FFmpeg
Data Structures | Macros | Functions
vlc.c File Reference
#include <inttypes.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/error.h"
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "libavutil/macros.h"
#include "libavutil/mem.h"
#include "libavutil/qsort.h"
#include "libavutil/reverse.h"
#include "vlc.h"

Go to the source code of this file.

Data Structures

struct  VLCcode
 

Macros

#define GET_DATA(v, table, i, wrap, size)
 
#define LOCALBUF_ELEMS   1500
 
#define COPY(condition)
 

Functions

static int alloc_table (VLC *vlc, int size, int use_static)
 
static av_always_inline uint32_t bitswap_32 (uint32_t x)
 
static int vlc_common_init (VLC *vlc, int nb_bits, int nb_codes, VLCcode **buf, int flags)
 
static int compare_vlcspec (const void *a, const void *b)
 
static int build_table (VLC *vlc, int table_nb_bits, int nb_codes, VLCcode *codes, int flags)
 Build VLC decoding tables suitable for use with get_vlc(). More...
 
static int vlc_common_end (VLC *vlc, int nb_bits, int nb_codes, VLCcode *codes, int flags, VLCcode localbuf[LOCALBUF_ELEMS])
 
int ff_vlc_init_sparse (VLC *vlc, int nb_bits, int nb_codes, const void *bits, int bits_wrap, int bits_size, const void *codes, int codes_wrap, int codes_size, const void *symbols, int symbols_wrap, int symbols_size, int flags)
 Build VLC decoding tables suitable for use with get_vlc2(). More...
 
int ff_vlc_init_from_lengths (VLC *vlc, int nb_bits, int nb_codes, const int8_t *lens, int lens_wrap, const void *symbols, int symbols_wrap, int symbols_size, int offset, int flags, void *logctx)
 Build VLC decoding tables suitable for use with get_vlc2() More...
 
static void add_level (VLC_MULTI_ELEM *table, const int is16bit, const int num, const int numbits, const VLCcode *buf, uint32_t curcode, int curlen, int curlimit, int curlevel, const int minlen, const int max, unsigned *levelcnt, VLC_MULTI_ELEM info)
 
static int vlc_multi_gen (VLC_MULTI_ELEM *table, const VLC *single, const int is16bit, const int nb_codes, const int numbits, VLCcode *buf, void *logctx)
 
int ff_vlc_init_multi_from_lengths (VLC *vlc, VLC_MULTI *multi, int nb_bits, int nb_elems, int nb_codes, const int8_t *lens, int lens_wrap, const void *symbols, int symbols_wrap, int symbols_size, int offset, int flags, void *logctx)
 Build VLC decoding tables suitable for use with get_vlc_multi() More...
 
void ff_vlc_free_multi (VLC_MULTI *vlc)
 
void ff_vlc_free (VLC *vlc)
 

Macro Definition Documentation

◆ GET_DATA

#define GET_DATA (   v,
  table,
  i,
  wrap,
  size 
)
Value:
{ \
const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
switch(size) { \
case 1: \
v = *(const uint8_t *)ptr; \
break; \
case 2: \
v = *(const uint16_t *)ptr; \
break; \
case 4: \
default: \
av_assert1(size == 4); \
v = *(const uint32_t *)ptr; \
break; \
} \
}

Definition at line 41 of file vlc.c.

◆ LOCALBUF_ELEMS

#define LOCALBUF_ELEMS   1500

Definition at line 80 of file vlc.c.

◆ COPY

#define COPY (   condition)
Value:
for (int i = 0; i < nb_codes; i++) { \
unsigned len; \
GET_DATA(len, bits, i, bits_wrap, bits_size); \
if (!(condition)) \
continue; \
if (len > 3*nb_bits || len > 32) { \
av_log(NULL, AV_LOG_ERROR, "Too long VLC (%u) in vlc_init\n", len);\
if (buf != localbuf) \
av_free(buf); \
return AVERROR(EINVAL); \
} \
buf[j].bits = len; \
GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
if (buf[j].code >= (1LL<<buf[j].bits)) { \
av_log(NULL, AV_LOG_ERROR, "Invalid code %"PRIx32" for %d in " \
"vlc_init\n", buf[j].code, i); \
if (buf != localbuf) \
av_free(buf); \
return AVERROR(EINVAL); \
} \
if (flags & VLC_INIT_INPUT_LE) \
buf[j].code = bitswap_32(buf[j].code); \
else \
buf[j].code <<= 32 - buf[j].bits; \
if (symbols) \
GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
else \
buf[j].symbol = i; \
j++; \
}

