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Code Issues Releases Activity

mpc: Convert to the new bitstream reader

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This commit is contained in:
Alexandra Hájková 2016-04-18 10:56:03 +02:00 committed by Diego Biurrun
parent b83aea7340
commit 6668bc80b5
3 changed files with 94 additions and 88 deletions
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73
libavcodec/mpc7.c
View File

@ -28,8 +28,9 @@
#include "libavutil/channel_layout.h"
#include "libavutil/internal.h"
#include "libavutil/lfg.h"
#include "avcodec.h"
#include "get_bits.h"
#include "bitstream.h"
#include "internal.h"
#include "mpegaudiodsp.h"
@ -53,7 +54,7 @@ static av_cold int mpc7_decode_init(AVCodecContext * avctx)
{
int i, j;
MPCContext *c = avctx->priv_data;
GetBitContext gb;
BitstreamContext bc;
LOCAL_ALIGNED_16(uint8_t, buf, [16]);
static int vlc_initialized = 0;
@ -78,18 +79,18 @@ static av_cold int mpc7_decode_init(AVCodecContext * avctx)
ff_mpadsp_init(&c->mpadsp);
c->bdsp.bswap_buf((uint32_t *) buf, (const uint32_t *) avctx->extradata, 4);
ff_mpc_init();
init_get_bits(&gb, buf, 128);
bitstream_init(&bc, buf, 128);
c->IS = get_bits1(&gb);
c->MSS = get_bits1(&gb);
c->maxbands = get_bits(&gb, 6);
c->IS = bitstream_read_bit(&bc);
c->MSS = bitstream_read_bit(&bc);
c->maxbands = bitstream_read(&bc, 6);
if(c->maxbands >= BANDS){
av_log(avctx, AV_LOG_ERROR, "Too many bands: %i\n", c->maxbands);
return -1;
}
skip_bits_long(&gb, 88);
c->gapless = get_bits1(&gb);
c->lastframelen = get_bits(&gb, 11);
bitstream_skip(&bc, 88);
c->gapless = bitstream_read_bit(&bc);
c->lastframelen = bitstream_read(&bc, 11);
av_log(avctx, AV_LOG_DEBUG, "IS: %d, MSS: %d, TG: %d, LFL: %d, bands: %d\n",
c->IS, c->MSS, c->gapless, c->lastframelen, c->maxbands);
c->frames_to_skip = 0;
@ -143,7 +144,7 @@ static av_cold int mpc7_decode_init(AVCodecContext * avctx)
/**
* Fill samples for given subband
*/
static inline void idx_to_quant(MPCContext *c, GetBitContext *gb, int idx, int *dst)
static inline void idx_to_quant(MPCContext *c, BitstreamContext *bc, int idx, int *dst)
{
int i, i1, t;
switch(idx){
@ -153,43 +154,43 @@ static inline void idx_to_quant(MPCContext *c, GetBitContext *gb, int idx, int *
}
break;
case 1:
i1 = get_bits1(gb);
i1 = bitstream_read_bit(bc);
for(i = 0; i < SAMPLES_PER_BAND/3; i++){
t = get_vlc2(gb, quant_vlc[0][i1].table, 9, 2);
t = bitstream_read_vlc(bc, quant_vlc[0][i1].table, 9, 2);
*dst++ = mpc7_idx30[t];
*dst++ = mpc7_idx31[t];
*dst++ = mpc7_idx32[t];
}
break;
case 2:
i1 = get_bits1(gb);
i1 = bitstream_read_bit(bc);
for(i = 0; i < SAMPLES_PER_BAND/2; i++){
t = get_vlc2(gb, quant_vlc[1][i1].table, 9, 2);
t = bitstream_read_vlc(bc, quant_vlc[1][i1].table, 9, 2);
*dst++ = mpc7_idx50[t];
*dst++ = mpc7_idx51[t];
}
break;
case 3: case 4: case 5: case 6: case 7:
i1 = get_bits1(gb);
