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libavc/encoder/ih264e_bitstream.h
Ram Mohan 29f519228a libavcenc: update bitstream context state only in successful writes 
During entropy error, even though the bitstream buffer is not written
with additional bytes, the bitstream context state is getting updated.
As the number of bits left in current word is updated, the get_num_bits
used for computing header and texture bits can become negative causing
overflow errors

Change-Id: I2f990071a9935b2ee328dbd3915dfbefccbab4c5
2023-09-27 13:57:19 -07:00

481 lines
17 KiB
C
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/******************************************************************************
*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*****************************************************************************
* Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore
*/
/**
*******************************************************************************
* @file
* ih264e_bitstream.h
*
* @brief
* This file contains encoder bitstream engine related structures and
* interface prototypes
*
* @author
* ittiam
*
* @remarks
* none
*
*******************************************************************************
*/
#ifndef IH264E_BITSTREAM_H_
#define IH264E_BITSTREAM_H_
/*****************************************************************************/
/* Constant Macros */
/*****************************************************************************/
/**
******************************************************************************
* @brief defines the maximum number of bits in a bitstream word
******************************************************************************
*/
#define WORD_SIZE 32
/**
******************************************************************************
* @brief The number of consecutive zero bytes for emulation prevention check
******************************************************************************
*/
#define EPB_ZERO_BYTES 2
/**
******************************************************************************
* @brief Emulation prevention insertion byte
******************************************************************************
*/
#define EPB_BYTE 0x03
/**
******************************************************************************
* @brief Stream buffer allocated per frame should be atleast MIN_STREAM_SIZE
******************************************************************************
*/
#define MIN_STREAM_SIZE 0x800
/*****************************************************************************/
/* Function Macros */
/*****************************************************************************/
/**
******************************************************************************
* @brief Macro to check if emulation prevention byte insertion is required
******************************************************************************
*/
#define SHOULD_INSERT_EPB(zero_run, next_byte) \
((zero_run) == EPB_ZERO_BYTES) && (0 == ((next_byte) & 0xFC))
/**
******************************************************************************
* @brief returns the bit position of a leading 1 (msb) in a code value
******************************************************************************
*/
#if !MSVC
#define GETRANGE(r,value) \
{ \
r = 0; \
if(0 == value) \
r = 1; \
else \
{ \
r = 32-CLZ(value); \
}\
}
#else
#define GETRANGE(r,value) \
{ \
unsigned long msb_one_bit = 0; \
r = _BitScanReverse(&msb_one_bit, value) ? (UWORD32)(msb_one_bit + 1) : 1 ; \
}
#endif
/**
******************************************************************************
* @brief returns bits required to code a value
******************************************************************************
*/
#define UE_LENGTH(bits,x) \
{ \
UWORD32 r_bit; \
GETRANGE(r_bit,x+1) \
bits =(((r_bit - 1) << 1)+1);\
} \
/**
******************************************************************************
* @brief Inserts 1 byte and Emulation Prevention Byte(if any) into bitstream
* Increments the stream offset and zero run correspondingly
******************************************************************************
*/
#define PUTBYTE_EPB(ptr,off,byte,zero_run) \
{ \
if( SHOULD_INSERT_EPB(zero_run, byte) ) \
{ \
ptr[off] = EPB_BYTE; \
off++; \
zero_run = 0; \
} \
\
ptr[off] = byte; \
off++; \
zero_run = byte ? 0 : zero_run+1; \
} \
/**
******************************************************************************
* @brief Ensures Byte alignment of the slice header
******************************************************************************
*/
#define BYTE_ALIGNMENT(ps_bitstrm) ih264e_put_rbsp_trailing_bits(ps_bitstrm)
/**
******************************************************************************
* @brief Gets number of bits coded
******************************************************************************
*/
#define GET_NUM_BITS(ps_bitstream) ((ps_bitstream->u4_strm_buf_offset << 3) \
+ 32 - ps_bitstream->i4_bits_left_in_cw);
/**
******************************************************************************
* @macro Align bitstream to byte - Remainig bits are filled with '1'
******************************************************************************
*/
#define BITSTREAM_BYTE_ALIGN(ps_bitstrm) \
if (ps_bitstrm->i4_bits_left_in_cw & 0x07) \
{ \
const WORD32 len = (WORD32)((ps_bitstrm->i4_bits_left_in_cw) & 0x07);\
ih264e_put_bits(ps_bitstrm, (UWORD32)((1 << len) - 1), len); \
} \
/*****************************************************************************/
/* Structures */
/*****************************************************************************/
/**
******************************************************************************
* @brief Bitstream context for encoder
******************************************************************************
*/
typedef struct bitstrm
{
/** points to start of stream buffer. */
UWORD8 *pu1_strm_buffer;
/**
* max bitstream size (in bytes).
