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FFmpeg/libavcodec/flac_parser.c
Andreas Rheinhardt 790f793844 avutil/common: Don't auto-include mem.h 
There are lots of files that don't need it: The number of object
files that actually need it went down from 2011 to 884 here.

Keep it for external users in order to not cause breakages.

Also improve the other headers a bit while just at it.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2024-03-31 00:08:43 +01:00

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/*
* FLAC parser
* Copyright (c) 2010 Michael Chinen
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* 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.
**/
#include "libavutil/attributes.h"
#include "libavutil/crc.h"
#include "libavutil/mem.h"
#include "flac_parse.h"
/** maximum number of adjacent headers that compare CRCs against each other */
#define FLAC_MAX_SEQUENTIAL_HEADERS 4
/** minimum number of headers buffered and checked before returning frames */
#define FLAC_MIN_HEADERS 10
/** estimate for average size of a FLAC frame */
#define FLAC_AVG_FRAME_SIZE 8192
/** scoring settings for score_header */
#define FLAC_HEADER_BASE_SCORE 10
#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
/** largest possible size of flac header */
#define MAX_FRAME_HEADER_SIZE 16
#define MAX_FRAME_VERIFY_SIZE (MAX_FRAME_HEADER_SIZE + 1)
typedef struct FifoBuffer {
uint8_t *buffer;
uint8_t *end;
uint8_t *rptr;
uint8_t *wptr;
int empty;
} FifoBuffer;
typedef struct FLACHeaderMarker {
int offset; /**< byte offset from start of FLACParseContext->buffer */
int link_penalty[FLAC_MAX_SEQUENTIAL_HEADERS]; /**< array of local scores
between this header and the one at a distance equal
array position */
int max_score; /**< maximum score found after checking each child that
has a valid CRC */
FLACFrameInfo fi; /**< decoded frame header info */
struct FLACHeaderMarker *next; /**< next CRC-8 verified header that
immediately follows this one in
the bytestream */
struct FLACHeaderMarker *best_child; /**< following frame header with
which this frame has the best
score with */
} FLACHeaderMarker;
typedef struct FLACParseContext {
AVCodecParserContext *pc; /**< parent context */
AVCodecContext *avctx; /**< codec context pointer for logging */
FLACHeaderMarker *headers; /**< linked-list that starts at the first
CRC-8 verified header within buffer */
FLACHeaderMarker *best_header; /**< highest scoring header within buffer */
int nb_headers_found; /**< number of headers found in the last
flac_parse() call */
int nb_headers_buffered; /**< number of headers that are buffered */
int best_header_valid; /**< flag set when the parser returns junk;
if set return best_header next time */
FifoBuffer fifo_buf; /**< buffer to store all data until headers
can be verified */
int end_padded; /**< specifies if fifo_buf's end is padded */
uint8_t *wrap_buf; /**< general fifo read buffer when wrapped */
int wrap_buf_allocated_size; /**< actual allocated size of the buffer */
FLACFrameInfo last_fi; /**< last decoded frame header info */
int last_fi_valid; /**< set if last_fi is valid */
} FLACParseContext;
static int frame_header_is_valid(AVCodecContext *avctx, const uint8_t *buf,
FLACFrameInfo *fi)
{
GetBitContext gb;
uint8_t subframe_type;
// header plus one byte from first subframe
init_get_bits(&gb, buf, MAX_FRAME_VERIFY_SIZE * 8);
if (ff_flac_decode_frame_header(avctx, &gb, fi, 127)) {
return 0;
}
// subframe zero bit
if (get_bits1(&gb) != 0) {
return 0;
}
// subframe type
// 000000 : SUBFRAME_CONSTANT
// 000001 : SUBFRAME_VERBATIM
// 00001x : reserved
// 0001xx : reserved
// 001xxx : if(xxx <= 4) SUBFRAME_FIXED, xxx=order ; else reserved
// 01xxxx : reserved
// 1xxxxx : SUBFRAME_LPC, xxxxx=order-1
subframe_type = get_bits(&gb, 6);
if (!(subframe_type == 0 ||
subframe_type == 1 ||
((subframe_type >= 8) && (subframe_type <= 12)) ||
(subframe_type >= 32))) {
return 0;
}
return 1;
}
static size_t flac_fifo_size(const FifoBuffer *f)
{
if (f->wptr <= f->rptr && !f->empty)
return (f->wptr - f->buffer) + (f->end - f->rptr);
return f->wptr - f->rptr;
}
static size_t flac_fifo_space(const FifoBuffer *f)
{
return f->end - f->buffer - flac_fifo_size(f);
}
/**
* 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.