i1 = bitstream_read_bit(bc);
for(i = 0; i < SAMPLES_PER_BAND; i++)
*dst++ = get_vlc2(gb, quant_vlc[idx-1][i1].table, 9, 2) - mpc7_quant_vlc_off[idx-1];
*dst++ = bitstream_read_vlc(bc, quant_vlc[idx - 1][i1].table, 9, 2) - mpc7_quant_vlc_off[idx - 1];
break;
case 8: case 9: case 10: case 11: case 12:
case 13: case 14: case 15: case 16: case 17:
t = (1 << (idx - 2)) - 1;
for(i = 0; i < SAMPLES_PER_BAND; i++)
*dst++ = get_bits(gb, idx - 1) - t;
*dst++ = bitstream_read(bc, idx - 1) - t;
break;
default: // case 0 and -2..-17
return;
}
}
static int get_scale_idx(GetBitContext *gb, int ref)
static int get_scale_idx(BitstreamContext *bc, int ref)
{
int t = get_vlc2(gb, dscf_vlc.table, MPC7_DSCF_BITS, 1) - 7;
int t = bitstream_read_vlc(bc, dscf_vlc.table, MPC7_DSCF_BITS, 1) - 7;
if (t == 8)
return get_bits(gb, 6);
return bitstream_read(bc, 6);
return av_clip_uintp2(ref + t, 7);
}
@ -200,7 +201,7 @@ static int mpc7_decode_frame(AVCodecContext * avctx, void *data,
const uint8_t *buf = avpkt->data;
int buf_size;
MPCContext *c = avctx->priv_data;
GetBitContext gb;
BitstreamContext bc;
int i, ch;
int mb = -1;
Band *bands = c->bands;
@ -237,45 +238,49 @@ static int mpc7_decode_frame(AVCodecContext * avctx, void *data,
return AVERROR(ENOMEM);
c->bdsp.bswap_buf((uint32_t *) c->bits, (const uint32_t *) buf,
buf_size >> 2);
init_get_bits(&gb, c->bits, buf_size * 8);
skip_bits_long(&gb, skip);
bitstream_init(&bc, c->bits, buf_size * 8);
bitstream_skip(&bc, skip);
/* read subband indexes */
for(i = 0; i <= c->maxbands; i++){
for(ch = 0; ch < 2; ch++){
int t = 4;
if(i) t = get_vlc2(&gb, hdr_vlc.table, MPC7_HDR_BITS, 1) - 5;
if(t == 4) bands[i].res[ch] = get_bits(&gb, 4);
if (i)
t = bitstream_read_vlc(&bc, hdr_vlc.table, MPC7_HDR_BITS, 1) - 5;
if (t == 4)
bands[i].res[ch] = bitstream_read(&bc, 4);
else bands[i].res[ch] = av_clip(bands[i-1].res[ch] + t, 0, 17);
}
if(bands[i].res[0] || bands[i].res[1]){
mb = i;
if(c->MSS) bands[i].msf = get_bits1(&gb);
if (c->MSS)
bands[i].msf = bitstream_read_bit(&bc);
}
}
/* get scale indexes coding method */
for(i = 0; i <= mb; i++)
for(ch = 0; ch < 2; ch++)
if(bands[i].res[ch]) bands[i].scfi[ch] = get_vlc2(&gb, scfi_vlc.table, MPC7_SCFI_BITS, 1);
if (bands[i].res[ch])
bands[i].scfi[ch] = bitstream_read_vlc(&bc, scfi_vlc.table, MPC7_SCFI_BITS, 1);
/* get scale indexes */
for(i = 0; i <= mb; i++){
for(ch = 0; ch < 2; ch++){
if(bands[i].res[ch]){
bands[i].scf_idx[ch][2] = c->oldDSCF[ch][i];
bands[i].scf_idx[ch][0] = get_scale_idx(&gb, bands[i].scf_idx[ch][2]);
bands[i].scf_idx[ch][0] = get_scale_idx(&bc, bands[i].scf_idx[ch][2]);
switch(bands[i].scfi[ch]){
case 0:
bands[i].scf_idx[ch][1] = get_scale_idx(&gb, bands[i].scf_idx[ch][0]);
bands[i].scf_idx[ch][2] = get_scale_idx(&gb, bands[i].scf_idx[ch][1]);
bands[i].scf_idx[ch][1] = get_scale_idx(&bc, bands[i].scf_idx[ch][0]);