Function Documentation

◆ alloc_table()

static int alloc_table ( VLC *  vlc,
int  size,
int  use_static 
)
static

Definition at line 60 of file vlc.c.

Referenced by build_table(), and mp_decode_layer2().

◆ bitswap_32()

static av_always_inline uint32_t bitswap_32 ( uint32_t  x)
static

Definition at line 82 of file vlc.c.

Referenced by build_table().

◆ vlc_common_init()

static int vlc_common_init ( VLC *  vlc,
int  nb_bits,
int  nb_codes,
VLCcode **  buf,
int  flags 
)
static

Definition at line 98 of file vlc.c.

Referenced by ff_vlc_init_from_lengths(), ff_vlc_init_multi_from_lengths(), and ff_vlc_init_sparse().

◆ compare_vlcspec()

static int compare_vlcspec ( const void *  a,
const void *  b 
)
static

Definition at line 118 of file vlc.c.

Referenced by ff_vlc_init_sparse().

◆ build_table()

static int build_table ( VLC *  vlc,
int  table_nb_bits,
int  nb_codes,
VLCcode *  codes,
int  flags 
)
static

Build VLC decoding tables suitable for use with get_vlc().

Parameters
vlcthe context to be initialized
table_nb_bitsmax length of vlc codes to store directly in this table (Longer codes are delegated to subtables.)
nb_codesnumber of elements in codes[]
codesdescriptions of the vlc codes These must be ordered such that codes going into the same subtable are contiguous. Sorting by VLCcode.code is sufficient, though not necessary.

Definition at line 138 of file vlc.c.

Referenced by vlc_common_end().

◆ vlc_common_end()

static int vlc_common_end ( VLC *  vlc,
int  nb_bits,
int  nb_codes,
VLCcode *  codes,
int  flags,
VLCcode  localbuf[LOCALBUF_ELEMS] 
)
static

Definition at line 229 of file vlc.c.

Referenced by ff_vlc_init_from_lengths(), ff_vlc_init_multi_from_lengths(), and ff_vlc_init_sparse().

◆ ff_vlc_init_sparse()

int ff_vlc_init_sparse ( VLC *  vlc,
int  nb_bits,
int  nb_codes,
const void *  bits,
int  bits_wrap,
int  bits_size,
const void *  codes,
int  codes_wrap,
int  codes_size,
const void *  symbols,
int  symbols_wrap,
int  symbols_size,
int  flags 
)

Build VLC decoding tables suitable for use with get_vlc2().

Parameters
[in,out]vlcThe VLC to be initialized; table and table_allocated must have been set when initializing a static VLC, otherwise this will be treated as uninitialized.
[in]nb_bitsThe number of bits to use for the VLC table; higher values take up more memory and cache, but allow to read codes with fewer reads. Corresponds to the bits parameter of get_vlc2().
[in]nb_codesThe number of provided bits, codes and (if supplied) symbol entries.
[in]bitsThe lengths (in bits) of the codes. Entries > 0 correspond to valid codes; entries == 0 will be skipped.
[in]bits_wrapStride (in bytes) of the bits table.
[in]codes_sizeSize of the bits. 1, 2 and 4 are supported.
[in]codesTable which gives the bit pattern of of each vlc code.
[in]codes_wrapStride (in bytes) of the codes table.
[in]codes_sizeSize of the codes. 1, 2 and 4 are supported.
[in]symbolsThe symbols, i.e. what is returned from get_vlc2() when the corresponding code is encountered. May be NULL, then 0, 1, 2, 3, 4,... will be used.
[in]symbols_wrapStride (in bytes) of the symbols table.
[in]symbols_sizeSize of the symbols. 1 and 2 are supported.
[in]flagsA combination of the VLC_INIT_* flags.

