FFmpeg
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FLAC parser. More...
#include "libavutil/attributes.h"
#include "libavutil/crc.h"
#include "libavutil/fifo.h"
#include "bytestream.h"
#include "parser.h"
#include "flac.h"
Go to the source code of this file.
Data Structures | |
struct | FLACHeaderMarker |
struct | FLACParseContext |
Macros | |
#define | FLAC_MAX_SEQUENTIAL_HEADERS 3 |
maximum number of adjacent headers that compare CRCs against each other | |
#define | FLAC_MIN_HEADERS 10 |
minimum number of headers buffered and checked before returning frames | |
#define | FLAC_AVG_FRAME_SIZE 8192 |
estimate for average size of a FLAC frame | |
#define | FLAC_HEADER_BASE_SCORE 10 |
scoring settings for score_header | |
#define | FLAC_HEADER_CHANGED_PENALTY 7 |
#define | FLAC_HEADER_CRC_FAIL_PENALTY 50 |
#define | FLAC_HEADER_NOT_PENALIZED_YET 100000 |
#define | FLAC_HEADER_NOT_SCORED_YET -100000 |
#define | MAX_FRAME_HEADER_SIZE 16 |
largest possible size of flac header | |
Functions | |
static int | frame_header_is_valid (AVCodecContext *avctx, const uint8_t *buf, FLACFrameInfo *fi) |
static uint8_t * | flac_fifo_read_wrap (FLACParseContext *fpc, int offset, int len, uint8_t **wrap_buf, int *allocated_size) |
Non-destructive fast fifo pointer fetching Returns a pointer from the specified offset. | |
static uint8_t * | flac_fifo_read (FLACParseContext *fpc, int offset, int *len) |
Return a pointer in the fifo buffer where the offset starts at until the wrap point or end of request. | |
static int | find_headers_search_validate (FLACParseContext *fpc, int offset) |
static int | find_headers_search (FLACParseContext *fpc, uint8_t *buf, int buf_size, int search_start) |
static int | find_new_headers (FLACParseContext *fpc, int search_start) |
static int | check_header_fi_mismatch (FLACParseContext *fpc, FLACFrameInfo *header_fi, FLACFrameInfo *child_fi, int log_level_offset) |
static int | check_header_mismatch (FLACParseContext *fpc, FLACHeaderMarker *header, FLACHeaderMarker *child, int log_level_offset) |
static int | score_header (FLACParseContext *fpc, FLACHeaderMarker *header) |
Score a header. | |
static void | score_sequences (FLACParseContext *fpc) |
static int | get_best_header (FLACParseContext *fpc, const uint8_t **poutbuf, int *poutbuf_size) |
static int | flac_parse (AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size) |
static av_cold int | flac_parse_init (AVCodecParserContext *c) |
static void | flac_parse_close (AVCodecParserContext *c) |
Variables | |
AVCodecParser | ff_flac_parser |
FLAC parser.
The FLAC parser buffers input until FLAC_MIN_HEADERS has been found. Each time it finds and verifies a CRC-8 header it sees which of the FLAC_MAX_SEQUENTIAL_HEADERS that came before it have a valid CRC-16 footer that ends at the newly found header. Headers are scored by FLAC_HEADER_BASE_SCORE plus the max of its crc-verified children, penalized by changes in sample rate, frame number, etc. The parser returns the frame with the highest score.
Definition in file flac_parser.c.
#define FLAC_MAX_SEQUENTIAL_HEADERS 3 |
maximum number of adjacent headers that compare CRCs against each other
Definition at line 43 of file flac_parser.c.
Referenced by check_header_mismatch(), find_headers_search_validate(), and score_header().
#define FLAC_MIN_HEADERS 10 |
minimum number of headers buffered and checked before returning frames
Definition at line 45 of file flac_parser.c.
Referenced by flac_parse(), and flac_parse_init().
#define FLAC_AVG_FRAME_SIZE 8192 |
estimate for average size of a FLAC frame
Definition at line 47 of file flac_parser.c.
Referenced by flac_parse(), and flac_parse_init().
#define FLAC_HEADER_BASE_SCORE 10 |
scoring settings for score_header
Definition at line 50 of file flac_parser.c.
Referenced by check_header_fi_mismatch(), and score_header().
#define FLAC_HEADER_CHANGED_PENALTY 7 |
Definition at line 51 of file flac_parser.c.
Referenced by check_header_fi_mismatch(), and check_header_mismatch().
#define FLAC_HEADER_CRC_FAIL_PENALTY 50 |
Definition at line 52 of file flac_parser.c.
Referenced by check_header_mismatch().
#define FLAC_HEADER_NOT_PENALIZED_YET 100000 |
Definition at line 53 of file flac_parser.c.
Referenced by check_header_mismatch(), find_headers_search_validate(), and score_header().
#define FLAC_HEADER_NOT_SCORED_YET -100000 |
Definition at line 54 of file flac_parser.c.
Referenced by score_header(), and score_sequences().
#define MAX_FRAME_HEADER_SIZE 16 |
largest possible size of flac header
Definition at line 57 of file flac_parser.c.
Referenced by find_headers_search_validate(), find_new_headers(), flac_parse(), and frame_header_is_valid().
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Definition at line 94 of file flac_parser.c.
Referenced by find_headers_search_validate(), and flac_parse().
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Non-destructive fast fifo pointer fetching Returns a pointer from the specified offset.
If possible the pointer points within the fifo buffer. Otherwise (if it would cause a wrap around,) a pointer to a user-specified buffer is used. The pointer can be NULL. In any case it will be reallocated to hold the size. If the returned pointer will be used after subsequent calls to flac_fifo_read_wrap then the subsequent calls should pass in a different wrap_buf so as to not overwrite the contents of the previous wrap_buf. This function is based on av_fifo_generic_read, which is why there is a comment about a memory barrier for SMP.
Definition at line 115 of file flac_parser.c.
Referenced by find_headers_search_validate(), flac_parse(), and get_best_header().
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Return a pointer in the fifo buffer where the offset starts at until the wrap point or end of request.
len will contain the valid length of the returned buffer. A second call to flac_fifo_read (with new offset and len) should be called to get the post-wrap buf if the returned len is less than the requested.
Definition at line 155 of file flac_parser.c.
Referenced by check_header_mismatch(), and find_new_headers().
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Definition at line 166 of file flac_parser.c.
Referenced by find_headers_search(), and find_new_headers().
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Definition at line 204 of file flac_parser.c.
Referenced by find_new_headers().
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Definition at line 228 of file flac_parser.c.
Referenced by flac_parse().
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Definition at line 272 of file flac_parser.c.
Referenced by check_header_mismatch(), and score_header().
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Definition at line 302 of file flac_parser.c.
Referenced by get_best_header(), and score_header().
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Score a header.
Give FLAC_HEADER_BASE_SCORE points to a frame for existing. If it has children, (subsequent frames of which the preceding CRC footer validates against this one,) then take the maximum score of the children, with a penalty of FLAC_HEADER_CHANGED_PENALTY applied for each change to bps, sample rate, channels, but not decorrelation mode, or blocksize, because it can change often.
Definition at line 410 of file flac_parser.c.
Referenced by score_sequences().
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Definition at line 450 of file flac_parser.c.
Referenced by flac_parse().
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Definition at line 467 of file flac_parser.c.
Referenced by flac_parse().
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Definition at line 503 of file flac_parser.c.
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Definition at line 688 of file flac_parser.c.
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Definition at line 700 of file flac_parser.c.
AVCodecParser ff_flac_parser |
Definition at line 715 of file flac_parser.c.