bands[i].scf_idx[ch][2] = get_scale_idx(&bc, bands[i].scf_idx[ch][1]);
break;
case 1:
bands[i].scf_idx[ch][1] = get_scale_idx(&gb, bands[i].scf_idx[ch][0]);
bands[i].scf_idx[ch][1] = get_scale_idx(&bc, bands[i].scf_idx[ch][0]);
bands[i].scf_idx[ch][2] = bands[i].scf_idx[ch][1];
break;
case 2:
bands[i].scf_idx[ch][1] = bands[i].scf_idx[ch][0];
bands[i].scf_idx[ch][2] = get_scale_idx(&gb, bands[i].scf_idx[ch][1]);
bands[i].scf_idx[ch][2] = get_scale_idx(&bc, bands[i].scf_idx[ch][1]);
break;
case 3:
bands[i].scf_idx[ch][2] = bands[i].scf_idx[ch][1] = bands[i].scf_idx[ch][0];
@ -290,11 +295,11 @@ static int mpc7_decode_frame(AVCodecContext * avctx, void *data,
off = 0;
for(i = 0; i < BANDS; i++, off += SAMPLES_PER_BAND)
for(ch = 0; ch < 2; ch++)
idx_to_quant(c, &gb, bands[i].res[ch], c->Q[ch] + off);
idx_to_quant(c, &bc, bands[i].res[ch], c->Q[ch] + off);
ff_mpc_dequantize_and_synth(c, mb, (int16_t **)frame->extended_data, 2);
bits_used = get_bits_count(&gb);
bits_used = bitstream_tell(&bc);
bits_avail = buf_size * 8;
if (!last_frame && ((bits_avail < bits_used) || (bits_used + 32 <= bits_avail))) {
av_log(avctx, AV_LOG_ERROR, "Error decoding frame: used %i of %i bits\n", bits_used, bits_avail);

83
libavcodec/mpc8.c
View File

@ -27,8 +27,9 @@
#include "libavutil/channel_layout.h"
#include "libavutil/lfg.h"
#include "avcodec.h"
#include "get_bits.h"
#include "bitstream.h"
#include "internal.h"
#include "mpegaudiodsp.h"
@ -42,22 +43,22 @@ static VLC q1_vlc, q2_vlc[2], q3_vlc[2], quant_vlc[4][2], q9up_vlc;
static const int q3_offsets[2] = { MPC8_Q3_OFFSET, MPC8_Q4_OFFSET };
static const int quant_offsets[6] = { MPC8_Q5_OFFSET, MPC8_Q6_OFFSET, MPC8_Q7_OFFSET, MPC8_Q8_OFFSET };
static inline int mpc8_dec_base(GetBitContext *gb, int k, int n)
static inline int mpc8_dec_base(BitstreamContext *bc, int k, int n)
{
int len = mpc8_cnk_len[k-1][n-1] - 1;
int code = len ? get_bits_long(gb, len) : 0;
int code = len ? bitstream_read(bc, len) : 0;
if (code >= mpc8_cnk_lost[k-1][n-1])
code = ((code << 1) | get_bits1(gb)) - mpc8_cnk_lost[k-1][n-1];
code = ((code << 1) | bitstream_read_bit(bc)) - mpc8_cnk_lost[k - 1][n - 1];
return code;
}
static inline int mpc8_dec_enum(GetBitContext *gb, int k, int n)
static inline int mpc8_dec_enum(BitstreamContext *bc, int k, int n)
{
int bits = 0;
const uint32_t * C = mpc8_cnk[k-1];
int code = mpc8_dec_base(gb, k, n);
int code = mpc8_dec_base(bc, k, n);
do {
n--;
@ -72,18 +73,18 @@ static inline int mpc8_dec_enum(GetBitContext *gb, int k, int n)
return bits;
}
static inline int mpc8_get_mod_golomb(GetBitContext *gb, int m)
static inline int mpc8_get_mod_golomb(BitstreamContext *bc, int m)
{
if(mpc8_cnk_len[0][m] < 1) return 0;
return mpc8_dec_base(gb, 1, m+1);
return mpc8_dec_base(bc, 1, m + 1);
}
static int mpc8_get_mask(GetBitContext *gb, int size, int t)
