[SCM] libav/experimental: cleanup mpeg1/2 bitstream parser
siretart at users.alioth.debian.org
siretart at users.alioth.debian.org
Sun Jun 30 15:36:05 UTC 2013
The following commit has been merged in the experimental branch:
commit 80097bbf712ca2f577b375d6ba94e3957b2c2e78
Author: Michael Niedermayer <michaelni at gmx.at>
Date: Tue Apr 22 13:55:12 2003 +0000
cleanup mpeg1/2 bitstream parser
Originally committed as revision 1813 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
index 98215bf..cc3bff1 100644
--- a/libavcodec/h263dec.c
+++ b/libavcodec/h263dec.c
@@ -325,14 +325,16 @@ static int mpeg4_find_frame_end(MpegEncContext *s, uint8_t *buf, int buf_size){
}
}
}
-
- for(; i<buf_size; i++){
+
+ if(vop_found){
+ for(; i<buf_size; i++){
state= (state<<8) | buf[i];
if((state&0xFFFFFF00) == 0x100){
pc->frame_start_found=0;
pc->state=-1;
return i-3;
}
+ }
}
pc->frame_start_found= vop_found;
pc->state= state;
diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c
index a218080..d16eaa1 100644
--- a/libavcodec/mpeg12.c
+++ b/libavcodec/mpeg12.c
@@ -1543,16 +1543,8 @@ static inline int mpeg2_decode_block_intra(MpegEncContext *s,
return 0;
}
-/* compressed picture size */
-#define PICTURE_BUFFER_SIZE 100000
-
typedef struct Mpeg1Context {
MpegEncContext mpeg_enc_ctx;
- uint32_t header_state;
- int start_code; /* current start code */
- uint8_t buffer[PICTURE_BUFFER_SIZE];
- uint8_t *buf_ptr;
- int buffer_size;
int mpeg_enc_ctx_allocated; /* true if decoding context allocated */
int repeat_field; /* true if we must repeat the field */
} Mpeg1Context;
@@ -1565,11 +1557,7 @@ static int mpeg_decode_init(AVCodecContext *avctx)
common_init(&s->mpeg_enc_ctx);
init_vlcs(&s->mpeg_enc_ctx);
- s->header_state = 0xff;
s->mpeg_enc_ctx_allocated = 0;
- s->buffer_size = PICTURE_BUFFER_SIZE;
- s->start_code = -1;
- s->buf_ptr = s->buffer;
s->mpeg_enc_ctx.picture_number = 0;
s->repeat_field = 0;
s->mpeg_enc_ctx.codec_id= avctx->codec->id;
@@ -1578,14 +1566,12 @@ static int mpeg_decode_init(AVCodecContext *avctx)
/* return the 8 bit start code value and update the search
state. Return -1 if no start code found */
-static int find_start_code(uint8_t **pbuf_ptr, uint8_t *buf_end,
- uint32_t *header_state)
+static int find_start_code(uint8_t **pbuf_ptr, uint8_t *buf_end)
{
uint8_t *buf_ptr;
- unsigned int state, v;
+ unsigned int state=0xFFFFFFFF, v;
int val;
- state = *header_state;
buf_ptr = *pbuf_ptr;
while (buf_ptr < buf_end) {
v = *buf_ptr++;
@@ -1599,7 +1585,6 @@ static int find_start_code(uint8_t **pbuf_ptr, uint8_t *buf_end,
val = -1;
found:
*pbuf_ptr = buf_ptr;
- *header_state = state;
return val;
}
@@ -1809,7 +1794,7 @@ static void mpeg_decode_extension(AVCodecContext *avctx,
static int mpeg_decode_slice(AVCodecContext *avctx,
AVFrame *pict,
int start_code,
- uint8_t *buf, int buf_size)
+ uint8_t **buf, int buf_size)
{
Mpeg1Context *s1 = avctx->priv_data;
MpegEncContext *s = &s1->mpeg_enc_ctx;
@@ -1874,7 +1859,7 @@ static int mpeg_decode_slice(AVCodecContext *avctx,
}
s->first_slice = 0;
- init_get_bits(&s->gb, buf, buf_size*8);
+ init_get_bits(&s->gb, *buf, buf_size*8);
s->qscale = get_qscale(s);
if(s->qscale == 0){
@@ -1928,7 +1913,6 @@ static int mpeg_decode_slice(AVCodecContext *avctx,
motion_x = s->mv[0][0][0];
motion_y = s->mv[0][0][1];
} else /*if (s->mv_type == MV_TYPE_FIELD)*/ {
- int i;
motion_x = s->mv[0][0][0] + s->mv[0][1][0];
motion_y = s->mv[0][0][1] + s->mv[0][1][1];
motion_x = (motion_x>>1) | (motion_x&1);
@@ -1996,6 +1980,8 @@ eos: //end of slice
emms_c();
+ *buf += get_bits_count(&s->gb)/8 - 1;
+
//intf("%d %d %d %d\n", s->mb_y, s->mb_height, s->pict_type, s->picture_number);
/* end of slice reached */
if (s->mb_y<<field_pic == s->mb_height && !s->first_field) {
@@ -2017,9 +2003,7 @@ eos: //end of slice
s->picture_number++;
/* latency of 1 frame for I and P frames */
/* XXX: use another variable than picture_number */
- if (s->last_picture_ptr == NULL) {
- return DECODE_SLICE_OK;
- } else {
+ if (s->last_picture_ptr != NULL) {
*pict= *(AVFrame*)&s->last_picture;
ff_print_debug_info(s, s->last_picture_ptr);
}
@@ -2170,17 +2154,55 @@ static void mpeg_decode_user_data(AVCodecContext *avctx,
}
}
+/**
+ * finds the end of the current frame in the bitstream.
