rtpvp8: fix bitstream parsing using the wrong kind of bitreader

VP8 uses a probabilistic bool coder, not a straight bit coder.
This fixes parsing when error-resilient is set.

This commit includes a copy of libvpx's bool coder, BSD licensed.

https://bugzilla.gnome.org/show_bug.cgi?id=652694
This commit is contained in:
Vincent Penquerc'h 2011-09-10 11:31:20 +01:00 committed by Tim-Philipp Müller
parent 97c3f3617c
commit 88aade4150
3 changed files with 263 additions and 68 deletions

68
gst/rtp/dboolhuff.c Normal file
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@ -0,0 +1,68 @@
/*
* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the dboolhuff.LICENSE file in this directory.
* See the libvpx original distribution for more information,
* including patent information, and author information.
*/
#include "dboolhuff.h"
const unsigned char vp8_norm[256] __attribute__ ((aligned (16))) = {
0, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
int
vp8dx_start_decode (BOOL_DECODER * br,
const unsigned char *source, unsigned int source_sz)
{
br->user_buffer_end = source + source_sz;
br->user_buffer = source;
br->value = 0;
br->count = -8;
br->range = 255;
if (source_sz && !source)
return 1;
/* Populate the buffer */
vp8dx_bool_decoder_fill (br);
return 0;
}
void
vp8dx_bool_decoder_fill (BOOL_DECODER * br)
{
const unsigned char *bufptr;
const unsigned char *bufend;
VP8_BD_VALUE value;
int count;
bufend = br->user_buffer_end;
bufptr = br->user_buffer;
value = br->value;
count = br->count;
VP8DX_BOOL_DECODER_FILL (count, value, bufptr, bufend);
br->user_buffer = bufptr;
br->value = value;
br->count = count;
}