static int mpc8_get_mask(BitstreamContext *bc, int size, int t)
{
int mask = 0;
if(t && t != size)
mask = mpc8_dec_enum(gb, FFMIN(t, size - t), size);
mask = mpc8_dec_enum(bc, FFMIN(t, size - t), size);
if((t << 1) > size) mask = ~mask;
return mask;
@ -97,7 +98,7 @@ static av_cold int mpc8_decode_init(AVCodecContext * avctx)
{
int i;
MPCContext *c = avctx->priv_data;
GetBitContext gb;
BitstreamContext bc;
static int vlc_initialized = 0;
int channels;
@ -122,17 +123,17 @@ static av_cold int mpc8_decode_init(AVCodecContext * avctx)
ff_mpc_init();
init_get_bits(&gb, avctx->extradata, 16);
bitstream_init(&bc, avctx->extradata, 16);
skip_bits(&gb, 3);//sample rate
c->maxbands = get_bits(&gb, 5) + 1;
channels = get_bits(&gb, 4) + 1;
bitstream_skip(&bc, 3); // sample rate
c->maxbands = bitstream_read(&bc, 5) + 1;
channels = bitstream_read(&bc, 4) + 1;
if (channels > 2) {
avpriv_request_sample(avctx, "Multichannel MPC SV8");
return AVERROR_PATCHWELCOME;
}
c->MSS = get_bits1(&gb);
c->frames = 1 << (get_bits(&gb, 3) * 2);
c->MSS = bitstream_read_bit(&bc);
c->frames = 1 << (bitstream_read(&bc, 3) * 2);
avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
avctx->channel_layout = (avctx->channels==2) ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO;
@ -238,7 +239,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
MPCContext *c = avctx->priv_data;
GetBitContext gb2, *gb = &gb2;
BitstreamContext bc2, *bc = &bc2;
int i, j, k, ch, cnt, res, t;
Band *bands = c->bands;
int off;
@ -258,13 +259,13 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
memset(c->Q, 0, sizeof(c->Q));
c->last_bits_used = 0;
}
init_get_bits(gb, buf, buf_size * 8);
skip_bits(gb, c->last_bits_used & 7);
bitstream_init(bc, buf, buf_size * 8);
bitstream_skip(bc, c->last_bits_used & 7);
if(keyframe)
maxband = mpc8_get_mod_golomb(gb, c->maxbands + 1);
maxband = mpc8_get_mod_golomb(bc, c->maxbands + 1);
else{
maxband = c->last_max_band + get_vlc2(gb, band_vlc.table, MPC8_BANDS_BITS, 2);
maxband = c->last_max_band + bitstream_read_vlc(bc, band_vlc.table, MPC8_BANDS_BITS, 2);
if(maxband > 32) maxband -= 33;
}
if(maxband > c->maxbands + 1)
@ -276,7 +277,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
last[0] = last[1] = 0;
for(i = maxband - 1; i >= 0; i--){
for(ch = 0; ch < 2; ch++){
last[ch] = get_vlc2(gb, res_vlc[last[ch] > 2].table, MPC8_RES_BITS, 2) + last[ch];
last[ch] = bitstream_read_vlc(bc, res_vlc[last[ch] > 2].table, MPC8_RES_BITS, 2) + last[ch];
if(last[ch] > 15) last[ch] -= 17;
bands[i].res[ch] = last[ch];
}
@ -288,8 +289,8 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
for(i = 0; i < maxband; i++)
if(bands[i].res[0] || bands[i].res[1])
cnt++;
t = mpc8_get_mod_golomb(gb, cnt);
mask = mpc8_get_mask(gb, cnt, t);
t = mpc8_get_mod_golomb(bc, cnt);
mask = mpc8_get_mask(bc, cnt, t);
for(i = maxband - 1; i >= 0; i--)
if(bands[i].res[0] || bands[i].res[1]){
