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h264parse: unobfuscate frame parsing code

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This commit is contained in:
Mark Nauwelaerts 2012-02-10 14:46:00 +01:00
parent c835325536
commit 1cbd755a2c
2 changed files with 102 additions and 109 deletions
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204
gst/videoparsers/gsth264parse.c
View file

@ -177,11 +177,7 @@ gst_h264_parse_reset_frame (GstH264Parse * h264parse)
GST_DEBUG_OBJECT (h264parse, "reset frame"); GST_DEBUG_OBJECT (h264parse, "reset frame");
/* done parsing; reset state */ /* done parsing; reset state */
h264parse->nalu.valid = FALSE; h264parse->current_off = -1;
h264parse->nalu.offset = 0;
h264parse->nalu.sc_offset = 0;
h264parse->nalu.size = 0;
h264parse->current_off = 0;
h264parse->picture_start = FALSE; h264parse->picture_start = FALSE;
h264parse->update_caps = FALSE; h264parse->update_caps = FALSE;
@ -656,10 +652,12 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse,
GstH264Parse *h264parse = GST_H264_PARSE (parse); GstH264Parse *h264parse = GST_H264_PARSE (parse);
GstBuffer *buffer = frame->buffer; GstBuffer *buffer = frame->buffer;
guint8 *data; guint8 *data;
guint size, current_off = 0; guint size;
gboolean drain; gint current_off = 0;
gboolean drain, nonext;
GstH264NalParser *nalparser = h264parse->nalparser; GstH264NalParser *nalparser = h264parse->nalparser;
GstH264NalUnit nalu; GstH264NalUnit nalu;
GstH264ParserResult pres;
/* expect at least 3 bytes startcode == sc, and 2 bytes NALU payload */ /* expect at least 3 bytes startcode == sc, and 2 bytes NALU payload */
if (G_UNLIKELY (GST_BUFFER_SIZE (buffer) < 5)) if (G_UNLIKELY (GST_BUFFER_SIZE (buffer) < 5))
@ -681,16 +679,38 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse,
data = GST_BUFFER_DATA (buffer); data = GST_BUFFER_DATA (buffer);
size = GST_BUFFER_SIZE (buffer); size = GST_BUFFER_SIZE (buffer);
drain = FALSE; drain = GST_BASE_PARSE_DRAINING (parse);
nalu = h264parse->nalu; nonext = FALSE;
current_off = h264parse->current_off; current_off = h264parse->current_off;
if (current_off < 0)
current_off = 0;
g_assert (current_off < size); g_assert (current_off < size);
GST_DEBUG_OBJECT (h264parse, "last parse position %d", current_off);
/* check for initial skip */
if (h264parse->current_off == -1) {
pres =
gst_h264_parser_identify_nalu_unchecked (nalparser, data, current_off,
size, &nalu);
switch (pres) {
case GST_H264_PARSER_OK:
if (nalu.sc_offset > 0) {
*skipsize = nalu.sc_offset;
goto skip;
}
break;
case GST_H264_PARSER_NO_NAL:
*skipsize = size - 3;
goto skip;
break;
default:
g_assert_not_reached ();
break;
}
}
GST_DEBUG_OBJECT (h264parse, "last parse position %u", current_off);
while (TRUE) { while (TRUE) {
GstH264ParserResult pres;
if (h264parse->packetized_chunked) if (h264parse->packetized_chunked)
pres = pres =
gst_h264_parser_identify_nalu_unchecked (nalparser, data, current_off, gst_h264_parser_identify_nalu_unchecked (nalparser, data, current_off,
@ -702,99 +722,85 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse,
switch (pres) { switch (pres) {
case GST_H264_PARSER_OK: case GST_H264_PARSER_OK:
GST_DEBUG_OBJECT (h264parse, "complete nal found. " GST_DEBUG_OBJECT (h264parse, "complete nal (offset, size): (%u, %u) ",
"current offset: %u, Nal offset: %u, Nal Size: %u", nalu.offset, nalu.size);
