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Parse NAL units in H264 parser.

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Patch by Ivan Schreter, schreter gmx net

Originally committed as revision 17488 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Ivan Schreter
2009-02-21 19:56:50 +00:00
committed by Carl Eugen Hoyos
parent 1790a5e908
commit ff6474dd15
1 changed files with 71 additions and 0 deletions
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71
libavcodec/h264_parser.c
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@@ -27,6 +27,8 @@
#include "parser.h"
#include "h264_parser.h"
#include "h264data.h"
#include "golomb.h"
#include <assert.h>
@@ -96,6 +98,73 @@ found:
return i-(state&5);
}
/*!
* Parse NAL units of found picture and decode some basic information.
*
* @param s parser context.
* @param avctx codec context.
* @param buf buffer with field/frame data.
* @param buf_size size of the buffer.
*/
static inline int parse_nal_units(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t *buf, int buf_size)
{
H264Context *h = s->priv_data;
const uint8_t *buf_end = buf + buf_size;
unsigned int slice_type;
int state;
const uint8_t *ptr;
/* set some sane default values */
s->pict_type = FF_I_TYPE;
h->s.avctx= avctx;
for(;;) {
int src_length, dst_length, consumed;
buf = ff_find_start_code(buf, buf_end, &state);
if(buf >= buf_end)
break;
--buf;
src_length = buf_end - buf;
switch (state & 0x1f) {
case NAL_SLICE:
case NAL_IDR_SLICE:
// Do not walk the whole buffer just to decode slice header
if (src_length > 20)
src_length = 20;
break;
}
ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
if (ptr==NULL || dst_length < 0)
break;
init_get_bits(&h->s.gb, ptr, 8*dst_length);
switch(h->nal_unit_type) {
case NAL_SPS:
ff_h264_decode_seq_parameter_set(h);
break;
case NAL_PPS:
ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
break;
case NAL_SEI:
ff_h264_decode_sei(h);
break;
case NAL_IDR_SLICE:
case NAL_SLICE:
get_ue_golomb(&h->s.gb); // skip first_mb_in_slice
slice_type = get_ue_golomb_31(&h->s.gb);
s->pict_type = golomb_to_pict_type[slice_type % 5];
return 0; /* no need to evaluate the rest */
}
buf += consumed;
}
/* didn't find a picture! */
av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");
return -1;
}
static int h264_parse(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
@@ -120,6 +189,8 @@ static int h264_parse(AVCodecParserContext *s,
assert(pc->last_index + next >= 0 );
ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
}
parse_nal_units(s, avctx, buf, buf_size);
}
*poutbuf = buf;