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flacparse: perform additional frame crc check if applicable

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... such as a frame header parsing throwing some suspicious warnings.
So we can be a bit more convinced we determine the right frame end.
This commit is contained in:
Mark Nauwelaerts 2012-03-19 12:01:40 +01:00
parent 58816039c2
commit 440d7034f0
1 changed files with 17 additions and 6 deletions
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23
gst/audioparsers/gstflacparse.c
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@ -381,7 +381,8 @@ typedef enum
static FrameHeaderCheckReturn static FrameHeaderCheckReturn
gst_flac_parse_frame_header_is_valid (GstFlacParse * flacparse, gst_flac_parse_frame_header_is_valid (GstFlacParse * flacparse,
const guint8 * data, guint size, gboolean set, guint16 * block_size_ret) const guint8 * data, guint size, gboolean set, guint16 * block_size_ret,
gboolean * suspect)
{ {
GstBitReader reader = GST_BIT_READER_INIT (data, size); GstBitReader reader = GST_BIT_READER_INIT (data, size);
guint8 blocking_strategy; guint8 blocking_strategy;
@ -575,6 +576,8 @@ gst_flac_parse_frame_header_is_valid (GstFlacParse * flacparse,
/* TODO: can we know we're on the last frame, to avoid warning ? */ /* TODO: can we know we're on the last frame, to avoid warning ? */
GST_WARNING_OBJECT (flacparse, "Block size is not constant"); GST_WARNING_OBJECT (flacparse, "Block size is not constant");
block_size = flacparse->block_size; block_size = flacparse->block_size;
if (suspect)
*suspect = TRUE;
} }
} }
} }
@ -623,6 +626,7 @@ gst_flac_parse_frame_is_valid (GstFlacParse * flacparse,
guint i, search_start, search_end; guint i, search_start, search_end;
FrameHeaderCheckReturn header_ret; FrameHeaderCheckReturn header_ret;
guint16 block_size; guint16 block_size;
gboolean suspect_start = FALSE, suspect_end = FALSE;
buffer = frame->buffer; buffer = frame->buffer;
data = GST_BUFFER_DATA (buffer); data = GST_BUFFER_DATA (buffer);
@ -633,7 +637,7 @@ gst_flac_parse_frame_is_valid (GstFlacParse * flacparse,
header_ret = header_ret =
gst_flac_parse_frame_header_is_valid (flacparse, data, size, TRUE, gst_flac_parse_frame_header_is_valid (flacparse, data, size, TRUE,
&block_size); &block_size, &suspect_start);
if (header_ret == FRAME_HEADER_INVALID) { if (header_ret == FRAME_HEADER_INVALID) {
*ret = 0; *ret = 0;
return FALSE; return FALSE;
@ -653,16 +657,23 @@ gst_flac_parse_frame_is_valid (GstFlacParse * flacparse,
for (i = search_start; i < search_end; i++, remaining--) { for (i = search_start; i < search_end; i++, remaining--) {
if ((GST_READ_UINT16_BE (data + i) & 0xfffe) == 0xfff8) { if ((GST_READ_UINT16_BE (data + i) & 0xfffe) == 0xfff8) {
GST_LOG_OBJECT (flacparse, "possible frame end at offset %d", i);
suspect_end = FALSE;
header_ret = header_ret =
gst_flac_parse_frame_header_is_valid (flacparse, data + i, remaining, gst_flac_parse_frame_header_is_valid (flacparse, data + i, remaining,
FALSE, NULL); FALSE, NULL, &suspect_end);
if (header_ret == FRAME_HEADER_VALID) { if (header_ret == FRAME_HEADER_VALID) {
if (flacparse->check_frame_checksums) { if (flacparse->check_frame_checksums || suspect_start || suspect_end) {
guint16 actual_crc = gst_flac_calculate_crc16 (data, i - 2); guint16 actual_crc = gst_flac_calculate_crc16 (data, i - 2);
guint16 expected_crc = GST_READ_UINT16_BE (data + i - 2); guint16 expected_crc = GST_READ_UINT16_BE (data + i - 2);
if (actual_crc != expected_crc) GST_LOG_OBJECT (flacparse,
"checking checksum, frame suspect (%d, %d)",
suspect_start, suspect_end);
if (actual_crc != expected_crc) {
GST_DEBUG_OBJECT (flacparse, "checksum did not match");
continue; continue;
}
} }
*ret = i; *ret = i;
flacparse->block_size = block_size; flacparse->block_size = block_size;
@ -1322,7 +1333,7 @@ gst_flac_parse_parse_frame (GstBaseParse * parse, GstBaseParseFrame * frame)
flacparse->offset = GST_BUFFER_OFFSET (buffer); flacparse->offset = GST_BUFFER_OFFSET (buffer);
ret = ret =
gst_flac_parse_frame_header_is_valid (flacparse, gst_flac_parse_frame_header_is_valid (flacparse,
GST_BUFFER_DATA (buffer), GST_BUFFER_SIZE (buffer), TRUE, NULL); GST_BUFFER_DATA (buffer), GST_BUFFER_SIZE (buffer), TRUE, NULL, NULL);
if (ret != FRAME_HEADER_VALID) { if (ret != FRAME_HEADER_VALID) {
GST_ERROR_OBJECT (flacparse, GST_ERROR_OBJECT (flacparse,
"Baseclass didn't provide a complete frame"); "Baseclass didn't provide a complete frame");