte(&s->pb) >> 2;
video_bound = get_byte(&s->pb) & 0x1f;
get_byte(&s->pb); /* reserved byte */
#if 0
printf("mux_rate=%d kbit/s\n", (m->mux_rate * 50 * 8) / 1000);
printf("rate_bound=%d\n", rate_bound);
printf("audio_bound=%d\n", audio_bound);
printf("video_bound=%d\n", video_bound);
#endif
size -= 6;
s->nb_streams = 0;
while (size > 0) {
c = get_byte(&s->pb);
size--;
if ((c & 0x80) == 0)
break;
val = get_be16(&s->pb);
size -= 2;
if (c >= 0xc0 && c <= 0xdf) {
/* mpeg audio stream */
type = CODEC_TYPE_AUDIO;
codec_id = CODEC_ID_MP2;
n = 1;
c = c | 0x100;
} else if (c >= 0xe0 && c <= 0xef) {
type = CODEC_TYPE_VIDEO;
codec_id = CODEC_ID_MPEG1VIDEO;
n = 1;
c = c | 0x100;
} else if (c == 0xb8) {
/* all audio streams */
/* XXX: hack for DVD: we force AC3, although we do not
know that this codec will be used */
type = CODEC_TYPE_AUDIO;
codec_id = CODEC_ID_AC3;
n = audio_bound;
c = 0x80;
/* c = 0x1c0; */
} else if (c == 0xb9) {
/* all video streams */
type = CODEC_TYPE_VIDEO;
codec_id = CODEC_ID_MPEG1VIDEO;
n = video_bound;
c = 0x1e0;
} else {
type = 0;
codec_id = 0;
n = 0;
}
for(i=0;i<n;i++) {
st = av_mallocz(sizeof(AVStream));
if (!st)
return -ENOMEM;
s->streams[s->nb_streams++] = st;
st->id = c + i;
st->codec.codec_type = type;
st->codec.codec_id = codec_id;
}
}
return 0;
}
static INT64 get_pts(ByteIOContext *pb, int c)
{
INT64 pts;
int val;
if (c < 0)
c = get_byte(pb);
pts = (INT64)((c >> 1) & 0x07) << 30;
val = get_be16(pb);
pts |= (INT64)(val >> 1) << 15;
val = get_be16(pb);
pts |= (INT64)(val >> 1);
return pts;
}
static int mpeg_mux_read_packet(AVFormatContext *s,
AVPacket *pkt)
{
MpegDemuxContext *m = s->priv_data;
AVStream *st;
int len, size, startcode, i, c, flags, header_len;
INT64 pts, dts;
/* next start code (should be immediately after */
redo:
m->header_state = 0xff;
size = MAX_SYNC_SIZE;
startcode = find_start_code(&s->pb, &size, &m->header_state);
// printf("startcode=%x pos=0x%Lx\n", startcode, url_ftell(&s->pb));
if (startcode < 0)
return -EIO;
if (startcode == PACK_START_CODE)
goto redo;
if (startcode == SYSTEM_HEADER_START_CODE)
goto redo;
if (startcode == PADDING_STREAM ||
startcode == PRIVATE_STREAM_2) {
/* skip them */
len = get_be16(&s->pb);
url_fskip(&s->pb, len);
goto redo;
}
/* find matching stream */
if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
(startcode >= 0x1e0 && startcode <= 0x1ef) ||
(startcode == 0x1bd)))
goto redo;
len = get_be16(&s->pb);
pts = 0;
dts = 0;
/* stuffing */
for(;;) {
c = get_byte(&s->pb);
len--;
/* XXX: for mpeg1, should test only bit 7 */
if (c != 0xff)
break;
}
if ((c & 0xc0) == 0x40) {
/* buffer scale & size */
get_byte(&s->pb);
c = get_byte(&s->pb);
len -= 2;
}
if ((c & 0xf0) == 0x20) {
pts = get_pts(&s->pb, c);
len -= 4;
dts = pts;
} else if ((c & 0xf0) == 0x30) {
pts = get_pts(&s->pb, c);
dts = get_pts(&s->pb, -1);
len -= 9;
} else if ((c & 0xc0) == 0x80) {
/* mpeg 2 PES */
if ((c & 0x30) != 0) {
fprintf(stderr, "Encrypted multiplex not handled\n");
return -EIO;
}
flags = get_byte(&s->pb);
header_len = get_byte(&s->pb);
len -= 2;
if (header_len > len)
goto redo;
if ((flags & 0xc0) == 0x40) {
pts = get_pts(&s->pb, -1);
dts = pts;
header_len -= 5;
len -= 5;
} if ((flags & 0xc0) == 0xc0) {
pts = get_pts(&s->pb, -1);
dts = get_pts(&s->pb, -1);
header_len -= 10;
len -= 10;
}
len -= header_len;
while (header_len > 0) {
get_byte(&s->pb);
header_len--;
}
}
if (startcode == 0x1bd) {
startcode = get_byte(&s->pb);
len--;
if (startcode >= 0x80 && startcode <= 0xbf) {
/* audio: skip header */
get_byte(&s->pb);
get_byte(&s->pb);
get_byte(&s->pb);
len -= 3;
}
}
/* now find stream */
for(i=0;i<s->nb_streams;i++) {
st = s->streams[i];
if (st->id == startcode)
goto found;
}
/* skip packet */
url_fskip(&s->pb, len);
goto redo;
found:
av_new_packet(pkt, len);
get_buffer(&s->pb, pkt->data, pkt->size);
pkt->pts = pts;
pkt->stream_index = i;
return 0;
}
static int mpeg_mux_read_close(AVFormatContext *s)
{
MpegDemuxContext *m = s->priv_data;
free(m);
return 0;
}
AVFormat mpeg_mux_format = {
"mpeg",
"MPEG multiplex format",
"video/x-mpeg",
"mpg,mpeg,vob",
CODEC_ID_MP2,
CODEC_ID_MPEG1VIDEO,
mpeg_mux_init,
mpeg_mux_write_packet,
mpeg_mux_end,
mpeg_mux_read_header,
mpeg_mux_read_packet,
mpeg_mux_read_close,
};
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