bands[i].msf = mask & 1;
@ -309,7 +310,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
if(bands[i].res[0] || bands[i].res[1]){
cnt = !!bands[i].res[0] + !!bands[i].res[1] - 1;
if(cnt >= 0){
t = get_vlc2(gb, scfi_vlc[cnt].table, scfi_vlc[cnt].bits, 1);
t = bitstream_read_vlc(bc, scfi_vlc[cnt].table, scfi_vlc[cnt].bits, 1);
if(bands[i].res[0]) bands[i].scfi[0] = t >> (2 * cnt);
if(bands[i].res[1]) bands[i].scfi[1] = t & 3;
}
@ -321,21 +322,21 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
if(!bands[i].res[ch]) continue;
if(c->oldDSCF[ch][i]){
bands[i].scf_idx[ch][0] = get_bits(gb, 7) - 6;
bands[i].scf_idx[ch][0] = bitstream_read(bc, 7) - 6;
c->oldDSCF[ch][i] = 0;
}else{
t = get_vlc2(gb, dscf_vlc[1].table, MPC8_DSCF1_BITS, 2);
t = bitstream_read_vlc(bc, dscf_vlc[1].table, MPC8_DSCF1_BITS, 2);
if(t == 64)
t += get_bits(gb, 6);
t += bitstream_read(bc, 6);
bands[i].scf_idx[ch][0] = ((bands[i].scf_idx[ch][2] + t - 25) & 0x7F) - 6;
}
for(j = 0; j < 2; j++){
if((bands[i].scfi[ch] << j) & 2)
bands[i].scf_idx[ch][j + 1] = bands[i].scf_idx[ch][j];
else{
t = get_vlc2(gb, dscf_vlc[0].table, MPC8_DSCF0_BITS, 2);
t = bitstream_read_vlc(bc, dscf_vlc[0].table, MPC8_DSCF0_BITS, 2);
if(t == 31)
t = 64 + get_bits(gb, 6);
t = 64 + bitstream_read(bc, 6);
bands[i].scf_idx[ch][j + 1] = ((bands[i].scf_idx[ch][j] + t - 25) & 0x7F) - 6;
}
}
@ -354,16 +355,16 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
break;
case 1:
for(j = 0; j < SAMPLES_PER_BAND; j += SAMPLES_PER_BAND / 2){
cnt = get_vlc2(gb, q1_vlc.table, MPC8_Q1_BITS, 2);
t = mpc8_get_mask(gb, 18, cnt);
cnt = bitstream_read_vlc(bc, q1_vlc.table, MPC8_Q1_BITS, 2);
t = mpc8_get_mask(bc, 18, cnt);
for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t <<= 1)
c->Q[ch][off + j + k] = (t & 0x20000) ? (get_bits1(gb) << 1) - 1 : 0;
c->Q[ch][off + j + k] = (t & 0x20000) ? (bitstream_read_bit(bc) << 1) - 1 : 0;
}
break;
case 2:
cnt = 6;//2*mpc8_thres[res]
for(j = 0; j < SAMPLES_PER_BAND; j += 3){
t = get_vlc2(gb, q2_vlc[cnt > 3].table, MPC8_Q2_BITS, 2);
t = bitstream_read_vlc(bc, q2_vlc[cnt > 3].table, MPC8_Q2_BITS, 2);
c->Q[ch][off + j + 0] = mpc8_idx50[t];
c->Q[ch][off + j + 1] = mpc8_idx51[t];
c->Q[ch][off + j + 2] = mpc8_idx52[t];
@ -373,7 +374,7 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
case 3:
case 4:
for(j = 0; j < SAMPLES_PER_BAND; j += 2){
t = get_vlc2(gb, q3_vlc[res - 3].table, MPC8_Q3_BITS, 2) + q3_offsets[res - 3];
t = bitstream_read_vlc(bc, q3_vlc[res - 3].table, MPC8_Q3_BITS, 2) + q3_offsets[res - 3];
c->Q[ch][off + j + 1] = t >> 4;
c->Q[ch][off + j + 0] = (t & 8) ? (t & 0xF) - 16 : (t & 0xF);
}
@ -384,17 +385,17 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
case 8:
cnt = 2 * mpc8_thres[res];
for(j = 0; j < SAMPLES_PER_BAND; j++){
t = get_vlc2(gb, quant_vlc[res - 5][cnt > mpc8_thres[res]].table, quant_vlc[res - 5][cnt > mpc8_thres[res]].bits, 2) + quant_offsets[res - 5];
