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pngdec: Implement parsing functionality

Browse source 
This allows to plug pngdec directly without a parser if that
is desired.

Parsing code is based on pngparse.
This commit is contained in:
Sebastian Dröge 2013-05-07 16:30:59 +02:00
parent 797ebfc32b
commit 0392a0dc3d
1 changed files with 106 additions and 0 deletions
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106
ext/libpng/gstpngdec.c
View file

@ -2,6 +2,9 @@
* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
* Copyright (C) 2012 Collabora Ltd.
* Author : Edward Hervey <edward@collabora.com>
* Copyright (C) 2013 Collabora Ltd.
* Author : Sebastian Dröge <sebastian.droege@collabora.co.uk>
* Olivier Crete <olivier.crete@collabora.com>
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
@ -29,6 +32,7 @@
#include <stdlib.h>
#include <string.h>
#include <gst/base/gstbytereader.h>
#include <gst/video/video.h>
#include <gst/video/gstvideometa.h>
#include <gst/video/gstvideopool.h>
@ -46,6 +50,8 @@ static gboolean gst_pngdec_start (GstVideoDecoder * decoder);
static gboolean gst_pngdec_stop (GstVideoDecoder * decoder);
static gboolean gst_pngdec_set_format (GstVideoDecoder * Decoder,
GstVideoCodecState * state);
static GstFlowReturn gst_pngdec_parse (GstVideoDecoder * decoder,
GstVideoCodecFrame * frame, GstAdapter * adapter, gboolean at_eos);
static GstFlowReturn gst_pngdec_handle_frame (GstVideoDecoder * decoder,
GstVideoCodecFrame * frame);
static gboolean gst_pngdec_decide_allocation (GstVideoDecoder * decoder,
@ -88,6 +94,7 @@ gst_pngdec_class_init (GstPngDecClass * klass)
vdec_class->stop = gst_pngdec_stop;
vdec_class->reset = gst_pngdec_reset;
vdec_class->set_format = gst_pngdec_set_format;
vdec_class->parse = gst_pngdec_parse;
vdec_class->handle_frame = gst_pngdec_handle_frame;
vdec_class->decide_allocation = gst_pngdec_decide_allocation;
@ -148,11 +155,17 @@ static gboolean
gst_pngdec_set_format (GstVideoDecoder * decoder, GstVideoCodecState * state)
{
GstPngDec *pngdec = (GstPngDec *) decoder;
GstVideoInfo *info = &state->info;
if (pngdec->input_state)
gst_video_codec_state_unref (pngdec->input_state);
pngdec->input_state = gst_video_codec_state_ref (state);
if (GST_VIDEO_INFO_FPS_N (info) != 1 && GST_VIDEO_INFO_FPS_D (info) != 1)
gst_video_decoder_set_packetized (decoder, TRUE);
else
gst_video_decoder_set_packetized (decoder, FALSE);
/* We'll set format later on */
return TRUE;
@ -392,6 +405,98 @@ beach:
return ret;
}
/* Based on pngparse */
#define PNG_SIGNATURE G_GUINT64_CONSTANT (0x89504E470D0A1A0A)
static GstFlowReturn
gst_pngdec_parse (GstVideoDecoder * decoder, GstVideoCodecFrame * frame,
GstAdapter * adapter, gboolean at_eos)
{
gsize toadd = 0;
GstByteReader reader;
gconstpointer data;
guint64 signature;
gsize size;
/* FIXME : The overhead of using scan_uint32 is massive */
size = gst_adapter_available (adapter);
GST_DEBUG ("Parsing PNG image data (%" G_GSIZE_FORMAT " bytes)", size);
if (size < 8)
goto need_more_data;
data = gst_adapter_map (adapter, size);
gst_byte_reader_init (&reader, data, size);
if (!gst_byte_reader_peek_uint64_be (&reader, &signature))
goto need_more_data;
if (signature != PNG_SIGNATURE) {
for (;;) {
guint offset;
offset = gst_byte_reader_masked_scan_uint32 (&reader, 0xffffffff,
0x89504E47, 0, gst_byte_reader_get_remaining (&reader));
if (offset == -1) {
gst_adapter_flush (adapter,
gst_byte_reader_get_remaining (&reader) - 4);
goto need_more_data;
}
if (!gst_byte_reader_skip (&reader, offset))
goto need_more_data;
if (!gst_byte_reader_peek_uint64_be (&reader, &signature))
goto need_more_data;
if (signature == PNG_SIGNATURE) {
/* We're skipping, go out, we'll be back */
gst_adapter_flush (adapter, gst_byte_reader_get_pos (&reader));
goto need_more_data;
}
if (!gst_byte_reader_skip (&reader, 4))
goto need_more_data;
}
}
if (!gst_byte_reader_skip (&reader, 8))
goto need_more_data;
for (;;) {
guint32 length;
guint32 code;
if (!gst_byte_reader_get_uint32_be (&reader, &length))
goto need_more_data;
if (!gst_byte_reader_get_uint32_le (&reader, &code))
goto need_more_data;
if (!gst_byte_reader_skip (&reader, length + 4))
goto need_more_data;
if (code == GST_MAKE_FOURCC ('I', 'E', 'N', 'D')) {
/* Have complete frame */
toadd = gst_byte_reader_get_pos (&reader);
GST_DEBUG_OBJECT (decoder, "Have complete frame of size %" G_GSIZE_FORMAT,
toadd);
goto have_full_frame;
}
}
g_assert_not_reached ();
return GST_FLOW_ERROR;
need_more_data:
return GST_VIDEO_DECODER_FLOW_NEED_DATA;
have_full_frame:
if (toadd)
gst_video_decoder_add_to_frame (decoder, toadd);
return gst_video_decoder_have_frame (decoder);
}
static gboolean
gst_pngdec_decide_allocation (GstVideoDecoder * bdec, GstQuery * query)
{
@ -497,6 +602,7 @@ gst_pngdec_start (GstVideoDecoder * decoder)
{
GstPngDec *pngdec = (GstPngDec *) decoder;
gst_video_decoder_set_packetized (GST_VIDEO_DECODER (pngdec), FALSE);
gst_pngdec_libpng_init (pngdec);
return TRUE;