* Encoded stream shall not exceed this size.
*/
UWORD32 u4_max_strm_size;
/**
* byte offset (w.r.t pu1_strm_buffer) where next byte would be written
* Bitstream engine makes sure it would not corrupt data beyond
* u4_max_strm_size bytes
*/
UWORD32 u4_strm_buf_offset;
/**
* current bitstream word; It is a scratch word containing max of
* WORD_SIZE bits. Will be copied to stream buffer when the word is
* full
*/
UWORD32 u4_cur_word;
/**
* signifies number of bits available in u4_cur_word
* bits from msb to i4_bits_left_in_cw of u4_cur_word have already been
* inserted next bits would be inserted from pos [i4_bits_left_in_cw-1]
* Range of this variable [1 : WORD_SIZE]
*/
WORD32 i4_bits_left_in_cw;
/**
* signifies the number of consecutive zero bytes propogated from previous
* word. It is used for emulation prevention byte insertion in the stream
*/
WORD32 i4_zero_bytes_run;
} bitstrm_t;
/**
******************************************************************************
* @brief Inserts 1 byte and Emulation Prevention Byte(if any) into bitstream
* Increments the stream offset and zero run correspondingly
******************************************************************************
*/
static inline IH264E_ERROR_T ih264e_put_byte_epb(bitstrm_t *ps_bitstrm, UWORD8 byte)
{
if (SHOULD_INSERT_EPB(ps_bitstrm->i4_zero_bytes_run, byte))
{
if ((ps_bitstrm->u4_strm_buf_offset + 1) >= ps_bitstrm->u4_max_strm_size)
{
return IH264E_BITSTREAM_BUFFER_OVERFLOW;
}
ps_bitstrm->pu1_strm_buffer[ps_bitstrm->u4_strm_buf_offset++] = EPB_BYTE;
ps_bitstrm->i4_zero_bytes_run = 0;
}
if ((ps_bitstrm->u4_strm_buf_offset + 1) >= ps_bitstrm->u4_max_strm_size)
{
return IH264E_BITSTREAM_BUFFER_OVERFLOW;
}
ps_bitstrm->pu1_strm_buffer[ps_bitstrm->u4_strm_buf_offset++] = byte;
ps_bitstrm->i4_zero_bytes_run = byte ? 0 : ps_bitstrm->i4_zero_bytes_run + 1;
return IH264E_SUCCESS;
}
/**
******************************************************************************
* flush the bits in cur word byte by byte and copy to stream *
* (current word is assumed to be byte aligned) *
******************************************************************************
*/
#define BITSTREAM_FLUSH(ps_bitstrm, err) \
{ \
WORD32 i; \
for (i = WORD_SIZE; i > ps_bitstrm->i4_bits_left_in_cw; i -= 8) \
{ \
UWORD8 u1_next_byte = (ps_bitstrm->u4_cur_word >> (i - 8)) & 0xFF; \
err |= ih264e_put_byte_epb(ps_bitstrm, u1_next_byte); \
} \
if (err == IH264E_SUCCESS) { \
ps_bitstrm->u4_cur_word = 0; \
ps_bitstrm->i4_bits_left_in_cw = WORD_SIZE; \
} \
}
/*****************************************************************************/
/* Extern Function Declarations */
/*****************************************************************************/
/**
******************************************************************************
*
* @brief Initializes the encoder bitstream engine
*
* @par Description
* This routine needs to be called at start of slice/frame encode
*
* @param[in] ps_bitstrm
* pointer to bitstream context (handle)
*
* @param[in] p1_bitstrm_buf
* bitstream buffer pointer where the encoded stream is generated in byte order
*
* @param[in] u4_max_bitstrm_size
* indicates maximum bitstream buffer size. (in bytes)
* If actual stream size exceeds the maximum size, encoder should
* 1. Not corrupt data beyond u4_max_bitstrm_size bytes
* 2. Report an error back to application indicating overflow
*
* @return success or failure error code
*
******************************************************************************
*/
IH264E_ERROR_T ih264e_bitstrm_init
(
bitstrm_t *ps_bitstrm,
UWORD8 *pu1_bitstrm_buf,
UWORD32 u4_max_bitstrm_size
);
/**
******************************************************************************
*
* @brief puts a code with specified number of bits into the bitstream
*
* @par Description
* inserts code_len number of bits from lsb of code_val into the
* bitstream. If the total bytes (u4_strm_buf_offset) exceeds max
* available size (u4_max_strm_size), returns error without corrupting data
* beyond it
*
* @param[in] ps_bitstrm
* pointer to bitstream context (handle)
*
* @param[in] u4_code_val
* code value that needs to be inserted in the stream.
