diff options
Diffstat (limited to 'media/ffvpx/libavcodec/flac_parser.c')
| -rw-r--r-- | media/ffvpx/libavcodec/flac_parser.c | 755 |
1 files changed, 755 insertions, 0 deletions
diff --git a/media/ffvpx/libavcodec/flac_parser.c b/media/ffvpx/libavcodec/flac_parser.c new file mode 100644 index 000000000..f5cc35a4f --- /dev/null +++ b/media/ffvpx/libavcodec/flac_parser.c @@ -0,0 +1,755 @@ +/* + * 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/fifo.h" +#include "bytestream.h" +#include "parser.h" +#include "flac.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 + +typedef struct FLACHeaderMarker { + int offset; /**< byte offset from start of FLACParseContext->buffer */ + int *link_penalty; /**< pointer to 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 */ + AVFifoBuffer *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; + init_get_bits(&gb, buf, MAX_FRAME_HEADER_SIZE * 8); + return !ff_flac_decode_frame_header(avctx, &gb, fi, 127); +} + +/** + * 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) +{ + AVFifoBuffer *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(FLACParseContext *fpc, int offset, int *len) +{ + AVFifoBuffer *f = fpc->fifo_buf; + 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 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_HEADER_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; + (*end_handle)->link_penalty = av_malloc(sizeof(int) * + FLAC_MAX_SEQUENTIAL_HEADERS); + if (!(*end_handle)->link_penalty) { + av_freep(end_handle); + av_log(fpc->avctx, AV_LOG_ERROR, + "couldn't allocate link_penalty\n"); + return AVERROR(ENOMEM); + } + + 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) + size = find_headers_search_validate(fpc, search_start + i); + } + + for (; i < buf_size - 1; i += 4) { + x = AV_RB32(buf + i); + if (((x & ~(x + 0x01010101)) & 0x80808080)) { + for (j = 0; j < 4; j++) { + if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8) + size = find_headers_search_validate(fpc, search_start + i + j); + } + } + } + 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 = av_fifo_size(fpc->fifo_buf) - (MAX_FRAME_HEADER_SIZE - 1); + read_len = search_end - search_start + 1; + buf = flac_fifo_read(fpc, 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]; + read_len = search_end - search_start + 1; + + /* search_start + 1 is the post-wrap offset in the fifo. */ + buf = flac_fifo_read(fpc, 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 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; + int 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 we have suspicious headers, check the CRC between them */ + if (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, 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, 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 = 0;//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 = av_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); + } + + if (header->fi.channels != fpc->avctx->channels || + !fpc->avctx->channel_layout) { + fpc->avctx->channels = header->fi.channels; + ff_flac_set_channel_layout(fpc->avctx); + } + 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) + return child->offset - av_fifo_size(fpc->fifo_buf); + 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) + 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_freep(&curr->link_penalty); + av_free(curr); + fpc->nb_headers_buffered--; + } + /* Release returned data from ring buffer. */ + av_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; + + fpc->nb_headers_buffered--; + 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_freep(&curr->link_penalty); + av_free(curr); + } + fpc->headers = fpc->best_header->next; + av_freep(&fpc->best_header->link_penalty); + av_freep(&fpc->best_header); + } + + /* Find and score new headers. */ + /* buf_size is to zero when padding, so check for this since we do */ + /* not want to try to read more input once we have found the end. */ + /* Note that as (non-modified) parameters, buf can be non-NULL, */ + /* while buf_size is 0. */ + while ((buf && buf_size && read_end < buf + buf_size && + fpc->nb_headers_buffered < FLAC_MIN_HEADERS) + || ((!buf || !buf_size) && !fpc->end_padded)) { + int start_offset; + + /* Pad the end once if EOF, to check the final region for headers. */ + if (!buf || !buf_size) { + fpc->end_padded = 1; + buf_size = MAX_FRAME_HEADER_SIZE; + 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 (!av_fifo_space(fpc->fifo_buf) && + av_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 ( av_fifo_space(fpc->fifo_buf) < read_end - read_start + && av_fifo_realloc2(fpc->fifo_buf, (read_end - read_start) + 2*av_fifo_size(fpc->fifo_buf)) < 0) { + av_log(avctx, AV_LOG_ERROR, + "couldn't reallocate buffer of size %"PTRDIFF_SPECIFIER"\n", + (read_end - read_start) + av_fifo_size(fpc->fifo_buf)); + goto handle_error; + } + + if (buf && buf_size) { + av_fifo_generic_write(fpc->fifo_buf, (void*) read_start, + read_end - read_start, NULL); + } else { + int8_t pad[MAX_FRAME_HEADER_SIZE] = { 0 }; + av_fifo_generic_write(fpc->fifo_buf, (void*) pad, sizeof(pad), NULL); + } + + /* Tag headers and update sequences. */ + start_offset = av_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 (buf && 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 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; + fpc->fifo_buf->wndx -= MAX_FRAME_HEADER_SIZE; + if (warp) { + fpc->fifo_buf->wptr += fpc->fifo_buf->end - + fpc->fifo_buf->buffer; + } + buf_size = 0; + read_start = read_end = NULL; + } + } + + for (curr = fpc->headers; curr; curr = curr->next) { + if (curr->max_score > 0 && + (!fpc->best_header || curr->max_score > fpc->best_header->max_score)) { + fpc->best_header = curr; + } + } + + 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 - + av_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; + 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. */ + fpc->fifo_buf = av_fifo_alloc_array(FLAC_MIN_HEADERS + 3, FLAC_AVG_FRAME_SIZE); + if (!fpc->fifo_buf) { + 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_freep(&curr->link_penalty); + av_free(curr); + curr = temp; + } + av_fifo_freep(&fpc->fifo_buf); + av_freep(&fpc->wrap_buf); +} + +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, +}; |