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gst/mpeg4videoparse/mpeg4videoparse.*: Improved version not damaging headers using a simple state machine.

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Original commit message from CVS:
2007-10-27  Julien MOUTTE  <julien@moutte.net>

* gst/mpeg4videoparse/mpeg4videoparse.c:
(gst_mpeg4vparse_align),
(gst_mpeg4vparse_drain), (gst_mpeg4vparse_chain),
(gst_mpeg4vparse_sink_setcaps), (gst_mpeg4vparse_sink_event),
(gst_mpeg4vparse_cleanup), (gst_mpeg4vparse_change_state),
(gst_mpeg4vparse_dispose), (gst_mpeg4vparse_base_init),
(gst_mpeg4vparse_class_init), (gst_mpeg4vparse_init),
(plugin_init):
* gst/mpeg4videoparse/mpeg4videoparse.h: Improved version not
damaging headers using a simple state machine.
This commit is contained in:
Julien Moutte 2007-10-27 08:20:59 +00:00
parent 936460ea72
commit adbe2a1b69
3 changed files with 106 additions and 37 deletions
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12
ChangeLog
View file

@ -1,3 +1,15 @@
2007-10-27 Julien MOUTTE <julien@moutte.net>
* gst/mpeg4videoparse/mpeg4videoparse.c: (gst_mpeg4vparse_align),
(gst_mpeg4vparse_drain), (gst_mpeg4vparse_chain),
(gst_mpeg4vparse_sink_setcaps), (gst_mpeg4vparse_sink_event),
(gst_mpeg4vparse_cleanup), (gst_mpeg4vparse_change_state),
(gst_mpeg4vparse_dispose), (gst_mpeg4vparse_base_init),
(gst_mpeg4vparse_class_init), (gst_mpeg4vparse_init),
(plugin_init):
* gst/mpeg4videoparse/mpeg4videoparse.h: Improved version not
damaging headers using a simple state machine.
2007-10-26 Tim-Philipp Müller <tim at centricular dot net>
* ext/x264/gstx264enc.c:

116
gst/mpeg4videoparse/mpeg4videoparse.c
View file

@ -51,51 +51,81 @@ GST_STATIC_PAD_TEMPLATE ("sink", GST_PAD_SINK,
GST_BOILERPLATE (GstMpeg4VParse, gst_mpeg4vparse, GstElement, GST_TYPE_ELEMENT);
static void
gst_mpeg4vparse_align (GstMpeg4VParse * parse)
{
guint flushed = 0;
/* Searching for a start code */
while (gst_adapter_available (parse->adapter) >= 4) {
/* If we have enough data, ensure we're aligned to a start code */
const guint8 *data = gst_adapter_peek (parse->adapter, 4);
if (data[0] == 0 && data[1] == 0 && data[2] == 1) {
GST_LOG_OBJECT (parse, "found start code with type %02X", data[3]);
parse->state = PARSE_START_FOUND;
break;
} else {
gst_adapter_flush (parse->adapter, 1);
flushed++;
parse->state = PARSE_NEED_START;
}
}
if (G_UNLIKELY (flushed)) {
GST_LOG_OBJECT (parse, "flushed %u bytes while aligning", flushed);
}
}
static GstFlowReturn
gst_mpeg4vparse_drain (GstMpeg4VParse * parse)
{
GstFlowReturn ret = GST_FLOW_OK;
const guint8 *data = NULL;
guint i = 0, available = 0;
guint available = 0;
while (gst_adapter_available (parse->adapter) >= 4) {
/* If we have enough data, ensure we're aligned to a start code */
data = gst_adapter_peek (parse->adapter, 4);
if (data[0] == 0 && data[1] == 0 && data[2] == 1) {
GST_LOG_OBJECT (parse, "found start code with type %02X", data[3]);
parse->found_start = TRUE;
break;
} else {
GST_LOG_OBJECT (parse, "flushing 1 byte");
gst_adapter_flush (parse->adapter, 1);
}
}
if (G_UNLIKELY (!parse->found_start)) {
GST_DEBUG_OBJECT (parse, "start code not found, need more data");
goto beach;
}
if (G_UNLIKELY (gst_adapter_available (parse->adapter) < 8)) {
GST_DEBUG_OBJECT (parse, "start code found, need more data to find next");
goto beach;
}
/* Found a start code, search for the next one */
available = gst_adapter_available (parse->adapter);
data = gst_adapter_peek (parse->adapter, available);
for (i = 4; i < available - 4; i++) {
/* We generate packets based on VOP start code */
if (data[i] == 0 && data[i + 1] == 0 && data[i + 2] == 1 &&
data[i + 3] == 0xB6) {
GstBuffer *out_buf = gst_adapter_take_buffer (parse->adapter, i);
GST_LOG_OBJECT (parse, "found next start code at %u", i);
while (parse->offset < available - 4) {
/* We generate packets based on VOP end code (next start code) */
if (data[parse->offset] == 0 && data[parse->offset + 1] == 0 &&
data[parse->offset + 2] == 1) {
switch (parse->state) {
case PARSE_START_FOUND:
if (data[parse->offset + 3] == 0xB6) {
GST_LOG_OBJECT (parse, "found VOP start marker at %u",
parse->offset);
parse->state = PARSE_VOP_FOUND;
}
/* Jump over it */
parse->offset += 4;
break;
case PARSE_VOP_FOUND:
{ /* We were in a VOP already, any start code marks the end of it */
GstBuffer *out_buf = gst_adapter_take_buffer (parse->adapter,
parse->offset);
GST_LOG_OBJECT (parse, "found VOP end marker at %u", parse->offset);
if (out_buf) {
gst_buffer_set_caps (out_buf, GST_PAD_CAPS (parse->srcpad));
gst_pad_push (parse->srcpad, out_buf);
}
parse->found_start = FALSE;
/* Restart now that we flushed data */
parse->offset = 0;
parse->state = PARSE_START_FOUND;
available = gst_adapter_available (parse->adapter);
data = gst_adapter_peek (parse->adapter, available);
break;
}
default:
GST_WARNING_OBJECT (parse, "unexpected parse state (%d)",
parse->state);
ret = GST_FLOW_UNEXPECTED;
goto beach;
}
} else { /* Continue searching */
parse->offset++;
}
}
@ -116,8 +146,27 @@ gst_mpeg4vparse_chain (GstPad * pad, GstBuffer * buffer)
gst_adapter_push (parse->adapter, buffer);
/* We need to get aligned on a start code */
if (G_UNLIKELY (parse->state == PARSE_NEED_START)) {
gst_mpeg4vparse_align (parse);
/* No start code found in that buffer */
if (G_UNLIKELY (parse->state == PARSE_NEED_START)) {
GST_DEBUG_OBJECT (parse, "start code not found, need more data");
goto beach;
}
}
/* We need at least 8 bytes to find the next start code which marks the end
of the one we just found */
if (G_UNLIKELY (gst_adapter_available (parse->adapter) < 8)) {
GST_DEBUG_OBJECT (parse, "start code found, need more data to find next");
goto beach;
}
/* Drain the accumulated blocks frame per frame */
ret = gst_mpeg4vparse_drain (parse);
beach:
gst_object_unref (parse);
return ret;
@ -176,7 +225,8 @@ gst_mpeg4vparse_cleanup (GstMpeg4VParse * parse)
gst_adapter_clear (parse->adapter);
}
parse->found_start = FALSE;
parse->state = PARSE_NEED_START;
parse->offset = 0;
}
static GstStateChangeReturn

9
gst/mpeg4videoparse/mpeg4videoparse.h
View file

@ -40,6 +40,12 @@ G_BEGIN_DECLS
typedef struct _GstMpeg4VParse GstMpeg4VParse;
typedef struct _GstMpeg4VParseClass GstMpeg4VParseClass;
typedef enum {
PARSE_NEED_START,
PARSE_START_FOUND,
PARSE_VOP_FOUND
} GstMpeg4VParseState;
struct _GstMpeg4VParse {
GstElement element;
@ -47,8 +53,9 @@ struct _GstMpeg4VParse {
GstPad * srcpad;
GstAdapter * adapter;
guint offset;
gboolean found_start;
GstMpeg4VParseState state;
};
struct _GstMpeg4VParseClass {