'wrap' and 'size' make it possible to use any memory configuration and types (byte/word/int) to store the 'bits', 'codes', and 'symbols' tables.

Definition at line 250 of file vlc.c.

Referenced by aac_static_table_init(), build_huff(), build_huff_tree(), build_vlc(), ccitt_unpack_init(), dnxhd_init_vlc(), generate_joint_tables(), huf_build_dec_table(), init_ralf_vlc(), read_hufftable(), and rv34_gen_vlc().

◆ ff_vlc_init_from_lengths()

int ff_vlc_init_from_lengths ( VLC *  vlc,
int  nb_bits,
int  nb_codes,
const int8_t *  lens,
int  lens_wrap,
const void *  symbols,
int  symbols_wrap,
int  symbols_size,
int  offset,
int  flags,
void *  logctx 
)

Build VLC decoding tables suitable for use with get_vlc2()

This function takes lengths and symbols and calculates the codes from them. For this the input lengths and symbols have to be sorted according to "left nodes in the corresponding tree first".

Parameters
[in,out]vlcThe VLC to be initialized; table and table_allocated must have been set when initializing a static VLC, otherwise this will be treated as uninitialized.
[in]nb_bitsThe number of bits to use for the VLC table; higher values take up more memory and cache, but allow to read codes with fewer reads.
[in]nb_codesThe number of provided length and (if supplied) symbol entries.
[in]lensThe lengths of the codes. Entries > 0 correspond to valid codes; entries == 0 will be skipped and entries with len < 0 indicate that the tree is incomplete and has an open end of length -len at this position.
[in]lens_wrapStride (in bytes) of the lengths.
[in]symbolsThe symbols, i.e. what is returned from get_vlc2() when the corresponding code is encountered. May be NULL, then 0, 1, 2, 3, 4,... will be used.
[in]symbols_wrapStride (in bytes) of the symbols.
[in]symbols_sizeSize of the symbols. 1 and 2 are supported.
[in]offsetAn offset to apply to all the valid symbols.
[in]flagsA combination of the VLC_INIT_* flags; notice that VLC_INIT_INPUT_LE is pointless and ignored.

Definition at line 306 of file vlc.c.

Referenced by atrac3_init_static_data(), atrac9_init_vlc(), build_canonical_huff(), build_vlc(), cfhd_init_vlc(), clv_init_static(), dv_init_static(), ff_mjpeg_build_vlc(), imc_init_static(), mobiclip_init_static(), mp_decode_frame(), mpc7_init_static(), mpegaudiodec_common_init_static(), mss4_init_vlc(), on2avc_decode_init(), qdmc_init_static_data(), read_code_table(), read_simple_vlc_prefix(), read_vlc_prefix(), rv10_build_vlc(), rv40_init_table(), rv40_init_tables(), smacker_decode_header_tree(), smka_decode_frame(), tm2_build_huff_table(), tscc2_init_vlc(), vp3_decode_init(), wma_decode_init(), and x8_init_vlc().

◆ add_level()

static void add_level ( VLC_MULTI_ELEM *  table,
const int  is16bit,
const int  num,
const int  numbits,
const VLCcode *  buf,
uint32_t  curcode,
int  curlen,
int  curlimit,
int  curlevel,
const int  minlen,
const int  max,
unsigned *  levelcnt,
VLC_MULTI_ELEM  info 
)
static

Definition at line 353 of file vlc.c.

Referenced by vlc_multi_gen().

◆ vlc_multi_gen()

static int vlc_multi_gen ( VLC_MULTI_ELEM *  table,
const VLC *  single,
const int  is16bit,
const int  nb_codes,
const int  numbits,
VLCcode *  buf,
void *  logctx 
)
static

Definition at line 397 of file vlc.c.

Referenced by ff_vlc_init_multi_from_lengths().