current_off, nalu.offset, nalu.size);
GST_DEBUG_OBJECT (h264parse, "current off. %u",
nalu.offset + nalu.size);
if (!h264parse->nalu.size && !h264parse->nalu.valid)
h264parse->nalu = nalu;
/* need 2 bytes of next nal */
if (!h264parse->packetized_chunked &&
(nalu.offset + nalu.size + 4 + 2 > size)) {
if (GST_BASE_PARSE_DRAINING (parse)) {
drain = TRUE;
} else {
GST_DEBUG_OBJECT (h264parse, "need more bytes of next nal");
current_off = nalu.sc_offset;
goto more;
}
} else if (h264parse->packetized_chunked) {
/* normal next nal based collection not possible,
* _chain will have to tell us whether this was last one for AU */
drain = h264parse->packetized_last;
}
break; break;
case GST_H264_PARSER_BROKEN_LINK:
return FALSE;
case GST_H264_PARSER_ERROR:
current_off = size - 3;
goto parsing_error;
case GST_H264_PARSER_NO_NAL:
/* don't expect to have found any NAL so far */
g_assert (h264parse->nalu.size == 0);
current_off = h264parse->nalu.sc_offset = size - 3;
goto more;
case GST_H264_PARSER_BROKEN_DATA:
GST_WARNING_OBJECT (h264parse, "input stream is corrupt; "
"it contains a NAL unit of length %d", nalu.size);
/* broken nal at start -> arrange to skip it,
* otherwise have it terminate current au
* (and so it will be skipped on next frame round) */
if (nalu.sc_offset == h264parse->nalu.sc_offset) {
*skipsize = nalu.offset;
GST_DEBUG_OBJECT (h264parse, "skipping broken nal");
goto invalid;
} else {
nalu.size = 0;
goto end;
}
case GST_H264_PARSER_NO_NAL_END: case GST_H264_PARSER_NO_NAL_END:
GST_DEBUG_OBJECT (h264parse, "not a complete nal found at offset %u", GST_DEBUG_OBJECT (h264parse, "not a complete nal found at offset %u",
nalu.offset); nalu.offset);
/* if draining, accept it as complete nal */
current_off = nalu.sc_offset; if (drain) {
/* We keep the reference to this nal so we start over the parsing nonext = TRUE;
* here */
if (!h264parse->nalu.size && !h264parse->nalu.valid)
h264parse->nalu = nalu;
if (GST_BASE_PARSE_DRAINING (parse)) {
drain = TRUE;
GST_DEBUG_OBJECT (h264parse, "draining NAL %u %u %u", size,
h264parse->nalu.offset, h264parse->nalu.size);
/* Can't parse the nalu */
if (size - h264parse->nalu.offset < 2) {
*skipsize = nalu.offset;
goto invalid;
}
/* We parse it anyway */
nalu.size = size - nalu.offset; nalu.size = size - nalu.offset;
GST_DEBUG_OBJECT (h264parse, "draining, accepting with size %u",
nalu.size);
/* if it's not too short at least */
if (nalu.size < 2)
goto broken;
break; break;
} }
/* otherwise need more */
goto more; goto more;
case GST_H264_PARSER_BROKEN_LINK:
g_assert_not_reached ();
break;
case GST_H264_PARSER_ERROR:
/* should not really occur either */
GST_DEBUG_OBJECT (h264parse, "error parsing Nal Unit");
/* fall-through */
case GST_H264_PARSER_NO_NAL:
g_assert_not_reached ();
break;
case GST_H264_PARSER_BROKEN_DATA:
GST_WARNING_OBJECT (h264parse, "input stream is corrupt; "
"it contains a NAL unit of length %u", nalu.size);
broken:
/* broken nal at start -> arrange to skip it,
* otherwise have it terminate current au
* (and so it will be skipped on next frame round) */
if (current_off == 0) {
GST_DEBUG_OBJECT (h264parse, "skipping broken nal");
*skipsize = nalu.offset;
goto skip;
} else {
GST_DEBUG_OBJECT (h264parse, "terminating au");
nalu.size = 0;
nalu.offset = nalu.sc_offset;
goto end;
}
break;
default:
g_assert_not_reached ();
break;