151
gst/rtp/dboolhuff.h Normal file
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@ -0,0 +1,151 @@
/*
* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the dboolhuff.LICENSE file in this directory.
* See the libvpx original distribution for more information,
* including patent information, and author information.
*/
#ifndef DBOOLHUFF_H
#define DBOOLHUFF_H
#include <stddef.h>
#include <limits.h>
#include <glib.h>
typedef size_t VP8_BD_VALUE;
# define VP8_BD_VALUE_SIZE ((int)sizeof(VP8_BD_VALUE)*CHAR_BIT)
/*This is meant to be a large, positive constant that can still be efficiently
loaded as an immediate (on platforms like ARM, for example).
Even relatively modest values like 100 would work fine.*/
# define VP8_LOTS_OF_BITS (0x40000000)
typedef struct
{
const unsigned char *user_buffer_end;
const unsigned char *user_buffer;
VP8_BD_VALUE value;
int count;
unsigned int range;
} BOOL_DECODER;
extern const unsigned char vp8_norm[256] __attribute__((aligned(16)));
int vp8dx_start_decode(BOOL_DECODER *br,
const unsigned char *source,
unsigned int source_sz);
void vp8dx_bool_decoder_fill(BOOL_DECODER *br);
/*The refill loop is used in several places, so define it in a macro to make
sure they're all consistent.
An inline function would be cleaner, but has a significant penalty, because
multiple BOOL_DECODER fields must be modified, and the compiler is not smart
enough to eliminate the stores to those fields and the subsequent reloads
from them when inlining the function.*/
#define VP8DX_BOOL_DECODER_FILL(_count,_value,_bufptr,_bufend) \
do \
{ \
int shift = VP8_BD_VALUE_SIZE - 8 - ((_count) + 8); \
int loop_end, x; \
size_t bits_left = ((_bufend)-(_bufptr))*CHAR_BIT; \
\
x = shift + CHAR_BIT - bits_left; \
loop_end = 0; \
if(x >= 0) \
{ \
(_count) += VP8_LOTS_OF_BITS; \
loop_end = x; \
if(!bits_left) break; \
} \
while(shift >= loop_end) \
{ \
(_count) += CHAR_BIT; \
(_value) |= (VP8_BD_VALUE)*(_bufptr)++ << shift; \
shift -= CHAR_BIT; \
} \
} \
while(0) \
static int vp8dx_decode_bool(BOOL_DECODER *br, int probability) {
unsigned int bit = 0;
VP8_BD_VALUE value;
unsigned int split;
VP8_BD_VALUE bigsplit;
int count;
unsigned int range;
split = 1 + (((br->range - 1) * probability) >> 8);
if(br->count < 0)
vp8dx_bool_decoder_fill(br);
value = br->value;
count = br->count;
bigsplit = (VP8_BD_VALUE)split << (VP8_BD_VALUE_SIZE - 8);
range = split;
if (value >= bigsplit)
{
range = br->range - split;
value = value - bigsplit;
bit = 1;
}
{
register unsigned int shift = vp8_norm[range];
range <<= shift;
value <<= shift;
count -= shift;
}
br->value = value;
br->count = count;
br->range = range;
return bit;
}
static G_GNUC_UNUSED int vp8_decode_value(BOOL_DECODER *br, int bits)
{
int z = 0;
int bit;
for (bit = bits - 1; bit >= 0; bit--)
{
z |= (vp8dx_decode_bool(br, 0x80) << bit);
}
return z;
}
static G_GNUC_UNUSED int vp8dx_bool_error(BOOL_DECODER *br)
{
/* Check if we have reached the end of the buffer.
*
* Variable 'count' stores the number of bits in the 'value' buffer, minus
* 8. The top byte is part of the algorithm, and the remainder is buffered
* to be shifted into it. So if count == 8, the top 16 bits of 'value' are
* occupied, 8 for the algorithm and 8 in the buffer.
*
* When reading a byte from the user's buffer, count is filled with 8 and
* one byte is filled into the value buffer. When we reach the end of the
* data, count is additionally filled with VP8_LOTS_OF_BITS. So when
* count == VP8_LOTS_OF_BITS - 1, the user's data has been exhausted.
*/
if ((br->count > VP8_BD_VALUE_SIZE) && (br->count < VP8_LOTS_OF_BITS))
{
/* We have tried to decode bits after the end of
* stream was encountered.
*/
return 1;
}
/* No error. */
return 0;
}
#endif