*/
static uint8_t *flac_fifo_read_wrap(FLACParseContext *fpc, int offset, int len,
uint8_t **wrap_buf, int *allocated_size)
{
FifoBuffer *f = &fpc->fifo_buf;
uint8_t *start = f->rptr + offset;
uint8_t *tmp_buf;
if (start >= f->end)
start -= f->end - f->buffer;
if (f->end - start >= len)
return start;
tmp_buf = av_fast_realloc(*wrap_buf, allocated_size, len);
if (!tmp_buf) {
av_log(fpc->avctx, AV_LOG_ERROR,
"couldn't reallocate wrap buffer of size %d", len);
return NULL;
}
*wrap_buf = tmp_buf;
do {
int seg_len = FFMIN(f->end - start, len);
memcpy(tmp_buf, start, seg_len);
tmp_buf = (uint8_t*)tmp_buf + seg_len;
// memory barrier needed for SMP here in theory
start += seg_len - (f->end - f->buffer);
len -= seg_len;
} while (len > 0);
return *wrap_buf;
}
/**
* 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.
**/
static uint8_t *flac_fifo_read(FifoBuffer *f, int offset, int *len)
{
uint8_t *start = f->rptr + offset;
if (start >= f->end)
start -= f->end - f->buffer;
*len = FFMIN(*len, f->end - start);
return start;
}
static int flac_fifo_grow(FifoBuffer *f, size_t inc)
{
size_t size_old = f->end - f->buffer;
size_t offset_r = f->rptr - f->buffer;
size_t offset_w = f->wptr - f->buffer;
size_t size_new;
uint8_t *tmp;
if (size_old > SIZE_MAX - inc)
return AVERROR(EINVAL);
size_new = size_old + inc;
tmp = av_realloc(f->buffer, size_new);
if (!tmp)
return AVERROR(ENOMEM);
// move the data from the beginning of the ring buffer
// to the newly allocated space
if (offset_w <= offset_r && !f->empty) {
const size_t copy = FFMIN(inc, offset_w);
memcpy(tmp + size_old, tmp, copy);
if (copy < offset_w) {
memmove(tmp, tmp + copy, offset_w - copy);
offset_w -= copy;
} else
offset_w = size_old + copy;
}
f->buffer = tmp;
f->end = f->buffer + size_new;
f->rptr = f->buffer + offset_r;
f->wptr = f->buffer + offset_w;
return 0;
}
static int flac_fifo_write(FifoBuffer *f, const uint8_t *src, size_t size)
{
uint8_t *wptr;
if (flac_fifo_space(f) < size) {
int ret = flac_fifo_grow(f, FFMAX(flac_fifo_size(f), size));
if (ret < 0)
return ret;
}
if (size)
f->empty = 0;
wptr = f->wptr;
do {
size_t len = FFMIN(f->end - wptr, size);
memcpy(wptr, src, len);
src += len;
wptr += len;
if (wptr >= f->end)
wptr = f->buffer;
size -= len;
} while (size > 0);
f->wptr = wptr;
return 0;
}
static void flac_fifo_drain(FifoBuffer *f, size_t size)
{
size_t size_cur = flac_fifo_size(f);
av_assert0(size_cur >= size);
if (size_cur == size)
f->empty = 1;
f->rptr += size;
if (f->rptr >= f->end)
f->rptr -= f->end - f->buffer;
}
static int flac_fifo_alloc(FifoBuffer *f, size_t size)
{
memset(f, 0, sizeof(*f));
f->buffer = av_realloc(NULL, size);
if (!f->buffer)
return AVERROR(ENOMEM);
f->wptr = f->buffer;
f->rptr = f->buffer;
f->end = f->buffer + size;
f->empty = 1;
return 0;
}
static void flac_fifo_free(FifoBuffer *f)
{
av_freep(&f->buffer);
memset(f, 0, sizeof(*f));
}
static int find_headers_search_validate(FLACParseContext *fpc, int offset)
{
FLACFrameInfo fi;
uint8_t *header_buf;
int size = 0;
header_buf = flac_fifo_read_wrap(fpc, offset,
MAX_FRAME_VERIFY_SIZE + AV_INPUT_BUFFER_PADDING_SIZE,
&fpc->wrap_buf,
&fpc->wrap_buf_allocated_size);
if (frame_header_is_valid(fpc->avctx, header_buf, &fi)) {
FLACHeaderMarker **end_handle = &fpc->headers;
int i;
size = 0;
while (*end_handle) {
end_handle = &(*end_handle)->next;
size++;
}
*end_handle = av_mallocz(sizeof(**end_handle));
if (!*end_handle) {
av_log(fpc->avctx, AV_LOG_ERROR,
"couldn't allocate FLACHeaderMarker\n");
