| /* |
| * 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 3 |
| /** 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 * 10) { |
| /* There is less than one valid flac header buffered for 10 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, |
| }; |