t = bitstream_read_vlc(bc, quant_vlc[res - 5][cnt > mpc8_thres[res]].table, quant_vlc[res - 5][cnt > mpc8_thres[res]].bits, 2) + quant_offsets[res - 5];
c->Q[ch][off + j] = t;
cnt = (cnt >> 1) + FFABS(c->Q[ch][off + j]);
}
break;
default:
for(j = 0; j < SAMPLES_PER_BAND; j++){
c->Q[ch][off + j] = get_vlc2(gb, q9up_vlc.table, MPC8_Q9UP_BITS, 2);
c->Q[ch][off + j] = bitstream_read_vlc(bc, q9up_vlc.table, MPC8_Q9UP_BITS, 2);
if(res != 9){
c->Q[ch][off + j] <<= res - 9;
c->Q[ch][off + j] |= get_bits(gb, res - 9);
c->Q[ch][off + j] |= bitstream_read(bc, res - 9);
}
c->Q[ch][off + j] -= (1 << (res - 2)) - 1;
}
@ -408,8 +409,8 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
c->cur_frame++;
c->last_bits_used = get_bits_count(gb);
if(get_bits_left(gb) < 8) // we have only padding left
c->last_bits_used = bitstream_tell(bc);
if (bitstream_bits_left(bc) < 8) // we have only padding left
c->last_bits_used = buf_size << 3;
if(c->cur_frame >= c->frames)
c->cur_frame = 0;

26
libavformat/mpc8.c
View File

@ -19,8 +19,8 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/get_bits.h"
#include "libavcodec/unary_legacy.h"
#include "libavcodec/bitstream.h"
#include "libavcodec/unary.h"
#include "apetag.h"
#include "avformat.h"
@ -107,17 +107,17 @@ static int mpc8_probe(AVProbeData *p)
return 0;
}
static inline int64_t gb_get_v(GetBitContext *gb)
static inline int64_t gb_get_v(BitstreamContext *bc)
{
int64_t v = 0;
int bits = 0;
while(get_bits1(gb) && bits < 64-7){
while (bitstream_read_bit(bc) && bits < 64 - 7) {
v <<= 7;
v |= get_bits(gb, 7);
v |= bitstream_read(bc, 7);
bits += 7;
}
v <<= 7;
v |= get_bits(gb, 7);
v |= bitstream_read(bc, 7);
return v;
}
@ -138,7 +138,7 @@ static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
int64_t size, pos, ppos[2];
uint8_t *buf;
int i, t, seekd;
GetBitContext gb;
BitstreamContext bc;
if (s->nb_streams == 0) {
av_log(s, AV_LOG_ERROR, "No stream added before parsing seek table\n");
@ -158,21 +158,21 @@ static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
if(!(buf = av_malloc(size + AV_INPUT_BUFFER_PADDING_SIZE)))
return;
avio_read(s->pb, buf, size);
init_get_bits(&gb, buf, size * 8);
size = gb_get_v(&gb);
bitstream_init8(&bc, buf, size);
size = gb_get_v(&bc);
if(size > UINT_MAX/4 || size > c->samples/1152){
av_log(s, AV_LOG_ERROR, "Seek table is too big\n");
return;
}
seekd = get_bits(&gb, 4);
seekd = bitstream_read(&bc, 4);
for(i = 0; i < 2; i++){
pos = gb_get_v(&gb) + c->header_pos;
pos = gb_get_v(&bc) + c->header_pos;
ppos[1 - i] = pos;
av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
}
for(; i < size; i++){
t = get_unary(&gb, 1, 33) << 12;
t += get_bits(&gb, 12);
t = get_unary(&bc, 1, 33) << 12;
t += bitstream_read(&bc, 12);
if(t & 1)
t = -(t & ~1);
pos = (t >> 1) + ppos[0]*2 - ppos[1];