+ * @return the position of the first byte of the next frame, or -1
+ */
+static int mpeg1_find_frame_end(MpegEncContext *s, uint8_t *buf, int buf_size){
+ ParseContext *pc= &s->parse_context;
+ int i;
+ uint32_t state;
+
+ state= pc->state;
+
+ i=0;
+ if(!pc->frame_start_found){
+ for(i=0; i<buf_size; i++){
+ state= (state<<8) | buf[i];
+ if(state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE){
+ i++;
+ pc->frame_start_found=1;
+ break;
+ }
+ }
+ }
+
+ if(pc->frame_start_found){
+ for(; i<buf_size; i++){
+ state= (state<<8) | buf[i];
+ if((state&0xFFFFFF00) == 0x100){
+ if(state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE){
+ pc->frame_start_found=0;
+ pc->state=-1;
+ return i-3;
+ }
+ }
+ }
+ }
+ pc->state= state;
+ return -1;
+}
+
/* handle buffering and image synchronisation */
static int mpeg_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
uint8_t *buf, int buf_size)
{
Mpeg1Context *s = avctx->priv_data;
- uint8_t *buf_end, *buf_ptr, *buf_start;
- int len, start_code_found, ret, code, start_code, input_size;
+ uint8_t *buf_end, *buf_ptr;
+ int ret, start_code, input_size;
AVFrame *picture = data;
MpegEncContext *s2 = &s->mpeg_enc_ctx;
-
dprintf("fill_buffer\n");
*data_size = 0;
@@ -2195,6 +2217,15 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
return 0;
}
+ if(s2->flags&CODEC_FLAG_TRUNCATED){
+ int next;
+
+ next= mpeg1_find_frame_end(s2, buf, buf_size);
+
+ if( ff_combine_frame(s2, next, &buf, &buf_size) < 0 )
+ return buf_size;
+ }
+
buf_ptr = buf;
buf_end = buf + buf_size;
@@ -2209,60 +2240,34 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
}
}
#endif
- while (buf_ptr < buf_end) {
- buf_start = buf_ptr;
+ for(;;) {
/* find start next code */
- code = find_start_code(&buf_ptr, buf_end, &s->header_state);
- if (code >= 0) {
- start_code_found = 1;
- } else {
- start_code_found = 0;
+ start_code = find_start_code(&buf_ptr, buf_end);
+ if (start_code < 0){
+ printf("missing end of picture\n");
+ return FFMAX(1, buf_ptr - buf - s2->parse_context.last_index);
}
- /* copy to buffer */
- len = buf_ptr - buf_start;
- if (len + (s->buf_ptr - s->buffer) > s->buffer_size) {
- /* data too big : flush */
- s->buf_ptr = s->buffer;
- if (start_code_found)
- s->start_code = code;
- } else {
- memcpy(s->buf_ptr, buf_start, len);
- s->buf_ptr += len;
- if( (!(s2->flags&CODEC_FLAG_TRUNCATED)) && (!start_code_found)
- && s->buf_ptr+4<s->buffer+s->buffer_size){
- start_code_found= 1;
- code= 0x1FF;
- s->header_state=0xFF;
- s->buf_ptr[0]=0;
- s->buf_ptr[1]=0;
- s->buf_ptr[2]=1;
- s->buf_ptr[3]=0xFF;
- s->buf_ptr+=4;
- }
- if (start_code_found) {
+
/* prepare data for next start code */
- input_size = s->buf_ptr - s->buffer;
- start_code = s->start_code;
- s->buf_ptr = s->buffer;
- s->start_code = code;
+ input_size = buf_end - buf_ptr;
switch(start_code) {
case SEQ_START_CODE:
- mpeg1_decode_sequence(avctx, s->buffer,
+ mpeg1_decode_sequence(avctx, buf_ptr,
input_size);
break;
case PICTURE_START_CODE:
/* we have a complete image : we try to decompress it */
mpeg1_decode_picture(avctx,
- s->buffer, input_size);
+ buf_ptr, input_size);
break;
case EXT_START_CODE:
mpeg_decode_extension(avctx,
- s->buffer, input_size);
+ buf_ptr, input_size);
break;
case USER_START_CODE:
mpeg_decode_user_data(avctx,
- s->buffer, input_size);
+ buf_ptr, input_size);
break;
default:
if (start_code >= SLICE_MIN_START_CODE &&
@@ -2274,15 +2279,16 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
if(avctx->hurry_up && s2->pict_type==B_TYPE) break;
/* skip everything if we are in a hurry>=5 */
if(avctx->hurry_up>=5) break;
-
+
if (!s->mpeg_enc_ctx_allocated) break;
ret = mpeg_decode_slice(avctx, picture,
- start_code, s->buffer, input_size);
+ start_code, &buf_ptr, input_size);
if (ret == DECODE_SLICE_EOP) {
- *data_size = sizeof(AVPicture);
- goto the_end;
+ if(s2->last_picture_ptr) //FIXME merge with the stuff in mpeg_decode_slice
+ *data_size = sizeof(AVPicture);
+ return FFMAX(1, buf_ptr - buf - s2->parse_context.last_index);
}else if(ret < 0){
if(ret == DECODE_SLICE_ERROR)
ff_er_add_slice(s2, s2->resync_mb_x, s2->resync_mb_y, s2->mb_x, s2->mb_y, AC_ERROR|DC_ERROR|MV_ERROR);
@@ -2293,11 +2299,7 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
}
break;
}
- }
- }
}
- the_end:
- return buf_ptr - buf;
}
static int mpeg_decode_end(AVCodecContext *avctx)
--
Libav/FFmpeg packaging
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