mirror of https://git.ffmpeg.org/ffmpeg.git
108 lines
3.0 KiB
C
108 lines
3.0 KiB
C
|
/*
|
||
|
|
* H.264 encoder
|
||
|
|
*
|
||
|
|
* FFmpeg is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU Lesser General Public
|
||
|
|
* License as published by the Free Software Foundation; either
|
||
|
|
* version 2.1 of the License, or (at your option) any later version.
|
||
|
|
*
|
||
|
|
* FFmpeg 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
|
||
|
|
* Lesser General Public License for more details.
|
||
|
|
*
|
||
|
|
* You should have received a copy of the GNU Lesser General Public
|
||
|
|
* License along with FFmpeg; if not, write to the Free Software
|
||
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
||
|
|
*/
|
||
|
|
|
||
|
|
|
||
|
|
#include "common.h"
|
||
|
|
#include "bitstream.h"
|
||
|
|
#include "mpegvideo.h"
|
||
|
|
#include "h264data.h"
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Write out the provided data into a NAL unit.
|
||
|
|
* @param nal_ref_idc NAL reference IDC
|
||
|
|
* @param nal_unit_type NAL unit payload type
|
||
|
|
* @param dest the target buffer, dst+1 == src is allowed as a special case
|
||
|
|
* @param destsize the length of the dst array
|
||
|
|
* @param b2 the data which should be escaped
|
||
|
|
* @returns pointer to current position in the output buffer or NULL if an error occured
|
||
|
|
*/
|
||
|
|
static uint8_t *h264_write_nal_unit(int nal_ref_idc, int nal_unit_type, uint8_t *dest, int *destsize,
|
||
|
|
PutBitContext *b2)
|
||
|
|
{
|
||
|
|
PutBitContext b;
|
||
|
|
int i, destpos, rbsplen, escape_count;
|
||
|
|
uint8_t *rbsp;
|
||
|
|
|
||
|
|
if (nal_unit_type != NAL_END_STREAM)
|
||
|
|
put_bits(b2,1,1); // rbsp_stop_bit
|
||
|
|
|
||
|
|
// Align b2 on a byte boundary
|
||
|
|
align_put_bits(b2);
|
||
|
|
rbsplen = put_bits_count(b2)/8;
|
||
|
|
flush_put_bits(b2);
|
||
|
|
rbsp = b2->buf;
|
||
|
|
|
||
|
|
init_put_bits(&b,dest,*destsize);
|
||
|
|
|
||
|
|
put_bits(&b,16,0);
|
||
|
|
put_bits(&b,16,0x01);
|
||
|
|
|
||
|
|
put_bits(&b,1,0); // forbidden zero bit
|
||
|
|
put_bits(&b,2,nal_ref_idc); // nal_ref_idc
|
||
|
|
put_bits(&b,5,nal_unit_type); // nal_unit_type
|
||
|
|
|
||
|
|
flush_put_bits(&b);
|
||
|
|
|
||
|
|
destpos = 5;
|
||
|
|
escape_count= 0;
|
||
|
|
|
||
|
|
for (i=0; i<rbsplen; i+=2)
|
||
|
|
{
|
||
|
|
if (rbsp[i]) continue;
|
||
|
|
if (i>0 && rbsp[i-1]==0)
|
||
|
|
i--;
|
||
|
|
if (i+2<rbsplen && rbsp[i+1]==0 && rbsp[i+2]<=3)
|
||
|
|
{
|
||
|
|
escape_count++;
|
||
|
|
i+=2;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if(escape_count==0)
|
||
|
|
{
|
||
|
|
if(dest+destpos != rbsp)
|
||
|
|
{
|
||
|
|
memcpy(dest+destpos, rbsp, rbsplen);
|
||
|
|
*destsize -= (rbsplen+destpos);
|
||
|
|
}
|
||
|
|
return dest+rbsplen+destpos;
|
||
|
|
}
|
||
|
|
|
||
|
|
if(rbsplen + escape_count + 1> *destsize)
|
||
|
|
{
|
||
|
|
av_log(NULL, AV_LOG_ERROR, "Destination buffer too small!\n");
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
// this should be damn rare (hopefully)
|
||
|
|
for (i = 0 ; i < rbsplen ; i++)
|
||
|
|
{
|
||
|
|
if (i + 2 < rbsplen && (rbsp[i] == 0 && rbsp[i+1] == 0 && rbsp[i+2] < 4))
|
||
|
|
{
|
||
|
|
dest[destpos++] = rbsp[i++];
|
||
|
|
dest[destpos++] = rbsp[i];
|
||
|
|
dest[destpos++] = 0x03; // emulation prevention byte
|
||
|
|
}
|
||
|
|
else
|
||
|
|
dest[destpos++] = rbsp[i];
|
||
|
|
}
|
||
|
|
*destsize -= destpos;
|
||
|
|
return dest+destpos;
|
||
|
|
}
|
||
|
|
|