return AVERROR(ENOMEM);
}
(*end_handle)->fi = fi;
(*end_handle)->offset = offset;
for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++)
(*end_handle)->link_penalty[i] = FLAC_HEADER_NOT_PENALIZED_YET;
fpc->nb_headers_found++;
size++;
}
return size;
}
static int find_headers_search(FLACParseContext *fpc, uint8_t *buf,
int buf_size, int search_start)
{
int size = 0, mod_offset = (buf_size - 1) % 4, i, j;
uint32_t x;
for (i = 0; i < mod_offset; i++) {
if ((AV_RB16(buf + i) & 0xFFFE) == 0xFFF8) {
int ret = find_headers_search_validate(fpc, search_start + i);
size = FFMAX(size, ret);
}
}
for (; i < buf_size - 1; i += 4) {
x = AV_RN32(buf + i);
if (((x & ~(x + 0x01010101)) & 0x80808080)) {
for (j = 0; j < 4; j++) {
if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8) {
int ret = find_headers_search_validate(fpc, search_start + i + j);
size = FFMAX(size, ret);
}
}
}
}
return size;
}
static int find_new_headers(FLACParseContext *fpc, int search_start)
{
FLACHeaderMarker *end;
int search_end, size = 0, read_len, temp;
uint8_t *buf;
fpc->nb_headers_found = 0;
/* Search for a new header of at most 16 bytes. */
search_end = flac_fifo_size(&fpc->fifo_buf) - (MAX_FRAME_HEADER_SIZE - 1);
read_len = search_end - search_start + 1;
buf = flac_fifo_read(&fpc->fifo_buf, search_start, &read_len);
size = find_headers_search(fpc, buf, read_len, search_start);
search_start += read_len - 1;
/* If fifo end was hit do the wrap around. */
if (search_start != search_end) {
uint8_t wrap[2];
wrap[0] = buf[read_len - 1];
/* search_start + 1 is the post-wrap offset in the fifo. */
read_len = search_end - (search_start + 1) + 1;
buf = flac_fifo_read(&fpc->fifo_buf, search_start + 1, &read_len);
wrap[1] = buf[0];
if ((AV_RB16(wrap) & 0xFFFE) == 0xFFF8) {
temp = find_headers_search_validate(fpc, search_start);
size = FFMAX(size, temp);
}
search_start++;
/* Continue to do the last half of the wrap. */
temp = find_headers_search(fpc, buf, read_len, search_start);
size = FFMAX(size, temp);
search_start += read_len - 1;
}
/* Return the size even if no new headers were found. */
if (!size && fpc->headers)
for (end = fpc->headers; end; end = end->next)
size++;
return size;
}
static int check_header_fi_mismatch(FLACParseContext *fpc,
FLACFrameInfo *header_fi,
FLACFrameInfo *child_fi,
int log_level_offset)
{
int deduction = 0;
if (child_fi->samplerate != header_fi->samplerate) {
deduction += FLAC_HEADER_CHANGED_PENALTY;
av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
"sample rate change detected in adjacent frames\n");
}
if (child_fi->bps != header_fi->bps) {
deduction += FLAC_HEADER_CHANGED_PENALTY;
av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
"bits per sample change detected in adjacent frames\n");
}
if (child_fi->is_var_size != header_fi->is_var_size) {
/* Changing blocking strategy not allowed per the spec */
deduction += FLAC_HEADER_BASE_SCORE;
av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
"blocking strategy change detected in adjacent frames\n");
}
if (child_fi->channels != header_fi->channels) {
deduction += FLAC_HEADER_CHANGED_PENALTY;
av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
"number of channels change detected in adjacent frames\n");
}
return deduction;
}
static int check_header_mismatch(FLACParseContext *fpc,
FLACHeaderMarker *header,
FLACHeaderMarker *child,
int log_level_offset)
{
FLACFrameInfo *header_fi = &header->fi, *child_fi = &child->fi;
int check_crc, deduction, deduction_expected = 0, i;