} }
current_off = nalu.offset + nalu.size;
GST_DEBUG_OBJECT (h264parse, "%p complete nal found. Off: %u, Size: %u", GST_DEBUG_OBJECT (h264parse, "%p complete nal found. Off: %u, Size: %u",
data, nalu.offset, nalu.size); data, nalu.offset, nalu.size);
/* simulate no next nal if none needed */
nonext = nonext || (h264parse->align == GST_H264_PARSE_ALIGN_NAL);
if (!nonext && !h264parse->packetized_chunked) {
if (nalu.offset + nalu.size + 4 + 2 > size) {
GST_DEBUG_OBJECT (h264parse, "not enough data for next NALU");
if (drain) {
GST_DEBUG_OBJECT (h264parse, "but draining anyway");
nonext = TRUE;
} else {
goto more;
}
}
}
gst_h264_parse_process_nal (h264parse, &nalu); gst_h264_parse_process_nal (h264parse, &nalu);
/* simulate no next nal if none needed */ if (nonext)
drain = drain || (h264parse->align == GST_H264_PARSE_ALIGN_NAL); break;
/* In packetized mode we know there's only on NALU in each input packet, /* In packetized mode we know there's only on NALU in each input packet,
* but we may not have seen the whole AU already, possibly need more */ * but we may not have seen the whole AU already, possibly need more */
if (h264parse->packetized_chunked) { if (h264parse->packetized_chunked) {
if (drain) if (h264parse->packetized_last)
break; break;
/* next NALU expected at end of current data */ /* next NALU expected at end of current data */
current_off = size; current_off = size;
@ -802,42 +808,30 @@ gst_h264_parse_check_valid_frame (GstBaseParse * parse,
} }
/* if no next nal, we know it's complete here */ /* if no next nal, we know it's complete here */
if (drain || gst_h264_parse_collect_nal (h264parse, data, size, &nalu)) if (gst_h264_parse_collect_nal (h264parse, data, size, &nalu))
break; break;
GST_DEBUG_OBJECT (h264parse, "Looking for more"); GST_DEBUG_OBJECT (h264parse, "Looking for more");
current_off = nalu.offset + nalu.size;
} }
end: end:
*skipsize = h264parse->nalu.sc_offset; *framesize = nalu.offset + nalu.size;
*framesize = nalu.offset + nalu.size - h264parse->nalu.sc_offset;
h264parse->current_off = current_off;
return TRUE; return TRUE;
parsing_error:
GST_DEBUG_OBJECT (h264parse, "error parsing Nal Unit");
more: more:
/* ask for best next available */ /* ask for best next available */
*framesize = G_MAXUINT; *framesize = G_MAXUINT;
if (!h264parse->nalu.size) {
/* skip up to initial startcode */
*skipsize = h264parse->nalu.sc_offset;
/* but mind some stuff will have been skipped */
g_assert (current_off >= *skipsize);
current_off -= *skipsize;
h264parse->nalu.sc_offset = 0;
} else {
*skipsize = 0; *skipsize = 0;
}
/* Restart parsing from here next time */ /* Restart parsing from here next time */
if (current_off > 0)
h264parse->current_off = current_off; h264parse->current_off = current_off;
return FALSE; return FALSE;
invalid: skip:
GST_DEBUG_OBJECT (h264parse, "skipping %d", *skipsize);
gst_h264_parse_reset_frame (h264parse); gst_h264_parse_reset_frame (h264parse);
return FALSE; return FALSE;
} }

3
gst/videoparsers/gsth264parse.h
View file

@ -67,10 +67,9 @@ struct _GstH264Parse
/* state */ /* state */
GstH264NalParser *nalparser; GstH264NalParser *nalparser;
GstH264NalUnit nalu;
guint align; guint align;
guint format; guint format;
guint current_off; gint current_off;
gboolean packetized_last; gboolean packetized_last;
gboolean packetized_chunked; gboolean packetized_chunked;