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// based on libmpeg2/header.c by Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
// #include <inttypes.h>
#include <stdio.h>
#include "config.h"
#include "mpeg_hdr.h"
static int frameratecode2framerate[16] = {
0,
// Official mpeg1/2 framerates: (1-8)
24000*10000/1001, 24*10000,25*10000,
30000*10000/1001, 30*10000,50*10000,
60000*10000/1001, 60*10000,
// Xing's 15fps: (9)
15*10000,
// libmpeg3's "Unofficial economy rates": (10-13)
5*10000,10*10000,12*10000,15*10000,
// some invalid ones: (14-15)
0,0
};
int mp_header_process_sequence_header (mp_mpeg_header_t * picture, unsigned char * buffer)
{
int width, height;
if ((buffer[6] & 0x20) != 0x20){
fprintf(stderr, "missing marker bit!\n");
return 1; /* missing marker_bit */
}
height = (buffer[0] << 16) | (buffer[1] << 8) | buffer[2];
picture->display_picture_width = (height >> 12);
picture->display_picture_height = (height & 0xfff);
width = ((height >> 12) + 15) & ~15;
height = ((height & 0xfff) + 15) & ~15;
picture->aspect_ratio_information = buffer[3] >> 4;
picture->frame_rate_code = buffer[3] & 15;
picture->fps=frameratecode2framerate[picture->frame_rate_code];
picture->bitrate = (buffer[4]<<10)|(buffer[5]<<2)|(buffer[6]>>6);
picture->mpeg1 = 1;
picture->picture_structure = 3; //FRAME_PICTURE;
picture->display_time=100;
return 0;
}
static int header_process_sequence_extension (mp_mpeg_header_t * picture,
unsigned char * buffer)
{
/* check chroma format, size extensions, marker bit */
if ( ((buffer[1] & 0x06) == 0x00) ||
((buffer[1] & 0x01) != 0x00) || (buffer[2] & 0xe0) ||
((buffer[3] & 0x01) != 0x01) )
return 1;
picture->progressive_sequence = (buffer[1] >> 3) & 1;
picture->mpeg1 = 0;
return 0;
}
static int header_process_picture_coding_extension (mp_mpeg_header_t * picture, unsigned char * buffer)
{
picture->picture_structure = buffer[2] & 3;
picture->top_field_first = buffer[3] >> 7;
picture->repeat_first_field = (buffer[3] >> 1) & 1;
picture->progressive_frame = buffer[4] >> 7;
// repeat_first implementation by A'rpi/ESP-team, based on libmpeg3:
picture->display_time=100;
if(picture->repeat_first_field){
if(picture->progressive_sequence){
if(picture->top_field_first)
picture->display_time+=200;
else
picture->display_time+=100;
} else
if(picture->progressive_frame){
picture->display_time+=50;
}
}
//temopral hack. We calc time on every field, so if we have 2 fields
// interlaced we'll end with double time for 1 frame
if( picture->picture_structure!=3 ) picture->display_time/=2;
return 0;
}
int mp_header_process_extension (mp_mpeg_header_t * picture, unsigned char * buffer)
{
switch (buffer[0] & 0xf0) {
case 0x10: /* sequence extension */
return header_process_sequence_extension (picture, buffer);
case 0x80: /* picture coding extension */
return header_process_picture_coding_extension (picture, buffer);
}
return 0;
}
//MPEG4 HEADERS
static unsigned char getbits(unsigned char *buffer, unsigned int from, unsigned char len)
{
unsigned int n;
unsigned char m, u, l, y;
n = from / 8;
m = from % 8;
u = 8 - m;
l = (len > u ? len - u : 0);
y = (buffer[n] << m);
if(8 > len)
y >>= (8-len);
if(l)
y |= (buffer[n+1] >> (8-l));
//fprintf(stderr, "GETBITS(%d -> %d): bytes=0x%x 0x%x, n=%d, m=%d, l=%d, u=%d, Y=%d\n",
// from, (int) len, (int) buffer[n],(int) buffer[n+1], n, (int) m, (int) l, (int) u, (int) y);
return y;
}
static int read_timeinc(mp_mpeg_header_t * picture, unsigned char * buffer, int n)
{
if(picture->timeinc_bits > 8) {
picture->timeinc_unit = getbits(buffer, n, picture->timeinc_bits - 8) << 8;
n += picture->timeinc_bits - 8;
picture->timeinc_unit |= getbits(buffer, n, 8);
n += 8;
} else {
picture->timeinc_unit = getbits(buffer, n, picture->timeinc_bits);
n += picture->timeinc_bits;
}
//fprintf(stderr, "TIMEINC2: %d, bits: %d\n", picture->timeinc_unit, picture->timeinc_bits);
return n;
}
int mp4_header_process_vol(mp_mpeg_header_t * picture, unsigned char * buffer)
{
unsigned int n, aspect=0, aspectw=0, aspecth=0, x=1, v;
//begins with 0x0000012x
picture->fps = 0;
picture->timeinc_bits = picture->timeinc_resolution = picture->timeinc_unit = 0;
n = 9;
if(getbits(buffer, n, 1))
n += 7;
n++;
aspect=getbits(buffer, n, 4);
n += 4;
if(aspect == 0x0f) {
aspectw = getbits(buffer, n, 8);
n += 8;
aspecth = getbits(buffer, n, 8);
n += 8;
}
if(getbits(buffer, n, 1)) {
n += 4;
if(getbits(buffer, n, 1))
n += 79;
n++;
} else n++;
n+=3;
picture->timeinc_resolution = getbits(buffer, n, 8) << 8;
n += 8;
picture->timeinc_resolution |= getbits(buffer, n, 8);
n += 8;
picture->timeinc_bits = 0;
v = picture->timeinc_resolution - 1;
while(v && (x<16)) {
v>>=1;
picture->timeinc_bits++;
}
picture->timeinc_bits = (picture->timeinc_bits > 1 ? picture->timeinc_bits : 1);
n++; //marker bit
if(getbits(buffer, n, 1)) { //fixed_vop_timeinc
n++;
n = read_timeinc(picture, buffer, n);
if(picture->timeinc_unit)
picture->fps = (picture->timeinc_resolution * 10000) / picture->timeinc_unit;
}
//fprintf(stderr, "ASPECT: %d, PARW=%d, PARH=%d, TIMEINCRESOLUTION: %d, FIXED_TIMEINC: %d (number of bits: %d), FPS: %u\n",
// aspect, aspectw, aspecth, picture->timeinc_resolution, picture->timeinc_unit, picture->timeinc_bits, picture->fps);
return 0;
}
int mp4_header_process_vop(mp_mpeg_header_t * picture, unsigned char * buffer)
{
int n;
n = 0;
picture->picture_type = getbits(buffer, n, 2);
n += 2;
while(getbits(buffer, n, 1))
n++;
n++;
getbits(buffer, n, 1);
n++;
n = read_timeinc(picture, buffer, n);
}
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