View file

@ -25,6 +25,7 @@
#include <gst/base/gstbitreader.h>
#include <gst/rtp/gstrtppayloads.h>
#include <gst/rtp/gstrtpbuffer.h>
#include "dboolhuff.h"
#include "gstrtpvp8pay.h"
#define FI_FRAG_UNFRAGMENTED 0x0
@ -130,6 +131,8 @@ gst_rtp_vp8_pay_parse_frame (GstRtpVP8Pay * self, GstBuffer * buffer)
guint8 tmp8 = 0;
guint8 *data;
guint8 partitions;
guint offset;
BOOL_DECODER bc;
reader = gst_bit_reader_new_from_buffer (buffer);
@ -150,7 +153,8 @@ gst_rtp_vp8_pay_parse_frame (GstRtpVP8Pay * self, GstBuffer * buffer)
header_size = data[2] << 11 | data[1] << 3 | (data[0] >> 5);
/* Include the uncompressed data blob in the header */
header_size += keyframe ? 10 : 3;
offset = keyframe ? 10 : 3;
header_size += offset;
if (!gst_bit_reader_skip (reader, 24))
goto error;
@ -166,109 +170,81 @@ gst_rtp_vp8_pay_parse_frame (GstRtpVP8Pay * self, GstBuffer * buffer)
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 8) || tmp8 != 0x2a)
goto error;
/* Skip horizontal size code (16 bits) vertical size code (16 bits),
* color space (1 bit) and clamping type (1 bit) */
if (!gst_bit_reader_skip (reader, 34))
/* Skip horizontal size code (16 bits) vertical size code (16 bits) */
if (!gst_bit_reader_skip (reader, 32))
goto error;
}
offset = keyframe ? 10 : 3;
vp8dx_start_decode (&bc, GST_BUFFER_DATA (buffer) + offset,
GST_BUFFER_SIZE (buffer) - offset);
if (keyframe) {
/* color space (1 bit) and clamping type (1 bit) */
vp8dx_decode_bool (&bc, 0x80);
vp8dx_decode_bool (&bc, 0x80);
}
/* segmentation_enabled */
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 1))
goto error;
if (tmp8 != 0) {
gboolean update_mb_segmentation_map;
gboolean update_segment_feature_data;
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 2))
goto error;
update_mb_segmentation_map = (tmp8 & 0x2) != 0;
update_segment_feature_data = (tmp8 & 0x1) != 0;
if (vp8dx_decode_bool (&bc, 0x80)) {
guint8 update_mb_segmentation_map = vp8dx_decode_bool (&bc, 0x80);
guint8 update_segment_feature_data = vp8dx_decode_bool (&bc, 0x80);
if (update_segment_feature_data) {
/* skip segment feature mode */
if (!gst_bit_reader_skip (reader, 1))
goto error;
vp8dx_decode_bool (&bc, 0x80);
/* quantizer update */
for (i = 0; i < 4; i++) {
/* quantizer update */
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 1))
goto error;
if (tmp8 != 0) {
/* skip quantizer value (7 bits) and sign (1 bit) */
if (!gst_bit_reader_skip (reader, 8))
goto error;
}
/* skip flagged quantizer value (7 bits) and sign (1 bit) */
if (vp8dx_decode_bool (&bc, 0x80))
vp8_decode_value (&bc, 8);
}
/* loop filter update */
for (i = 0; i < 4; i++) {
/* loop filter update */
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 1))
goto error;
if (tmp8 != 0) {
/* skip lf update value (6 bits) and sign (1 bit) */
if (!gst_bit_reader_skip (reader, 7))
goto error;
}
/* skip flagged lf update value (6 bits) and sign (1 bit) */
if (vp8dx_decode_bool (&bc, 0x80))
vp8_decode_value (&bc, 7);
}
}
if (update_mb_segmentation_map) {
/* segment prob update */
for (i = 0; i < 3; i++) {
/* segment prob update */
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 1))
goto error;
if (tmp8 != 0) {
/* skip segment prob */
if (!gst_bit_reader_skip (reader, 8))
goto error;
}
/* skip flagged segment prob */
if (vp8dx_decode_bool (&bc, 0x80))
vp8_decode_value (&bc, 8);
}
}
}
/* skip filter type (1 bit), loop filter level (6 bits) and
* sharpness level (3 bits) */
if (!gst_bit_reader_skip (reader, 10))
goto error;
vp8_decode_value (&bc, 1);
vp8_decode_value (&bc, 6);
vp8_decode_value (&bc, 3);
/* loop_filter_adj_enabled */
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 1))
goto error;
if (vp8dx_decode_bool (&bc, 0x80)) {
if (tmp8 != 0) {
/* loop filter adj enabled */
/* mode_ref_lf_delta_update */
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 1))
goto error;
if (tmp8 != 0) {
/* mode_ref_lf_data_update */
int i;
/* delta update */
if (vp8dx_decode_bool (&bc, 0x80)) {
for (i = 0; i < 8; i++) {
/* 8 updates, 1 bit indicate whether there is one and if follow by a
* 7 bit update */
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 1))
goto error;
if (tmp8 != 0) {
/* skip delta magnitude (6 bits) and sign (1 bit) */
if (!gst_bit_reader_skip (reader, 7))
goto error;
}
if (vp8dx_decode_bool (&bc, 0x80))
vp8_decode_value (&bc, 7);
}
}
}
if (!gst_bit_reader_get_bits_uint8 (reader, &tmp8, 2))
if (vp8dx_bool_error (&bc))
goto error;
tmp8 = vp8_decode_value (&bc, 2);
partitions = 1 << tmp8;
/* Check if things are still sensible */