◆ ff_vlc_init_multi_from_lengths()

int ff_vlc_init_multi_from_lengths ( VLC *  vlc,
VLC_MULTI *  multi,
int  nb_bits,
int  nb_elems,
int  nb_codes,
const int8_t *  lens,
int  lens_wrap,
const void *  symbols,
int  symbols_wrap,
int  symbols_size,
int  offset,
int  flags,
void *  logctx 
)

Build VLC decoding tables suitable for use with get_vlc_multi()

This function takes lengths and symbols and calculates the codes from them. For this the input lengths and symbols have to be sorted according to "left nodes in the corresponding tree first".

Parameters
[in,out]vlcThe VLC to be initialized; table and table_allocated must have been set when initializing a static VLC, otherwise this will be treated as uninitialized.
[in,out]multiThe VLC_MULTI to be initialized; table and table_allocated must have been set when initializing a static VLC, otherwise this will be treated as uninitialized.
[in]nb_bitsThe number of bits to use for the VLC table; higher values take up more memory and cache, but allow to read codes with fewer reads.
[in]nb_elemsThe max possible number of elements.
[in]nb_codesThe number of provided length and (if supplied) symbol entries.
[in]lensThe lengths of the codes. Entries > 0 correspond to valid codes; entries == 0 will be skipped and entries with len < 0 indicate that the tree is incomplete and has an open end of length -len at this position.
[in]lens_wrapStride (in bytes) of the lengths.
[in]symbolsThe symbols, i.e. what is returned from get_vlc2() when the corresponding code is encountered. May be NULL, then 0, 1, 2, 3, 4,... will be used.
[in]symbols_wrapStride (in bytes) of the symbols.
[in]symbols_sizeSize of the symbols. 1 and 2 are supported.
[in]offsetAn offset to apply to all the valid symbols.
[in]flagsA combination of the VLC_INIT_* flags; notice that VLC_INIT_INPUT_LE is pointless and ignored.

Definition at line 446 of file vlc.c.

Referenced by build_huff(), and huff_build().

◆ ff_vlc_free_multi()

void ff_vlc_free_multi ( VLC_MULTI *  vlc)

Definition at line 504 of file vlc.c.

Referenced by decode_plane(), decode_plane10(), ff_vlc_init_multi_from_lengths(), huff_build(), and magy_decode_end().

◆ ff_vlc_free()

void ff_vlc_free ( VLC *  vlc)

Definition at line 509 of file vlc.c.

Referenced by build_huff(), build_vlc(), cfhd_init_vlc(), cook_decode_close(), decode_argb_frame(), decode_close(), decode_end(), decode_plane(), decode_plane10(), decode_rgb24_frame(), decode_rle(), decode_yuv_frame(), dist_bundle_close(), dnxhd_decode_close(), dnxhd_init_vlc(), ff_ivi_dec_huff_desc(), ff_ivi_decode_close(), ff_mjpeg_decode_dht(), ff_mjpeg_decode_end(), ff_wma_end(), fraps2_decode_plane(), generate_joint_tables(), hq_hqa_decode_close(), hqx_decode_close(), huf_build_dec_table(), huff_build(), image_ctx_free(), init_default_huffman_tables(), ivi_free_buffers(), jpg_free_context(), magy_decode_end(), mp_decode_frame(), on2avc_free_vlcs(), photocd_decode_close(), read_huffman_code_normal(), read_huffman_tables(), read_hufftable(), read_old_huffman_tables(), read_vlc_prefix(), smacker_decode_header_tree(), smka_decode_frame(), tm2_free_codes(), vorbis_free(), vp3_decode_end(), vp6_build_huff_tree(), and vp6_decode_free_context().

AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
table
static const uint16_t table[]
Definition: prosumer.c:205
wrap
#define wrap(func)
Definition: neontest.h:65
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
bitswap_32
static av_always_inline uint32_t bitswap_32(uint32_t x)
Definition: vlc.c:82
bits
uint8_t bits
Definition: vp3data.h:128
NULL
#define NULL
Definition: coverity.c:32
size
int size
Definition: twinvq_data.h:10344
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:255
code
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
Definition: filter_design.txt:178
VLC_INIT_INPUT_LE
#define VLC_INIT_INPUT_LE
Definition: vlc.h:180
len
int len
Definition: vorbis_enc_data.h:426
bits_size
#define bits_size
Definition: bitstream.h:113
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:474
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