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107 lines
3.0 KiB
107 lines
3.0 KiB
/* |
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* H.264 encoder |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "common.h" |
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#include "bitstream.h" |
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#include "mpegvideo.h" |
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#include "h264data.h" |
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/** |
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* Write out the provided data into a NAL unit. |
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* @param nal_ref_idc NAL reference IDC |
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* @param nal_unit_type NAL unit payload type |
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* @param dest the target buffer, dst+1 == src is allowed as a special case |
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* @param destsize the length of the dst array |
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* @param b2 the data which should be escaped |
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* @returns pointer to current position in the output buffer or NULL if an error occurred |
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*/ |
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static uint8_t *h264_write_nal_unit(int nal_ref_idc, int nal_unit_type, uint8_t *dest, int *destsize, |
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PutBitContext *b2) |
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{ |
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PutBitContext b; |
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int i, destpos, rbsplen, escape_count; |
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uint8_t *rbsp; |
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if (nal_unit_type != NAL_END_STREAM) |
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put_bits(b2,1,1); // rbsp_stop_bit |
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// Align b2 on a byte boundary |
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align_put_bits(b2); |
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rbsplen = put_bits_count(b2)/8; |
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flush_put_bits(b2); |
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rbsp = b2->buf; |
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init_put_bits(&b,dest,*destsize); |
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put_bits(&b,16,0); |
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put_bits(&b,16,0x01); |
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put_bits(&b,1,0); // forbidden zero bit |
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put_bits(&b,2,nal_ref_idc); // nal_ref_idc |
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put_bits(&b,5,nal_unit_type); // nal_unit_type |
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flush_put_bits(&b); |
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destpos = 5; |
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escape_count= 0; |
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for (i=0; i<rbsplen; i+=2) |
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{ |
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if (rbsp[i]) continue; |
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if (i>0 && rbsp[i-1]==0) |
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i--; |
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if (i+2<rbsplen && rbsp[i+1]==0 && rbsp[i+2]<=3) |
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{ |
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escape_count++; |
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i+=2; |
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} |
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} |
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if(escape_count==0) |
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{ |
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if(dest+destpos != rbsp) |
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{ |
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memcpy(dest+destpos, rbsp, rbsplen); |
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*destsize -= (rbsplen+destpos); |
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} |
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return dest+rbsplen+destpos; |
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} |
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if(rbsplen + escape_count + 1> *destsize) |
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{ |
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av_log(NULL, AV_LOG_ERROR, "Destination buffer too small!\n"); |
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return NULL; |
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} |
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// this should be damn rare (hopefully) |
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for (i = 0 ; i < rbsplen ; i++) |
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{ |
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if (i + 2 < rbsplen && (rbsp[i] == 0 && rbsp[i+1] == 0 && rbsp[i+2] < 4)) |
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{ |
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dest[destpos++] = rbsp[i++]; |
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dest[destpos++] = rbsp[i]; |
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dest[destpos++] = 0x03; // emulation prevention byte |
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} |
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else |
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dest[destpos++] = rbsp[i]; |
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} |
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*destsize -= destpos; |
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return dest+destpos; |
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} |
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