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new bitstream reader API (old get_bits() based one is emulated and will still be supported in the future cuz its simpler)

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minor optimizations to get_vlc

Originally committed as revision 725 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer
2002-07-09 10:35:10 +00:00
parent 436483c2ec
commit 8db1a1dde0
4 changed files with 344 additions and 525 deletions
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37
libavcodec/mpegaudiodec.c
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@@ -1457,11 +1457,8 @@ static void seek_to_maindata(MPADecodeContext *s, long backstep)
UINT8 *ptr;
/* compute current position in stream */
#ifdef ALT_BITSTREAM_READER
ptr = s->gb.buffer + (s->gb.index>>3);
#else
ptr = s->gb.buf_ptr - (s->gb.bit_cnt >> 3);
#endif
ptr = s->gb.buffer + (get_bits_count(&s->gb)>>3);
/* copy old data before current one */
ptr -= backstep;
memcpy(ptr, s->inbuf1[s->inbuf_index ^ 1] +
@@ -1547,9 +1544,7 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
{
int s_index;
int linbits, code, x, y, l, v, i, j, k, pos;
UINT8 *last_buf_ptr;
UINT32 last_bit_buf;
int last_bit_cnt;
GetBitContext last_gb;
VLC *vlc;
UINT8 *code_table;
@@ -1608,36 +1603,20 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
/* high frequencies */
vlc = &huff_quad_vlc[g->count1table_select];
last_buf_ptr = NULL;
last_bit_buf = 0;
last_bit_cnt = 0;
last_gb.buffer = NULL;
while (s_index <= 572) {
pos = get_bits_count(&s->gb);
if (pos >= end_pos) {
if (pos > end_pos && last_buf_ptr != NULL) {
if (pos > end_pos && last_gb.buffer != NULL) {
/* some encoders generate an incorrect size for this
part. We must go back into the data */
s_index -= 4;
#ifdef ALT_BITSTREAM_READER
s->gb.buffer = last_buf_ptr;
s->gb.index = last_bit_cnt;
#else
s->gb.buf_ptr = last_buf_ptr;
s->gb.bit_buf = last_bit_buf;
s->gb.bit_cnt = last_bit_cnt;
#endif
s->gb = last_gb;
}
break;
}
#ifdef ALT_BITSTREAM_READER
last_buf_ptr = s->gb.buffer;
last_bit_cnt = s->gb.index;
#else
last_buf_ptr = s->gb.buf_ptr;
last_bit_buf = s->gb.bit_buf;
last_bit_cnt = s->gb.bit_cnt;
#endif
last_gb= s->gb;
code = get_vlc(&s->gb, vlc);
dprintf("t=%d code=%d\n", g->count1table_select, code);
if (code < 0)