[FFmpeg-devel] [PATCH] png parser

[Peter Holik]

> On Thu, Jun 04, 2009 at 10:40:55AM +0200, Peter Holik wrote:
>> > On Mon, Jun 01, 2009 at 12:27:52PM +0200, Peter Holik wrote:
>> >> Hi!
>> >>
>> >> I've now reworked my patch to really parse a png for end of frame.
>> >>
>> >> Now you can filter out png's of any stream like
>> >>
>> >> cat garbage a.png garbage b.png garbage | ffmpeg -f image2pipe -vcodec png -i - c%d.png
>> >>
>> >> cu Peter
>> >>  Makefile     |    1
>> >>  allcodecs.c  |    1
>> >>  png_parser.c |  124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files
changed, 126 insertions(+)
>> >> 63f7cd1bb826726f1d2a9e7254410cd7ec98a81c  png-parser.patch
>> >> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
>> >> index 14ef9f4..189231b 100644
>> >> --- a/libavcodec/Makefile
>> >> +++ b/libavcodec/Makefile
>> >> @@ -411,6 +411,7 @@ OBJS-$(CONFIG_MLP_PARSER)              += mlp_parser.o mlp.o
>> >>  OBJS-$(CONFIG_MPEG4VIDEO_PARSER)       += mpeg4video_parser.o h263.o mpeg12data.o
>> mpegvideo.o
>> >> error_resilience.o
>> >>  OBJS-$(CONFIG_MPEGAUDIO_PARSER)        += mpegaudio_parser.o mpegaudiodecheader.o
>> >> mpegaudiodata.o
>> >>  OBJS-$(CONFIG_MPEGVIDEO_PARSER)        += mpegvideo_parser.o mpeg12.o mpeg12data.o
>> mpegvideo.o
>> >> error_resilience.o
>> >> +OBJS-$(CONFIG_PNG_PARSER)              += png_parser.o
>> >>  OBJS-$(CONFIG_PNM_PARSER)              += pnm_parser.o pnm.o OBJS-$(CONFIG_VC1_PARSER)     
        += vc1_parser.o
>> >>  OBJS-$(CONFIG_VP3_PARSER)              += vp3_parser.o
>> >> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c index e8d5d27..362021f 100644
>> >> --- a/libavcodec/allcodecs.c
>> >> +++ b/libavcodec/allcodecs.c
>> >> @@ -334,6 +334,7 @@ void avcodec_register_all(void)
>> >>      REGISTER_PARSER  (MPEG4VIDEO, mpeg4video);
>> >>      REGISTER_PARSER  (MPEGAUDIO, mpegaudio);
>> >>      REGISTER_PARSER  (MPEGVIDEO, mpegvideo);
>> >> +    REGISTER_PARSER  (PNG, png);
>> >>      REGISTER_PARSER  (PNM, pnm);
>> >>      REGISTER_PARSER  (VC1, vc1);
>> >>      REGISTER_PARSER  (VP3, vp3);
>> >> diff --git a/libavcodec/png_parser.c b/libavcodec/png_parser.c new file mode 100644
>> >> index 0000000..64f2356
>> >> --- /dev/null
>> >> +++ b/libavcodec/png_parser.c
>> >> @@ -0,0 +1,124 @@
>> >> +/*
>> >> + * PNG parser
>> >> + * Copyright (c) 2009 Peter Holik
>> >> + *
>> >> + * 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 libavcodec/png_parser.c
>> >> + * PNG parser
>> >> + */
>> >> +
>> >> +#include "parser.h"
>> >> +#include "bytestream.h"
>> >> +#include "png.h"
>> >> +
>> >> +static int png_parse(AVCodecParserContext *s, AVCodecContext *avctx, +                    
const uint8_t **poutbuf, int *poutbuf_size, +                     const uint8_t *buf, int
buf_size)
>> >> +{
>> >> +    ParseContext *pc = s->priv_data;
>> >> +    uint8_t *bytestream;
>> >> +    uint8_t *bytestream_start;
>> >> +    uint8_t *bytestream_end;
>> >> +
>> >> +    /* EOF considered as end of frame */
>> >> +    if (buf_size == 0)
>> >> +        goto flush;
>> >> +
>> >> +    *poutbuf      = NULL;
>> >> +    *poutbuf_size = 0;
>> >> +
>> >> +    /* first add new buffer to parsebuffer */
>> >> +    bytestream_start = av_fast_realloc(pc->buffer, &pc->buffer_size, +                     
    pc->index + buf_size + FF_INPUT_BUFFER_PADDING_SIZE); +    if(!bytestream_start)
>> >> +        goto fail;
>> >> +    pc->buffer = bytestream_start;
>> >> +    memcpy(&pc->buffer[pc->index], buf, buf_size);
>> >
>> > mandatory copying is unacceptable
>> > the case where each input is exactly a png frame for example should be free of any
timeconsuming operation
>> >
>> > maybe ff_combine_frame() would be usefull
>>
>> But ff_combine_frame also does memcpy, so there is no difference to my approach.
>
> ff_combine_frame() does not always memcpy, your code does always

change my patch to only memcpy when input is not exactly a png frame.

cu Peter
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