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flac_parser: only buffer the estimated amount of input needed.

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Patch by Michael Chinen [mchinen at gmail]

Originally committed as revision 25933 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Chinen 2010-12-12 00:52:57 +00:00 committed by Justin Ruggles
parent 97f7fe687a
commit 7edbd5361c
1 changed files with 18 additions and 11 deletions
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29
libavcodec/flac_parser.c
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@ -42,6 +42,8 @@
#define FLAC_MAX_SEQUENTIAL_HEADERS 3 #define FLAC_MAX_SEQUENTIAL_HEADERS 3
/** minimum number of headers buffered and checked before returning frames */ /** minimum number of headers buffered and checked before returning frames */
#define FLAC_MIN_HEADERS 10 #define FLAC_MIN_HEADERS 10
/** estimate for average size of a FLAC frame */
#define FLAC_AVG_FRAME_SIZE 8192
/** scoring settings for score_header */ /** scoring settings for score_header */
#define FLAC_HEADER_BASE_SCORE 10 #define FLAC_HEADER_BASE_SCORE 10
@ -476,6 +478,7 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
FLACParseContext *fpc = s->priv_data; FLACParseContext *fpc = s->priv_data;
FLACHeaderMarker *curr; FLACHeaderMarker *curr;
int nb_headers; int nb_headers;
int read_size = 0;
if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
FLACFrameInfo fi; FLACFrameInfo fi;
@ -543,20 +546,25 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
/* Pad the end once if EOF, to check the final region for headers. */ /* Pad the end once if EOF, to check the final region for headers. */
if (!buf_size) { if (!buf_size) {
fpc->end_padded = 1; fpc->end_padded = 1;
buf_size = MAX_FRAME_HEADER_SIZE; buf_size = read_size = 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_size = FFMIN(buf_size, nb_desired * FLAC_AVG_FRAME_SIZE);
} }
/* Fill the buffer. */ /* Fill the buffer. */
if (av_fifo_realloc2(fpc->fifo_buf, if (av_fifo_realloc2(fpc->fifo_buf,
buf_size + av_fifo_size(fpc->fifo_buf)) < 0) { read_size + av_fifo_size(fpc->fifo_buf)) < 0) {
av_log(avctx, AV_LOG_ERROR, av_log(avctx, AV_LOG_ERROR,
"couldn't reallocate buffer of size %d\n", "couldn't reallocate buffer of size %d\n",
buf_size + av_fifo_size(fpc->fifo_buf)); read_size + av_fifo_size(fpc->fifo_buf));
goto handle_error; goto handle_error;
} }
if (buf) { if (buf) {
av_fifo_generic_write(fpc->fifo_buf, (void*) buf, buf_size, NULL); av_fifo_generic_write(fpc->fifo_buf, (void*) buf, read_size, NULL);
} else { } else {
int8_t pad[MAX_FRAME_HEADER_SIZE]; int8_t pad[MAX_FRAME_HEADER_SIZE];
memset(pad, 0, sizeof(pad)); memset(pad, 0, sizeof(pad));
@ -565,7 +573,7 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
/* Tag headers and update sequences. */ /* Tag headers and update sequences. */
start_offset = av_fifo_size(fpc->fifo_buf) - start_offset = av_fifo_size(fpc->fifo_buf) -
(buf_size + (MAX_FRAME_HEADER_SIZE - 1)); (read_size + (MAX_FRAME_HEADER_SIZE - 1));
start_offset = FFMAX(0, start_offset); start_offset = FFMAX(0, start_offset);
nb_headers = find_new_headers(fpc, start_offset); nb_headers = find_new_headers(fpc, start_offset);
@ -593,7 +601,7 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
fpc->fifo_buf->wptr += fpc->fifo_buf->end - fpc->fifo_buf->wptr += fpc->fifo_buf->end -
fpc->fifo_buf->buffer; fpc->fifo_buf->buffer;
} }
buf_size = 0; buf_size = read_size = 0;
} }
} }
@ -615,7 +623,7 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
*poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size, *poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size,
&fpc->wrap_buf, &fpc->wrap_buf,
&fpc->wrap_buf_allocated_size); &fpc->wrap_buf_allocated_size);
return buf_size ? buf_size : (fpc->best_header->offset - return buf_size ? read_size : (fpc->best_header->offset -
av_fifo_size(fpc->fifo_buf)); av_fifo_size(fpc->fifo_buf));
} }
if (!buf_size) if (!buf_size)
@ -625,16 +633,15 @@ static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
handle_error: handle_error:
*poutbuf = NULL; *poutbuf = NULL;
*poutbuf_size = 0; *poutbuf_size = 0;
return buf_size; return read_size;
} }
static int flac_parse_init(AVCodecParserContext *c) static int flac_parse_init(AVCodecParserContext *c)
{ {
FLACParseContext *fpc = c->priv_data; FLACParseContext *fpc = c->priv_data;
/* There will generally be FLAC_MIN_HEADERS buffered in the fifo before /* There will generally be FLAC_MIN_HEADERS buffered in the fifo before
it drains. 8192 is an approximate average size of a flac frame */ it drains. This is allocated early to avoid slow reallocation. */
fpc->fifo_buf = av_fifo_alloc(8192 * FLAC_MIN_HEADERS); fpc->fifo_buf = av_fifo_alloc(FLAC_AVG_FRAME_SIZE * (FLAC_MIN_HEADERS + 3));
return 0; return 0;
} }