deduction = check_header_fi_mismatch(fpc, header_fi, child_fi,
log_level_offset);
/* Check sample and frame numbers. */
if ((child_fi->frame_or_sample_num - header_fi->frame_or_sample_num
!= header_fi->blocksize) &&
(child_fi->frame_or_sample_num
!= header_fi->frame_or_sample_num + 1)) {
FLACHeaderMarker *curr;
int64_t expected_frame_num, expected_sample_num;
/* If there are frames in the middle we expect this deduction,
as they are probably valid and this one follows it */
expected_frame_num = expected_sample_num = header_fi->frame_or_sample_num;
curr = header;
while (curr != child) {
/* Ignore frames that failed all crc checks */
for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++) {
if (curr->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY) {
expected_frame_num++;
expected_sample_num += curr->fi.blocksize;
break;
}
}
curr = curr->next;
}
if (expected_frame_num == child_fi->frame_or_sample_num ||
expected_sample_num == child_fi->frame_or_sample_num)
deduction_expected = deduction ? 0 : 1;
deduction += FLAC_HEADER_CHANGED_PENALTY;
av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
"sample/frame number mismatch in adjacent frames\n");
}
if (fpc->last_fi.is_var_size == header_fi->is_var_size) {
if (fpc->last_fi.is_var_size &&
fpc->last_fi.frame_or_sample_num + fpc->last_fi.blocksize == header_fi->frame_or_sample_num) {
check_crc = 0;
} else if (!fpc->last_fi.is_var_size &&
fpc->last_fi.frame_or_sample_num + 1 == header_fi->frame_or_sample_num) {
check_crc = 0;
} else {
check_crc = !deduction && !deduction_expected;
}
} else {
check_crc = !deduction && !deduction_expected;
}
/* If we have suspicious headers, check the CRC between them */
if (check_crc || (deduction && !deduction_expected)) {
FLACHeaderMarker *curr;
int read_len;
uint8_t *buf;
uint32_t crc = 1;
int inverted_test = 0;
/* Since CRC is expensive only do it if we haven't yet.
This assumes a CRC penalty is greater than all other check penalties */
curr = header->next;
for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS && curr != child; i++)
curr = curr->next;
if (header->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY ||
header->link_penalty[i] == FLAC_HEADER_NOT_PENALIZED_YET) {
FLACHeaderMarker *start, *end;
/* Although overlapping chains are scored, the crc should never
have to be computed twice for a single byte. */
start = header;
end = child;
if (i > 0 &&
header->link_penalty[i - 1] >= FLAC_HEADER_CRC_FAIL_PENALTY) {
while (start->next != child)
start = start->next;
inverted_test = 1;
} else if (i > 0 &&
header->next->link_penalty[i-1] >=
FLAC_HEADER_CRC_FAIL_PENALTY ) {
end = header->next;
inverted_test = 1;
}
read_len = end->offset - start->offset;
buf = flac_fifo_read(&fpc->fifo_buf, start->offset, &read_len);
crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf, read_len);
read_len = (end->offset - start->offset) - read_len;
if (read_len) {
buf = flac_fifo_read(&fpc->fifo_buf, end->offset - read_len, &read_len);
crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), crc, buf, read_len);
}
}
if (!crc ^ !inverted_test) {
deduction += FLAC_HEADER_CRC_FAIL_PENALTY;
av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
"crc check failed from offset %i (frame %"PRId64") to %i (frame %"PRId64")\n",
header->offset, header_fi->frame_or_sample_num,
child->offset, child_fi->frame_or_sample_num);
}
}
return deduction;
}
/**
* 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.