*
* @param[in] code_len
* indicates code length (in bits) of code_val that would be inserted in
* bitstream buffer size.
*
* @remarks Assumptions: all bits from bit position code_len to msb of
* code_val shall be zero
*
* @return success or failure error code
*
******************************************************************************
*/
IH264E_ERROR_T ih264e_put_bits
(
bitstrm_t *ps_bitstrm,
UWORD32 u4_code_val,
WORD32 code_len
);
/**
******************************************************************************
*
* @brief inserts a 1-bit code into the bitstream
*
* @par Description
* inserts 1bit lsb of code_val into the bitstream
* updates context members like u4_cur_word, u4_strm_buf_offset and
* i4_bits_left_in_cw. If the total words (u4_strm_buf_offset) exceeds max
* available size (u4_max_strm_size), returns error without corrupting data
* beyond it
*
* @param[in] ps_bitstrm
* pointer to bitstream context (handle)
*
* @param[in] u4_code_val
* code value that needs to be inserted in the stream.
*
* @remarks Assumptions: all bits from bit position 1 to msb of code_val
* shall be zero
*
* @return success or failure error code
*
******************************************************************************
*/
IH264E_ERROR_T ih264e_put_bit
(
bitstrm_t *ps_bitstrm,
UWORD32 u4_code_val
);
/**
******************************************************************************
*
* @brief inserts rbsp trailing bits at the end of stream buffer (NAL)
*
* @par Description
* inserts rbsp trailing bits, updates context members like u4_cur_word and
* i4_bits_left_in_cw and flushes the same in the bitstream buffer. If the
* total words (u4_strm_buf_offset) exceeds max available size
* (u4_max_strm_size), returns error without corrupting data beyond it
*
* @param[in] ps_bitstrm
* pointer to bitstream context (handle)
*
* @return success or failure error code
*
******************************************************************************
*/
IH264E_ERROR_T ih264e_put_rbsp_trailing_bits
(
bitstrm_t *ps_bitstrm
);
/**
******************************************************************************
*
* @brief puts exponential golomb code of a unsigned integer into bitstream
*
* @par Description
* computes uev code for given syntax element and inserts the same into
* bitstream by calling ih264e_put_bits() interface.
*
* @param[in] ps_bitstrm
* pointer to bitstream context (handle)
*
* @param[in] u4_code_num
* unsigned integer input whose golomb code is written in stream
*
* @remarks Assumptions: code value can be represented in less than 16bits
*
* @return success or failure error code
*
******************************************************************************
*/
IH264E_ERROR_T ih264e_put_uev
(
bitstrm_t *ps_bitstrm,
UWORD32 u4_code_num
);
/**
******************************************************************************
*
* @brief puts exponential golomb code of a signed integer into bitstream
*
* @par Description
* computes sev code for given syntax element and inserts the same into
* bitstream by calling ih264e_put_bits() interface.
*
* @param[in] ps_bitstrm
* pointer to bitstream context (handle)
*
* @param[in] syntax_elem
* signed integer input whose golomb code is written in stream
*
* @remarks Assumptions: code value can be represented in less than 16bits
*
* @return success or failure error code
*
******************************************************************************
*/
IH264E_ERROR_T ih264e_put_sev
(
bitstrm_t *ps_bitstrm,
WORD32 syntax_elem
);
/**
******************************************************************************
*
* @brief insert NAL start code prefix (0x000001) into bitstream with an option
* of inserting leading_zero_8bits (which makes startcode prefix as 0x00000001)
*
* @par Description
* Although start code prefix could have been put by calling ih264e_put_bits(),
* ih264e_put_nal_start_code_prefix() is specially added to make sure emulation
* prevention insertion is not done for the NAL start code prefix which will
* surely happen otherwise by calling ih264e_put_bits() interface.
*
* @param[in] ps_bitstrm
* pointer to bitstream context (handle)
*
* @param[in] insert_leading_zero_8bits
* flag indicating if one more zero bytes needs to prefixed before start code
*
* @return success or failure error code
*
******************************************************************************
*/
IH264E_ERROR_T ih264e_put_nal_start_code_prefix
(
bitstrm_t *ps_bitstrm,
WORD32 insert_leading_zero_8bits
);
#endif /* IH264E_BITSTREAM_H_ */
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