**/
static int score_header(FLACParseContext *fpc, FLACHeaderMarker *header)
{
FLACHeaderMarker *child;
int dist = 0;
int child_score;
int base_score = FLAC_HEADER_BASE_SCORE;
if (header->max_score != FLAC_HEADER_NOT_SCORED_YET)
return header->max_score;
/* Modify the base score with changes from the last output header */
if (fpc->last_fi_valid) {
/* Silence the log since this will be repeated if selected */
base_score -= check_header_fi_mismatch(fpc, &fpc->last_fi, &header->fi,
AV_LOG_DEBUG);
}
header->max_score = base_score;
/* Check and compute the children's scores. */
child = header->next;
for (dist = 0; dist < FLAC_MAX_SEQUENTIAL_HEADERS && child; dist++) {
/* Look at the child's frame header info and penalize suspicious
changes between the headers. */
if (header->link_penalty[dist] == FLAC_HEADER_NOT_PENALIZED_YET) {
header->link_penalty[dist] = check_header_mismatch(fpc, header,
child, AV_LOG_DEBUG);
}
child_score = score_header(fpc, child) - header->link_penalty[dist];
if (FLAC_HEADER_BASE_SCORE + child_score > header->max_score) {
/* Keep the child because the frame scoring is dynamic. */
header->best_child = child;
header->max_score = base_score + child_score;
}
child = child->next;
}
return header->max_score;
}
static void score_sequences(FLACParseContext *fpc)
{
FLACHeaderMarker *curr;
int best_score = FLAC_HEADER_NOT_SCORED_YET;
/* First pass to clear all old scores. */
for (curr = fpc->headers; curr; curr = curr->next)
curr->max_score = FLAC_HEADER_NOT_SCORED_YET;
/* Do a second pass to score them all. */
for (curr = fpc->headers; curr; curr = curr->next) {
if (score_header(fpc, curr) > best_score) {
fpc->best_header = curr;
best_score = curr->max_score;
}
}
}
static int get_best_header(FLACParseContext *fpc, const uint8_t **poutbuf,
int *poutbuf_size)
{
FLACHeaderMarker *header = fpc->best_header;
FLACHeaderMarker *child = header->best_child;
if (!child) {
*poutbuf_size = flac_fifo_size(&fpc->fifo_buf) - header->offset;
} else {
*poutbuf_size = child->offset - header->offset;
/* If the child has suspicious changes, log them */
check_header_mismatch(fpc, header, child, 0);
}
ff_flac_set_channel_layout(fpc->avctx, header->fi.channels);
fpc->avctx->sample_rate = header->fi.samplerate;
fpc->pc->duration = header->fi.blocksize;
*poutbuf = flac_fifo_read_wrap(fpc, header->offset, *poutbuf_size,
&fpc->wrap_buf,
&fpc->wrap_buf_allocated_size);
if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
if (header->fi.is_var_size)
fpc->pc->pts = header->fi.frame_or_sample_num;
else if (header->best_child)
fpc->pc->pts = header->fi.frame_or_sample_num * header->fi.blocksize;
}
fpc->best_header_valid = 0;
fpc->last_fi_valid = 1;
fpc->last_fi = header->fi;
/* Return the negative overread index so the client can compute pos.
This should be the amount overread to the beginning of the child */
if (child) {
int64_t offset = child->offset - flac_fifo_size(&fpc->fifo_buf);
if (offset > -(1 << 28))
return offset;
}
return 0;
}
static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
FLACParseContext *fpc = s->priv_data;
FLACHeaderMarker *curr;
int nb_headers;
const uint8_t *read_end = buf;
const uint8_t *read_start = buf;
if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
FLACFrameInfo fi;
if (frame_header_is_valid(avctx, buf, &fi)) {
s->duration = fi.blocksize;
if (!avctx->sample_rate)
avctx->sample_rate = fi.samplerate;
if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
fpc->pc->pts = fi.frame_or_sample_num;
if (!fi.is_var_size)
fpc->pc->pts *= fi.blocksize;
}
}
*poutbuf = buf;
*poutbuf_size = buf_size;
return buf_size;
}
fpc->avctx = avctx;
if (fpc->best_header_valid && fpc->nb_headers_buffered >= FLAC_MIN_HEADERS)
return get_best_header(fpc, poutbuf, poutbuf_size);
/* If a best_header was found last call remove it with the buffer data. */
if (fpc->best_header && fpc->best_header->best_child) {
FLACHeaderMarker *temp;
FLACHeaderMarker *best_child = fpc->best_header->best_child;
/* Remove headers in list until the end of the best_header. */
for (curr = fpc->headers; curr != best_child; curr = temp) {
if (curr != fpc->best_header) {
av_log(avctx, AV_LOG_DEBUG,
"dropping low score %i frame header from offset %i to %i\n",
curr->max_score, curr->offset, curr->next->offset);
}
temp = curr->next;
av_free(curr);
fpc->nb_headers_buffered--;
}
/* Release returned data from ring buffer. */
flac_fifo_drain(&fpc->fifo_buf, best_child->offset);
/* Fix the offset for the headers remaining to match the new buffer. */
for (curr = best_child->next; curr; curr = curr->next)
curr->offset -= best_child->offset;
best_child->offset = 0;
fpc->headers = best_child;
if (fpc->nb_headers_buffered >= FLAC_MIN_HEADERS) {
fpc->best_header = best_child;
return get_best_header(fpc, poutbuf, poutbuf_size);
}
fpc->best_header = NULL;
} else if (fpc->best_header) {
/* No end frame no need to delete the buffer; probably eof */
FLACHeaderMarker *temp;
for (curr = fpc->headers; curr != fpc->best_header; curr = temp) {
temp = curr->next;
av_free(curr);
fpc->nb_headers_buffered--;
}
fpc->headers = fpc->best_header->next;
av_freep(&fpc->best_header);
fpc->nb_headers_buffered--;
}
/* Find and score new headers. */
/* buf_size is zero when flushing, so check for this since we do */
/* not want to try to read more input once we have found the end. */
/* Also note that buf can't be NULL. */
while ((buf_size && read_end < buf + buf_size &&
fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
|| (!buf_size && !fpc->end_padded)) {
int start_offset, ret;
/* Pad the end once if EOF, to check the final region for headers. */
if (!buf_size) {
fpc->end_padded = 1;
read_end = read_start + MAX_FRAME_HEADER_SIZE;
} else {
/* The maximum read size is the upper-bound of what the parser
needs to have the required number of frames buffered */
int nb_desired = FLAC_MIN_HEADERS - fpc->nb_headers_buffered + 1;
read_end = read_end + FFMIN(buf + buf_size - read_end,
nb_desired * FLAC_AVG_FRAME_SIZE);
}
if (!flac_fifo_space(&fpc->fifo_buf) &&
flac_fifo_size(&fpc->fifo_buf) / FLAC_AVG_FRAME_SIZE >
fpc->nb_headers_buffered * 20) {
/* There is less than one valid flac header buffered for 20 headers
* buffered. Therefore the fifo is most likely filled with invalid
* data and the input is not a flac file. */
goto handle_error;
}
/* Fill the buffer. */
if (buf_size) {
ret = flac_fifo_write(&fpc->fifo_buf, read_start,
read_end - read_start);
} else {
int8_t pad[MAX_FRAME_HEADER_SIZE] = { 0 };
ret = flac_fifo_write(&fpc->fifo_buf, pad, sizeof(pad));
}
if (ret < 0) {
av_log(avctx, AV_LOG_ERROR, "Error buffering data\n");
goto handle_error;
}
/* Tag headers and update sequences. */
start_offset = flac_fifo_size(&fpc->fifo_buf) -
((read_end - read_start) + (MAX_FRAME_HEADER_SIZE - 1));
start_offset = FFMAX(0, start_offset);
nb_headers = find_new_headers(fpc, start_offset);
if (nb_headers < 0) {
av_log(avctx, AV_LOG_ERROR,
"find_new_headers couldn't allocate FLAC header\n");
goto handle_error;
}
fpc->nb_headers_buffered = nb_headers;
/* Wait till FLAC_MIN_HEADERS to output a valid frame. */
if (!fpc->end_padded && fpc->nb_headers_buffered < FLAC_MIN_HEADERS) {
if (read_end < buf + buf_size) {
read_start = read_end;
continue;
} else {
goto handle_error;
}
}
/* If headers found, update the scores since we have longer chains. */
if (fpc->end_padded || fpc->nb_headers_found)
score_sequences(fpc);
/* restore the state pre-padding */
if (fpc->end_padded) {
int empty = flac_fifo_size(&fpc->fifo_buf) == MAX_FRAME_HEADER_SIZE;
int warp = fpc->fifo_buf.wptr - fpc->fifo_buf.buffer < MAX_FRAME_HEADER_SIZE;
/* HACK: drain the tail of the fifo */
fpc->fifo_buf.wptr -= MAX_FRAME_HEADER_SIZE;
if (warp) {
fpc->fifo_buf.wptr += fpc->fifo_buf.end -
fpc->fifo_buf.buffer;
}
fpc->fifo_buf.empty = empty;
read_start = read_end = NULL;
}
}
for (curr = fpc->headers; curr; curr = curr->next) {
if (!fpc->best_header || curr->max_score > fpc->best_header->max_score) {
fpc->best_header = curr;
}
}
if (fpc->best_header && fpc->best_header->max_score <= 0) {
// Only accept a bad header if there is no other option to continue
if (!buf_size || read_end != buf || fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
fpc->best_header = NULL;
}
if (fpc->best_header) {
fpc->best_header_valid = 1;
if (fpc->best_header->offset > 0) {
/* Output a junk frame. */
av_log(avctx, AV_LOG_DEBUG, "Junk frame till offset %i\n",
fpc->best_header->offset);
/* Set duration to 0. It is unknown or invalid in a junk frame. */
s->duration = 0;
*poutbuf_size = fpc->best_header->offset;
*poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size,
&fpc->wrap_buf,
&fpc->wrap_buf_allocated_size);
return buf_size ? (read_end - buf) : (fpc->best_header->offset -
flac_fifo_size(&fpc->fifo_buf));
}
if (!buf_size)
return get_best_header(fpc, poutbuf, poutbuf_size);
}
handle_error:
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size ? read_end - buf : 0;
}
static av_cold int flac_parse_init(AVCodecParserContext *c)
{
FLACParseContext *fpc = c->priv_data;
int ret;
fpc->pc = c;
/* There will generally be FLAC_MIN_HEADERS buffered in the fifo before
it drains. This is allocated early to avoid slow reallocation. */
ret = flac_fifo_alloc(&fpc->fifo_buf, (FLAC_MIN_HEADERS + 3) * FLAC_AVG_FRAME_SIZE);
if (ret < 0) {
av_log(fpc->avctx, AV_LOG_ERROR,
"couldn't allocate fifo_buf\n");
return AVERROR(ENOMEM);
}
return 0;
}
static void flac_parse_close(AVCodecParserContext *c)
{
FLACParseContext *fpc = c->priv_data;
FLACHeaderMarker *curr = fpc->headers, *temp;
while (curr) {
temp = curr->next;
av_free(curr);
curr = temp;
}
fpc->headers = NULL;
flac_fifo_free(&fpc->fifo_buf);
av_freep(&fpc->wrap_buf);
}
const AVCodecParser ff_flac_parser = {
.codec_ids = { AV_CODEC_ID_FLAC },
.priv_data_size = sizeof(FLACParseContext),
.parser_init = flac_parse_init,
.parser_parse = flac_parse,
.parser_close = flac_parse_close,
};
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